Key to species of the genus Cratyna in Korea

1. Gonostylus oval to spherical with a rounded apex (Figs 1 B, 2B, 3B); tegmen rounded (Figs 1 A, 2A, 3A) usually with a semicircular aedeagal margin............................................................................... 2

- Gonostylus narrow (Fig. 6 B) or with triangular apex; tegmen trapezoid (Figs. 5 A, 6A) and simple...................... 5

2. Gonostylus without apical tooth (Figs 1 B, 2B, 3B)........................................................... 3

- Gonostylus with apical tooth (i.e. Fig. 6 B, see also Tuomikoski, 1960: 36)................. C. (Spathobdella) longispina

3. Maxillary palpus one-segmented (Fig. 2 D); medial part of inner side of gonostylus with unpaired spines (Fig. 2 B)........................................................................................... C. (Cratyna) nigerrima

- Maxillary palpus two or three-segmented (Figs 1 D, 3D); medial part of inner side of gonostylus with 2 paired spines (Figs 1 B, 3B)................................................................................................ 4

4. Maxillary palpus three-segmented (Fig. 1 D); medial spines on inner side of gonostylus on one lobe (Fig. 1 B)................................................................................................. C. (Cratyna) ambigua

- Maxillary palpus two-segmented (Fig. 3 D); medial spines on inner side of gonostylus on two separate lobes (Figs 3 A, 3B, 4)......................................................... C. (Cratyna) suwonensis Shin, Menzel & Lee sp. nov.

5. Wing vein R5 with macrotrichia on dorsal side only; gonostylus short and triangular, with distinct strong sabre-like tooth with elongated setae (Fig. 6 B); maxillary palpus one-segmented (second segment sometimes present but vestigial) and basal segment club-like (Fig. 6 D); legs short and thick....................................... C. (Peyerimhoffia) vagabunda

- Wing vein R5 with macrotrichia on both sides; gonostylus narrow, with strong and long tooth and three spines (Fig. 5 B); maxillary palpus three-segmented and basal segment usually narrow (Fig. 5 D); legs long and slender................................................................................................. C. (Diversicratyna) salomonis