Sympatric sister species with divergent morphological features of psammophilic catfishes of the south-eastern Brazilian genus Microcambeva (Siluriformes: Trichomycteridae)

Publication date: Available online 20 January 2020Source: Zoologischer AnzeigerAuthor(s): Wilson J.E. M. Costa, Paulo Vilardo, Axel M. KatzAbstractAn undescribed species of Microcambeva, a genus of small psammophilic catfishes from the Atlantic Forest of south-eastern Brazil, was found together the congener M. ribeirae inhabiting the same sand stretch of a stream, in the Rio Ribeira do Iguape basin. The new species and its sympatric congener exhibit highly divergent morphological features, but a multigene phylogeny support them as sister taxa. The new species, M. filamentosa sp. nov., is readily distinguished from all other congeners by the presence of long barbels, long filamentous first pectoral-fin ray and a hypertrophied predorsal adipose fold. Microcambeva filamentosa and M. ribeirae share two unique apomorphic features: a single supraorbital pore s6 situated on the centre of the dorsal surface of the head and a deep concavity between the dorsal process of the opercle and the opercular odontode patch, conditions that are independently acquired in other psammophilic trichomycterids. A comparative context, involving other trichomycterid lineages exhibiting similar morphological adaptations, highly suggests that morphological differences between M. filamentosa and M. ribeirae are related to different strategies to exploit their habitat. In M. ribeirae, the short and thickened first pectoral-fin ray is interpreted as an adaptation to the fish posing propped on the substratum...

Source: A Journal of Comparative Zoology - January 21, 2020 Category: Zoology Source Type: research