Three new species of Ancistrus kner (Teleostei: Siluriformes: Loricariidae) from the upper Tapajos and Tocantins rivers

Three new species of Ancistrus Kner (Teleostei: Siluriformes: Loricariidae) from the upper Tapajos and Tocantins rivers. - Three new species of Ancistrus are described: Ancistrus tombador sp. n. from the upper rio Tapajos basin, and Ancistrus reisi sp. n. and Ancistrus jataiensis sp. n. from the upper rio Tocantins basin. The three species differ from their congeners by the absence of an adipose fin. Loss of the adipose fin was only rarely observed in Ancistrini. In the three new species it is replaced by a series of small unpaired platelets forming a low crest. Ancistrus tombador further differs from all congeners by a unique combination of characters: naked margin of snout large and tentacles usually absent in both sexes; body very narrow (cleithral width 27.5-31.2% SL); long caudal peduncle particularly depressed (depth 8.3-9.2% SL). Ancistrus reisi is distinguished from A. jataiensis by measurements, including: predorsal length (respectively: 43.8-46.4% SL versus 47.5-49.3% SL); occipital depth (14.9-17.0% SL versus 17.0-19.5% SL); and caudal peduncle length (27.7-30.9% SL, versus 24.6-27.1% SL).