Key to Species of the Genus Colon in Korea and Japan

1. Metafemur not showing sexual dimorphism [male metafemur little wider than female (Fig. 11)] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Colon ( Myloechus) koreanus n. sp.

1'. Metafemur showing sexual dimorphism [male metafemur bearing a projection (Fig. 12), or triangular and sharply expanded posteriorly] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2

2. Body length less than 2.5 mm [C. (M.) appendiculatum Sahlberg sometimes less than 2.5 mm] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3

2'. Body length longer than 2.5 mm [C. (M.) appendiculatum usually more than 3.0 mm] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5

3. Dorsum usually brown or dark brown, but rarely a little reddish; projection of male metafemur with more than five thick setae at apex - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) appendiculatum Sahlberg

3'. Dorsum a little reddish; projection of male metafemur without thick apical setae --------------------------------------------------------------------------------------------------------------- 4

4. Pronotum relatively strongly punctate; male metafemur strongly rounded - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) kishii Nakane

4'. Pronotum moderately punctate; male metafemur weakly triangular - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) japonicum Hisamatsu

5. Pronotum relatively sharply curved along lateral margins; pronotum at widest point about 2.5–2.7 times as wide as apical margin - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 6

5'. Pronotum moderately curved along lateral margins; pronotum at widest point about 2.2 times as wide as apical margin - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8

6. Body less than 3.0 mm; male metafemur with a slender projection markedly and posteriorly extended at apical 1/4 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) itoi Hisamatsu

6'. Body longer than 2.0 mm; male metafemur without long projections - - - - - - - - - - - - - - 7

7. Body length 3.2–3.6 mm; male metafemur triangularly expanded at hind corners - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) babai Nakane

7'. Body length 4.0 mm; male metafemur with a small projection about at apical 1/4 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) hiraii Nakane

8. Projection of male metafemur with more than five thick setae at apex - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) appendiculatum Sahlberg

8'. Projection without apical setae - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9

9. Body length 4.0 mm; male metafemur triangularly expanded at hind corner and not bearing long projections; distributed in Ryukyus (Japanese Oriental region) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) tametomoi Hoshina

9'. Body length 2.8–3.2 mm; male metafemur with a slender and striking projection at about apical 1/5 of hind margin; distributed in Korea and Japan (Palaearctic region) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C. (M.) shini n. sp.