Abstracts

Systematics of Lamontichthys Miranda-Ribeiro (Siluriformes: Loricariidae), with the description of two new species

Andrea de Carvalho Paixão; Mônica Toledo-Piza

Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo. Caixa Postal 11461, 05422-970 São Paulo, SP, Brazil. andreapaixao@usp.br, mtpiza@usp.br

ABSTRACT

The taxonomic revision of the genus Lamontichthys Miranda-Ribeiro, based on the examination of 164 specimens of different river drainages throughout the Amazon basin, revealed the presence of six species of which two are new. Lamontichthys filamentosus occurs in the upper and middle portions of the rio Amazonas basin; L. llanero in the río Orinoco basin; L. maracaibero in the lago Maracaibo basin; and L. stibaros in the upper río Amazonas basin. Lamontichthys avacanoeiro, new species, occurs in the upper rio Tocantins basin; and L. parakana, new species, in the lower rio Tocantins basin. The new species represent a considerable extension in the so far known distribution of the genus. A parsimony analysis, including 87 osteological and external morphological characters from Lamontichthys and related taxa (total of 16), resulted in three most parsimonious trees with 194 steps (CI = 0.73 and RI = 0.78). The hypothesis of monophyly of Lamontichthys is corroborated and supported by six derived characters. Within Lamontichthys two monophyletic assemblages are recognized, one includes L. avacanoeiro and L. stibaros, the other includes L. maracaibero and the clade formed by L. filamentosus and L. llanero. The relationships of Lamontichthys parakana, a species that was not included in the phylogenetic analysis is discussed. The monophyly and relationships of the monotypic genus Pterosturisoma microps are also discussed.

Key words: Loricariinae, Armored catfish, Taxonomy, Neotropical freshwater, Phylogeny.

RESUMO

A revisão taxonômica do gênero Lamontichthys, realizada com base no exame de 164 exemplares de diversas drenagens da bacia amazônica, revelou a existência de seis espécies, das quais duas são novas. Lamontichthys filamentosus ocorre na bacia do alto e médio rio Amazonas; L. llanero, na bacia do rio Orinoco; L. maracaibero, na bacia do lago Maracaibo; e L. stibaros, na bacia do alto rio Amazonas. Lamontichthys avacanoeiro, espécie nova, ocorre na bacia do alto rio Tocantins e L. parakana, espécie nova, na bacia do baixo rio Tocantins. As novas espécies representam uma considerável ampliação da distribuição geográfica do gênero. Uma análise de parcimônia, incluindo 87 caracteres osteológicos e de morfologia externa de 16 táxons, incluindo Lamontichthys e grupos relacionados, resultou em três cladogramas mais parcimoniosos com 194 passos (CI = 0.73 and RI = 0.78). A hipótese de monofiletismo de Lamontichthys é corroborada e sustentada por seis sinapomorfias. Entre as espécies de Lamontichthys, dois grupos monofiléticos são reconhecidos, um incluindo L. avacanoeiro e L. stibaros e outro L. maracaibero e um clado formado por L. filamentosus e L. llanero. A relação de Lamontichthys parakana com as demais espécies do gênero é discutida, apesar da espécie não ter sido incluída na análise filogenética. O monofiletismo e as relações do gênero monotípico Pterosturisoma microps são também discutidos.

Introduction

Species of armored catfishes of the genus Lamontichthys Miranda-Ribeiro, comprise small to medium fishes, reaching approximately 20 cm in standard length, and occur in the northern and central regions of South America in the rio Solimões-Amazonas, rio Tocantins, and río Orinoco river basins and in the lago Maracaibo drainage. They inhabit the bottom of rapid flowing streams, but currently very little is known about the biology of the species of Lamontichthys in their natural habitats (Taphorn & Lilyestrom, 1984). As most other catfishes, they have the body completely covered with dermal plates, a ventral sucker-like mouth and jaws provided with very small teeth that are used to scrape the substrate. In addition to having the dorsal and ventral most principal caudal-fin rays elongated, a common feature among loricariids, a few species of Lamontichthys possess the pectoral-fin spine and/or the dorsal-fin spine prolonged into a filament that may far exceed the body length, and large specimens sometimes possess a well developed hunch, dorsally on the head.

Among loricariids, Lamontichthys is currently included in the subfamily Loricariinae Bonaparte, whose members are traditionally recognized externally by the possession of a depressed caudal peduncle, the first unbranched principal caudal-fin rays generally prolonged into a long filament, and by the absence of an adipose fin (Reis et al., 2006; Covain & Fisch-Muller, 2007). The Loricariinae currently comprises 34 genera and approximately 200 species (de Pinna, 1998; Ferraris Jr., 2003, 2007) and the subfamily has been considered monophyletic based on various synapomorphies (Schaefer, 1987; Montoya-Burgos et al., 1998). Armbruster (2004) recently discussed the hypotheses of relationships of the Loricariinae within the Loricariidae. Within the subfamily, Lamontichthys has been traditionally grouped together with the genera Cteniloricaria Isbrücker & Nijssen, Harttiella Boeseman, Harttia Steindachner, Pterosturisoma Isbrücker & Nijssen, Sturisoma and Sturisomatichthys Isbrücker & Nijssen (Boeseman, 1971; Isbrücker, 1978, 1980). A recent study focused on the systematics of the Loricariinae was carried out by Rapp Py-Daniel (1997).

The taxonomic history of Lamontichthys is relatively recent and the genus currently includes five nominal species, four of which are considered as valid (Ferraris Jr., 2003, 2007). The genus was first proposed by Miranda-Ribeiro (1939: 12) to include Harttia filamentosa LaMonte, from the rio Juruá, a tributary of the right margin of rio Solimões. Subsequently, Boeseman (1971: 6) considered Lamontichthys a junior synonym of Parasturisoma Miranda-Ribeiro. Isbrücker & Nijssen (1978b) examined the holotype of the type-species of Parasturisoma (Loricaria brevirostris Eigenmann & Eigenmann) and concluded that it is a member of the genus Sturisoma Swainson. The authors also diagnosed Lamontichthys based on the presence of seven branched pectoral-fin rays (vs. six in the remaining genera of the Loricariinae; Isbrücker & Nijssen, 1976), described L. stibaros, based on two specimens from Ecuador, and redescribed Lamontichthys filamentosus (LaMonte). Harttia filamentissima Eigenmann & Allen was provisionally considered by Isbrücker & Nijssen (1978b) as a junior synonym of Lamontichthys filamentosus. Although those authors observed variation in a few meristic and morphometric characters of L. filamentosus, the small number of specimens available for study at that time (only 15), precluded a more detailed evaluation of the meaning of such variation. More recently, Taphorn & Lilyestrom (1984) described two new species of Lamontichthys, L. maracaibero and L. llanero, from the lago Maracaibo drainage and the río Orinoco basin respectively, extending considerably the known distribution of the genus to the north and increasing to four the number of valid species in the genus.

No additional taxonomic studies of Lamontichthys were carried out subsequently to that of Taphorn & Lilyestrom (1984). Recently, examination of material deposited in various collections revealed that species of Lamontichthys are more widely distributed than previously recorded and in addition there are two additional undescribed species in the genus.

Current knowledge about the species level taxonomy and hypotheses of phylogenetic relationships of Lamontichthys derived from the studies mentioned above provide an appropriate framework for a more detailed study focusing on the systematics of Lamontichthys.

The main objectives of the present study are to: 1) describe two new species of Lamontichthys and provide new diagnosis for all valid species; 2) update information about the geographic distribution of the recognized species; 3) evaluate the hypothesis of monophyly of Lamontichthys; 4) propose a hypothesis of phylogenetic relationships among the species of Lamontichthys.

Material and Methods

Species accounts. The taxonomic section of this study was based on the analysis of meristic and morphometric characters, color pattern, and external morphological features, of 164 specimens of Lamontichthys. Counts and measurements were made on the left side of specimens, except when the structure being measured or counted was recognizably abnormal or damaged, in which case corresponding data were taken from the right side.

Measurements were taken point to point with digital calipers. Counts were done with the help of a stereomicroscope. Counts and measurements follow Boeseman (1971, 1976), Isbrücker & Nijssen (1978a) and Taphorn & Lilyestrom (1984) with some modifications and with the inclusion of additional data as follows: dentary length: from the lateral to the medial tips of the dentary; caudal-peduncle depth: measured at the vertical through the anterior border of the last dorsal plate; length of branched dorsal-fin ray: measured from base to tip of first branched dorsal-fin ray; length of branched pectoral-fin ray: measured from base to tip of first branched pectoral-fin ray; caudal peduncle depth: measured at the anterior border of the penultimate postdorsal plate, which corresponds to the narrower point of the caudal peduncle.

Counts of body plates follow Schaefer (1997) and Reis & Pereira (2000) except as follows: lateroventral thoracic plates: number of plates between the last pectoral-fin ray and the unbranched pelvic-fin ray, and only those in contact with the lateral plates of the mid-ventral series; ventral thoracic plates: number of plates in the largest oblique row located between the contralateral series of lateroventral thoracic plates (Fig. 1).

According to Reis & Pereira (2000: 1030), counts of coalescing plates refer to the number of plates in the midventral series in which the two keels are very close. In Lamontichthys, these two keels are not very evident, but through examination of cleared and stained specimens it was observed that the point in which the two keels meet is always coincident with the last plate of the mid-ventral series. In the specimens in alcohol, although the three series of lateral plates are not easily visualized, it is possible to distinguish the last plate of the mid-ventral series paired with the lateral plate of the median series. These two plates possess canals of the lateral sensory system. The last plate of the median series is triangular and situated on the base of the caudal-fin.

Roman numerals designate unbranched rays; uppercase roman numerals designate fin-spines. Lamontichthys filamentosus possesses the dorsal and pectoral-fin spines and L. llanero the dorsal-fin spine prolonged into long filaments that are often damaged. Therefore, in order to compare variation in dorsal and pectoral-fin lengths of all Lamontichthys species we chose to take this measurement from the base to the tip of the first branched fin ray.

The terms "tooth" and "odontods" follow Ørvig (1977), who considers tooth as dental units which are situated on the jaws and pharyngeal plates and odontods are dental units which occupy positions anywhere else in the dermal skeleton. Dentition terminology follows Schaefer (1987) and Müller & Weber (1992).

Meristic and morphometric characters were summarized using the program SYSTAT 10.0. Samples from proximate localities were first compared and grouped in one larger sample when no differences were detected. This was done successively until all samples were included in the analysis. Counts and measurements are presented in tables. Subunits of the head are given as proportions of head length (HL). Head length and measurements of body subunits are given as proportions of standard length (SL). In the "Material examined" section of each species account, lots are grouped by country and within each country, by state or department, followed by institutional abbreviation, catalog number, number of specimens in the lot, number of cleared and stained (cs) specimens when present, their range of standard lengths, and specific locality data. Institutional abbreviations follow Leviton et al. (1985) and Leviton & Gibbs (1988) except for Universidade Federal do Rio de Janeiro, Rio de Janeiro (UFRJ).

Formal descriptions are provided only for the new species. Redescriptions of Lamontichthys filamentosus, L. llanero, L. maracaibero, and L. stibaros are not presented since their original descriptions or more recent redescriptions provide information to unambiguously diagnose each species (LaMonte, 1935; Isbrücker & Nijssen, 1978b; Taphorn & Lilyestrom, 1984). For these species we provide a synonymy list; diagnosis, geographical distribution, general remarks, and a list of examined material.

Osteological characters were not included in the species diagnoses due to the lack of cleared and stained specimens of all species for comparison.

Phylogenetic procedures. The phylogenetic study of Lamontichthys was based on the examination of 87 morphological characters, both osteological and from external morphology, in 16 taxa that include five species of Lamontichthys and representatives of nine genera of the Loricariinae proposed as more closely related to Lamontichthys (Boeseman, 1971; Isbrücker, 1978, 1980; Rapp Py-Daniel, 1997) plus one species of Hypostomus and one of Neoplecostomus. Rapp Py-Daniel's (1997) unpublished study comprises the most recent and detailed cladistic analysis of the Loricariinae and provided the basis for selection of taxa and characters for the phylogenetic analysis carried out in the present study. For this reason and with the consent of the author, in the "Description of characters" section, Rapp Py-Daniel (1997), is credited for all characters or character states that were originally proposed in that study. Many characters were redefined after examination and reinterpretation of data available in the literature, and others were proposed for this just time in the present study. Specimens for osteological study were cleared and counterstained for cartilage and bone using a modification of the method outlined by Taylor & Van Dyke (1985). Cleared and stained specimens were dissected under a stereomicroscope using ophthalmologic instruments. Drawings were made by the first author with the aid of a camera lucida connected to a stereomicroscope. Unless noted in the figure legend, illustrations in lateral view are always oriented with the anterior side to the left, regardless of the side of the specimen used to prepare the illustration, and those in dorsal or ventralview with anterior side to top.

Osteological terminology follows Lundberg & Baskin (1969) and Schaefer (1987). Vertebral counts follow Schaefer (1997: 27), in considering each of the five vertebrae of the "Weberian apparatus" all fused in loricariids, and the vertebra that is incorporated in the hypural plate, as separate elements. Precaudal vertebrae refer to those anterior to the vertebra articulated with the first anal-fin pterygiophore, and caudal vertebrae are those posterior to the latter vertebra.

One of the new species diagnosed in this study, Lamontichthys parakana, was not included in the phylogenetic analysis due to the reduced number of specimens available which did not allow the preparation of cleared and stained material for the examination of osteological characters. For this species only the external characters are presented in the text.

The monophyly of Lamontichthys and the phylogenetic relationships among its species were inferred using the cladistic methodology first proposed by Hennig (1950, 1966) and subsequently discussed by various authors. Detailed explanations about the principles of the cladistic method and its operational aspects are available in Nelson & Platnick (1981), Wiley (1981), Wiley et al. (1991), Swofford et al. (1996) and Amorim (2002). Parsimony analysis was employed to generate hypothesis of phylogenetic relationships and character state transformations using NONA (Goloboff, 1999) associated with Winclada ver. 1.00.08 (Nixon, 2002). The heuristic search was performed with 1000 replications (mult*1000), keeping five trees in each replication (hold/5), and a multiple tree bisectionreconnection (TBR) + TBR search strategy. The cladograms were rooted on Neoplecostomus ribeirensis.

The most parsimonious hypotheses generated by the analysis were summarized in a strict consensus cladogram. No specific optimization method, i. e. accelerated transformation optimization (ACCTRAN), or delayed transformation optimization (DELTRAN) was used to optimize characters on the resulting cladograms (i. e. in the list of synapomorphies, ambiguous characters are listed separately from the unambiguous characters).

This study is focused on the evaluation of the monophyly of Lamontichthys and the phylogenetic relationships among its species. Characters pertaining to the question of phylogenetic relationships among other genera of the Loricariinae were included with the objective of providing a framework on which to study the relationships within Lamontichthys. Therefore, the scheme of relationships among outgroups that resulted from the present analysis should not be regarded as an attempt to propose a hypothesis of relationships among these taxa. In order to do that, we would have to survey a much larger number of characters and taxa. Discussion of character optimization, polarity and proposed synapomorphies are only provided for the portion of the cladogram pertinent to the question of monophyly of Lamontichthys and intrageneric relationships.

Multistate characters that showed a sequence of similarity among their states were treated as ordered (or "minimally connected" - Slowinski, 1993), and includes characters 3, 4, 8, 14, 15, 19, 28, 30, 40, 41, 48, 50, 51, 55, 59, 66, 69, 70, 75, 76, 79, 82, and 85. The initial point of this sequence is represented by state "0". Multistate characters that did not show any apparent sequence of similarity were treated as unordered (or "maximally connected" - Slowinski, 1993) and includes characters 7,10, 13, 16, 21, 23, 25, 34, 35, 39, 52, 53, 63, 65, 67, 71, 72, 77, 80, 83, and 84.

Species listed below followed by an asterisk (*) provided the morphological basis for the phylogenetic analysis of Lamontichthys and are organized alphabetically by genus. The remaining species were examined as comparative material. Whenever a character is mentioned in the text for an outgroup genus without a species cited, it refers to the species listed below, and does not imply that the character is present in all species of the genus.

Cleared and stained specimens are indicated by "cs" and those in alcohol are indicated by "alc". Species name is followed by institutional catalog number, number of specimens in the lot, their range of standard lengths and specific locality data.

Comparative taxa: Brazil: Acestridium discus: MZUSP 88944, 1cs, 66.1, 7alc, 34.1-64.9, Amazonas, Rio Preto da Eva, rio Preto da Eva; Farlowella nattereri*: MZUSP 57658, 1cs, 112.9, Amazonas, rio Madeira; Harttia: H. carvalhoi: MZUSP 48598, 1cs, 62.6, 5alc, 69.6-76.6, São Paulo, Pindamonhangaba, tributary of Ribeirão Grande; H. kronei: MZUSP 62390, 1cs, 59.9, São Paulo, Ribeira, Iporanga, rio Betari; H. leiopleura: MZUSP 42701, 2cs, 52.7-58.6, Minas Gerais, Nova Lima, rio das Velhas, tributary of rio Mutuca, paratypes; H. loricariformis*: MZUSP 66187, 1cs, 67.7, Minas Gerais, Muriaé, rio Glória; H. punctata*: MZUSP 40825, 1cs, 68.0, Tocantins, upper Tocantins, rio Bezerra; MNRJ 12726, 1cs, 59.8, 19 (of 120) alc, Goiás, upper Tocantins, córrego Bateias; Harttia sp.: MZUSP 100919, 1cs, 58.8, 2alc, São Paulo, Tietê, Perus, córrego Laranjeiras; H. torrenticola: MZUSP 37170, 1cs, 54.4, Minas Gerais, rio das Velhas, tributary of rio Paraopeba, paratype; Hypostomus sp.*: MZUSP 100921, 1cs, 58.7, 1alc, no locality data; Loricaria sp.*: MZUSP 23847, 1cs, 124.2, Pará, igarapé Açu, near São Domingos do Capim; Neoplecostomus ribeirensis*: MZUSP 100920, 1cs, 45.3, 1alc, São Paulo, Ribeirão das Laranjeiras; Pseudoloricaria punctata*: MZUSP 34542, 1cs, Roraima, rio Branco, Cachoeira do Bem-querer; Pterosturisoma microps*: MZUSP 79909, 1cs, 75.9, Amazonas, rio Solimões below rio Iça; Rineloricaria sp.*: MZUSP 23748, 1cs, 91.5, 16alc, Pará, Oriximiná; Sturisoma sp.*: MZUSP 50112, 1cs, 115.2, Acre, rio Purus. Colombia: Sturisomatichthys leightoni*: ANSP 84179, 1cs, 101.3, 2alc, rio Magdalena basin, Honda.

