A new species of Moenkhausia (Characiformes: Acestrorhamphidae) from the Amazon basin at Serra do Cachimbo, Pará, Brazil

Abstract

A new species of Moenkhausia is described from the headwaters of the Curuá and Teles Pires River basin, localities restricted to the Serra do Cachimbo, Pará, Brazil. The new species is diagnosed by the presence of dark blotches concentrated on the anterior portion of scales from the second to seventh longitudinal series, presence of red pigmentation on the adipose and caudal fins in life, green coloration in the ventral portion of the eye and absence of a longitudinal black stripe on body. The new species is morphologically similar and probably closely related to other Moenkhausia species endemic to the Brazilian Shield tributaries, particularly those restricted to the Serra do Cachimbo, sharing with them unique pigmentation traits. The ichthyofauna of the Serra do Cachimbo is notably distinct and characterized by high levels of endemism, likely influenced by geological barriers such as rapids and waterfalls that act as biogeographic barriers. The restricted and disjunct distribution of the new species in tributaries of Xingu and Tapajós basins suggests a historic headwater capture event in the Serra do Cachimbo plateau.

Keywords:
Biogeography; Headwater capture; Moenkhausia clorophthalma; Tapajós; Xingu