Etymology.

The name of this species is a noun in apposition referring to the “Curupí”, a goblin of the Guaraní mythology whose legend says that it chases women in the forests when they venture alone to get firewood.

Diagnosis and comparisons.

Medium sized species of Tityus belonging to the bolivianus complex. Tityus curupi is most closely related to T. uruguayensis; both species can be separated because the external VSM carinae of tergite V of T. uruguayensis are short and straight, occupying the median third of the segment (Fig 3G), whereas in T. curupi these carinae are more developed occupying the median half of the segment, and are curved towards the external margin, forming a semi-arc and partially surrounding the lateral macrosetae (Fig 3H).

The external VSM carinae of tergite IV are also more developed in T. curupi than in T. uruguayensis; in T. uruguayensis these carinae are restricted to the posterior margin of the segment occupying less than a posterior quarter of it (Fig 3G), whereas in T. curupi they occupy the posterior half or even two thirds, of the segment (Fig 3H).

The subaculear tuberlcle of the telson is also useful to separate T. curupi n. sp. from T. uruguayensis; in T. curupi n. sp. the posterior apex is pointy, the ventral margin clearly serrated and the dorsal paired spines most usually clearly separated (Fig 5E and 5F). In T. uruguayenis, on the other hand, the distal margin of the subaculear tubercle is dull, the ventral margin, only slightly undulated, and the dorsal paired spines reduced, and most usually fused in a single tiny granule (Fig 5D) [1].

Tityus curupi is larger in average size than T. uruguayensis, total length of males of T. uruguayensis varies from 25 to 30 mm [1], whereas in males of T. curupi it varies from 36 to 42 mm; total length of females of T. uruguayensis varies from 28 to 39 mm [1], whereas in females of T. curupi it varies from 36 to 47 mm.

The most conspicuous diagnostic characters to separate both species are from the pigment pattern; T. curupi bears three medium sized spots on the tergites which occupy less than a quarter of the segment each, leaving two longitudinal broad depigmented dorsal stripes (Fig 3B) whereas T. uruguayensis presents three large dark spots that occupy almost a third of the segment each, leaving only two thin depigmented dorsal stripes (Fig 3A). The dorsal surface of pedipalpal femur and patella of T. uruguayensis are densely pigmented (Fig 3E), whereas in T. curupi they are depigmented (Fig 3F). Tityus uruguayensis presents two VSM dark spots in the posterior third of metasomal segments, that in metasomal segment V can extend over the VSM carinae reaching the anterior third of the segment (Fig 3C), whereas in T. curupi the ventral surface of metasomal segments is usually depigmented, or presents abarely visible brownish spot in the posterior margin of each segment, which can extend over the VL carinae on segments I-IV, and over the VM carina in segment V (Fig 3D).

Due to its size and pigment pattern T. curupi n. sp. could be confused with Tityus trivittatus Kraepelin 1898 which occurs in neighbouring areas of lowlands of Corrientes province [1], but not in the hills of Paraje Tres Cerros. Both species can be easily separated because in females of T. trivittatus the first (or basal) median lamella of pectines is not lobular and is similar in size in females and males [1], whereas in females of T. curupi. n. sp it is clearly lobular (Fig 5G) and much larger than in males (Fig 5H). Both species can also be separated because the hemispermatophore of T. curupi n. sp. lacks the median lobe and its external lobe is dorsally fused to the trunk by a thin lamina (Fig 6B), whereas the hemispermatophore of T. trivittatus bears a median lobe, and its external lobe is not fused dorsally to the trunk of the hemispermatophore [1].

Description: Based on the holotype ♂, and paratypes (MACN).

