A new species of Characidium Reinhardt (Characiformes: Crenuchidae) from the Rio Huallaga, central Peruvian Amazon, with a review of secondary sexual characters in the genus

Characidium pumarinri n. sp. is described from the affluents of Rio Huallaga, a tributary of Rio Maranon that drains the eastern slopes of the Andes, in the Peruvian Amazon. The new species has a deep body (24-31% in L-S), 11-17 well-marked dark bars and remarkable sexual dimorphism related to colour pattern, in which males have darker anal, dorsal, pectoral and pelvic fins than females. C. pumarinri resembles some species allocated in Clade C4, mainly by having a high number of transversal bars and a deep body. In addition, a thorough review and further descriptions of the secondary sexual characteristics in Characidium are provided.

Automated summary

Characidium pumarinri n. sp. is a newly discovered species of deep-bodied characid fish found in the tributaries of the Peruvian Amazon. This species exhibits remarkable sexual dimorphism in color patterns, with males having darker fins than females.