A new species of honeycombed Chydorus Leach, 1816 (Cladocera: Anomopoda: Chydoridae) from tundra of North-East Russia

A new cladoceran of the faviformis-group of the genus Chydorus Leach, 1816 (Cladocera: Chydoridae), characterized by a honeycomb-like sculpture of valves and head shield, is described from tundra lakes and ponds in North-East Russia. Morphology of the new species was studied using optical and scanning electron microscopy. Chydorus izvekovae sp. nov. differs from all other species of the faviformis-group in a narrow labral keel with elongated apex, and in a greater number of meshes on the valves and head shield. Other species of the faviformis-group in the Western Hemisphere are distributed in the tropical-subtropical zone, they also inhabit mostly shallow waters with well-developed macrophyte zone.