Results

Taxonomic account. In the present study six species of Lamontichthys are recognized, two of which are new and recorded from the rio Tocantins basin. Lamontichthys parakana, new species is represented only by three specimens, and L. avacanoeiro, new species is recognized on the basis of 22 specimens.

Lamontichthys P. de Miranda Ribeiro

Lamontichthys P. de Miranda Ribeiro, 1939: 12 [type-species: Harttia filamentosa LaMonte, 1935, by original designation and monotypy].

Diagnosis. Species of Lamontichthys can be distinguished from all other loricariids by the presence of seven branched rays in the pectoral-fin (vs. six). Harttia leiopleura Oyakawa and Rineloricaria daraha Rapp Py-Daniel & Fichberg also possess seven branched pectoral-fin rays. Species of Lamontichthys can be distinguished from Harttia leiopleura by the presence of dermal plates on the upper lip and lateroventral plates on the thoracic region (vs. absent; Oyakawa, 1993) and from Rineloricaria daraha by having button-like papillae on the ventral surface on the lower lip (vs. long digitiform papillae), the lack of a postorbital notch and by having 14 caudal-fin rays (vs. 12; Rapp Py Daniel & Fichberg, 2008).

Five other characters observed only in skeletal preparations and detailed under "Character analysis and description" further distinguish Lamontichthys from other loricariids: 1) the trapezoidal shape of the lower pharyngeal plate, with the medial and lateral borders almost parallel, the medial border larger than the posterior border and at least twice as large as the lateral border (character 13); 2) the triangular and relatively elongate posterior expansion of the first epibranchial (character 14); 3) the large coronoid process in the dentary (character 23); 4) the contact (or proximity) between the proximal portions of the first three anal-fin pterygiophores (character 69); 5) the presence of two broad apophysis on the second preural centrum (character 77).

Common names. The common names used for Lamontichthys usually refer to more than one species of the genus or even to other Loricariinae. Brazil: "bode-cachoeira", "bode-cachimbo" and "bode-casco-de-anta" (Silvano et al., 2001; Cunha & Almeida, 2002); Colombia: "bomba" (Galvis et al., 1997); Ecuador: "raspabalsa" (Ferraris Jr., 2003: 336); Finland: "siimaeva" (Varjo et al., 2004); Germany: "filament-störwels" (Baensch & Riehl, 1997); Peru: "shitari" (Ortega & Vari, 1986); Venezuela: "tabla" or "paleta" (F. Provenzano, pers. comm.), and "paleta gibosa" (Taphorn & Lilyestrom, 1984b).

Geographic distribution. South American drainages including the upper and central portions of rio Solimões-Amazonas, the drainages of río Ucayali, río Marañon and río Napo, the upper regions of rio Purus and rio Juruá, rio Madeira and rio Tocantins basins. It also occurs in the middle and upper río Orinoco basin, and in the lago Maracaibo drainage (Fig. 2).

Key to the species of Lamontichthys

Lamontichthys avacanoeiro, new species

Fig. 8

Holotype. MNRJ 32795, 150.5 mm SL, Brazil, Goiás, rio Tocantins, pools below U.H.E. Serra da Mesa, 1996, D. F. Moraes et al.

Paratypes. (22 specimens; 47.6-159.9 mm SL). Brazil. Goiás: MNRJ 18553, 1 cs, 7 alc, 76.0-145.6, same data of holotype; MZUSP 54090, 2, 47.6-58.4, rio Tocantinzinho and tributaries, Serra da Mesa, 48º21'66"S 13º53'33"W, 28 Out 1996, Expedition MZUSP/MNRJ; MZUSP 61974, 5, 1cs*, 113.7-159.9, upper rio Tocantins, Minaçu, Serra da Mesa, 26 Out 1996, A. Akama & O. T. Oyakawa; MZUSP 79750, 5, 90.9-96.8, upper rio Tocantins, Uruaçu, rio Passa Três, above Ponte Nova, on road BR 153, 10 Jun 1998, D. F. Moraes.

Non-types. (4 specimens; 83.4-106.8 mm SL): Brazil: Goiás: MNRJ 23641, 1, 100.3, upper rio Tocantins, rio das Almas; MNRJ 23642, 1, 106.8, upper rio Tocantins, rio Bagagem, above ferry-boat to Garimpinho; MNRJ 23643, 2, 83.4-83.7, upper rio Tocantins, Niquelândia, rio Traíras, above Indianópolis.

Diagnosis.Lamontichthys avacanoeiro differs from all congeners in the shorter first branched dorsal-fin ray (22.626.0%, vs. 26.4-40.5% SL) in specimens larger than 70 mm SL.

Lamontichthys avacanoeiro can be further distinguished from L. filamentosus, L. llanero, and L. maracaibero by the anterior tip of the snout with an oval shaped area without plates (vs. tip of snout totally covered with plates or, with only a very small area lacking plates), and by the teeth with long cusps (vs. short) (Fig. 3). Lamontichthys avacanoeiro can be further distinguished from L. filamentosus and L. llanero by the lower lip semi-oval shaped (vs. semicircular) (Fig. 9). Lamontichthys avacanoeiro also differs from L. maracaibero in having more than one plate between the base of the last pelvic-fin ray and the anterior margin of the anus (vs. one plate) (Figs. 1 and 5) and in the greater abdominal length in specimens larger than 150 mm SL (17.6-17.7% [n = 2], vs. 14.1-16.3% SL [n = 5]). Lamontichthys avacanoeiro can be distinguished from L. parakana by the more posterior location of the anal-fin origin (at the vertical through the distal tip of the last dorsal-fin ray, vs. anterior to that point), by the shorter unbranched anal-fin ray (16.9-20.3%, vs. 21.4-24.8% SL), and by the smaller orbital diameter (13.6-16.2%, vs. 16.617.3% HL) in specimens larger than 70 mm SL.

Lamontichthys avacanoeiro also differs from specimens of L. parakana larger than 100 mm SL in the narrower head (91.3-100.9%, vs. 101.3-106.1% HL).

Description. Morphometric and meristic data presented in Table 1. Largest specimen 159.9 mm SL. Head and trunk totally covered with plates. Body depressed, deeper at vertical through dorsal-fin origin, gradually more depressed posteriorly to caudal-fin base and, anteriorly, to snout tip. Head ellipse shaped in dorsal view. Dorsal profile of head slightly convex. Dorsal profile of body straight from posterior tip of supraoccipital to dorsal-fin origin, posteroventrally slanted from latter point to vertical through tip of longest anal fin ray, straight from that point to caudal-fin base. Largest body width at cleithrum, gradually narrower posteriorly to 20^th to 21^st lateral plate of median series, more abruptly posteriorly into caudal-fin base. Caudal peduncle long, narrow and very depressed. Ventral profile of body and head straight from snout tip to base of caudal fin. Pectoral-fin origin at vertical through posterior margin of orbit. Dorsal-fin origin immediately anterior to vertical through pelvic-fin origin. Analfin origin at or slightly posterior to vertical through distal tip of last dorsal-fin ray.

Eyes located dorsally, anterior to vertical through pectoralfin origin. Interorbital distance shorter or equal to distance from orbit to exposed borders of cleithrum. Mouth ventral, upper and lower lips semi-oval shaped. Lower lip extending short of vertical through anterior margin of orbit and covered with small papillae on ventral surface and along its border. Dorsal surface of lower lip smooth. Upper lip narrower than lower lip, its ventral surface (internal) with small papillae and dorsal surface (external) with small, round plates covered with odontods. Maxillary barbel inconspicuous, united by membrane to lateral border of lower lip.

Teeth setiform, long, hook-shaped and bicuspid. Tooth cusps long, flattened and unequal, with round tips, darker than rest of tooth. Median cusp slightly longer and broader than lateral cusp. Number of jaw teeth increasing with growth. Number of premaxillary teeth approximately 8% greater than number of dentary teeth. Emergent teeth placed in two irregularly arranged rows; teeth gradually smaller laterally. Replacement teeth oriented at 90 degrees relative to emergent teeth and covered with skin. Anteroventral tip of snout without plates, forming distinct naked portion, approximately oval shaped, covered with stiff connective tissue. Anterior border of head covered with small and flexible plates between snout tip and anterolateral margin of upper lip. Lateral border of head covered with large dorsal plates anteroventrally curved.

Three horizontal keels along trunk, on lateral plates, converging from plate 5 to 15 or 16, continuing as a single keel posteriorly. Lower keel more evident, upper keel less evident. Last lateral plate of median series small and triangular, with one diminutive plate on each side of its base, located between two other plates of similar shape (one upper and other lower), above caudal-fin base. Lateral plates of median series, 31 to 34. Lateroventral thoracic plates 6 to 9 in specimens larger than 50 mm SL. Ventral thoracic plates, small, lozenge shaped, irregularly arranged in oblique rows; longest row with 8 to 10 plates delimited by ventrolateral thoracic plates. Region of abdomen anterior to anus covered with small, lozenge-shaped plates followed by three large polygonal plates, and the anal plate larger and bordering anterior margin of anus.

Pectoral- and dorsal-fin spines, unbranched pelvic- and anal-fin rays not projecting as long filaments. Unbranched caudal-fin rays projecting as long filaments. Branched caudalfin rays gradually longer toward dorsal and ventral unbranched rays. Dorsal most branched caudal-fin ray longer than ventral most ray. Unbranched pelvic-fin ray reaching to vertical through second ventral plate, located posterior to base of last anal-fin ray, unbranched anal-fin ray reaching to vertical through seventh ventral plate, located posterior to the base of last anal-fin ray. Dorsal-fin rays II,7; pectoral-fin rays I,7; pelvic-fin rays i,5; anal-fin rays i,5; caudal-fin rays i,12,i.

Color in alcohol. Ground coloration of head and body of adults and juveniles varying between brown and yellow. Ventral region of head and body lighter, uniformly yellow. Dorsal region of upper lip dark brown. Straight unpigmented median stripe from base of last anal-fin ray to base of unbranched lower caudal-fin ray. Fins and dorsal region of body and head with dark brown and yellow spots. One dark brown, longitudinal band extending from base of dorsal fin to base of caudal fin.

Etymology. The species name, avacanoeiro, is in reference to the Avá-canoeiros, inhabitants from the upper rio Tocantins basin. Avá-canoeiros, an American group that historically inhabited the area of the upper rio Tocantins, drainage from which the examined specimens of the species in this study originated.

Geographic distribution. Upper rio Tocantins basin (Fig. 2).

Comments. The occurrence of Lamontichthys in the upper rio Tocantins was first reported by Rapp Py-Daniel (pers. comm.), based on specimens collected in the region of Serra da Mesa, State of Goiás, Brazil. Specimens from lots MNRJ 23641 - 23643 are in poor condition, therefore they were not designated as paratypes.

Lamontichthys filamentosus (LaMonte, 1935)

Fig. 10

Harttia filamentosa LaMonte, 1935: 5-6, fig. 4 [original description; type locality: Brazil, Amazonas, rio Juruá drainage, vicinity of mouth of rio Embira, tributary of the rio Tarauacá, 7º30'S 70º15'W]; Conci & Michelangeli, 1974: 226 [listed].

Lamontichthys filamentosa: Miranda-Ribeiro, 1939: 12 [original description of genus; designation of typespecies]; Gosline, 1945: 108 [listed]; Barzanti & Oldani, 1976: 130-137 [incorrect identification; based on four specimens of probably, Loricaria sp., Loricariinae; Argentina, rio Paraná basin - specimens not examined].

Harttia filamentissima Eigenmann & Allen, 1942: 211, 445, pl. VIII figs. 1 and 2 [original description; type locality: Peru, Loreto, río Huallaga; Fowler, 1945: 109 [listed; Peru]; Gosline, 1945: 108 [listed]; Tovar Serpa, 1967: 222 [listed; Peru]; Ovchynnyk, 1968: 258 [Chicherota, near the mouth of the río Bobonaza, tributary of the upper río Pastaza, specimen not examined].

Lamontichthys filamentosus: Ovchynnyk, 1968: 258 [Eastern Ecuador]; Isbrücker & Nijssen, 1976: 121-122 [7 branched pectoral-fin rays as diagnostic for Lamontichthys; Harttia filamentissima presumed to be a synonym of L. filamentosus]; Isbrücker & Nijssen, 1978b: 57-80, fig. 1-4, 7, 10a,c, 14, table Ia, IIa-h, IIIa [redescription; Harttia filamentissima as synonym of L. filamentosus; photographs of types of both species; specimens not examined]; Isbrücker, 1978: 88 [listed]; Isbrücker, 1980: 91 [listed]; Ortega & Vari 1986: 17 [literature compilation; Peru]; Burgess, 1989: 426-427, 440 [description]; Barriga, 1991: 66 [eastern drainages of Ecuador]; Lauzanne et al., 1991: 70, 73, table I and IV [Bolivia, upper rio Madeira basin, rio Chapare; specimens not examined]; Eschmeyer, 1998: 578 [listed]; Chernoff et al., 1999a, 1999b: 59 [Bolivia, upper río Orthon basin]; Sarmiento et al., 1999: 92 [Bolivia, Pando, río Tahuamanu]; Machado-Allison et al., 1999: 50 [Bolivia, Pando, upper and middle río Tahuamanu, specimens not examined]; Begossi et al., 1999: 79, table I [Brazil, Acre, upper rio Juruá; common name]; Silvano et al., 2001: 158159 [Brazil, Acre, upper rio Juruá; common name; photograph]; Isbrücker, 2001: 27, 29 [listed]; Ferraris Jr., 2003: 336 [listed]; Buckup et al. 2007:88 [listed]; Ferraris Jr., 2007: 263 [listed].

Parasturisoma filamentosa: Boeseman, 1971: 9 [listed].

Parasturisoma filamentissima: Boeseman, 1971: 9 [listed].

Diagnosis. Specimens of Lamontichthys filamentosus larger than 60 mm SL are distinguished from all congeners by having the pectoral-fin spine extending into a very long filament that may exceed four times the length of the first branched pectoralfin ray (vs. not extending into a long filament in the remaining species of Lamontichthys) (Fig. 10). The pectoral-fin filament is very fragile, breaks off easily, and it is frequently damaged in preserved specimens.

Lamontichthys filamentosus is further distinguished from all other Lamontichthys species, except L. llanero, by having the dorsal-fin spine prolonged into a long filament that may reach the posterior margin of the caudal fin (vs. dorsal-fin spine not extending into a long filament) and by the lower lip with a semicircular shape (Fig. 9a) (vs. semi-oval, Fig. 9b). Lamontichthys filamentosus is further distinguished from L. llanero by having a broader head (97.4-111.1%, vs. 82.6-96.9% HL).

Lamontichthys filamentosus is distinguished from L. maracaibero, L. stibaros, and L. parakana by having fewer lateral plates on the mid-ventral series (14 to 18, vs. 18 to 20). The presence of more than one plate between the base of the innermost pelvic-fin ray and the anterior margin of the anus further distinguishes Lamontichthys filamentosus from L. maracaibero, which has only one plate (Figs. 1 and 5).

Lamontichthys filamentosus is further distinguished from L. stibaros, L. avacanoeiro, and L. parakana by having the anterior portion of the snout almost totally covered with plates (vs. anterior portion of the snout with a large nude area lacking plates) and by the teeth with short cusps (vs. long) (Fig. 3). The longer first branched dorsal-fin ray further distinguishes Lamontichthys filamentosus from L. avacanoeiro (27.8-39.9%, vs. 20.5-26.0% SL). Morphometric and meristic data are presented in Table 1.

Geographic distribution. Upper and middle rio Amazonas basin (Fig. 2). Lamontichthys filamentosus occurs in sympatry with L. stibaros in the drainages of río Ucayali and río Marañón (upper rio Amazonas basin).

Comments. Specimens smaller than 80 mm SL differ from adults in having various poorly defined transversal bands on the back, between the base of the last dorsal-fin ray and the base of the caudal fin.

Fins of specimens from the upper rio Madeira (FMNH 107021, 1, 119.6 mm SL), upper rio Juruá (MZUSP 50379 and 50497, 3, 158.3-172.5 mm SL) and one specimen from upper rio Purus basin (MCP 28834, 154.9 mm SL) have gray and light brown small spots, forming short transversal bands more evident on the pectoral-fin spine and unbranched pelvic-fin ray. In addition, the specimens from the upper rio Madeira basin (FMNH 107021) and upper rio Purus basin (MCP 28834) also have the head relatively larger than the other specimens of similar size (18.2-19.3%, vs. 16.5-18,0% SL, n = 13, 119.4-172.5 mm SL). Isbrücker & Nijssen (1978b) previously reported on the variation of color pattern in specimens of L. filamentosus from the río Chapare, upper rio Madeira basin in Bolivia, and suggested that those specimens could represent a distinct subspecies or species. Although some differences were observed in specimens from the upper rio Juruá, rio Purus and rio Madeira basins, the reduced (n = 6) number of specimens from these localities do not allow to infer if these differences are significant, and we therefore chose to conservatively assign them to L. filamentosus.

Although the holotype of Harttia filamentissima Eigenmann & Allen (1942: 211) was not examined, information from the literature and photographs (available at www.calacademy.org) allowed us to confirm the synonymy of this species with L. filamentosus, previously proposed by Isbrücker & Nijssen (1978b).

