Thursday, December 31, 2020

[Ichthyology • 2020] Microcambeva bendego • A New Catfish Species of Microcambeva Costa & Bockmann 1994 (Siluriformes: Trichomycteridae) from A Coastal Basin in Rio de Janeiro State, southeastern Brazil


Microcambeva bendego
de Medeiros, Moreira, de Pinna & Lima, 2020


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.

Keywords: Pisces, Taxonomy, Microcambevinae, Fluminense ecoregion, Atlantic Forest, Guanabara bay, CT-Scan


Figure 1. Microcambeva bendego, new species, holotype, MNRJ 52042, 28.1 mm SL.
Rio Guapiaçu, near Cachoeiras de Macacu, rio Guapi-Macacu basin, Guapimirim Municipality, Rio de Janeiro State, southeastern Brazil.
a. lateral view; b. dorsal view; c. ventral view. Scale: 10 mm.


Figure 2. Ventral view of holotype of Microcambeva bendego, new species, holotype, MNRJ 52042, 28.1 mm SL, white arrow indicates the finger-like projections. Scale bar: 1.0mm.


 
Lucas Silva de Medeiros, Cristiano Rangel Moreira, Mario de Pinna and Sergio M. Q. Lima. 2020. A New Catfish Species of Microcambeva Costa & Bockmann 1994 (Siluriformes: Trichomycteridae) from A Coastal Basin in Rio de Janeiro State, southeastern Brazil. Zootaxa. 4895(1); 111–123. DOI: 10.11646/zootaxa.4895.1.6