A New Species of the Neotropical Catfish Genus Trichomycterus (Siluriformes: Trichomycteridae) Representing a New Body Shape for the Family
Trichomycterus crassicaudatus is described as a new species from the Rio Iguaçu basin in southern Brazil. The new species has an exceptionally deep posterior region of the body (caudal peduncle depth 22.8–25.4% SL), resulting in an overall shape which distinguishes it at once from all other members of the Trichomycteridae. The caudal fin of the species is broad-based and forked, a shape also distinguishing it from all other species in the family. A number of autapomorphic modifications of T. crassicaudatus are associated with the deepening of the caudal region, including an elongation of the hemal and neural spines of the vertebrae at the middle of the caudal peduncle. Phylogenetic relationships of the new species are yet unresolved, but it shares a similar color pattern and a thickening of caudal-fin procurrent rays with T. stawiarski, a poorly-known species also from the Rio Iguaçu basin. Coloration and body shape also include similarities with T. lewi from Venezuela.Abstract
Trichomycterus crassicaudatus, holotype, MZUSP 88518, 108.8 mm SL, left lateral view.
Head of Trichomycterus crassicaudatus, holotype, MZUSP 88518, 108.8 mm SL: (A) Lateral view; (B) dorsal view; (C) ventral view.
Map of southern Brazil showing the type locality of Trichomycterus crassicaudatus, new species. Black circle represents type locality and more sites.
Radiograph of the left lateral view of the caudal peduncle of Trichomycterus crassicaudatus, holotype, MZUSP 88518, 108.8 mm SL.
Contributor Notes
Associate Editor: C. J. Ferraris.