Material examined (63 specimens; 38.8-172.5 mm SL): Bolivia: FMNH 107021, 1, 119.6, upper rio Madeira, Pando, 1.5 km above mouth of río Muyumanu. Brazil: Acre: MZUSP 50379, 1, 172.5, upper rio Juruá, Colocação São João; MZUSP 50497, 2, 158.3158.7, upper rio Juruá, mouth of rio Tejo; MCP 28834, 2, 154,9168,8, upper rio Purus, Bujari, igarapé Antimari, BR 364, 58 km SE of Sena Madureira. Amazonas: MZUSP 57463, 1, 62.3, rio Amazonas, below rio Madeira; MZUSP 75367, 1, 38.8, rio Amazonas, below rio Negro; INPA 17927, 2, 75.8-79.4; MZUSP 57460, 1, 65.9, rio Solimões, below rio Purus. Ecuador: FMNH 104334, 1, 155.7, Napo, río Napo. Peru: Amazonas: LACM 41724-9, 10, 120.2-150.8, Marañón, río Santiago; LACM 417059, 11, 130.7-153.3; LACM 41729-29, 13, 128.2-154.1, Marañón, río Santiago in La Poza; LACM 41741-9, 13, 82.5-169.0, 1cs*, 119.4, LACM 42001-7, 1, 162.8, LACM 41740-13, 1, 167.4, confluence of río Marañon with río Nieva; LACM 42005-6, 1, 155.8, Marañón, near Caterpiza; LACM 39884-7, 1, 139.2, Marañón, Galilea, río Santiago.

Lamontichthys llanero Taphorn & Lilyestrom, 1984

Fig. 11

Lamontichthys llanero Taphorn & Lilyestrom, 1984a: 96-98, fig. 2, table 1 [original description; type locality: "Venezuela, Portuguesa, río Guanare Viejo cerca de La Hoyada"]; Provenzano et al., 1998: 11, 21, 23 [type listed]; Eschmeyer, 1998: 923 [listed]; Armbruster, 2004 [phylogenetic relationships]; Armbruster, 1998: 665, table 1 [analysis of the digestive tract]; Mojica, 1999: 562 [listed]; Isbrücker, 2001: 29 [listed]; Ferraris Jr., 2003: 336 [listed]; Ferraris Jr., 2007: 264 [listed]

Diagnosis.Lamontichthys llanero is distinguished from all other congeners, except L. filamentosus, by having the lower lip semicircular in shape (vs. semi-oval, Fig. 9). Lamontichthys llanero differs from L. filamentosus in the narrower head (82.6-96.9%, vs. 97.4-111.1% HL). Lamontichthys llanero has the interorbital distance larger (n = 36) and only rarely equal (n = 2) to the distance from the orbit to the exposed border of the cleithrum. All other species of Lamontichthys possess the interorbital distance shorter or equal to the distance from the orbit to the exposed border of the cleithrum (Fig. 6).

The presence of two plates between the base of the last pelvic-fin ray and the anterior border of the anus (vs. one) (Figs. 1 and 5), and 7 to 10 lateroventral thoracic plates in specimens larger than 50 mm SL (vs. 5 to 6) further distinguishes L. llanero from L. maracaibero. Specimens of Lamontichthys llanero larger than 70 mm SL further differs from L. stibaros, L. avacanoeiro, and L. parakana; in having the snout entirely covered with plates or with only a round inconspicuous area lacking plates at its anterior tip (vs. with a large oval area lacking plates), and teeth with short cusps (vs. long) (Fig. 3). Lamontichthys llanero further differs from L. avacanoeiro in the longer first branched dorsal-fin ray, in specimens larger than 50 mm SL (30.9-40.5%, vs. 21.9-26.0% SL). Morphometric and meristic data are presented in Table 2.

Geographic distribution. Río Orinoco basin (Fig. 2).

Comments.Lamontichthys llanero has been collected near the margins of rivers varying from less than 10 m until 1 km of width, in areas with muddy waters, and sand or mud in the bottom (F. Provenzano, pers. comm.).

Material examined (37 specimens; 32.4-162.5 mm SL): Colombia: Meta: ANSP 131621, 1, 118.3, río Guayariba; ANSP 131617, 1, 106.2, confluence of río Guayariba with río Metica; ANSP 131619, 1, 96.3, río Metica; ANSP 131623, 1, 84.0, río Negro; Venezuela: Apure: INHS 28391, 1, 45.2, Caño. Barinas: INHS 29957, 5 (of 9), 91.1-132.4, 1cs*, 105.2, tributary of río Masparro; INHS 29900, 3, 88.0-116.7, río Masparro. Cojedes: INHS 28989, 2, 32.4-86.1, río San Carlos; INHS 32029, 1, 87.9, río San Carlos; INHS 60236, 1, 36.3, río Pao. Guarico: MBUCV-V 31534 7, 86.3-152.2, río Orituco; ANSP 131624, 2, 64.2-75.7, 18 km SSE Calabozo; ZMA 120469, 1, 146.8, río Guarico basin. Portuguesa: INHS 28649, 1, 162.5, Mata Larga, río Portuguesa; INHS 35687, 3 (of 4), 117.5-144.0, río Portuguesa, 3 km NE El Barriero; INHS 31993, 1, 80.1, río Guanare; INHS 69262, 3 (of 4), 81.2-124.9, Caño Los Manires; INHS 34097, 1, 70.3, río Tucupido; INHS 54657, 1, 110.7, río Portuguesa; INHS 56125, 1, 110.1, río Guanare; INHS 56151, 3 (of 4), 97.3-150.2, río Portuguesa.

Lamontichthys maracaibero Taphorn & Lilyestrom, 1984

Fig. 12

Lamontichthys maracaibero Taphorn & Lilyestrom, 1984a: 94-95, 98, fig.1, table 1 [original description; type locality: "Venezuela, Zulia, Distrito Miranda, río Motatán in el Puente Tres de Febrero"; paratypes from río Motatán and río Ariguisá]; Taphorn & Lilyestrom, 1984b: 17, 29 [key and common name; lago Maracaibo, Venezuela]; Galvis et al., 1997: 88 [description, habits, common names, illustrations, río Catatumbo system in Colombia and Venezuela]; Provenzano et al., 1998: 11-12, 21, 23 [type listed]; Eschmeyer, 1998: 1014 [listed]; Mojica, 1999: 562 [listed]; Isbrücker, 2001: 29 [listed]; Ferraris Jr., 2003: 336 [listed]; Ferraris Jr., 2007: 264 [listed].

Diagnosis. Lamontichthys maracaibero differs from all congeners in the presence of a single plate (vs. two plates) between the pelvic-fin base and the anterior margin of the anus (Figs. 1 and 5).

Specimens of L. maracaibero larger than 150 mm SL possess a deeper body at the predorsal region (14.0-15.1%, n = 6, vs. 11.5-13.5%, n = 26) relative to the other species of Lamontichthys (except for L. parakana for which specimens larger than 150 mm SL were not available for comparison), forming a hump between the head and the dorsal-fin origin. Lamontichthys maracaibero is further distinguished from L. filamentosus and L. llanero by the semi-oval shape of the lower lip (vs. semicircular) (Fig. 9); and from L. llanero by the reduced number of lateroventral thoracic plates in specimens smaller than 50 mm SL (5 to 6 plates, vs. 7 to 10), and from L. stibaros, L. avacanoeiro, and L. parakana by having the snout totally covered with plates at its anterior tip (vs. presence of an area lacking plates) and by the teeth with short cusps (vs. long) (Fig. 3). The specimens of Lamontichthys maracaibero larger than 100 mm SL also differs from L. stibaros, L. avacanoeiro, and L. parakana in the relatively shorter head (16.7-17.8%, vs. 19.8-23.0% SL) and shorter dentary (14.8-19.1%, vs. 18.4-23.4% HL). Morphometric and meristic data are presented in Table 2.

Geographic distribution. Lago Maracaibo basin (Fig. 2).

Material examined (9 specimens; 63.4-210.2 mm SL): Colombia: ICNMHN 2166, 5, 149.1-210.2, Catatumbo, Santander, río Catatumbo, córrego La Gabarra. Venezuela: Trujillo: lago Maracaibo drainage: MCNG 3592, 1, 154.9, holotype; MCNG 3593, 1 (of 4), 63.4, 1 cs*, 83.8, paratypes, Betijoque, río Motatãn, bridge "Tres de Febrero". Zulia: INHS 35473, 1, 131.3, río Santa Rosa.

Lamontichthys parakana, new species

Fig. 13

Holotype. INPA 3010, 112.7 mm SL, Brazil, Pará, lower rio Tocantins basin, rio Tocantins, below dam of Tucuruí, 31 Ago 1984, Ichthyology team of INPA. Paratype. INPA 31251, 2, 72.2-119.0 mm SL, same data as holotype.

Diagnosis.Lamontichthys parakana differs from all other species of the genus in the more anterior position of the analfin (anal-fin origin situated anterior to the vertical through the distal tip of the last dorsal-fin ray, vs. anal-fin originating posteriorly).

Lamontichthys parakana further differs from the other species of Lamontichthys, except L. avacanoeiro and L. stibaros, in the lack of plates on the anterior tip of the snout (vs. snout entirely covered with plates or with an inconspicuous naked area), in the teeth with long cusps (vs. short) (Fig. 3), and in the longer dentary in specimens larger than 50 mm SL (20.1-22.6%, vs. 11.5-19.1% HL).

The semi-oval shaped lower lip further distinguishes Lamontichthys parakana from L. filamentosus and L. llanero that have the lower lip semicircular shaped (Fig. 9).

Among the species of Lamontichthys, L. parakana is more similar to L. avacanoeiro and L. stibaros, from which it may be distinguished by the broader head (101.3-106.1%, vs. 78.9-101.4% HL) and the greater orbital diameter (16.6-17.3%, vs. 13.7-15.5% HL), in specimens larger than 100 mm SL.

Lamontichthys parakana also differs from L. avacanoeiro in the longer length of the first branched dorsal-fin ray (26.431.0%, vs. 20.5-26.7% SL).

Description. Morphometric and meristic data presented in Table 3. Largest specimen 119.0 mm SL (n = 3). Head and trunk totally covered with plates. Body depressed, deeper at vertical through dorsal-fin origin, gradually more depressed posteriorly, to caudal-fin base and anteriorly, to snout tip. Head ellipse shaped in dorsal view, with slight prominence at anterior tip. Dorsal profile of head slightly convex. Dorsal profile of body slightly convex from posterior tip of supraoccipital to dorsal-fin origin, posteroventrally slanted from latter point to vertical through tip of last anal fin ray, straight to caudal-fin base. Largest body width at cleithrum, gradually narrower to 18^th to 19^th lateral plate of median series more abruptly so posteriorly, into base of caudal-fin. Caudal peduncle long, narrow and very depressed. Ventral profile of head and body straight from snout tip into base of caudal-fin. Pectoral-fin origin at vertical through posterior border of orbit. Dorsal-fin origin immediately anterior of vertical through pelvic-fin origin. Base of last anal-fin ray at vertical through distal tip of last dorsal-fin ray.

Eyes located dorsally, anterior to vertical through pectoralfin origin. Interorbital distance shorter or equal to distance from orbit to exposed borders of cleithrum. Mouth ventral. Upper and lower lip semi-oval shaped. Lower lip extending short of vertical through anteriormost margin of orbit, covered with small papillae on ventral surface and along its border. Dorsal surface of lower lip smooth. Upper lip narrower, with small papillae on ventral surface (internal) and with small round plates covered with odontods on dorsal surface (external). Maxillary barbel inconspicuous, united by membrane to lateral border of lower lip.

Teeth setiform, long, hook-shaped and bicuspid. Tooth cusps long, flattened and unequal, with round tips, darker than rest of tooth. Median cusp slightly longer and broader than lateral cusp. Number of jaw teeth increasing with growth. Number of premaxillary teeth approximately 16% greater than number of dentary teeth. Emergent teeth placed in two irregularly arranged rows; teeth gradually smaller laterally. Replacement teeth oriented at 90 degrees relative to emergent teeth and covered with skin.

Anteroventral tip of snout without plates, with distinguishable naked portion, approximately oval shaped, covered with stiff connective tissue. Anterior border of head with small, flexible plates between snout tip and anterolateral margin of upper lip. Lateral border of head covered with larger dorsal plates anteroventrally curved.

Three inconspicuous horizontal keels along body, from plates 6 to 14 or 16. Last plate of median lateral series diminutive and triangular, located on caudal-fin base, between two slightly larger plates of similar shape (one upper and one lower, upper plate slightly larger than lower plate). Lateral plates of median series, 32-33. Small ventral thoracic plates lozenge shaped, arranged in irregular, oblique rows. Longest row with 7 to 8 plates delimited by lateroventral thoracic plates. Region of abdomen anterior to anus covered with small, lozenge shaped plates, followed by one larger plate that form anterior border of anus.

Pectoral- and dorsal-fin spines, unbranched pelvic- and anal-fin rays not projecting into long filaments. Unbranched caudal-fin rays of both specimens damaged, except lower unbranched caudal- fin ray from one specimen which projects as long filament. Branched caudal-fin rays gradually longer toward upper and lower unbranched rays. Dorsal most branched caudal-fin ray slightly longer than ventral most ray. Unbranched pelvic-fin ray reaching vertical through anterior border of first ventral plate posterior to base of anal fin. Unbranched anal-fin ray reaching eighth ventral plate posterior to base of anal fin.

Dorsal-fin rays II,7; pectoral-fin rays I,7; pelvic-fin rays i,5; anal-fin rays i,5; caudal-fin rays i,12,i.

Color in alcohol. Coloration of paratype faded, uniform yellow. Color pattern based only on holotype. Ground coloration of head and body brown or yellow. Ventral region of head and body lighter, uniform yellow. Dorsal region of upper lip dark brown. Straight unpigmented median stripe from last anal-fin ray to base of unbranched lower caudal-fin ray. Dorsal region of body with three longitudinal, dark brown bands extending from base of dorsal fin to base of caudal fin. Two of these bands extending ventrally to cover lateral plates. Third band extending along dorsal midline of body, from dorsal-fin base to caudal-fin base. Bands gradually narrower posteriorly. A transversal, dark brown band between bases of pectoral-fins, with anterior margin at posterior tip of supraoccipital. Dorsal portion of head dark brown with slightly lighter areas. All fin rays with dark brown pigmentation. Anterior half of dorsal-fin dark brown, remaining of fin hyaline. Paired fins and anal-fin dark brown. Caudal-fin base and three upper most and lower most branched rays dark brown.

Etymology. The species name, parakana, is in reference to the Parakanã, inhabitants of the margins of the lower rio Tocantins, in the State of Pará. Parakanã, an American group that historically inhabited the area of the lower rio Tocantins, drainage from which the examined specimens of the species in this study originated.

Geographic distribution. Known from the type locality at lower rio Tocantins, below Tucuruí Dam (Fig. 2).

Lamontichthys stibaros Isbrücker & Nijssen, 1978

Fig. 14

Lamontichthys stibaros Isbrücker & Nijssen, 1978b: 66-69, figs. 8 and 9, 10d, 14, table Ic, Ii-j, IIIb [original description; type locality: Ecuador, "Prov. Pastaza, rio Amazon system, rio Bobonaza in Chicherota, 02º25'S 76º38'W, altitude aprox. 260-280 m, upper rio Pastaza"]; Isbrücker, 1980: 92 [listed]; Ortega & Vari, 1986: 17 [literature compilation; Peru]; Burgess, 1989: 426-427 [listed; description]; Barriga, 1991: 66 [literature compilation; Oriental Ecuador]; Ferraris & Vari, 1992: 27 [type listed]; Eschmeyer, 1998: 1611 [listed]; Isbrücker, 2001: 29 [listed]; Ferraris Jr., 2003: 336 [listed]; Ferraris Jr., 2007: 264 [listed]; Sullivan et al., 2006: [Siluriform higher-level relationships; molecular data, specimen not examined].

Diagnosis.Lamontichthys stibaros differs from all other species of the genus, with the exception of L. avacanoeiro and L. parakana, in the lack of plates on the anterior tip of the snout (vs. anterior portion of snout totally covered with plates or with an inconspicuous naked area), in the teeth with long cusps (vs. short) (Fig. 3), and in the lower lip semi-oval shaped (vs. semicircular) (Fig. 3).

Lamontichthys stibaros differs from L. avacanoeiro and L. parakana in the longer first branched dorsal-fin ray (29.736.8%, vs. 22.6-31.0% SL), in specimens larger than 70 mm SL. It further differs from L. avacanoeiro in the longer first branched pectoral-fin ray (21.7-25.1%, vs. 19.2-22.0% SL) and from L. parakana in the narrower head (89.1-101.4%, vs. 101.3106.1% HL).

The presence of 19 to 20 lateral plates along the mid-ventral series (vs. 14 to 18) and the longer dentary (18.6-23.2%, vs. 11.517.3% HL) in specimens larger then 70 mm SL also distinguishes

L. stibaros from L. filamentosus and L. llanero. Lamontichthys stibaros differs from L. maracaibero in having more than one plate between the base of the last pelvic-fin ray and the anterior border of the anus (vs. one plate) (Figs. 1 and 5) and in the uniform color pattern of the fins (vs. with brown and gray spots). Morphometric and meristic data are presented in Table 3.

Geographic distribution. Upper rio Amazonas basin (Fig. 2). Lamontichthys stibaros occurs in sympatry with L. filamentous in the drainages of río Santiago, río Marañón and río Ucayali, in Peru.

Material examined (25 specimens; 27.2-172.8 mm SL): Peru: Amazonas: LACM 39897-1, 3, 42.2-89.5, río Santiago; LACM 39884-3, 2, 100.2-120.1, Marañón, río Santiago; LACM 39647-1, 1, 172.6, Marañón, río Cenepa, close to río Tujushiku. Ayacucho: ROM 47093, 2, 122.6-150.1, near to confluence between río Mantaro and Tambo Apurimac. Ucayali: FMNH 84137, 7, 27.2-58.2, río San Alejandro; FMNH 84131, 2, 43.8-47.3; FMNH 84112, 3, 63.386.6, río San Alejandro; FMNH 84111, 6, 49.3-100.1, 1 cs*, 62.4, río San Alejandro.

