Redescription of ‘Chasmocranus’ brachynema (Heptapteridae: Heptapterini)

Abstract

The endangered species ‘Chasmocranus’ brachynema is redescribed and diagnosed among other Heptapterini by having the adipose fin extensively fused with the caudal fin, caudal fin shallowly bifurcate, and anal-fin insertion posterior to a vertical through the adipose-fin insertion, in addition to peculiarities of the head and mouth morphology. The species seems to be very rare, known only from five preserved specimens from the main channels of the Paraná and Mogi-Guaçu rivers, and from a tributary of the rio Ivaí, all in the Upper Paraná ecoregion.