Microcambeva

Abstract: Microcambeva bendego, a small psammophilous catfish species, is described from the rio Guapi-Macacu basin at Guanabara Bay in Rio de Janeiro State, an Atlantic Forest remnant. This coastal drainage has been explored by several naturalists and fish researchers since the 19th century. It is a drainage with remarkably high endemism and species richness, and some recently-described and threatened species. The new species is distinguished from all congeners by two distinctive characters: long finger-like projections in the branchial isthmus and a large opercular patch of odontodes with 19 odontodes. Due to the paucity of specimens (n=3) osteological features of the new species were accessed by CT-Scan images of the holotype. Microcambeva bendego shares putative synapomorphies with two congeners, M. ribeirae and M. filamentosa, such as the fusion of supraorbital pore s6, the absence of ossification in the anterior autopalatine cartilage, the presence of an elongated and wide posterior process of the autopalatine, and a concavity on the dorsal process of the opercle. Those characters suggest that M. bendego is more closely related to those two species from the rio Ribeira de Iguape basin than to other congeners. The biogeography and conservation status of M. bendego are also discussed.

Abstract: Microcambeva barbata, n. gen. et sp., is described from rio Sao Joao, Estado do Rio de Janeiro. It is proposed as the sister group of Malacoglanis and Sarcoglanis, on the basis of three characters: pectoral fin longer than the head, pectoral fin rays projecting well beyond the fin membrane, and a forked caudal fin. Monophyly of the Sarcoglanidinae is confirmed by the unique possession of a long lateral process on the premaxilla and a separate anterior ossification on the palatine. A sister group relationship between the Sarcoglanidinae and the Glanapteryginae is supported by four synapomorphies: a posteriorly directed dorsal process on the quadrate, a large dorsal anteriorly directed process on the hyomandibula, vomer reduced and generalized miniaturization. A more inclusive group composed of Sarcoglanidinae, Glanapteryginae, Tridentinae, Vandeliinae and Stegophilinae is considered monophyletic, since they all exhibit a reduced interopercular patch of odontodes, a reduced or absent metapterygoid, reductio...

Abstract: A second species of Microcambeva, M. ribeirae, is described from the Rio Ribeira do Iguape basin, S o Paulo, southeastern Brazil, which constitutes the southernmost record for sarcoglanidine catfishes. It is distinguished from M. barbata by a series of morphological features, including nasal barbel extent, position of the eye, first pectoral-fin ray extent, position of the anal fin, position of the posterior pore of the supraorbital canal, frontal shape, cranial fontanel extent, lateral process of the sphenotic, absence of the anterior ossification of palatine, and size of the posterior process of the palatine and supraorbital bone.

Abstract: The osteology of Sarcoglanis simplex, a rare, miniature South American catfish, is described for the first time based on a single, 17 mm adult specimen that was both cleared and Alizarin-stained, and visualized with microfocus computed tomography (MicroCT). Previously, the internal skeletal features of this species could be predicted based only on conditions observed in its closest relatives within the subfamily Sarcoglanidinae of the Trichomycteridae. The relatively new MicroCT technique successfully revealed fine details of the skeletal morphology of this tiny fish. As predicted, Sarcoglanis shares with Stauroglanis, Stenolicmus, Malacoglanis, Microcambeva, and Ammoglanis an anterior ossification of the palatine and a large posteriorly directed dorsal process on the quadrate. Contrary to predictions, however, the mesethmoid of Sarcoglanis does not have the distal ends of the cornua distinctly wider than at their bases, and the anterior margin of the mesethmoid is not convex.