Description of characters and phylogenetic analysis

Characters and their respective states analyzed in this study are grouped according to the region of the body with which they are associated.

Neurocranium

1. Ventral depression at anterior tip of mesethmoid: (0) absent; (1) present (CI = 100; RI = 100).

The mesethmoid of loricariids varies considerably in shape but usually its posterior portion is relatively elongate, narrow, and cylindrical. The lateral projections (cornuas) at the anterior tip of the ossification may be extremely reduced or absent (Schaefer, 1990: 175; 1998: 394) and the median anteroventral portion is usually thin and lacks a groove or cavity.

Uniquely among taxa examined, the mesethmoid of L. filamentosus, L. llanero, and L. maracaibero possesses an anteroventral depression (Fig. 15a). A strong, anteriorly directed ligament attaches to this groove and is, apparently, connected to plates on the snout tip.

2. Tissue adhered to anterior tip of mesethmoid: (0) present; (1) absent (CI = 50; RI = 0).

A thick layer of tissue, strongly adhered to the anterior tip of the mesethmoid, which may be covered by plates, is present in all taxa examined except Farlowella and Pseudoloricaria. This feature was previously described by Rapp Py-Daniel (1997: character 8).

3. Shape of mesethmoid disk: (0) robust, circular in lateral view with margins of disk much broader than central portion; (1) laminar shaped, circular in lateral view; (2) laminar shaped, rectangular to triangular in lateral view, similar to a keel (CI = 66; RI = 83).

The ventral surface of the mesethmoid of astroblepids and loricariids possesses a vertical process on the median longitudinal line close to the premaxillae and is referred to as the mesethmo-premaxillary articular condyle or mesthmoid disk (Schaefer, 1987: 5; 1998: 384). Ligaments that sustain the premaxillae are inserted on this process and enable their ample mobility (Schaefer, 1987).

In Lamontichthys, Harttia, Hypostomus, Neoplecostomus, Pterosturisoma, and Sturisomatichthys, the mesethmoid disk is robust, circular in lateral view and with the margins of the disk much broader than the central portion (Figs. 15 and 16a). In the two conditions considered as derived, the mesethmoid disk is more delicate (Fig. 16b-c). In Farlowella and Sturisoma, although the disk is also approximately circular in lateral view it is laminar shaped. In Loricaria, Pseudoloricaria, and Rineloricaria, the mesethmoid disk is also laminar shaped, but the lamina is thin and rectangular to triangular in lateral view, similar to a keel.

4. Position of mesethmoid disk relative to anterior mesethmoid margin: (0) terminal, on anterior margin of mesethmoid; (1) subterminal, at short distance from anterior margin of mesethmoid; (2) non-terminal, far from anterior margin of mesethmoid (CI = 50; RI = 33).

The position of the mesethmoid disk relative to the anterior mesethmoid margin is variable within the Loricariidae (Schaefer, 1991; 1998: 384; Armbruster, 2004). The Ancistrinae, a few Hypoptopomatinae, Hypostominae, and Neoplecostomus possess the mesethmoid disk located at the terminal anterior margin of the mesethmoid, a condition shared with the Astroblepidae (Fig. 16a, Schaefer, 1987: fig. 3; 1991: 7). Other loricariids possess the mesethmoid disk in a non-terminal position, at varying distances from the anterior margin of the bone (Figs. 15 and 16b-c). The distance between the mesethmoid disk and the anterior margin of the mesethmoid is short in Lamontichthys, Harttia, Loricaria, Pseudoloricaria, Pterosturisoma, and Rineloricaria, and longer in Farlowella, Sturisoma, and Sturisomatichthys.

5. Anterior portion of vomer: (0) thick, with short anterior prolongations; (1) elongate, with one or two long and narrow prolongations (CI = 50; RI = 83).

In Loricariids the vomer is elongate with reduced lateral wings, and is sutured anteriorly to the mesethmoid and posteriorly to the parasphenoid (Schaefer, 1987: 5). The anterior portion varies in shape and the posterior portion is tapered at the end, forming an elongate tip (Rapp Py-Daniel, 1997: character 9).

In Lamontichthys, Harttia, Neoplecostomus, and Sturisomatichthys the vomer has a thick anterior portion, with very short anterior prolongations (Fig. 15). In the derived condition, present in Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma the anterior portion of the vomer is elongate, and has one or two long and narrow prolongations (Fig. 16b-c). Schaefer (1987: 5; 1997a: 23) observed a similar condition in Hypostomus plecostomus (Hypostominae) and in Otocinclus (Hypoptopomatinae).

6. Dorsal projection (or lateral wall) on dorsolateral region of lateral ethmoid: (0) extending along entire lateral border of bone; (1) extending approximately from posterior half of lateral border of bone (CI = 33; RI = 60).

The lateral ethmoid in loricariids encapsulates the nasal organ from below (Howes, 1983; Schaefer, 1991). Anteriorly, the lateral ethmoid has a concave face, with cartilage, that articulates with the autopalatine. Posteriorly, the lateral (vertical), ventral (horizontal) and medial (vertical) walls of the capsule are open only dorsally. The meeting of these walls shape part of the anterior border of the orbit.

In the Callichthyidae (except Aspidoras, Brochis, and Corydoras) and most loricariids, including Neoplecostomus, the lateral wall is formed by the anterior condyle of the lateral ethmoid that completely encapsulates the nasal organ (Howes, 1983: 331; Schaefer, 1998: 394). This condition occurs in Farlowella, Loricaria, Pseudoloricaria, Rineloricaria, and Sturisomatichthys.

In Lamontichthys, Harttia, Pterosturisoma, and Sturisoma the lateral wall of the lateral ethmoid is formed more posteriorly, leaving anteriorly a small portion lacking an ossified wall (Fig. 17; Howes, 1983: 331), a condition shared with the Hypoptopomatinae (Schaefer, 1998: 394).

Pterosturisoma microps possesses the dorsal border of the nasal fossa circular, while in the other taxa the border is oval. This condition was not codified in the present analysis, however it may be tentatively proposed as autapomorphic for this species.

7. Type of contact between lateral ethmoid and dorsal border of metapterygoid: (0) through posterior process; (1) through posterior process and anterior short suture; (2) through interdigitating margins, with no process (CI = 66; RI = 66).

Among the Siluriformes, only in the family Loricariidae the ventral surface of the lateral ethmoid contacts the dorsal border of the metapterygoid (Schaefer, 1987). In Lamontichthys, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys this contact is limited to the posterior portion of the dorsal border of the metapterygoid, which articulates with the lateral ethmoid by processes present on both ossifications, a condition shared with Neoplecostomus and most loricariids (Fig. 18a). In the derived condition, Farlowella and Hypostomus possess an additional contact characterized by a short suture in the anterior portion of the metapterygoid (Fig. 18c). In Loricaria, Pseudoloricaria, and Rineloricaria, the dorsal border of the metapterygoid contacts the lateral ethmoid by an interdigitating type of contact (Fig. 18b).

Schaefer (1991: 7; 1998: 394) reported the presence of a vertical lamina in the lateral ethmoid contacting the metapterygoid in various loricariids (Ancistrinae, most Hypoptopomatinae, Hypostominae, most Loricariinae, and Neoplecostomus), however, he did not describe variation in the type of contact between these structures.

8. Lateral process of sphenotic: (0) long; (1) short; (2) inconspicuous or absent (CI = 66; RI = 0).

Located lateral to the supraoccipital, the sphenotic forms the dorsoposterior portion of the orbit in the majority of the Loricariidae and bears part of the temporal laterosensory canal (Schaefer, 1987: 6). The sphenotic of loricariids is usually square-shaped with one long lateral process. Schaefer (1987: 6) considered the lateral process of the sphenotic in loricariids as homologous to the prominent "lateral spine" representative of the Siluriformes in general. However, Howes (1983: 95) considered that the lateral spine present in the sphenotic of primitive Teleostei is absent in Siluriformes, including the Diplomystidae (Arratia, 1987: 92), Scoloplacidae (Schaefer, 1990: 180) and the Loricariidae.

Astroblepids and many loricariids possess a long lateral process of variable width on the sphenotic (Armbruster, 2004: 26), while other loricariids possess a relatively short and wide or inconspicuous process. Variation in the size of this process is accompanied by several degrees of participation of the sphenotic in the margin of the orbit.

Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, and Sturisomatichthys possess a long sphenotic process of variable width, a condition shared with other loricariids such as Hypostomus and Neoplecostomus (Fig. 19). In this condition, the sphenotic contributes with 1/5 or more to the dorsoposterior margin of the orbit.

Sturisoma possesses a short and wide lateral process, and the sphenotic contributes with approximately 1/5 of the border of the orbit, and in Pterosturisoma this process is much shorter and the sphenotic has little or no contribution to the margin of the orbit (Fig. 20).

Observation of this character is better accomplished with the sphenotic separate from the rest of the neurocranium.

9. Orbital notch in sphenotic: (0) absent; (1) present (CI = 100; RI = 100).

The orbital notch is formed by an anteroventral laminar expansion of the sphenotic, in the region where the sphenotic forms the posterior margin of the orbit, and its presence is considered derived within loricariids and proposed as autapomorphic for the tribe Loricariini (Boeseman, 1971: 17).

Among examined taxa, the presence of an orbital notch is restricted to the clade that includes members of the Loricariini, Loricaria, Pseudoloricaria, and Rineloricaria (Fig. 19).

Hyoid Arch and Branchial Arches

10. Relative width of ventral laminar expansion along posterior border of anterior ceratohyal: (0) widens abruptly in lateral portion; (1) widens gradually from medial to lateral portion, narrow; (2) widens gradually from medial to lateral portion, broad (CI = 50; RI = 66).

In the Astroblepidae and Loricariidae the anterior and posterior ceratohyals possess a ventral laminar expansion along their posterior borders, forming an angle of approximately 90º with the remaining of the hyoid arch (anterohyal of Schaefer, 1987: 12). Schaefer & Lauder (1986) discussed various specializations in the musculature and osteology of the hyoid arch in the Astroblepidae and Loricariidae associated with the life-style of members of these families. These fishes continue to respire while maintaining the suck pressure of the oral disk (Alexander, 1965: 136). In addition, the ceratohyal of the Loricariidae possesses expansions forming a broad surface for the attachment of the associated musculature (Schaefer & Lauder, 1986: 500).

The ventral expansion of the posterior border of the anterior ceratohyal varies among loricariids. In Farlowella, Hypostomus, Loricaria, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisomatichthys the laminar expansion widens abruptly in the lateral portion of the bone.

In Lamontichthys (except L. avacanoeiro), Harttia, and Sturisoma, the ventral expansion of the anterior ceratohyal is relatively narrow overall, and it widens gradually along the extension of the bone (Fig. 21). Although in L. avacanoeiro the ventral expansion of the anterior ceratohyal also widens gradually along the extension of the bone the ossification is relatively broad, distinctly wider than the expansion in the other species of Lamontichthys.

11. Ossification in basibranchial 3: (0) absent; (1) present (CI = 100; RI = 100).

The first basibranchial commonly present in the Otophysi is absent in the Siluriformes (Arratia, 1987: 41). The branchial arches of the Loricariidae possess three basibranchials (2, 3 and 4), with basibranchial 2 being ossified, basibranchial 4 cartilaginous, and basibranchial 3 having variable degrees of ossification among taxa (Schaefer, 1987: 12). The Ancistrinae, many Hypoptopomatinae, Hypostominae and Neoplecostomus possess the basibranchial 3 cartilaginous (Schaefer, 1987: 12), a condition herein observed in Hypostomus and Neoplecostomus.

The presence of ossification in basibranchial 3 is considered derived within the Loricariidae and occurs in Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys.

12. Shape of first hypobranchial: (0) stick-shaped; (1) fanshaped (CI = 100; RI = 100).

Loricariids possess five pairs of hypobranchials, the first pair is ossified and the others cartilaginous (Schaefer, 1987: 12). The first hypobranchial in loricariids is usually stickshaped and slightly wider in the medial tip. However, some loricariids possess a derived condition, wherein the lateral portion of the first hypobranchial is considerably broader than the medial portion resulting in a fan-shaped ossification (Armbruster, 2004: 11). In the present study, a fan shaped first hypobranquial was observed only in Loricaria and Pseudoloricaria. In the other loricariids examined, including Lamontichthys, the first hypobranchial is stick-shaped, gradually widening towards the lateral margin (Fig. 22).

13. Shape of lower pharyngeal plate: (0) stick-shaped, slightly expanded; (1) triangular; (2) approximately rectangular, with posterior border parallel to anterior border, medial and lateral borders of similar length; (3) quadrangular, medial and lateral borders parallel, medial border approximately same length of posterior border and slightly longer than lateral border; (4) trapezoidal, medial and lateral borders almost parallel, medial border larger than the posterior border and at least twice larger than the lateral border (CI = 100; RI = 100).

The fifth ceratobranchial in the Otophysi is modified into a plate&–like ossification with teeth, and within the Loricariidae there is wide variation in the shape of the pharyngeal plate (Schaefer, 1987: 12). The fifth ceratobranchial in Neoplecostomus is a somewhat broad ossification with a narrow dorsal end, a condition considered plesiomorphic for the Siluriformes (Fig. 23; Arratia, 1987: 41).

Armbruster (2004: 9) characterized the shape of the lower pharyngeal plate of most Loricariinae as widened at least anteriorly to form a hatchetlike structure. In the present study, four different conditions may be further distinguished regarding the lower pharyngeal of the Loricariinae. Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisomatichthys possess the lower pharyngeal plate approximately triangular and little expanded. In Harttia this structure is also little expanded, however it is somewhat rectangular-shaped, with the posterior border parallel to anterior border and medial and lateral borders of similar length (Fig. 24a).

The lower pharyngeal plate is considerably enlarged in Lamontichthys and Sturisoma. In Sturisoma the lower pharyngeal plate is approximately quadrangular, the medial and lateral borders are parallel, and the medial border has approximately the same length of the posterior border and is slightly longer than the lateral border (Fig. 24b). In Lamontichthys, the lower pharyngeal plate is approximately trapezoidal, with the medial border larger than the posterior border and, at least, twice as large as the lateral border (Fig. 25a).

14. Posterior expansion of first epibranchial: (0) absent; (1) triangular, short; (2) triangular, relatively elongate (CI = 40; RI = 66).

The posterior border of the first epibranchial in Lamontichthys has a long triangular laminar expansion that is projected medially (Fig. 26a). In the other Loricariinae examined, this projection is absent or relatively short. Farlowella, Harttia, Loricaria, and Rineloricaria do not possess any projection in the posterior border of this bone (Fig. 26c), and Pseudoloricaria, Pterosturisoma, Sturisoma, and Sturisomatichthys possess a short laminar projection (Fig. 26b).

Schaefer (1987: 12) described the presence of a posterior process in the first epibranchial for Hypostomus plecostomus, and the condition of this species was coded as 1 in the present study.

15. Uncinate process at posterior border of third epibranchial: (0) absent; (1) short; (2) long (CI = 50; RI = 66).

The third epibranchial in the majority of the Loricariidae possesses an uncinate process with varying degrees of development (Rapp Py-Daniel, 1997: character 75). When present, the process arises from the posteromedial border of the epibranchial, and extends into the medial portion of the brachial arches. A small dorsolateral process is present in the third epibranchial of Hypostomus plecostomus (Schaefer, 1987: 14) and Harttia loricariformis (Fig. 27).

The third epibranchial in Lamontichthys, Farlowella, Harttia punctata, Neoplecostomus, Pterosturisoma, Sturisoma, and Sturisomatichthys possesses a relatively long process extending meso-posteriorly (Fig. 27), and Loricaria, Pseudoloricaria, and Rineloricaria lack such a process on the third epibranchial.

16. Shape of upper pharyngeal tooth plate: (0) drop-shaped, anterior portion slightly narrower than posterior; (1) half-moon shaped to triangular, anterior portion much narrower; (2) circular to quadrangular, convex; (3) laminar and triangular shaped, with a fold on the posterior margin (CI = 100; RI = 100).

The Siluriformes possess a single pair of upper pharyngeal plates, connected to the fourth pharyngobranchial (Fink & Fink, 1981: 323). Teeth arranged in various patterns on the upper pharyngeal plate make contact with the dorsal surface of the fifth ceratobranchial, or lower pharyngeal plate.

The upper pharyngeal plate of Lamontichthys, Harttia, Pterosturisoma, and Sturisomatichthys possess a robust ventral surface and a dorsal laminar projection (Fig. 28a). Teeth are located on the ventral surface, which is triangular shaped with a narrow anterior portion. The upper pharyngeal plate of Neoplecostomus and other loricariids, such as Acestridium discus, lacks a dorsal laminar projection and the ventral surface is drop-shaped with a slightly narrow anterior portion, and completely covered by teeth (Figs. 23 and ^28c).

The upper pharyngeal plate of Sturisoma is laminar and triangular shaped, and differs considerably from other examined taxa in having the teeth in a small folded area on the posterior border of the plate and along the medial border (Fig. 25b). This condition is proposed as autapomorphic for Sturisoma. The ventral surface, which usually has teeth in other taxa, is covered by branchial filaments, while the dorsal surface is smooth.

Loricaria, Pseudoloricaria, and Rineloricaria possess a relatively large pharyngeal plate, slightly convex, circular to quadrangular shaped with teeth distributed on the entire ventral face (^{Fig. 28b}).

Schaefer (1991: 12; 1998: 396) described the general condition of the upper pharyngeal plates in the Loricariidae, as plane, relatively large and wedge-shaped. Members of the Hypoptopomatinae (Otothyris, Pseudotothyris, and Schizolecis) alternatively have a small, compact and rounded upper pharyngeal tooth plate. Armbruster (2004: 12) described two distintict conditions of this plate in the Loricariidae. In the present study four different conditions regarding the shape of the upper pharyngeal plate among examined specimens of Loricariidae were observed.

