A new species of Moenkhausia (Characiformes: Characidae) from the rio Madeira basin, Brazil, with comments on the evolution and development of the trunk lateral line system in characids

A new Moenkhausia (Characiformes: Characidae) from rio Brao Norte, rio Tapajs basin, with comments on the fish endemism of Serra do Cachimbo plateau

A new species of Moenkhausia is described from the rio Brao Norte, a tributary of Rio Teles Pires draining the Serra do Cachimbo, rio Tapajs basin, Par, Brazil. The new species is diagnosed from all congeners, except M. moisae and M. pirauba, by having a high number of scales in the longitudinal series (4346 vs. 2341 in other Moenkhausia species). It can also be distinguished from the aforementioned species based on the combination of the following characters: a single humeral blotch, 2125 branched anal-fin rays, and a round and symmetrical caudal blotch not continuous anteriorly with the dark midlateral stripe. The new tetra herein described represents an additional, possibly endemic, taxon from the headwaters draining from Serra do Cachimbo, in the Brazilian Shield.

Molecular species delimitation and description of a new species of Phenacogaster (Teleostei, Characidae) from the southern Amazon basin

Phenacogaster is the most species-rich genus of the subfamily Characinae with 23 valid species broadly distributed in riverine systems of South America. Despite the taxonomic diversity of the genus, little has been advanced about its molecular diversity. A recent molecular phylogeny indicated the presence of undescribed species within Phenacogaster that is formally described here. We sampled 73 specimens of Phenacogaster and sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene in order to undertake species delimitation analyses and evaluate their intra- and interspecific genetic diversity. The results show the presence of 14 species, 13 of which are valid and one undescribed. The new species is known from the tributaries of the Xingu basin, the Rio das Mortes of the Araguaia basin, and the Rio Teles Pires of the Tapajós basin. It is distinguished by the incomplete lateral line, position of the humeral blotch near the pseudotympanum, and shape of the caudal-peduncle blotch. Meristic data and genetic differentiation relative to other Phenacogaster species represent strong evidence for the recognition of the new species and highlight the occurrence of an additional lineage of P.franciscoensis.