Two new amazonian species of ancistrus with vestigial adipose fin, with an appraisal on adipose fin loss in neotropical armoured catfishes (Teleostei: Loricariidae)

Abstract

Two new species of Ancistrus are described from Amazon basin: A. krenakarore from rio Itapacura, a tributary of the right margin of the lower rio Tapajós drainage; and A. karajas from small headwater streams of rio Parauape- bas, a tributary of left margin of lower rio Tocantins drainage, both from Para State, Brazil. The two new species differ from all congeners except A. jataiensis, A. parecis, A. reisi, A. tolima, A. tombador, A. verecundus and A. veri- caucanus by the absense or vestigial adipose fin (vs. presence of a fully-developed fin). The new species differ from all congeners without adipose fin by the presence of only one preadipose plate and by a combination of morphometric characters; and differ from each other by color pattern. © 2016 by Vcrlag Dr. Friedrich Pfeil, München, Germany.