A new cryptic species of Imparfinis (Siluriformes: Heptapteridae) from the Orinoco River basin, revealed by an iterative approach.

An iterative analysis of Imparfinis, combining phylogenetic analysis based on COI gene and multivariate morphometrics, revealed a new cryptic species from Andean tributaries of the Orinoco River basin, which is described herein. The new species is sister to a clade constituted by I. hasemani and I. pijpersi, both from river basins of the Guiana shield, being also the most geographically proximate species. However, the new species is most similar in general appearance to I. guttatus from the Madeira and Paraguay River drainages, being almost undistinguishable by conventional characters of the external morphology, differing only by morphometric attributes overall. The new species can be distinguished from remaining congeners by a unique combination of characters, including lower lobe of caudal fin darker than upper lobe; maxillary barbel reaching or surpassing pelvic-fin insertion; 12-15 gill rakers on first gill arch; 40-42 total vertebrae; and 9-10 ribs. The new species constitutes the only representative from the Orinoco River basin belonging to Imparfinis sensu stricto. This article is protected by copyright. All rights reserved.