17. Molariform teeth on upper and lower pharyngeal plate: (0) absent; (1) present (uninformative).

Loricariids commonly possess only conical teeth on the upper and lower pharyngeal plates. However, many members of the Loricariini possess both conical and molariform teeth in both plates (Rapp Py-Daniel 1997: character 90; Armbruster, 2004: 9), a condition observed in Loricaria among examined taxa.

Jaws and dentition

The Loricariidae surpasses all other Loricarioidea in the high diversity of shapes and sizes of jaws and teeth, probably a consequence of the adaptation to different kinds of microhabitats and substrates explored by these fishes. Associated with the variation of jaws and teeth, there are several other specializations in the feeding mechanisms and in the hyoid apparatus (Schaefer & Lauder, 1986: 504).

18. Length of posterior process of palatine: (0) short, not extending beyond anterior condyle of lateral ethmoid; (1) long, extending beyond anterior condyle of lateral ethmoid (CI = 50; RI = 0).

The palatine in loricariids is narrow and cylindrical. Anteriorly there is a cartilaginous tip that articulates with the maxilla and posteriorly there is an articular surface for the lateral ethmoid (Arratia, 1990: 209). Medial to this latter articular surface is a ventral posterior process, extremely reduced in loricariids in comparison to other Siluriformes (Fig. 15a; Schaefer, 1987: 10; Schaefer, 1997: 25; Reis, 1998: 124). Lamontichthys avacanoeiro and Loricaria, in contrast, possess a long posterior process compared to other loricariids (Fig. 15b). In these two species, the posterior process of the palatine extends ventrally beyond the anterior condyle of the lateral ethmoid. In other loricariids, the posterior process fails to reach the condyle of the lateral ethmoid.

According to Schaefer (1990: 185), in loricariids, one of the two subdivisions of the extensor tentaculi muscle inserts on the posterior process of the palatine.

19. Lateral flange of palatine: (0) absent; (1) present and incomplete; (2) present and complete (CI = 66; RI = 66).

In loricariids, the palatine is usually a cylindrical bone lacking lateral edges (Schaefer, 1997: fig. 12e; Armbruster, 2004: 17). In a few taxa there is a flange projecting from the lateral border of the bone that is already present early in ontogeny (Arratia, 1990: 209). In many members of the Loricariini the flange extends along the entire lateral margin of the autopalatine, a condition observed in Pseudoloricaria and Rineloricaria. In Loricaria, exclusively, the flange is somewhat shorter extending along 2/3 of the lateral margin of the autopalatine (Rapp Py-Daniel, 1997: character 23).

20. Palatine splint: (0) present; (1) absent (CI = 50; RI = 50).

The palatine splint is an ossification of questionable homology that occurs in the Astroblepidae, Scoloplacidae, Loricariidae, some Trichomycteridae and Callichthyidae (Schaefer, 1987: 10; 1997: 25; Reis, 1998: 124). In loricariids the ossification is thin, elongate and straight with a wide anterior tip, and contacts the anterior cartilage of the autopalatine (Fig. 29). Posteriorly, it extends parallel to the autopalatine, and reaches the lateral ethmoid.

The palatal splint is present in all examined taxa except Farlowella, Loricaria, and Pseudoloricaria.

21. Length of cup-shaped portion of premaxilla relative to cup shaped portion of dentary: (0) similar; (1) distinctly longer; (2) distinctly shorter (CI = 100; RI = 100).

The premaxilla and dentary in the Loricariidae are distinctly cup-shaped anteriorly and contain several rows of teeth (Schaefer, 1987: 11; 1997: 25). The relative length of the cup-shaped region of the premaxilla compared to that of the dentary varies among examined taxa. Lamontichthys avacanoeiro, L. maracaibero, L. stibaros, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys have these regions of similar length (Fig. 29), a condition shared with Hypostomus and Neoplecostomus.

Loricaria, Pseudoloricaria, and Rineloricaria have the cup-shaped region of the premaxilla distinctly shorter than that of the dentary. In contrast, L. filamentosus and L. llanero have the cup-shaped region of the premaxilla distinctly longer than that of the dentary.

Lamontichthys parakana, not included in this analysis, has the cup-shaped region of the premaxilla only slightly longer than that of the dentary (state 0).

22. Length versus width of cup-shaped region of premaxilla: (0) two to three times longer than wide; (1) length and width equivalent. (CI = 100; RI = 100).

The cup-shaped region of premaxilla in L. avacanoeiro, L. filamentosus, L. llanero, L. maracaibero, L. stibaros, and in the outgroups Farlowella, Harttia, Hypostomus, Neoplecostomus, Pterosturisoma, Sturisoma, and Sturisomatichthys is rectangular shaped, with the length twice to three times longer than its width (Fig. 29). In the derived condition present in Loricaria, Pseudoloricaria, and Rineloricaria, it is approximately square shaped.

23. Coronoid process of dentary: (0) large, with small robust area; (1) large, with large robust area; (2) small; (3) absent (CI = 100; RI = 100).

The dentary of most siluriforms possesses a well developed and conspicuous coronoid process for insertion of the adductor muscles (Schaefer, 1987). The coronoid process in loricariids, when present, is usually strong and concave posteriorly (Howes, 1983). In Farlowella, Pterosturisoma, Sturisoma, and Sturisomatichthys the coronoid process is large and has a small heavily ossified and robust area along its posterior margin (Fig. 30), a condition shared with Hypostomus and Neoplecostomus.

Three derived conditions of the coronoid process were observed among examined taxa. Lamontichthys also possesses a large coronoid process, but in this genus the robust area is more developed and occupies almost the entire posterior region of the coronoid process (Fig. 31b). Species of Harttia possess a relatively small coronoid process (Fig. 31a), and Loricaria, Pseudoloricaria, and Rineloricaria lack a coronoid process in the dentary.

24. Posteroventral lamina of dentary: (0) present; (1) absent (CI = 100; RI = 100).

The dentary of loricariids usually has a long posteroventral lamina of bone that overlies the posterior face of the anguloarticular (Schaefer, 1987: 12). Among the Loricariinae, this condition was observed in Lamontichthys avacanoeiro, L. filamentosus, L. llanero, L. maracaibero, L. stibaros, and in the outgroups Farlowella, Harttia, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys (Fig. 31). Pseudoloricaria and Loricaria lack a posteroventral lamina of bone in the dentary.

25. Process on posteroventral lamina of bone of dentary: (0) absent or very narrow; (1) present, relatively distant from main body of dentary; (2) present, close to main body of dentary (CI = 100; RI = 100).

As detailed under the previous character, the dentary of many loricariids possesses a posteroventral lamina of bone that overlaps the anguloarticular. The geniohyoideus muscle inserts on this lamina and provides high mobility of the dentary and of the hyoid arch (Schaefer & Lauder, 1986: 499). In Lamontichthys, Hypostomus, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Sturisoma, Sturisomatichthys, and Rineloricaria the muscle is inserted directly on the posteroventral lamina of the dentary. In Harttia there is a small laminar process located at the anterior portion of the posteroventral lamina of the dentary onto which the geniohyoideus muscle is inserted (Fig. 31a). Farlowella possesses a similar process, which is instead situated posteriorly on the posteroventral lamina of the dentary.

Pseudoloricaria and Loricaria, that lack the posteroventral lamina of the dentary (character 24), were not coded for this character.

26. Shape of maxillary teeth: (0) teeth delicate, long and narrow, tooth cusp forming angle of approximately 90º with longer axis of tooth and ventrally directed; (1) teeth robust, relatively short and wide, tooth cusp forming an angle of approximately 180º with the longer axis of tooth and medially directed (CI = 100; RI = 100).

Loricariid fishes are primarily herbivorous, benthic algae scrapers and greatly exceeds all other loricarioides in the arrangement, number, shape and size of teeth (Schaefer & Lauder, 1986). The most common pattern of dentition in the family, present in Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys, is that of delicate, long and narrow setiform teeth, bicuspid and strongly curved (Fig. 32a; Isbrücker, 1981; Schaefer, 1987; Müller & Weber, 1992). The cusps, when observed from a lateral view, form an angle of approximately 90º with the longer axis of the tooth.

In contrast, Loricaria, Pseudoloricaria, and Rineloricaria possess relatively strong, short and wide teeth, with only a gentle curvature (Fig. 32b). In addition, the tooth cusps form an angle of approximately 180º with the longer axis of the tooth.

27. Size of tooth cusps: (0) long, main cusp approximately twice as large and broad than lateral cusp; (1) short, main cusp slightly larger and wider than lateral cusp (CI = 50; RI = 80).

Bicuspid teeth are present in the families Scoloplacidae, Loricariidae and Astroblepidae, but only members of the Loricariidae possess asymmetric cusps (Schaefer, 1990: 185). In the most common condition found in loricariids, the main cusp is longer and wider than the lateral cusp (Müller & Weber, 1992). Although differences in cusp size have not been utilized in phylogenetic analysis of loricariids, Isbrücker & Nijssen (1978b: 70) illustrated teeth of representatives of the Loricariinae, in which it is possible to clearly distinguish between short and long cusps.

Lamontichthys stibaros, L. avacanoeiro, Harttia, and Sturisomatichthys share with Hypostomus and Neoplecostomus teeth with long cusps (Fig. 3a). Hypostomus and Neoplecostomus have teeth with the main cusp twice as large and wide than the lateral cusp. Harttia has teeth with the main cusp twice as large and only slightly broader than the lateral cusp, and the remaing species of Lamontichthys have teeth with cusps of similar size, or with the main cusp only slightly longer and wider than the lateral cusp. The latter condition is also present in L. parakana, a species not included in the analysis. The variation in cusp size is relatively continuous among taxa and therefore it was not coded as distinct character states.

Lamontichthys filamentosus, L. llanero, L. maracaibero, Farlowella, Pterosturisoma, and Sturisoma possess teeth with short cusps, with the main cusp usually slightly longer and wider than the lateral cusp (Fig. 3b).

Loricaria, Pseudoloricaria, and Rineloricaria were not coded for this character due to their distinct tooth morphology (character 26).

28. Number of teeth in each premaxilla or dentary: (0) more than 50; (1) between 20 and 50; (2) fewer than 20 (CI = 66; RI = 88).

The number of teeth in each premaxilla or dentary in loricariids is higly variable and Boeseman (1971: 10) was the first author to propose groupings within the Loricariinae based on variation on the number of jaw teeth. Among the nonloricariine Loricariidae, Schaefer (1997: 109) considered the presence of 12 to 18 teeth in each jaw as plesiomorphic for the Hypoptopomatinae. Garavello et al. (1998) showed that variation in the number of teeth could be used to diagnose species of the genus Otothyris.

Lamontichthys, Harttia, and Sturisomatichthys possess between 50 and 100 teeth in each premaxilla or dentary. Farlowella, Pterosturisoma, and Sturisoma possess between 20 and 50 teeth in each premaxilla or dentary, a condition shared with Hypostomus and Neoplecostomus. In Loricaria, Pseudoloricaria, and Rineloricaria the number of jaw teeth rarely reaches 20.

There is a slight difference between the number of teeth in the premaxilla and in the dentary of loricariids. However, such difference is included within the range of variation of the states defined for this character. The number of teeth in the premaxilla and dentary of loricariids increases with growth. In the present study only adult specimens were considered for this character.

Suspensorium

29. Projection of posterior border of hyomandibula: (0) present; (1) absent (CI = 50; RI = 0).

The hyomandibula of loricariids is a relatively large, square shaped bone. The posterior border is usually straight, with a crest for the insertion of the adductor mandibulae muscle (Schaefer, 1987: 8). In Lamontichthys and in the outgroups Farlowella, Harttia, Loricaria, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisomatichthys, the crest is in direct contact with the pterotic-supracleithrum. In Hypostomus and Sturisoma the hyomandibula extends posteriorly to this crest, and the contact with the pterotic-supracleithrum is made via this posterior projection.

30. Contribution of pterotic-supracleithrum to hyomandibulacranium articulation: (0) wide, as large as contribution of prootic; (1) short, less than contribution of prootic; (2) absent, with exclusive participation of prootic (CI = 100; RI = 100).

Schaefer (1997: 104) proposed that a contribution of the pterotic-supracleithrum and of the prootic in the hyomandibula-cranium articulation is plesiomorphic for the Loricariidae and this condition is present in Neoplecostomus, the Loricariinae, Ancistrinae, many Hypostominae, and in the tribe Otothyrini (Hypoptopomatinae). However, that author did not indicate the degree of participation of each ossification to this articulation and proposed that the lack of contribution of the prootic to the hyomandibula-cranium articulation in members of the Hypostominae and in the tribe Hypoptopomatini (Hypoptopomatinae) as a derived condition. The lack of contribution of the prootic to the hyomandibulacranium articulation reported for some loricariids (Armbruster, 2004: 13) was not observed in taxa examined in the present study.

Three different conditions regarding the contribution of the pterotic-supracleithrum to the hyomandibula-cranium articulation occur among examined taxa. Lamontichthys, Harttia, Hypostomus, and Neoplecostomus possess an equivalent contribution of the prootic and pteroticsupracleithrum to the facet of the hyomandibula-cranium articulation (Fig. 33a). Farlowella, Pterosturisoma, Sturisoma, and Sturisomatichthys possess a smaller contribution of the pterotic-supracleithrum to the facet of the hyomandibulacranium articulation relative to that of the prootic (Fig. 33b). In Loricaria, Pseudoloricaria, and Rineloricaria, the pterotic-supracleithrum is excluded from this articulation, and only the prootic connects to the hyomandibula. Although in Farlowella, the contribution of the pterotic-supracleithrum to the hyomandibula-cranium articulation is particularly small, the ossification is still present in the facet of the hyomandibula and that species was therefore coded as having state 1.

31. Crest on lateral surface of hyomandibula for insertion of levator arcus palatini muscle: (0) present; (1) absent (CI = 50; RI = 0).

Most Siluriformes including loricariids possess a crest on the hyomandibula, where the levator arcus palatini muscle is inserted(Arratia, 1987; Armbruster, 2004: 15). This muscle originates in the sphenotic, and connects the hyomandibula with the lateral border of the skull (Howes, 1983). The levator arcus palatini muscle is extremely reduced in Farlowella, Hypostomus, Loricaria, and Neoplecostomus, and it is absent in some species of the latter genus (Howes, 1983: 322). In the Hypoptopomatinae the reduction of this muscle is directly proportional to the reduction of the extension of the hyomandibular crest (Schaefer, 1991: 10)

Among the Loricariinae, Lamontichthys, Farlowella, Harttia, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys possess the lateral face of the hyomandibula with a very narrow crest, while in Loricaria and Pterosturisoma the crest is absent (Fig. 34).

In the single specimen of L. stibaros examined (FMNH 84111, 62.4 mm SL) the hyomandibula crest does not cross the entire extension of the hyomandibula. The single specimen of L. maracaibero examined (MCNG 3593, 83.8 mm SL) possesses a complete crest, a condition present in the other species of the genus examined in the present study, all represented by larger specimens. Arratia (1987) reported that juveniles of Diplomystes possess a rudimental crest, while in the adult it is well developed, except in the adult of D. camposensis. The lack of both juveniles and adults of all species of Lamontichthys in the present study did not allow comparison of the degree of development of the crest of the homandibula within the genus. Therfore, only the presence or absence of the crest on the lateral face of the hyomandibula was considered in the present study.

32. Ventral process of preopercle: (0) inconspicuous or absent; (1) well developed (CI = 50; RI = 75).

The preopercle of loricariids is usually an elongate ossification, with the anterior and posterior tips narrower, and it bears a branch of the laterosensory canal (Schaefer, 1991: 11). The anterior portion of the dorsal border of the preopercle of loricariids is sutured with the quadrate and the posterior portion is sutured with the hyomandibula. The posterior portion of the ventral border of the preopercle in some Loricariinae has a ventral process that articulates with a bony plate (Rapp Py-Daniel, 1997: character 53), which bears a branch of the laterosensory canal ("canal-bearing plate" of Schaefer, 1987: 22). This process occurs in Lamontichthys, and in the outgroups Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys (Fig. 29). On the other hand in Loricaria, Pseudoloricaria, and Rineloricaria the ventral process of the preopercle is absent or inconspicuous, a condition that also occurs in Hypostomus and Neoplecostomus.

33. Exposed region on posterodorsal portion of preopercle: (0) present; (1) absent, totally covered by skin (CI = 33; RI = 60).

The Siluriformes usually possess the preopercle covered by skin, lacking any exposed surface (Reis, 1998: 143) a condition observed in Lamontichthys and the outgroups Farlowella, Harttia, Pterosturisoma, and Sturisomatichthys (Fig. 20a). Reis (1998: 143) reported the presence of a partially exposed preopercle in members of the family Callichthyidae. Similarly, Loricaria, Pseudoloricaria, Rineloricaria, and Sturisoma possess the posterodorsal portion of the preopercle exposed and usually ornamented with odontods, a condition shared with Hypostomus and Neoplecostomus (Fig. 20b).

Laterosensory canal system

34. Position of canal-bearing cheek plate on head: (0) lateral; (1) ventrolateral; (2) ventral (CI = 66; RI = 66).

Members of the Loricariidae possess a plate anterior to the opercle that receives the terminus of the preopercular laterosensory canal ("canal-bearing plate" of Schaefer, 1987: 22; 1991: 11; "canal-bearing cheek plate" of Schaefer, 1991: 20).

Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys possess the canal-bearing cheek plate located ventrally on the head (Fig. 1), while in Rineloricaria, Loricaria, and Pseudoloricaria it occupies the lateral region of the head. In Neoplecostomus, part of the canal-bearing cheek plate occupies the lateral region of the head and part the ventral region.

35. Orientation of laterosensory canal on canal-bearing cheek plate: (0) cranium-caudal; (1) medial; (2) laterolateral (CI = 66; RI = 66).

