(Crustacea, Cladocera, Aloninae): a new species of the -group, with identification key to Neotropical species.

Background: The subfamily Aloninae has been the focus of extensive studies on the Chydoridae because it has a higher diversity of species and due to the necessity of a detailed redescription of many taxa, especially using characters related to thoracic appendages. The polyphyletic genus was redefined recently, and many species complexes were translocated to natural groups. The -group is a candidate for removal from because it forms a well-defined complex of species, besides possessing higher species diversity. At present, 50 % of the known species occur in the Neotropics.

Results: In this study, we described , a new species of -group distributed in southern South America. The new species shares with other species similarities in general features of limbs but, for instance, differs from South American because it has a short postabdomen. sp. nov. differs from Andean because it has thick denticles on the postabdomen and longitudinal lines on the carapace are absent. Differences in the limbs were also observed.

Conclusions: sp. nov. is part of the group that contains species with complete connection between the main head pores. Like other species of the -group, sp. nov. also has similarities with the genus . The relationship between these two species groups still needs to betested.