A new species of the loricariid catfish genus Hemipsilichthys from southern Rio de Janeiro coastal rivers, southeastern Brazil (Teleostei: Siluriformes)

Abstract

Hemipsilichthys nimius, new species, is described from the upper Perequê-Açu River in Parati, in the southern coast of Rio de Janeiro State, southeastern Brazil. The new species is distinguished from the remaining 18 Hemipsilichthys species by modally having eight branched rays in the dorsal fin (vs. seven branched rays), by possessing a posteriorly expanded dorsal-fin membrane connecting the last dorsal-fin ray to the dorsum and, except from H. gobio and H. papillatus, by having teeth cusps equal in size (vs. small lateral cusp or unicuspid teeth in both dentary and premaxilla). From H. gobio and H. papillatus it is further distinguished by the larger orbital diameter and by its V-shaped dorsal-fin spinelet. Hemipsilichthys nimius shares with H. gobio and H. papillatus several characters that might be indicative of close relationships. These putative phylogenetic relationships are discussed.