Total length: 36.77–42.00 mm (n = 2; mean = 39.39) in ♂; 36.00–47.50mm (n = 6; mean = 41.70) in ♀. Color: Base color yellowish, with dark brown pattern in chelicerae, carapace and tergites (Fig 2B and 2C). Chelicerae: light yellow with a dense reticulate pattern in manus. Carapace: with black areas around ocular tubercle and lateral eyes; with a dark triangle raging from the ocular tubercle to the frontal margin; lateral areas with dark reticular pattern; with two posterolateral dark spots. Tergites I–VI (Fig 3B) each with three triangular dark spots extending the entire length of the segment, two lateral, and a median dark spot; these spots are not connected to each other, leaving two wide unpigmented stripes, however in the posterior margin of the segment between lateral and median spots, there is an area with an orange pigment, different from the yellowish base color. Tergite VII with a lateral faint dark spot on each side, and a median triangular spot extending the anterior two thirds of the segment. Sternites, sternum, genital opercula and pectines unpigmented. Metasomal segments I-IV unpigmented or with a faint brownish spot in the posterior margin of the segment, extending over the VL carinae; segment V unpigmented or with faint brownish pigment in the posterior third of the segment, extending as a ventro-median stripe over the VSM carina (Fig 3D). Telson, vesicle unpigmented, or with faint reddish pattern on ventral surface, acculeus dark reddish-brown. Pedipalps: completely unpigmented in most specimens, but in some specimens some areas with a faint brownish pattern in femur, patella and over pedipalp carinae and fingers (Fig 3F). Legs: unpigmented or with a faint brownish pattern in the distal half of femur and in patella. Carapace: Anterior margin with a conspicuous broad median notch that divides the anterior margin into two lobes. Surface densely granular. Anteromedian longitudinal sulcus, interocular sulcus; posteromedian longitudinal and lateral sulci present and conspicuous. Median ocular tubercle well developed, and clearly protruding above carapace in lateral profile; median ocelli well developed, approximately one diameter apart. Three small lateral ocelli on each side of carapace. Anterior median carinae, median ocular carinae, lateral carinae, and posterior carinae all granular and well developed. Chelicerae: Tegument granular, especially near the distal margin. Dentition typical for the genus. Teeth well developed. Pedipalps: Femur (Fig 4G), surface sparsely granular; DE, DI, VE and VI carinae granular and well developed, extending the entire length of the segment; internal margin with an interno-median (IM) carina extending the entire length of the segment. Patella (Fig 4F) intercarinal surfaces sparsely granular DI, DM, DE, IM VI, VE and EM carinae granular, extending the entire length of the segment. Chela manus slender (s4A−E), DI, DE, DS, D, SD, E, VE, VI, and IM carinae granular and well developed (Fig 4A); fixed and movable fingers thin, elongated and slightly curved internally; movable finger with 14, or more usually 15, sub-parallel denticle rows, being the basal row longitudinal and sometimes formed by the fusion of two denticle rows; fixed finger with 14 or 15 sub-parallel denticle rows, being the basal row longitudinal and always formed by the fusion of two or three denticles rows; each of these denticles rows presents and apical enlarged tooth and two basal enlarged teeth, which are two or three times bigger than the rest of the denticles; the apical enlarged tooth presents a hyaline and a chitinized setae in the base of it; the most apical of the basal enlarged denticles presents a single hyaline setae in its base, and the most basal presents a chitinized setae in its base; at the apical margin of each finger there is an apical tooth with four lamellar setae surrounding its basal margin. Movable finger with a basal lobe poorly developed, slightly more so in ♂; fixed finger with a small shallow notch facing the basal lobe. Trichobothrial pattern Orthobothriotaxic Type A; femur with 11 trichobothria, α configuration and trichobothria D₂ placed on the internal surface (Fig 4G); patella with 13 trichobothria (Fig 4F); chela with 15 trichobothria, being esb petit (Fig 4A–4E). Legs: Intercarinal surfaces granular. Carinae granular, extending the entire length of the segment. Basitarsi each with two