A redescription of deep-channel ghost knifefish, Sternarchogiton preto (Gymnotiformes: Apteronotidae), with assignment to a new genus

Abstract

From a study of morphological and molecular datasets we determine that a species originally described as Sternarchogiton preto does not form a monophyletic group with the other valid species of Sternarchogiton including the type species, S. nattereri. Previously-published phylogenetic analyses indicate that this species is sister to a diverse clade comprised of six described apteronotid genera. We therefore place it into a new genus diagnosed by the presence of three cranial fontanels, first and second infraorbital bones independent (not fused), the absence of an ascending process on the endopterygoid, and dark brown to black pigments over the body surface and fins membranes. We additionally provide a redescription of this enigmatic species with an emphasis on its osteology, and provide the first documentation of secondary sexual dimorphism in this species.