A New Trichomycterus (Siluriformes: Trichomycteridae) from Aguarague National Park of the Bolivian Preandean Region, with Comments on Relationships within of the Genus

Abstract

The Andean and preandean regions are characterized by the presence of several endorheic drainage basins, each of which has evolved a characteristic fish fauna, some of which are poorly known or hitherto inaccessible. We describe here a new species of Trichomycterus from Aguarague National Park, Bolivia. Trichomycterus aguarague is considered to belong to a species assemblage comprised of T. alterus, T. boylei, T. ramosus, and T. belensis, a group diagnosed by three putative apomorphic conditions: (1) base of the maxillary barbel wide and engrossed like a skin flap or fold, (2) premaxillary bone smaller than maxilla, and (3) odontodes embedded in thick integument that covers interopercle. Alternatively, T. aguarague and T. alterus share an unusual number of five or fewer abdominal vertebrae, which is a synapomorphy for the group composed of Scleronema, Ituglanis, and the Stegophilinae+Tridentinae+Vandelliinae+Glanapteryginae+Sarcoglanidinae clade. The new species differs from all congeners in having the following combination of characters: caudal peduncle depth 13.5 – 16.0% SL, 15 or 16 pairs of ribs, 15 dorsal procurrent rays, 12 ventral procurrent rays, 8 pectoral fin rays; 9 anal fin rays; barbels and skin of trunk with numerous, minute thread-like papillae.