A new species of the genus Ilyocryptus Sars, 1862 (Cladocera: Anomopoda: Ilyocryptidae) from the East Asian Palaearctic

A new Palaearctic species of the genus Ilyocryptus Sars, 1862 (Cladocera: Anomopoda: Ilyocryptidae) is described based on samples from Republic of Korea, Japan, and the Far East of Russia. This taxon was mis-identified by some previous authors as I. agilis Kurz, 1878. Among the agilis-like species sensu Kotov & Elias-Gutierrez (2009), I. yooni sp.nov. is unique in absence of any setules or denticles near preanal teeth on the postabdomen. It also differs from its closest relative I. agilis s.str. in (1) a more sharp dorsal keel; (2) short setae at postero-ventral portion of valve; (3) a long abdominal projection; (4) presence of spinules on internal wall of anus; (5) shorter antenna I; (6) distal burrowing spine not projected behind distal end on basal segment of antenna II; (7) spine on proximal segment of antennal exopod not longer than the next segment; (8) setae at bases of the flap at inner-distal portion of limb III of different size and armature. Apparently I. yooni sp. nov. is a member of the Far East endemic species complex, recently defined by Kotov et al. (2011, 2012).