A new fairy shrimp, Branchinecta piurae sp. nov. (Branchiopoda: Anostraca), from Peru

South American species of Branchinecta that inhabit high altitude biotopes are so far represented by B. brushi and B. papillata. Here we describe a new species inhabiting these extreme habitats, B. piurae sp. nov., whose closest species is B. papillata. Differential characters of B. piurae are the lack, in males, of proximal and distal anteromedial bulges with spines at the second antenna basal antennomere which are conversely present in males of B. papillata; instead, the males of B. piurae have scattered, triangular spines over the anterior and medial surfaces at the distal half of the basal antennomere. In females of B. piurae, the dorsal surface of thoracic segments are provided with well-marked rough protuberances mainly on segments 3 to 10, features that are not observed in B. papillata. As far as is known, Branchinecta piurae sp. nov. is endemic to the Peruvian and Ecuadorian Andes, appearing at altitudes around 3,700???3,800 m a.s.l, and latitudes from 2??47??? to 5??04??? S. The results of the genetic analyses based both on mitochondrial and nuclear markers provide a clear support for the morphological description of B. piurae as a new species. We also provide genetic sequences of B. papillata, B. ferox from Spain and B. orientalis from Spain and Mongolia, and show that Palaearctic Branchinecta species are not directly related to B. piurae and B. papillata. In the phylogeny derived from COI, the last two species form a sister clade to the American Branchinecta clade, including several North American species, or in the 16S phylogeny, only B. papillata is at the base. Our results suggest a different history about the genus in America than previous hypotheses. New molecular studies are needed that include additional South American species in order to better explore the diversity and biogeographical patterns of the genus Branchinecta.