The laterosensory canal on the canal-bearing cheek plate of loricariids (see plate in Fig. 1), commonly travels anteriorly from the posterolateral to the anterolateral portion, running close to the lateral margin of the cheek-plate (Rapp Py-Daniel, 1997: character 161). This condition occurs in Lamontichthys, Farlowella, Harttia, Pterosturisoma, and Sturisomatichthys among examined members of the subfamily Loricariinae. A different condition occurs in Hypostomus, Loricaria, Pseudoloricaria, and Rineloricaria, in which the laterosensory canal is directed laterally and travels along the median line of the cheek plate, from its dorsal to its ventral border. In Sturisoma, the laterosensory canal travels from the posterolateral portion of the cheek plate, running anteromedially to reach the anterolateral portion.

36. Laterosensory canal on supracaudal plates: (0) absent; (1) present (CI = 100; RI = 100).

The plesiomorphic condition for the Siluriformes is to have a continuous and complete laterosensory canal on the body, that extends near to or lateral to the hypural plate, is partially included in ossicles, and gives off numerous short tubules that open in the skin by diminutive pores (Arratia & Huaquin, 1995: 90).

In Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys the lateral line continues on the elongate plate posterior to the hypural plate. In Hypostomus and Neoplecostomus, the lateral line falls short of the elongate plate posterior to the hypural plate (Fig. 35).

According to Schaefer (1991: 20), in Neoplecostomus, some Hypoptopomatinae, and in the majority of the other loricariids the lateral line is complete and extends from the pterotic-supracleithrum, posteriorly to the last lateral plate of the median series on the base of the caudal-fin. Schaefer (1991: 20) and Armbruster (2004: 23) reported that the lateral line of Callichthyidae, Astroblepidae and many loricariids (Hypoptopomatinae, Neoplecostomus, and some members of the other loricariid subfamilies) terminates anteriorly to the hypural plate, while in some Hypostominae, Ancistrinae and many Loricariinae it terminates lateral to the hypural plate. Armbruster (2004: 75) proposed the presence of laterosensory canal on the elongate plate posterior to the hypural plate as synapomorphic for the Loricariinae.

Infraorbital series

Loricariids possess between five and six infraorbitals (Schaefer, 1987: 8), modified into bony plates and usually covered by odontods (Fink & Fink, 1981: 315; Arratia, 1987: 96). Five infraorbitals are present in Neoplecostomus and in the Hypoptopomatinae and six infraorbitals is a condition shared with the Astroblepidae (Schaefer, 1997: 23).

37. Plate between infraorbital 2 and 3: (0) absent; (1) present (uninformative).

In Lamontichthys filamentosus, L. llanero, L. maracaibero, L. stibaros, Farlowella, Harttia, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the posterior border of infraorbital 2 contacts the anterior border of infraorbital 3 along its entire extension, and there is no plate between these two ossifications (Fig. 20). In the derived condition, present in L. avacanoeiro and L. parakana, there is a plate that lacks a laterosensory canal that is situated between infraorbitals 2 and 3, and restricts the contact between these two ossifications (Fig. 36).

Weberian apparatus and Axial skeleton

38. Suture between basioccipital and Baudelot's ligament: (0) present; (1) absent (CI = 100; RI = 100).

The Siluriformes, in general, possess the Baudelot's ligament ossified, arising from a small process of the supracleithrum and inserting directly on the basioccipital (Chardon, 1968: 190; Fink & Fink, 1981: 335). Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys possess a ventral and lateral prolongation of the posterior portion of the basioccipital that is in contact with Baudelot's ligament. In Loricaria, Pseudoloricaria, and Rineloricaria, a ventral prolongation of the posterior border of the exoccipital is situated between the basioccipital and the Baudelot's ligament (Fig. 37). These different conditions were previously described by Rapp Py-Daniel (1997: character 18).

39. Flange on lateral region of seventh precaudal vertebra: (0) absent; (1) present, anteriorly directed; (2) present, posteriorly directed (CI= 100; RI = 100).

Members of the subfamily Loricariinae have a flange projecting from the dorsolateral side of the seventh precaudal vertebra that extends dorsally along the side of the neural spine. In all examined members of the Loricariinae except Lamontichthys avacanoeiro, the flange is directed anteriorly (Fig. 38a). In L. avacanoeiro, this flange is directed posteriorly. Members of the Loricariidae in general seem to lack a lateral flange on the seventh precaudal vertebra (Fig. 38b).

40. Hemal spine on last precaudal vertebra: (0) absent; (1) present, shorter or same length of associated vertebral centrum; (2) present, longer than associated vertebral centrum (uninformative).

Pterosturisoma possesses the hemal spine of the last precaudal vertebra considerably elongate and narrow distally, with a length of approximately twice that of the corresponding vertebral centrum (Fig. 39). In Neoplecostomus and in the great majority of the Loricariinae (Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys) this spine is considerably shorter, its length equal or less than the length of the corresponding vertebral centrum (Figs. 40 and 41).

41. Bifid hemal spine on first caudal vertebra: (0) very short, almost inconspicuous; (1) medium, length approximately 1/2 width of corresponding vertebra; (2) long, approximately, as long as corresponding vertebra (CI = 100; RI = 100).

In Hypostomus, the hemal spine of the first caudal vertebra is very short and only its distal posterior tip is split to receive the first anal-fin pterygiophore. The bifid hemal spine of the first caudal vertebra in Neoplecostomus is longer, its length approximately 1/2 of the corresponding vertebral width (Fig. 41). In members of the Loricariinae there is a further elongation of this structure and in Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys, the bifid hemal spine of the first caudal vertebra is as long as the corresponding vertebral width (Fig. 40).

In Pterosturisoma two very long contralateral projections originate from the proximal region of the hemal spine (Fig. 39). It is not clear whether these processess are homologous to the bifid hemal spines or represent distinct structures (Rapp Py-Daniel, 1997: 64) and this species was therefore coded as "?".

42. Presence of completely expanded, hemal spines on caudal vertebrae: (0) from first caudal vertebra; (1) from fifth, sixth or seventh caudal vertebra (uninformative).

Neoplecostomus and members of the Loricariinae possess completely expanded hemal spines ranging from the fifth, sixth or seventh caudal vertebrae (vertebrae 20 to 23), to the last body vertebra (Figs. 39-41). According to Schaefer (1987: 17), in Hypostomus plecostomus the hemal spines are completely expanded along their length in all caudal vertebrae (posterior to vertebrae 14), a condition observed in the specimens of Hypostomus examined in the present study.

43. Bilateral projections on vertebrae: (0) absent; (1) present (CI = 100; RI = 100).

Members of the Loricariinae possess ventrally directed bilateral projections on the proximal portion of the hemal spines, as well as dorsally directed bilateral projections on the proximal portion of the neural spines, a feature previously described by Rapp Py-Daniel (1997: 106) as a synapomorphy for Loricariinae. These projections are strong and narrow, their length not exceeding one third of the vertebral width (Figs. 39 and 40). The two anterior most pairs of these projections usually do not contact the body plates, while the more posterior ones possess the distal tips firmly sutured to these plates. The dorsally directed bilateral projections are present from vertebrae 9 to 11, and the ventrally directed bilateral projections, from approximately vertebrae 13 to 15.

44. Orientation of ventrally directed bilateral projections on second caudal vertebra: (0) ventral to slightly anteriorly or posteriorly directed; (1) distinctly posteriorly directed; (2) distinctly anteriorly directed (CI = 66; RI = 66).

The ventrally directed bilateral projections of the second caudal vertebra of the majority of the Loricariinae are directed ventrally or only slightly anterior or posterior and their distal tips lack any type of contact with the body plates. In Harttia the ventrally directed bilateral projections of the second caudal vertebra are directed posteriorly and their distal tips also lack any type of contact with the body plates (Fig. 42a). Lamontichthys llanero has the ventrally directed bilateral projections of the second caudal vertebra anteriorly directed and the distal tips are strongly sutured to the hemal spine of the first caudal vertebra (Fig. 42b).

This character does not apply to Hypostomus and Neoplecostomus because these taxa lack ventrally directed bilateral projections.

45. Contact between ventrally directed bilateral projections of third caudal vertebra and ventral plates of body: (0) absent; (1) present (uninformative).

The ventrally directed bilateral projections of the third caudal vertebra of the majority of Loricariinae (except Harttia loricariformis) possess their distal tips pointed and lacking any type of contact with the ventral plates (Fig. 39). In Harttia loricariformis, the distal tips of these projections are strongly attached to the ventral plates of the body (Fig. 42a).

Hypostomus and Neoplecostomus were not coded for this character due to lack of bilateral projections on the vertebrae of these taxa.

46. Length of posterior process of hemal spine of second preural centrum: (0) long; (1) short (CI = 100; RI = 100).

The hemal spine of the second preural centrum in all examined taxa extends posteriorly as a process along the ventral margin of the hypural plate (Fig. 43).

In all members of the Loricariinae this process is short not extending beyond half the length of the hypural plate. Alternatively, in Hypostomus and Neoplecostomus this process is long almost reaching the vertical through the posterior margin of the hypural plate.

47. Cartilage on posterior tip of hemal spine of second preural centrum: (0) present; (1) absent (CI = 100; RI = 100).

Harttia, Hypostomus, and Neoplecostomus among examined taxa possess cartilage on the posterior tip of the hemal spine of the second preural centrum. This feature was previously reported in members of the Astroblepidae, Ancistrinae, Hypoptopomatinae, Hypostominae, and Neoplecostominae, and in Harttia among the Loricariinae by Rapp-Py Daniel (1997: character 135).

48. Relative length of neural spine of second preural centrum: (0)reaches vertical through posterodorsal tip of hypural plate; (1) reaches vertical through 1/2 to 3/4 length of hypural plate; (2) reaches vertical through 1/3 length of hypural plate (CI = 100; RI = 100).

Three different conditions of the relative length of the neural spine of the second preural centrum were described by Rapp Py-Daniel (1997: character 134) for the Loricariidae. Among examined taxa, Hypostomus possess an elongate neural spine of the second preural centrum that extends parallel to the dorsal border of the hypural plate to the vertical through its posterodorsal tip (Fig. 43c). In all other examined taxa the neural spine of the second preural centrum is shorter. In Lamontichthys, Harttia, Neoplecostomus, Pterosturisoma, Sturisoma, and Sturisomatichthys, the neural spine of the second preural centrum reaches the vertical through 1/2 to 3/4 length of the hypural plate (Fig. 43). In Farlowella, Loricaria, Pseudoloricaria, and Rineloricaria the neural spine of the second preural centrum reaches the vertical through 1/3 the length of the hypural plate.

49. Caudal peduncle depth: (0) cylindrical or moderately depressed; (1) depressed (CI = 100; RI = 100).

According to Alexander (1965: 142), one of the main modifications along the evolution of the Siluriformes was the depression of the body in adaptation to a bottom-feeding habit.

One extreme of this modification occurs in the Loricariidae, whose members have the ventral surface of the body very flat. In addition, the caudal peduncle of loricariids is slightly depressed, though still cylindrical in overall shape. Thesubfamily Loricariinae and the genera Acestridium, Niobichthys, and Oxyropsis (Hypoptopomatinae) possess the caudal peduncle extremely depressed. Schaefer (1987: 20) hypothesized a depressed caudal peduncle to be a synapomorphy for the subfamily Loricariinae. This feature has been used to diagnose the Loricariinae since the original recognition of this taxon (Bonaparte, 1831; Eigenmann & Eigenmann, 1890).

50. Number of precaudal vertebrae: (0) 14 or more; (1) 13; (2) 12; (3) 11 (CI = 100; RI = 100).

The Loricariidae possess 26 to 42 vertebrae between the basioccipital and the hypural plate (Schaefer, 1987: 24; 1990: 190; 1997: 105). The increase in the total number of vertebrae is derived within loricariids (Schaefer, 1987: 24), with the greatest number present in the subfamily Loricariinae, with 33-37 vertebrae (vs. 30 or fewer). The Astroblepidae and Callichthyidae possess 16-18 precaudal vertebrae and the Loricariidae 12-16 (Hypostominae and Ancistrinae with 1316; Hypoptopomatinae and Loricariinae with 12) (Schaefer, 1987: 24). Within the Loricariinae there is a secondary reduction in the number of precaudal vertebrae. Lamontichthys and Harttia possess 13 precaudal vertebrae, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma possess 12 precaudal vertebrae, and Sturisomatichthys has 11 precaudal vertebrae (Rapp Py-Daniel, 1997: character 110).

51. Number of caudal vertebrae: (0) 23-25; (1) 19-22; (2) 12-18 (CI = 50; RI = 75).

Among examined taxa Hypostomus and Neoplecostomus possess 12 to 18 caudal vertebrae and all members of the Loricariinae possess 19 or more. Harttia, Loricaria, Pseudoloricaria, Rineloricaria, and Sturisomatichthys possess 19 to 22 caudal vertebrae and Lamontichthys, Farlowella, Pterosturisoma, and Sturisoma possess 23 to 25 caudal vertebrae (Rapp Py-Daniel, 1997: character 111).

Dorsal-fin

52. Spinelet: (0) shaped as strong and short spine, articulated with first pterygiophore; (1) shaped as small plate; (2) absent (CI = 50; RI = 33).

The majority of the Siluriformes possess the first element of the dorsal-fin (often termed the spinelet, Schaefer, 1987: 17) shaped as a strong, short, and spine-like element that acts as a locking system for the second much longer dorsal-fin spine (Alexander, 1965), a condition observed in Hypostomus, among examined taxa. The spinelet is variably reduced or lost in several memberos of the Loricariidae (Schaefer, 1987: 18; Armbruster, 2004: 33).

In Lamontichthys (including L. parakana), Harttia punctata, Neoplecostomus, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys the spinelet is shaped as a plate-like structure (Fig. 44), and Farlowella, Harttia loricariformis, Loricaria, and Pseudoloricaria lack the spinelet.

53. Type of articulation between proximal portion of dorsalfin spine and second dorsal-fin pterygiophore: (0) through condyle on dorsal region of pterygiophore; (1) through simple contact with pterygiophore, with no condyle; (2) via chainlink structure (CI = 66; RI = 50).

The second element of the dorsal-fin in the Siluriformes is usually modified into a defensive spine (Reed, 1924), and the proximal end of this spine articulates with a dorsal condyle of the second pterygiophore (Fig. 45a; Schaefer, 1987: 23), a condition observed in Hypostomus, among examined taxa.

In Lamontichthys, Farlowella, Harttia punctata, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys the dorsal-fin spine articulates with the second pterygiophore via a chain-like structure (Fig. 45b), a condition proposed as synapomorphic for the Loricariinae by Schaefer (1987: 23) and posteriorly corroborated by Armbruster (2004: 33). In Harttia loricariformis and Neoplecostomus the dorsal surface of the second pterygiophore is flat, lacking any structure for articulation.

The dorsal-fin pterygiophores of the majority of loricariids possess transverse processes, which provide support for the dermal body plates. Usually, the processes of the anterior most pterygiophores are long, and decrease in size posteriorly (Schaefer, 1991: 18). The number of dorsal-fin pterygiophores bearing transverse processes varies within the Loricariidae (Armbruster, 2004: 33). Variations pertaining to the dorsal-fin pterygiophores observed in the present study are discussed under characters 54 to 59.

54. Length of transverse process of first dorsal-fin pterygiophore relative to second dorsal-fin pterygiophore: (0) shorter; (1) of similar length (uninformative).

The first and the second dorsal-fin pterygiophores of loricariids possess a pair of relatively long transverse processes, involved in the support of the nuchal plate and first rays of the dorsal-fin (Schaefer, 1991: 18). In Neoplecostomus these processes are of similar length, and in the other loricariid examined, the lateral processes of the first dorsal-fin pterygiophore are shorter than those of the second. This character was previously described by Rapp-Py Daniel (1997: character 120).

55. Orientation of transverse process of second dorsal-fin pterygiophore: (0) lateral at proximal portion and anterolateral at distal portion; (1) anterolateral throughout entire extension; (2) anterolateral at proximal portion and anterior at distal portion (CI = 66; RI = 83).

Different types of orientation of the lateral process of the second dorsal-fin pterygiophore were described for the Loricariidae by Rapp Py-Daniel (1997: character 118). The condition in which the lateral process of the second dorsalfin pterygiophore is directed anterolaterally along its entire extension occurs in Lamontichthys, Pterosturisoma, Sturisoma, and Sturisomatichthys (Fig. 46a). The lateral process of the second dorsal-fin pterygiophore directed anterolaterally at its proximal portion and anteriorly at its distal portion occurs in Loricaria, Pseudoloricaria, and Rineloricaria (Fig. 46b). The lateral process of second dorsalfin pterygiophore directed lateral at its proximal portion and anterolateral at its distal portion occurs in Farlowella, Harttia, Hypostomus, and Neoplecostomus (Fig. 46c).

56. Contact between transverse process of third and fourth dorsal-fin pterygiophores and dorsal body plates: (0) present; (1) absent (uninformative).

In the majority of the loricariids examined (with the exception of Neoplecostomus) the lateral processes of the third and fourth dorsal-fin pterygiophores are long and contact the ventral surface of the dorsal body plates (Fig. 44). According to Schaefer (1991: 18) Neoplecostomus lacks transverse processess on the third and fourth pterygiophores, however, two very short processes are present in the specimen of N. ribeirensis examined in the present study and they fail to reach the dorsal plates.

57. Transverse process on fifth dorsal-fin pterygiophore: (0) absent; (1) present (CI = 50; RI = 50).

The majority of the Loricariinae examined possess a transverse process on the fifth dorsal-fin pterygiophore (Fig. 44). Sturisomatichthys lacks these processes, a condition that also occurs in Hypostomus and Neoplecostomus.

58. Transverse process of sixth dorsal-fin pterygiophore: (0) absent; (1) present (CI = 50; RI = 75).

Harttia, Hypostomus, Neoplecostomus, and Sturisomatichthys lack a transverse process on the sixth dorsal-fin pterygiophore. Small transverse processes are present in Lamontichthys, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma (Fig. 44).