well-developed, equal-length pedal spurs; the external one presents an external, very well developed, macroseta. Telotarsi short, ventrally with abundant chitinized setae, and some VL hyaline setae with following counts, on legs I and II: 4/3, III and IV: 4/4.Ungues well developed, equal in length and curved. Sternum: Sub-triangular (Fig 5G and 5H). Genital opercula: Medium sized. Sclerites subtriangular, in ♀ the posterior margin of the sclerites is perpendicular to the axis of the body, whereas in ♂ it forms an acute angle (Fig 5G and 5H). Pectines: With a single row of median lamellae; first median lamella conspicuously more enlarged in females than in males (Fig 5G and 5H). Fulcra present, small and subcircular. Pectinal teeth medium sized; tooth count: 14–15 in ♂ (n = 6; median = 15), 13–16 in ♀ (n = 7; median = 15). Tergites: Pretegites with fine granulation, separated from the rest of the tergite by a well-developed transversal carina. Tergites I–VI, surfaces granular becoming more coarsely so in the posterior half of the segment; with three longitudinal carinae, one Dorsal-Median extending the entire length of the segment and two Dorso-submedian in the anterior third of the segment, joining the transversal carina of pretergite, and forming a semi-arc. The dorsal median carina is formed by a single row of granules that becomes double in its median part. Tergite VII surfaces granular, Dorsal-median carina extending the anterior two thirds of the segment, formed by a double row of granules in its anterior half, fusing in a single row in the second half; with four longitudinal Dorso-submedian carinae extending the entire length of the segment, fusing anteriorly to each other in a subcircular transversal carinae, that also fuses in its anterior margin with the transversal carina of pretergite. Sternites: Sternite I finely granular near the lateral margins, with two VSM furrows joining in the anterior margin and surrounding a glandular subtriangular area, also delimitated by a row of setae, this gland is more conspicuous in males than in females; with small, elliptical spiracles. Sternite II: tegument finely granular, with scattered setae and two small VSM furrows reduced to an indent, with small, elliptical spiracles. Sternite III: similar to II but with a posteromedian, subtriangular gland, more conspicuous in males. Sternite IV: similar to II but with four longitudinal carinae, formed by a single row of granules, the external carinae occupy the posterior two thirds of the segment, whereas the internal carinae occupy the posterior half of the segment. Sternite V: tegument granular, with four VSM carinae (Fig 3H), the external carinae are placed in the median part of the segment and forming a semi-arc towards the external margin, the internal carinae are longitudinal and placed in the posterior two thirds of the segment; in some specimens there is a poorly developed VM carina in the anterior third of the segment. Metasoma: Metasomal segment I: intercarinal surfaces finely granular; DL, LSM, LIM, VL and VSM carinae granular end extending the entire length of the segment; distal granules of the DL carinae slightly spinoid (Fig 5B); between DL and LSM carinae there is an intermediate poorly developed carina in some specimens. Segment II similar to segment I but LIM carina is only present in the posterior half of the segment. Segments II and IV similar to segment II but without LIM carina. Segment V, elongated (Fig 5C), dorsolateral margin with a poorly developed LSM carina, VL and VM carinae granular and extending the entire length of the segment (Fig 5A); with poorly developed VSM carinae, formed by tiny granules, but extending almost the entire length of the segment. Telson: Vesicle oval, being slightly more globose in females (Fig 5E and 5F). Surface smooth, except for a poorly developed VM carina and some scattered setae. Subaculear tubercle subtriangular, inferior margin partially serrated and connecting to the VM carina, base of the superior margin with two granules that in some specimens are fused to each other. Aculeus strongly curved. Hemispermatophore: Slender (Fig 6A). Pars reflexa poorly developed. Lobe region poorly developed, Internal lobe short, Basal lobe hook-like, External lobe barely visible, connected to the trunk of the hemispermatophore by a thin cuticular lamina (as in the rest of the species of the bolivianus complex) (Fig 6B).

