A new species in the Daphnia curvirostris (Crustacea: Cladocera) complex from the eastern Palearctic with molecular phylogenetic evidence for the independent origin of neckteeth

Little is known of the biology and diversity of the environmental model genus Daphnia beyond the Nearctic and western Palearctic. Here, we describe Daphnia sinevi sp. nov., a species superficially similar to Daphnia curvirostris Eylmann, 1878, from the Far East of Russia. We estimated its phylogenetic position in the subgenus Daphnia s. str. with a rapidly evolving mitochondrial protein coding gene [NADH-2 (ND2)] and a nuclear protein-coding gene [heat shock protein 90 (HSP90)]. Daphnia curvirostris, D. sinevi sp. nov., Daphnia tanakai and D. sp. from Ootori-Ike, Japan, (which, probably, is D. morsei Ishikawa, 1895) formed a monophyletic clade modestly supported by ND2 and strongly supported by HSP90. Our results provide evidence of hidden species diversity in eastern Palearctic Daphnia, independent origins of defensive neckteeth and phylogenetic informativeness of nuclear protein-coding genes for zooplankton genera.