59. Connecting bone: (0) present, contacting first or second dorsal-fin pterygiophore; (1) present, not contacting any pterygiophore; (2) absent (CI = 50; RI = 50).

The connecting bone or lateral bone (Bailey & Baskin, 1976; Schaefer, 1987: 26) is a laminar ossification located between the parapophysis of the sixth vertebra and the first or second dorsal-fin pterygiophore that is present in many loricariids, the Astroblepidae and the Scoloplacidae and occurs as an unossified tendon in callichthyids (Schaefer, 1990: 193; Armbruster, 2004: 32).

In the Astroblepidae, Scoloplacidae, and many loricariids the posterior tip of the lateral bone contacts the second dorsal-fin pterygiophore (Bailey & Baskin, 1976; Schaefer, 1987: 26). This condition occurs in Lamontichthys, Harttia, Hypostomus, Loricaria, and Neoplecostomus among examined taxa (Fig. 46a).

In Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys although present, the posterior tip of the lateral bone does not contact any pterygiophore (Fig. 46b). Farlowella lacks a connecting bone.

Pectoral fin and girdle

60. Number of branched pectoral-fin rays: (0) 6; (1) 7 (CI = 100; RI = 100).

The majority of the Siluriformes, including the more basal taxa, have eight or more branched rays in the pectoral-fin (de Pinna, 1996: 37). However, in the Loricariidae there is a reduction of this number to five to seven rays. Neoplecostomus, the Hypostominae, the Ancistrinae and the majority of the members of the Loricariinae and Hypoptopomatinae possess six branched rays in the pectoralfin (Schaefer, 1987, 1998). Schaefer (1998: 399) considered the presence of seven branched rays in the pectoral-fin as a derived condition within the Hypoptopomatinae. Among the Loricariinae, all species of Lamontichthys (including L. parakana), Harttia leiopleura, and Rineloricaria daraha (Rapp Py Daniel & Fichberg, 2008) possess seven branched rays, while some species of Farlowella possess only five (Boeseman, 1971). The presence of seven branched rays in the pectoral-fin was originally proposed as a diagnostic character for Lamontichthys by Isbrücker & Nijssen (1976, 1978b).

61. Length of cleithrum symphysis relative to coracoid symphysis: (0) similar to twice as short; (1) twice as long (CI = 100; RI = 100).

The cleithrum and coracoid in loricariids articulate with their counterparts by means of interdigitating sutures along their symphyses, the extension of which is variable, a feature previously observed by Rapp-Py Daniel (1997: character 142).

In Lamontichthys, Harttia, Farlowella, Hypostomus, Neoplecostomus, Pterosturisoma, Sturisoma, and Sturisomatichthys, the length of the symphysis of the cleithrum is approximately equal to twice as short as the coracoid symphysis (Fig. 47). Alternatively, in Loricaria, Pseudoloricaria, and Rineloricaria, the symphysis of the cleithrum is twice as long as the coracoid symphysis.

62. Bony lamina on ventrolateral portion of coracoid: (0) absent; (1) present (CI = 50; RI = 75).

The ventral surface of the pectoral girdle of loricariids possesses a fossa between the cleithrum and coracoid, termed the abductor fossa or arrector fossa that lodges the arrector ventralis profundus and arrector ventralis superficialis muscles, responsible for the movement of the pectoral fin (Schaefer, 1987: 24; 1991: 18).

In Lamontichthys avacanoeiro, L. parakana (the latter species not included in the analysis), Harttia, Hypostomus, and Neoplecostomus, there is no bony lamina covering the fossa, resulting in a complete exposure of the arrector fossa (Fig. 48a).

Within the Loricariinae, Lamontichthys filamentosus, L. llanero, L. maracaibero, L. stibaros, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys possess a bony lamina on the ventrolateral region of the coracoid that covers the lateral portion of the arrector fossa (Figs. 47 and 48b). This lamina connects the cleithrum anteriorly to the coracoid posteriorly and it was previously discussed by Schaefer (1987: 24).

A third condition of this character was proposed by Schaefer (1987: 24; 1991: 18; 1998: 397) as synapomorphic for the Hypoptopomatinae a taxon not included in the present study.

Although Lamontichthys avacanoeiro and L. parakana lack a bony lamina in the ventrolateral portion of the coracoid, these two species possess a thin bony plate, covered by odontods, embedded in the skin and firmly attached to the coracoid in the same position as the osseous lamina in the other taxa. These two species were coded as "0".

Pelvic fin and girdle

63. Contact between internal anterior processes of basipterygium: (0) in contact along their entire medial margins; (1) in contact anteriorly and posteriorly at midline, with a small foramen in between; (2) not in contact, with distal tip of each process close to each other or connected by ligaments (uninformative).

In the Loricariidae each basipterygium possess a pair of anterior processes, one internal and one lateral (Schaefer, 1987: 19) or anteromesial and anterolateral processes, respectively (Armbruster, 2004: 37). Different types of contact between the anteromesial processes of the basipterygia occur among examined taxa.

In members of the subfamily Loricariinae, the contralateral anteromesial processes are either not in contact, or contact each other only at their distal tips (Fig. 49a, ^b ). The remaining loricariids possess additional regions of contact and in Neoplecostomus they are in contact along their entire medial margins (Fig. 49c).

In Lamontichthys stibaros, the distal tips of the anteromesial processes are connected by ligaments.

64. Orientation of anteromesial processes of basipterygium: (0) antero-medial; (1) medial (CI = 100; RI = 100).

Harttia possesses the anteromesial processes of the basipterygium medially directed, a condition previously reported by Rapp Py-Daniel (1997: character 152) for the genus.

65. Relative width of two laminar expansions of anterolateral process of basipterygium: (0) dorsal wider than ventral; (1) dorsal and ventral of similar widths; (2) dorsal narrower than ventral (CI = 100; RI = 100).

In loricariids, the anterolateral process of the basipterygium possesses two laminar expansions for the attachment of the arrector dorsalis muscles (external process ridge of Shelden, 1937). One of these expansions is oriented ventral or ventrolaterally, and the other dorsal or dorsolaterally. Rapp Py-Daniel (1997: character 155) previously reported differences in the relative width of these laminar expansions in the Loricariinae.

In Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys both expansions are well developed and of similar widths. In Loricaria, Pseudoloricaria, and Rineloricaria, the dorsal expansion is considerably narrower than the ventral. Hypostomus and Neoplecostomus have the dorsal expansion of the anterolateral process of the basipterygium considerably wider than the ventral.

66. Presence and relative size of lateropterygium: (0) large; (1) medium; (2) small; (3) absent (CI = 100; RI = 100).

The lateropterygium is a bony structure that is connected with the lateral margin of the basipterygium dorsal to the insertion of the pelvic-fin rays, and is present in the Astroblepidae and Loricariidae (Shelden, 1937; Howes, 1983: 336). Armbruster (2004: 39) observed variation in the form of the lateropterygium among loricariids. Due to the difficulty in coding the variation observed in the format of the lateropterygium in the taxa examined in this study, such variation was coded in terms of differences in the relative size of the structure.

Neoplecostomus and Hypostomus possess a relatively large lateropterygium, its size approximately twice the length of that structure in Lamontichthys and Harttia (coded as having a medium sized lateropterygium) (Fig. 49). In the latter two genera the lateropterygium is twice the size of that structure in Farlowella, Loricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, taxa with a considerably small lateropterygium.

Howes (1983: 336) proposed that the lack of a lateropterygium is derived in the subfamily Loricariinae, a condition herein observed in Pseudoloricaria.

Anal-fin

The anal-fin in the majority of loricariids is formed by one relatively large anterior unbranched ray, followed by four branched rays, all supported by five pterygiophores. The anal-fin pterygiophores have the proximal and medial radials fused, with only the distal radial present as a separate element (Schaefer, 1987: 18).

67. First anal-fin pterygiophore: (0) completely covered by skin; (1) with small exposed area; (2) with large exposed area (uninformative).

Neoplecostomus possesses the first anal-fin pterygiophore completely covered by skin, lacking any exposed surface and Hypostomus possesses only one small exposed area. In all examined taxa of the Loricariinae the first anal-fin pterygiophore has a relatively large exposed area that supports dermal plates.

68. Centrum of articulation of first anal-fin pterygiophore: (0) centrum 15; (1) centra 12, 13 or 14 (CI = 100; RI = 100).

The articulation of the first anal-fin pterygiophore with the vertebral column in all examined taxa of the Loricariinae is on centra 12, 13 or 14. In Farlowella, Loricaria, Sturisomatichthys, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma, the articulation is on centra 12 or 13 and in Lamontichthys and Harttia the articulation is slightly posterior, on centra 13 or 14. In both cases, most often, the articulation is on centrum 13.

In the Astroblepidae and Callichthyidae, the articulation of the first anal-fin pterygiophore with the vertebral column is on centra 17, 18 or 19 and in the Loricariidae it varies from centra 13 to 17 (Schaefer, 1987: 25). Within loricariids, in the Hypostominae and Ancistrinae the articulation varies from centra 14 to 17, while in the Hypoptopomatinae and Loricariinae on centrum 13. This latter condition was proposed by that author as synapomorphic for the family Loricariidae.

69. Relative distance of adjacent proximal portions of first three anal-fin pterygiophores: (0) relatively distant; (1) relatively close; (2) in contact (CI = 66; RI = 80).

The anal-fin pterygiophores of the majority of loricariids are expanded along the anteroposterior axis. The degree of separation among the proximal region of the first three analfin pterygiophores varies among taxa, and three distinct conditions were defined by Rapp Py-Daniel (1997: character 122). Hypostomus has the proximal tips of the first three analfin pterygiophores relatively separate from each other (Schaefer, 1987: fig. 11a). In Harttia, Loricaria, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the proximal regions of the first three anal-fin pterygiophores are less separate, but are not in contact, while in Lamontichthys and Farlowella the proximal tips of the first three anal-fin pterygiophores are in (or almost) in contact (Figs. 39-41).

Caudal-fin

70. Number of principal caudal-fin rays: (0) 16 (i,7+7,i); (1) 14 (i,6+6,i); (2) 11-12 (i,5+5,i; i,5+4,i) (CI = 100; RI = 100).

There is a trend toward a reduction in the number of principal caudal-fin rays within the Siluriformes. Diplomystidae has 18 principal rays, but most Siluriformes possess 17 or fewer principal rays in the caudal-fin (Lundberg & Baskin, 1969: 35). Members of the Loricariidae usually possess 16 principal rays in caudal-fin (Schaefer, 1991: 17). In the subfamily Loricariinae there is a reduction of this number to 11-14 principal rays (Lundberg & Baskin, 1969: 35; Schaefer, 1987: 17; 1991: 17).

Lamontichthys, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys possess 14 principal caudal-fin rays. Farlowella, Loricaria, Pseudoloricaria, and Rineloricaria possess 11-12 principal caudal-fin rays.

71. Relative length and shape of upper and lower lobes of hypural plate: (0) symmetric, posterior border vertically aligned; (1) asymmetric, lower lobe extending beyond posterior margin of upper lobe; (2) symmetric, posterior border "V"- shaped (uninformative).

In the Loricariidae, the five hypurals and the uroneural are fused forming the "hypural plate", the parahypural is fused to hypurals 1 and 2; the uroneural and/or the epural are fused to hypurals 3, 4 and 5.

Within the Loricariidae there is variation in the shape of the posterior border of the hypural elements (Schaefer, 1987: 25). Neoplecostomus possesses a vertical posterior border with symmetric caudal lobes. In the Loricariinae the caudal fin-lobes are also symmetric, however the posterior border is "V" shaped due to the more posteriorly elongate median portion of the hypural plate. This condition was proposed by Schaefer (1987: 25) as synapomorphic for the subfamily Loricariinae.

Asymmetric caudal lobes occur in most loricariids including members of the Hypostominae (Schaefer, 1987: 25), represented in this study by Hypostomus.

72. Shape of hypurapophysis: (0) short, robust, approximately triangular; (1) short, robust, approximately quadrate; (2) relatively elongate, robust, keel-shaped; (3) broad, laminar, wing-shaped (CI = 100; RI = 100).

The hypurapophyses are projections on the parahypural and first and second hypurals of the caudal-fin skeleton of the Siluriformes, which serve as the insertion site for muscles involved in the movement of the caudal-fin rays (Schaefer, 1987: 17). Loricariids possess hypurapophysis type C (Lundberg & Baskin, 1969: 14), the most common among the Siluriformes in which the primary hypurapophysis is continuous with a secondary hypurapophysis on hypurals 1 and 2.

In the present study, four different conditions regarding shape of the hypurapophysis are recognized. Neoplecostomus and many loricariids possess a short and robust hypurapophysis, triangular to approximately quadrateshaped. Within the Loricariinae, Harttia possesses a robust hypurapophysis, relatively wide and keel-shaped, and in Lamontichthys, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the structures are broad, laminar and wingshaped (Figs. 43 and ⁵⁰ ).

73. Relative length of hypurapophysis: (0) short, not projecting to second preural centrum; (1) long, projecting to second preural centrum (CI = 100; RI = 100).

In loricariids in general, the hypurapophysis is short and does not project anteriorly to the second preural centrum. However, in all taxa of the Loricariinae examined the hypurapophysis extends anteriorly to the second preural centrum (Figs. 43 and ⁵⁰ ).

74. Process on ventral surface of hypurapophysis: (0) absent; (1) present (uninformative).

The ventral surface of the hypurapophysis of Lamontichthys avacanoeiro possesses a narrow ossified process posteroventrally oriented, probably serving as an additional site for the attachment of the caudal-fin musculature (^{Fig. 50} ; Schaefer, 1987: 17). There are no reports of any process on the hypurapophysis of other Siluriformes.

75. Presence and relative size of epural: (0) large, length approximately equal to height of lower lobe of hypural plate; (1) small, length shorter than 1/2 of height of lower lobe of hypural plate; (2) absent as a separate element (CI = 40; RI = 25).

The Siluriformes primitively possess a single epural, relatively large, separate from the dorsal hypurals (Lundberg & Baskin, 1969: 11). Among loricariids, this condition occurs in the Neoplecostominae, Hypoptopomatinae, and some Hypostominae, while in the Loricariinae and many Hypostominae there is a tendency of fusion of the epural to hypurals or reduction in epural size (Fig. 43; Schaefer, 1987: 17). Rapp Py-Daniel (1997: character 127) previously reported variation on the relative size of the epural in the Loricariinae.

Lamontichthys filamentosus, L. llanero, L. stibaros, L. avacanoeiro, Harttia, Pseudoloricaria, Pterosturisoma, and Sturisoma possess a separate epural. However, it is a relatively small ossification, shorter than half the height of the lower lobe of the hypural plate (^{Fig. 50} ). The epural is lacking as a separate element in L. maracaibero, Farlowella, Loricaria, Rineloricaria, and Sturisomatichthys.

76. Notch at median posterior border of hypural plate: (0) present, elongate, extending to 1/2 of length hypural plate; (1) present, extending to approximately 1/4 length of hypural plate; (2) extremely reduced or absent (uninformative).

The hypural plate of loricariids possesses a notch at its posterior median border, demarcating the separation between the upper and lower lobes (Schaefer, 1987: 17). There is a wide degree of variation in the extent of this notch in the family, including taxa that lack the notch. In the plesiomorphic condition for loricariids, present in Neoplecostomus, there is a deep notch in the hypural plate (Fig. 43b; Schaefer, 1991: 16).

In Lamontichthys filamentosus, L. llanero, L. maracaibero, L. stibaros, L. avacanoeiro, Harttia, Hypostomus, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the notch is relatively shorter extending to approximately 1/4 of the length of the hypural plate (Figs. 43a, c and ⁵⁰ ). In Farlowella, the notch is extremely reduced and inconspicuous.

77. Apophysis on second preural centrum: (0) absent; (1) one; (2) two, narrow; (3) two, broad (CI = 60; RI = 60).

The second preural centrum of the Siluriformes in general lack lateral bony projections (apophyses) but Rapp Py-Daniel (1997: character 130) reported the presence of one or two apophyses, on both sides of the second preural centrum in many loricariids. These apophyses are longitudinal, flangelike, and extend along the lateral portion of the vertebral centrum. The second preural centrum of Harttia, Neoplecostomus, Sturisoma, and Sturisomatichthys lack any apophyses (Fig. 43a, b). Farlowella and Pterosturisoma possess two narrow apophyses, and Lamontichthys, Loricaria, Pseudoloricaria, and Rineloricaria possess two broad apophyses (^{Fig. 50} ).

Schaefer (1987: 15, fig. 10) did not mention any apophysis on the second preural centrum of Hypostomus plecostomus, however, in the present study a single narrow apophysis was observed in the caudal skeleton of a specimen of Hypostomus examined (Fig. 43c).

Adipose fin

78. Adipose fin: (0) present; (1) absent (CI = 100; RI = 100).

The adipose fin, located between the dorsal-fin and the caudal-fin, is common among the Siluriformes. However, many Loricariidae lack this structure, such as the Loricariinae, members of the Hypoptopomatinae, Neoplecostominae and most of Rhinelepini (Armbruster, 2004: 31).

Miscellaneous

79. Groove on snout, anterior of nostril: (0) present, anterior portion formed by distinct fold of skin; (1) present, anterior portion not formed by distinct fold of skin; (2) absent (CI = 100; RI = 100).

Many loricariids possess a groove on the snout, extending longitudinally, from the anteriormost point of each nostril until the anteroventral border of the snout. The posterior portion of this groove runs between dermal plates or on the plates, and possess odontods along its margins. In Lamontichthys, Farlowella, Loricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys the anterior region of the groove is similar to the posterior region (Fig. 51).

In Harttia, Hypostomus, and Neoplecostomus, the anterior portion of this groove is formed by a distinct fold in the skin that runs on the plates (Fig. 52). Pseudoloricaria lacks a groove on the snout.

80. Surface of snout tip: (0) without plates, with thick layer of soft connective tissue covered by papillae; (1) without plates, with thick layer of soft connective tissue without papillae; (2) with plates on thick layer of soft connective tissue; (3) with plates, without thick layer of soft connective tissue (CI = 60; RI = 66).

