Key for determination of species from the D. similis group in Old World based on male characters 1 Anal teeth as in female (not reduced)................................................................ D. similis - Anal teeth in distal portion of postabdomen reduced in size and number.......................................... 2 2 Compound eye very large, occupies almost whole anterior portion of head, which forms an inflated dome....... D. sinensis - Compound eye relatively small, anteriormost portion of head without a dome...................................... 3 3 Fornix rounded; usually distalmost anal tooth usually relatively strong; no additional seta on exopodite V..... D. similoides - Fornix sharp and pointed; distalmost anal teeth minute; additional seta on exopodite V............... D. inopinata sp. nov.

Published as part of Popova, Ekaterina V., Petrusek, Adam, Kořínek, Vladimír, Mergeay, Joachim, Bekker, Eugeniya I., Karabanov, Dmitry P., Galimov, Yan R., Neretina, Tatyana V., Taylor, Derek J. & Kotov, Alexey A., 2016, Revision of the Old World Daphnia (Ctenodaphnia) similis group (Cladocera: Daphniidae), pp. 1-40 in Zootaxa 4161 (1) on page 32, DOI: 10.11646/zootaxa.4161.1.1, http://zenodo.org/record/272238