Trichomycterus trefauti

description

Description: Morphometric data for holotype and paratypes are given in Table 1. Body elongate, roughly cylindrical close to head and gradually more compressed towards caudal fin. Dorsal and ventral profiles of trunk slightly convex. Dorsal and ventral profiles of caudal peduncle straight (Fig. 2). Integument thick, especially over base of pectoral and caudal fins. Small papillae on lips, and scattered on dorsal surface of head. Head wide and depressed, trapezoidal, slightly longer than wide, transverse section at posterior tip of opercle wider than anteriorly at nostril, anterior margin slightly rounded. Head lateral to eye slightly swollen by jaw muscles in large and small specimens. Dorsal and ventral profiles of head convex. Eyes rounded, dorsolaterally oriented. Eye covered by thin skin, transparent at its center, gradually opaque towards rim, distinctly separated from surface of eyeball. Ocular structures readily visible on surface of skin, not deeply sunken. Orbital rim not free. Anterior nare slightly larger than posterior, surrounded by fleshy flap of integument. Posterior nare surrounded anteriorly by thin flap of integument. Anterior and posterior nares about one third of

New species of the catfish genus Trichomycterus (Siluriformes, Trichomycteridae) from the headwaters of the rio São Francisco basin, Brazil

diagnosis

Diagnosis: Trichomycterus trefauti differs from all other known members of the subfamily Trichomycterinae by the autapomorphic presence of an elliptical, vertically elongated, brown spot, at caudal­fin base (vs. without elliptical spot at caudal­fin base), and the combination of homogeneously gray color pattern (vs. yellowish, presence of stripes or bands, or lack of color pattern), first pectoral­fin ray prolonged as a filament (vs. not prolonged), subterminal mouth (vs. inferior or terminal mouth), two supraorbital pores at interorbital space (vs. one supraorbital pore at mesial line), caudal fin truncate with attenuated edges (vs. caudal fin rounded), pelvic fins covering anus and urogenital openings (vs. not covering), interorbital space very wide — 39.8 – 45.9 % HL (vs. more or less than 39.8 – 45.9 % HL), maxillary barbels very long — 84.2 – 93.0 % HL (vs. more or less than 84.2 – 93.0 % HL), rictal barbels very long — 67.6 – 74.3 % HL (vs. more or less than 67.6 – 74.3 % HL).

New species of the catfish genus Trichomycterus (Siluriformes, Trichomycteridae) from the headwaters of the rio São Francisco basin, Brazil

etymology

Etymology: Named after Dr. Miguel Trefaut Rodrigues, who discovered and collected the first specimens of the species. Systematic and taxonomic comments: The genus Trichomycterus has been recognized as nonmonophyletic (Arratia, 1990, 1998, de Pinna, 1989; 1998), as is also true for the subfamily Trichomycterinae (de Pinna, 1989; 1998). Arratia (1990) proposed four “ unique derived characters ” for Trichomycterinae (1 ­ “ basioccipital ” … ” with well developed anterior membranous processes which lie ventrolateral to parasphenoid and prootics ”, 2 ­ “ an enarthrodial articulation between preopercle and opercle ” … ” is present in adults ”, 3 ­ “ vomer with only one long posterior process ”, and 4 ­ “ pronounced notch ” … ” on the posteroventral margin of ceratobranchial ”). These features are present in all analyzed Trichomycterinae species prepared for C & S and X­ray, including Trichomycterus trefauti. However, a more recent analysis (Costa & Bockmann, 1993) proposed Scleronema and the genus Ituglanis composed of species previously located in Trichomycterus, as two sequential monophyletic groups more related to the Glanapteryginae, Sarcoglanidinae, Tridentinae, Stegophilinae, and V

New species of the catfish genus Trichomycterus (Siluriformes, Trichomycteridae) from the headwaters of the rio São Francisco basin, Brazil

materials_examined

Comparative material Copionodon pecten MZUSP 48962 (7 ex. Alc. 3 ex. C & S); MZUSP 42462 (5 ex.) Paratypes; C. orthiocarinatus MZUSP 42464 (1 ex.) Paratype; C. lianae MZUSP 42470 (2 ex.) Paratypes; MZUSP 39995 (1 ex. C & S); Glaphyropoma rodriguesi MZUSP 42466 (3 ex.) Paratypes; Trichogenes longipinnis MZUSP 40238 (2 ex); MZUSP 63478 (15 ex. Alc., 3 ex. C & S); Bullockia maldonadoi CAS 63842, Holotype; CAS 63843 (43 ex.) Paratypes; MZUSP 36958 (1 ex. C & S); Eremophilus candidus MNRJ 11762 (2 ex. C & S) Paratypes; E. mutisii MZUSP 35409 (1 ex. C & S) AMNH 56092 (1 ex. C & S); CAS 6595 (13 ex.); Hatcheria macraei MZUSP 35687 (3 C & S); H. patagoniensis CAS 63844 (2 ex.) Paratypes; H. titcombi CAS 28557, Holotype; Ituglanis amazonicus MUSP 30449 (1 ex.); I. eichorniarum MZUSP 37763 (1 ex.); MNRJ 780 (2 ex.) Syntypes; I. gracilior FMNH 53264 (X­ray) Holotype; I. guianensis FMNH 52676 (X­ray) Holotype; I. laticeps CAS 32458 (1 ex.); I. metae CAS 118214 (1 ex.); CAS 124227 (1 ex.); CAS 58138, Holotype; I. parahybae FMNH 58576 (X­ray) Holotype; I. proops MZUSP 84190 (12 ex. Alc, 2 ex. C & S); MNRJ 781 (3 ex.) Syntypes; Ituglanis n. sp. MNRJ 11489 (13 ex. 5 C & S); Pygidium angustirostris

New species of the catfish genus Trichomycterus (Siluriformes, Trichomycteridae) from the headwaters of the rio São Francisco basin, Brazil