The snout of the majority of the loricariids may be completely covered by plates, or the plates may be absent exposing a thick layer of soft connective tissue attached to the anterior tip of the mesethmoid (Schaefer, 1991: 20; Armbruster, 2004: 43).

Harttia, Hypostomus, Neoplecostomus, Rineloricaria, and Sturisoma lack plates on the snout tip and the soft connective tissue that is exposed possesses numerous, diminute and delicate papillae. Lamontichthys stibaros and L. avacanoeiro also lack plates on the snout tip but the soft connective tissue exposed lacks papillae. Lamontichthys parakana (not included in the analysis) also possesses this latter condition.

Lamontichthys filamentosus, L. llanero, L. maracaibero, Loricaria, Pseudoloricaria, Pterosturisoma, and Sturisomatichthys possess small plates covering a thick layer of soft connective tissue on the snout tip. This feature is more evident in adults. In juveniles of L. filamentosus the plates on the snout tip are not developed.

Although Farlowella has the snout tip covered by plates, it lacks the thick layer of soft connective tissue underneath the plates.

81. Plates on the upper lip: (0) absent; (1) present (CI = 50; RI = 83).

The majority of the Siluriformes possess lips without specializations. However, the Astroblepidae and the Loricariidae possess the lips modified into a sucking disk (Howes, 1983: 309; Armbruster, 2004: 42). The internal surface of the upper lip of loricariids is covered by papillae, but the external surface may have dermal plates.

Harttia, Loricaria, Pseudoloricaria, and Rineloricaria lack plates on the external surface of the upper lip, and in Lamontichthys, Farlowella, Pterosturisoma, Sturisoma, and Sturisomatichthys, these plates are present and covered by odontods (Fig. 51).

Although the species of Harttia possess a few diminutive plates on the anterior border of the snout, these plates do not cover the external surface of the upper lip.

82. Central buccal papillae: (0) absent; (1) present, small; (2) present, large (CI = 50; RI = 71).

Many loricariids possess a projection inside the mouth, on the median transversal line, behind the symphysis of the premaxillae. Armbruster (2004: 39) reported this structure as either absent or very small in Astroblepus, Lithogenes, and most loricariids. In the present study the presence of a small central buccal papillae and the absence of this structure were coded as different states. In Harttia and Lamontichthys (including L. parakana) this structure is relatively small and similar to the other papillae present in the mouth of loricariids (Fig. 9). Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Sturisoma, and Sturisomatichthys share with Hypostomus a relatively large, tongue-like central bucal papillae, with a wide basal portion.

83. Odontods on lateral plates of median series: (0) covering all plate, similar to odontods of other body plates; (1) covering all plate, slightly longer on posterior border of plates; (2) long and restricted to posterior portion of plate; (3) covering all plate with one or two rows of odontods increasing in length and width along the median portion of each plate (CI = 75; RI = 75).

Members of the Loricariidae possess the body plates, fin rays, skull bones, opercular series and pectoral and pelvic girdles covered by odontods (Howes, 1983: 309).

The odontods of the lateral plates of the median series in Hypostomus and Neoplecostomus cover all plate and have similar morphology and size as the odontods of the remaining of body. The odontods of the lateral plates of the median series of the body in members of the Loricariinae examined in the present study are rather, more developed than the odontods of the remaining of the body. In Lamontichthys, Farlowella, and Harttia, the odontods cover all plate and are slightly larger on the posterior margin of the plate forming an inconspicuous keel along the median series of plates (Fig. 53a; state 1). The odontods of the lateral plates of the median series of Loricaria, Pseudoloricaria, Rineloricaria, and Sturisoma also cover all plate but instead, have one or two rows of odontods increasing in length and width along the median portion of each plate (Fig. 53b). In Pterosturisoma the odontods are restricted to the posterior portion of each lateral plate of the median series, although they may be absent in a few plates along the median series (Fig. 53c).

The differences in size and distribution of the odontods on the lateral plates of the median series (states 1, 2 and 3) together with those on the mid-ventral series result in longitudinal keels of various degrees of development.

84. Predorsal plates between posterior tip of supraoccipital and nuchal plate: (0) three or more small plates not aligned along the midline; (1) two pairs of large plates, fused in the midline; (2) three pairs of large plates, fused in the midline; (3) six or more pairs of large plates, fused in the midline (CI = 60; RI = 0).

In the Loricariinae the predorsal plates are typically paired, large and fused in the median line of the body, while in Neoplecostomus these plates are relatively small and are not aligned in the median line of the body. Lamontichthys, Harttia, Pseudoloricaria, Pterosturisoma, and Rineloricaria possess only two paired predorsal plates. In the derived conditions, there is an increase of the number of predorsal plates. Loricaria, Sturisoma, and Sturisomatichthys possess three paired predorsal plates, while Farlowella possesses six paired predorsal plates (Fig. 54). According to Boeseman (1971: 16), members of the Loricariinae possess two plates between the supraoccipital and the nuchal plate, with a greater number in Farlowella (6-8) and Sturisoma (2-3).

85. Number of predorsal plates between neural spine of sixth and seventh vertebrae: (0) three; (1) two; (2) one (uninformative).

Lamontichthys, Harttia, Loricaria, Pterosturisoma, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys possess two predorsal plates on the body in the region between the sixth and the seventh vertebra (Fig. 38). In Farlowella, there is a reduction of this number, and only a single plate is present in this region, a condition also present in Acestridium discus (Hypoptopomatinae).

86. Supracaudal plates: (0) short and numerous; (1) elongate and few (CI = 100; RI = 100).

Loricariids have plates on the base of the caudal-fin, posterior to the last row of plates of the caudal peduncle(Schaefer, 1987: 25). In the Loricariinae, there are usually 3-5 supracaudal plates on each side, horizontally elongate andjoined by conective tissue to the lateral region of the caudal-fin. In other loricariids these plates are short and numerous (six or more plates) (Fig. 35).

Schaefer (1987: 25) proposed the presence of elongate plates on the base of the caudal-fin as synapomorphic for the subfamily Loricariinae, but did not refer to the number of plates.

87. Long filament at distal tip of dorsal-fin spine: (0) absent; (1) present (CI = 100; RI = 100).

Many members of the Loricariinae possess the unbranched caudal-fin rays projecting as long filaments. There are few reports about the presence of long filaments in the other fins probably because it is a fragile structure and commonly damaged in specimens, and/or because there are relatively few taxa with long filaments in the unbranched fin-ray. Many members of the Loricariinae possess the pectoral-fin spine forming only a short filament, however L. filamentosus and Pterosturisoma possess elongate filaments.

Isbrücker & Nijssen (1974) considered the presence of a long filament in the dorsal-fin as diagnostic for Planiloricaria. Species of Sturisoma and Loricaria also possess this feature. Among the loricariids included in the present analysis, L. filamentosus and L. llanero possess the dorsal-fin spine projecting as a long filament sometimes longer than the standard length of the specimens.

Phylogenetic reconstruction. The parsimony analysis, including 87 osteological and external morphology characters of Lamontichthys and related groups (Table 4), resulted in three most parsimonious cladograms with 194 steps, consistency index of 0.73 and retention index of 0.78 (Fig. 55). The cladograms differ only in the hypothesized phylogenetic relationships of two outgroup taxa Pterosturisoma and Sturisoma. The list of synapomorphies that support hypothesis of the monophyly of Lamontichthys and relationships among its species are detailed below.

Monophyly of Lamontichthys

Character 13 (1>4): Trapezoidal shape of lower pharyngeal plate.

Character 14 (1>2): Triangular and relatively long posterior expansion of first epibranchial.

Character 23 (0>1): Large coronoid process of dentary, with large robust area, not concave.

Character 60 (0>1): Presence of I-7 pectoral-fin rays.

Character 69 (1>2): Proximal portions of first three anal-fin pterygiophores in (or almost) in contact. Independently acquired in Farlowella.

Character 77 (0>3): Presence of two broad apophyses on second preural centrum. Independently acquired in clade formed by Loricaria, Pseudoloricaria, and Rineloricaria. Ambiguous characters:

Character 10 (0>1): Narrow ventral laminar expansion along posterior border of anterior ceratohyal gradually widening from medial to lateral portion. Also present in Harttia and Sturisoma.

Character 51 (1>0): Presence of 23-25 caudal vertebrae. Also present in Farlowella, Sturisoma, and Pterosturisoma .

Character 58 (0>1): Presence of transverse process on sixth dorsal-fin pterygiophore. Also present in Farlowella, Pterosturisoma, Rineloricaria, and Sturisoma.

Character 82 (1>2): Presence of large central buccal papillae. Also present in Harttia.

Monophyly of clade formed by Lamontichthys avacanoeiro and L. stibaros

Character 80 (2>1): Snout tip covered by soft connective tissue lacking papillae.

Autapomorphies of Lamontichthys avacanoeiro

Character 10 (1>2): Broad ventral laminar expansion along posterior border of anterior ceratohyal gradually widening from medial to lateral portion.

Character 18 (0>1): Posterior process of palatine extending beyond anterior condyle of lateral ethmoid. Independently acquired in Loricaria.

Character 37 (0>1): Presence of one dermal plate between infraorbitals 2 and 3.

Character 39 (1>2): Presence of flange on lateral region of seventh precaudal vertebra posteriorly directed.

Character 62 (1>0): Lack of bony lamina covering part of arrector fossa on ventrolateral portion of coracoid.

Character 74 (0>1): Presence of process on ventral surface of hypurapophysis.

No autapomorphies were found to diagnose Lamontichthys stibaros in the present study.

Monophyly of clade formed by Lamontichthys filamentosus, L. llanero, and L. maracaibero

Character 1(0>1): Presence of ventral groove on anterior tip of mesethmoid.

Character 27 (0>1): Teeth with short cusps, main cusp slightly larger and broader than lateral cusp. Independently acquired in clade formed by Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma.

Monophyly of clade formed by Lamontichthys filamentosus and L. llanero

Character 21 (0>1): Cup-shaped region of premaxilla distinctly longer than cup-shaped region of dentary.

Character 87 (0>1): Dorsal-fin spine projecting as long filament sometimes longer than standard length of specimens.

No autapomorphies were found to diagnose Lamontichthy s filamentosus in the present study.

Autapomorphies of Lamontichthys llanero

Character 44 (0>1): Ventral bilateral projections on second caudal vertebra distinctly posteriorly directed and with distal tip sutured to first anal-fin pterygiophore.

Autapomorphies of Lamontichthys maracaibero

Character 75 (1>2): Lack of epural as a separate element. Independently acquired in Sturisomatichthys, and clade formed by Farlowella, Loricaria, Pseudoloricaria, and Rineloricaria sp.

Discussion

The monophyly of Lamontichthys. In the present study six characters are proposed as synapomorphic for Lamontichthys. One of them, the presence of seven branched pectoral-fin rays was previously proposed by Isbrücker & Nijssen (1976, 1978b) as diagnostic for Lamontichthys. This character state also occurs in Harttia leiopleura and Rineloricaria daraha, but all other species of Harttia and Rineloricaria possess six branched pectoral fin rays, therefore it apparently was independenlty acquired in the latter two species. The two species described herein, L. avacanoeiro and L. parakana also possess seven branched pectoral-fin rays. The remaining five characters are proposed as synapomorphic for the genus for the first time in the present study. Three of these synapomorphies are exclusive of Lamontichthys among examined taxa (characters 13, 14 and 23).

Phylogenetic relationships among the species of Lamontichthys. The present study represents the first attempt to propose a hypothesis of relationships among the species of Lamontichthys. Within the genus, two main clades are recognized, one formed by L. maracaibero, L. filamentosus, and L. llanero, and the other by L. avacanoeiro and L. stibaros (Fig. 55).

The clade formed by L. maracaibero, L. filamentosus, and L. llanero is supported by two synapomorphies, one of which is uniquely derived for this clade (character 1) and one homoplastic (character 27). Within this clade L. filamentosus is proposed as the sister taxa to L. llanero on the basis of two uniquely derived characters (characters 21 and 87).

The clade formed by L. avacanoeiro and L. stibaros is supported by one exclusive derived character (character 80). Although L. parakana was not included in the phylogenetic analysis, the presence of I, 7 pectoral-fin rays (character 60) clearly diagnose the species as a member of Lamontichthys.

Within Lamontichthys, L. parakana shares with L. avacanoeiro the presence of one plate without a laterosensorial canal between infraorbital 2 and 3 (character 37), a condition present only in these two species among all taxa examined in this study; and the lack of an osseous lamina in the ventrolateral region of the coracoid, covering the lateral portion of the abductor fossa of the pectoral girdle (character 62), a feature present in these two species and Harttia among examined loricariines. Therefore, it is tentatively proposed that L. parakana is more closely related to L. avacanoeiro.

Comments on Pterosturisoma microps. The genus Pterosturisoma was described by Isbrücker & Nijssen (1978b) on the basis of the examination of type-specimens of Harttia microps Eigenmann & Allen (1942: 211) from Peru, in the upper rio Amazonas basin. In that study, the authors pointed out the similarity of this species with the then known species of Lamontichthys, both in the general appearance of the body and in the presence of the filamentous extension of the pectoral-fin spine. However, Pterosturisoma differs from Lamontichthys in the presence of six branched pectoral-fin rays (vs. seven in Lamontichthys), the more developed pores of the lateral line, the narrow dorsal region of the cleithrum (vs. wide), and the horizontal flattening of the predorsal plates.

Two autapomorphies are herein proposed for Pterosturisoma microps: 1) the lack of a crest on the lateral surface of hyomandibula for the insertion of the levator arcus palatini muscle (independently acquired in Loricaria) (character 31, 0>1); 2) the elongate and narrow distal portion of the hemal spine of the last precaudal vertebra (character 40, 1>2). Isbrücker & Nijssen (1978b) included Pterosturisoma in the tribe Harttiini based on the presence of the lateropterygium, a well developed palatine splint, and large maxillae.

In the present analysis, Pterosturisoma appears within a clade that includes Sturisoma, Farlowella, Rineloricaria, Pseudoloricaria, Loricaria, and Sturisomatichthys (Fig. 55), however, its phylogenetic relationships within this clade remains unresolved.

Comments on the patterns of geographic distribution of Lamontichthys. Up to the present, Lamontichthys filamentosus was recorded for the upper rio Amazonas basin. In the present study, the known distribution range of the species is extended eastwards to the middle Amazon basin (rio Amazonas-Solimões between the mouths of rio Purus and rio Madeira) (Fig. 2). Lamontichthys stibaros also occurs in the upper rio Amazonas and is found in sympatry with L. filamentosus in the drainages of río Ucayali and río Marañon. All other species of Lamontichthys have allopatric distributions. Two of them occur in Venezuela, L. llanero in the upper portions of tributaries of the rio Orinoco, and L. maracaibero, in the lago Maracaibo system. The two remaining species of Lamontichthys, described in the present study, occur in the Brazilian drainage of rio Tocantins and represent a considerable extension of the known distribution range of the genus. Lamontichthys avacanoeiro occurs in various localities in the upper portions of that river basin and L. parakana is known only from the type locality in the lower rio Tocantins, below Tucuruí Dam (Fig. 2).

Based on the available information on the distribution of Lamontichthys (Western Amazon, rio Orinoco, and lago Maracaibo), Lima & Ribeiro (in press) characterized the distribution of the genus as clearly presenting a foreland distribution pattern, in which a foreland basin is defined as elongated, tectonically imposed lowlands, located between uplands areas of the Andean chain in the west, and the Brazilian Shield in the East. Lima & Ribeiro (in press) also commented on the fact that many fish taxa that has a lowland distribution pattern in the western-central Amazon basin also occur in the rio Tocantins system. Therefore, it is interesting to note that the two new species of Lamontichthys described herein also occur within that river drainage.

Acknowledgements

A previous version of this work was part of a dissertation submitted by the first author in partial fulfillment of a Master's degree in Zoology at Instituto de Biociências of Universidade de São Paulo. The latter institution and Museu de Zoologia da Universidade de São Paulo provided work space and access to all facilities. We are indebted to the following individuals and institutions for the loan of specimens, information, and other types of assistance: John G. Lundberg and Mark Sabaj Pérez (ANSP); Jaime Sarmiento (Colección Boliviana de Fauna, La Paz); Flávio Bockmann (FFCLRP/LIRP-USP); Barry Chernoff and Mary Anne Rogers (FMNH); José Ivan Mojica (ICNMHN); Larry Page and Mike Retzer (INHS); Lúcia Rapp Py-Daniel, Marcelo Rocha and Maria A. S. Brazil (INPA); Jeff A. Siegel (LACM); Francisco Provenzano (MBUVC); Donald Taphorn (MCNG); Roberto E. Reis and José F. P. Silva (MCP); Wolmar B. Wosiacki and Cristiano Trinca (MPEG); Paulo A. Buckup, Marcelo R. Britto, Arion T.Aranda (MNRJ); OsvaldoT. Oyakawa, José L. de Figueiredo, and Vivian Oliveira(MZUSP); Richard Winterbottom (ROM); Érica Caramaschi and Renata Bartolette (UFRJ); and Richard P. Vari (USNM). Eduardo Baena prepared photographs of figures 8, 10, 11 and 13. Carlos Magenta provided help with image editing. The maps of South America are based on a map prepared by Marilyn Weitzman. Flávio C. T. Lima and Alexandre Ribeiro kindly provided access to an unpublished version of a manuscript on the biogeography of South American freshwater fishes. For helpful discussions and suggestions on many topics related to the present study we thank Flávio C. T. Lima, Marcelo R. Britto, Mario de Pinna, and especially, Osvaldo T. Oyakawa. This manuscript greatly benefited from the suggestions of Lúcia Rapp Py-Daniel and an anonymous reviewer. Financial support for this project was provided by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, 02/01341-1), PRONEX - FINEP/CNPq (661058/19972), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

Literature Cited

Accepted September 22, 2009

Published December 18, 2009

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