Distribution and ecology.

Tityus curupi n. sp. has only been collected in its type locality in the low hill range of Paraje Tres Cerros, in north eastern Corrientes province, in northern Argentina (Fig 2). Tityus curupi n. sp. has been collected in the three hills of the area (Figs 1A and 2B–2D), but not in the surrounding grasslands and forests. Tityus curupi n. sp. is a litophilous species which only occurs in the rocky reliefs of the hills. At night most specimens were observed hunting in crevices between stones. Tityus curupi n. sp. is in sympatry with only one scorpion species Bothriurus jesuita Ojanguren-Affilastro 2003; however this bothriurid, which is common in northeastern Argentina [50, 51], occupies a different microhabitat, being more common in the plains surrounding the hills.

Tityus curupi n. sp.

Two males of T. curupi n. sp. presented 2n = 32 holokinetic chromosomes at mitosis (Fig 7A). Postpachytene cells showed 16 achiasmatic bivalents (16II) (Fig 7B), compounded of chromosomes decreasing in size from 4.4 to 2.2% of the TCL (Table A in S2 Table). Cells at second meiotic division presented n = 16 chromosomes (Fig 7C). FISH with 28S rDNA probes revealed conspicuous signals at the terminal region of both chromosomes of the second largest bivalent, comprising almost one third of its length (Fig 7D). C-banding revealed conspicuous bands at the terminal region of one bivalent, that colocalize with the rDNA site and small bands at the terminal regions of almost all the other chromosomes (Fig 7E). FISH with (TTAGG)_n telomeric probes revealed a bouquet configuration at leptotene/early zygotene (Fig 7F). At postpachytene, telomeric signals were detected at the terminal regions of all chromosomes, without any interstitial signals (Fig 7G). The other male presented 2n = 31 chromosomes (Fig 7H), and at meiosis I showed 14 bivalents and one trivalent (14II+III); the latter consist of a large chromosome (similar in size to the chromosomes of the larger bivalents) and two smaller chromosomes (Fig 7I). Cells at second meiotic division presented n = 15 or n = 16 chromosomes (Fig 7J and 7K). This cytotype showed rDNA sites with the same features of the cytotype with only bivalents (Fig 7L). C-banding pattern was similar to that observed in the cytotype with only bivalents, plus one interstitial C-band in a large chromosome (Fig 7M), that corresponds to the large chromosome of the trivalent (Fig 7N).

Tityus uruguayensis.

The nine males of T. uruguayensis presented 2n = 31 holokinetic chromosomes at mitosis, similar in size to the ones in T. curupi n. sp. (Fig 8A). All the males presented a heptavalent at postpachytene, compounded of chromosomes of uneven size: two large of different size (5.3 and 4.1% of the TCL), four medium (3.0, 3.1, 2.5 and 2.3% of the TCL) and one small chromosome (1.7% of the TCL), which were numbered one to seven (see inset in Fig 8B; Table B in S2 Table). In seven of these males the remaining chromosomes appeared as bivalents (12II+VII) (Fig 8B), compounded of chromosomes decreasing in size from 4.3 to 2.3% of the TCL (Table B in S2 Table). Each of the other two males showed 10 bivalents plus different quadrivalents: one male presented a ring quadrivalent formed by chromosomes of similar size (10II+RIV+VII) (Fig 8H), while the other presented a chain quadrivalent composed of two large, one medium and one small chromosome (10II+CIV+VII) (Fig 8K). Cells at second meiotic division presented n = 15 or n = 16 chromosomes in all the analyzed males (Fig 8C and 8D). FISH with 28S rDNA probes revealed signals at the terminal region of two chromosome pairs that constitute two bivalents at meiosis I in all cytotypes (Fig 8E, 8I and 8L). In the chain quadrivalent cytotype, an extra signal was detected in one terminal region of the second chromosome of the heptavalent (Fig 8L). C-banding revealed conspicuous terminal bands that colocalized with the ribosomal clusters and smaller bands at the terminal region of almost all chromosomes in the three cytotypes (Fig 8F, 8J and 8M). FISH with (TTAGG)_n telomeric probes also revealed a bouquet configuration at leptotene/early zygotene and at postpachytene, telomeric signals were exclusively detected at the terminal regions of all chromosomes (Fig 8G).

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Fig 8.

Male mitosis and meiosis of Tityus uruguayensis. after Giemsa staining (A-D, H, K), C-Banding stained with DAPI (F, J, M), FISH with 28S rDNA (E, I, L) and (TTAGG)_n telomeric probes (G). A. Mitotic metaphase (2n = 31); B. Prometaphase I (12II+VII). Inset: scheme of the heptavalent; C, D. Metaphase II cells of a male with 12II+VII (n = 15 and n = 16, respectively); E, F, G. Prometaphase I (12II+VII); H, I, J. Prometaphase I (10II+RIV+VII); K. Prometaphase I (10II+CIV+VII). Inset: scheme of the chain quadrivalent; L, M. Prometaphase I. White arrowheads indicate 28S rDNA hybridization signals. Empty arrowheads indicate C-bands corresponding to rDNA sites. Asterisks indicate the chain quadrivalent. Scale bar = 10 μm.

https://doi.org/10.1371/journal.pone.0181337.g008