Populations of the high altitude anostracan Branchinecta papillota from the type locality in the Atacama Altiplano (Iquique province, Chile) and from the Cumbres Calchaquíes (Tucumán province, Argentina) and specimens of B. achalensis from the type locality (La Posta, Pampa de Achala, Córdoba province, Argentina) were compared and new observations on the morphological diversity of the species were made. A basal branching in the male antenna 2 distal article, only observed in one branchinectid to date, was found in the Argentinean populations of both species.