Trachipterus fukuzakii Fitch 1964

Trachipterus fukuzakii Fitch, 1964 — TRACHIPTERIDAE

Tapertail ribbonfish (En); Listoncillo pabilo (Sp) (Figure 3, Tables 1 and 4)

Material examined. 1 specimen (UCR 2901-2.001); adult, 1071 mm TL, 1049 mm SL, collected near Golfito, Puntarenas, Costa Rica, eastern Pacific Ocean, 8° 36' 17.25" N, 83° 12' 35.23" W, on 25 October 2010, by Federico Hampl using long line.

Diagnostic characters. A member of Trachipteridae in congruence with the diagnostic characters listed for the family in Heemstra & Kannemeyer (1984, 1986b), Olney (2003d) and Nelson (2006). Generic and specific diagnostic characters are listed below, all in accordance with descriptions of specimens by Fitch (1964) and Savinykh & Baitalyuk (2011).

Ventral portion of tail covered by spiny plates (vs. smooth, not covered by spiny plates in species of Desmodema); caudal fin divided in two lobes (vs. not divided in two lobes in species of Desmodema); dorsal-fin rays about 160 (vs. 115–150 in species of Zu); lateral line straight, as a series of oval spiny plates (vs. as a zigzag series of elongate spiny plates in species of Zu); ventral edge of body straight (vs. usually scalloped in species of Zu) and with bony tubercles (without bony tubercles in species of Zu); precaudal vertebrae 26 (vs. usually more than 30 in all other known species of Trachipterus), preanal vertebrae 40 (vs. usually more than 45 in all other known species of Trachipterus), total vertebrae 71 (vs. usually more than 80 in all other known species of Trachipterus; Fitch 1964, Heemstra & Kannemeyer 1984, Savinykh & Baitalyuk 2011).

Description. Measurements and counts, as well as comparative data, are presented in Table 4. Body elongate, ribbon-like, highly compressed, covered with oval-shaped spiny plates. Dorsal profile sloping down evenly and in a straight line from the forehead, dorsal to the orbit, posteriorly to the caudal region; ventral profile nearly straight (parallel with the body axis) for almost its entire length; posterior to anus, the dorsal and ventral profiles gradually converge forming an elongate and tapered tail whose length correspond to about 33% of SL; ventral contour of body with several rows of stiff, pointed, fleshy papillae which diminish in size caudally. Maximum body depth about one head length anterior to the anus.

Head length about 30% of snout-vent length; snout length about 82% of eye diameter; end of maxilla anterior to the center of the orbit. Dorsal-fin origin posterior to the middle of the orbit; first dorsal-fin rays apparently elongated but broken, subsequent rays relatively short, becoming longer toward the center region of the body, with the maximum height of fin anterodorsal to the anus; pectoral fins low; pelvic fins completely reduced to the bases, with no shortened pelvic-fin rays or nubbins; caudal fin divided in two lobes, the upper lobe upturned, with eight rays, the lower lobe, on the horizontal axis of the body, represented by six rudimentary spiny nubbins.

inconspicuous) or unavailable are representeđ with an en-đash (Q).

Character UCR 2901-2.0 0 1 Fitch (1964) Fitch (1967) Charter & Moser (1996 a) Morphometrics

Color in live not recorded. Color in alcohol (see Figure 3) brown, with the head, opercular region and tail darker, a small, ovate dark blotch at the dorsal contour under the rays 20–23, and narrow dark streaks on both the dorsal and ventral contours running out the caudal-fin base.

Remarks. The species T. altivelis (originally described from the coast of Chile) as diagnosed by Fitch (1964), and according to Hamilton (1915), Palmer (1961) and Heemstra & Kannemeyer (1984), overlaps, in all meristics and most measurements presented, with the descriptions of the species T. trachypterus (originally described from the Mediterranean Sea). Although Fitch (1964) synonymizes T. weychardi Philippi, 1874, T. seleniris Snyder, 1908 and T. rexsalmonorum Jordan & Gilbert, 1894 (the first described from the coast of Chile, the two remaining described from the coast of California, USA) with T. altivelis, the author does not address any relationship with T. trachypterus since the species was not originally described from the eastern Pacific Ocean. Recently, Savinykh & Baitalyuk (2011), in an attempt to clarify the taxonomic status of the genus in the northern Pacific Ocean, based on the examination of several specimens, as well as literature records, conclude that only two species (T. fukuzaki and T. trachypterus) should be considered as valid in the northeastern Pacific Ocean. The authors considered T. altivelis and T. ishikawae Jordan & Snyder, 1901 (a species from the western and central North Pacific Oceans) as junior synonyms of T. trachypterus based on their inability to diagnose such species using meristic characters, in accordance with Hamilton (1915) and Palmer’s (1961) observations. As noted above (and in the key; see below), both species (T. fukuzaki and T. trachypterus) can be clearly separated mainly by the vertebrae number (which is lower in T. fukuzaki).

Although T. fukuzakii has a postulated distribution extending from Oregon, USA, to Chile (see Table 1), there are no published records between the Gulf of California, Mexico (Del Moral-Flores et al. 2013) and the Peru-Chile coasts (Pequeño 1989, 2011, Chirichigno & Vélez 1998). Our specimen represents, on the basis of Bussing & López (1994, 2005, 2009, 2011), the first documented record of the species in lower Central American (Costa Rican) Pacific waters.