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.