New species of Scleromystax Günther, 1864 (Siluriformes: Callichthyidae) - extending the meridional distribution of genera endemic to the Atlantic Forest

ABSTRACT The genus Scleromystax includes species occurring in several coastal river basins from southern Bahia to southern Santa Catarina States. Examination of Scleromystax specimens sampled from the laguna dos Patos drainage revealed a new taxon, further extending the distribution of the genus to the southern border of the Atlantic forest. The new species differs from its congeners by the second infraorbital ventrally expanded. It is also distinct, except from S. macropterus and S. salmacis , by roughly oblique, elongate, dark brown blotches along body; large specimens displaying cranial fontanel completely occluded, leaving just a shallow fossae; and sexually dimorphic features inconspicuous, i.e. preopercular (cheek) region similar in males and females, and dorsal and pectoral fins of males slightly longer than in females. Herein, we also extend the record of Scleromystax salmacis to the rio Tramandaí drainage