A New Species of the Loricariid Catfish Genus Loricariichthys (Teleostei: Siluriformes) from Eastern Brazil

A new species of Loricariichthys is described from the Rio Itabapoana and Rio Itapemirim basins, two small, adjacent, yet independent, coastal drainages in south Espírito Santo State. Loricariichthys melanurus, new species, is distinguished from most congeners by the anterior margin of abdominal plates falling at or slightly ahead of the transverse line between the pectoral-fin spines, not reaching the level of the lower end of the gill slits, further on other features of external morphology. The new species can be differentiated from L. castaneus, the most similar and geographically closest species, by the possession of a conspicuous black marginal band at the distal portion of middle and lower caudal-fin rays and a darkened distal half of dorsal fin, which are absent in the former. Samples analyzed of the two species have a COI pairwise genetic distance of 4.6%. The paleodrainage reconstruction inferred for a sea-level-retreat of maximum glacial period of the Pleistocene suggests that neither the Itabapoana and Itapemirim Rivers, nor the other coastal rivers of eastern Brazil, where L. castaneus occurs, have been in contact during this period.