Two new species of the catfish genus Trichomycterus (Siluriformes: Trichomycteridae) from the rio Ribeira de Iguape Basin, southeastern Brazil

Abstract

Two new species of the trichomycterid catfish genus Trichomycterus from the rio Ribeira de Iguape basin, southeastern Brazil, are described. Trichomycterus tupinamba differs from the other species of the Trichomycterinae in having the first pectoral-fin ray not prolonged as a filament, the caudal fin is truncate with attenuated edges, two paired supraorbital pores s6, eye oriented dorsally, a subterminal mouth, anal and urogenital openings mid-way between the pelvic-fin margin and anal-fin origin, a dark spot at the base of the nasal barbel, a longitudinal row of dark spots along the midline of the flank from the opercle to the caudal-fin base, a pectoral-girdle width of 13.1-17.7 % of standard length, and a caudal-peduncle depth of 8.7-10.3 % of standard length. Trichomycterus jacupiranga differs from all other species of the Trichomycterinae in having the first pectoral-fin ray prolonged as a short filament, one fused supraorbital pore s6, a pelvic fin that covers the anal and urogenital openings, anal and urogenital openings that are closer to the anal-fin origin than to the pelvic-fin base, a truncated caudal fin with attenuated edges, and the following morphometric characteristics: head length 20.7-22.4 % standard length, preanal length 57.1-70.9 % standard length, pectoral girdle width 17.4-20.6 % standard length, trunk length 33.6-37.5 % standard length, pectoral-fin length 16.8-22.7 % standard length, dorsal-fin base length 12.8-14.1 % standard length, anal-fin base length 8.4-10.8 % standard length, head width 90.6-104.6 % head length, snout length 40.0-46.9 % head length, mouth width 27.0-37.3 % head length, and eye diameter 10.4-16.5 % head length. Distribution, ecological data and diagnostic features are presented for both new species.