Revised artificial key of the 11 nominal species of Callogobius from Taiwan

1a. Pelvic fin frenum absent................................................................................ 2

1b. Pelvic fin frenum present............................................................................... 4

2a. Body with distinct, saddle-like blotches............................................................ C. clitellus

2b. Body with irregular patches of pigmentation................................................................ 3

3a. Ctenoid scales covering till pectoral fin base; body ivory............................................... C. sclateri

3b. Ctenoid scales covering till vertical position of D2; body brown................................... C. flavobrunneus

4a. Pelvic fins completely fused into cup-shaped sucker.......................................................... 5

4b. Pelvic fins partially fuse, connecting membrane with a notch................................................... 6

5a. Caudal fin length greater that head length.................................................................. 7

5b. Caudal fin length lesser that head length................................................................... 8

6a. Dorsal fins with wide interspace; body dark brown.................................................. C. okinawae

6b. Dorsal fins with little interspace; body whitish.............................................................. 9

7a. D2 I, 10; body white with dark brown blotches...................................................... C. stellatus

7b. D2 I, 13–15; body brownish with mottled blotches............................................... C. tanegasimae

8a. Anal fin ray mostly 7; Pred 5–6; D2 base without black spot.................................... C. nigromarginatus

8b. Anal fin ray mostly 8; Pred 7–9; D2 base with black spot.............................................. C. shunkan

9a. Paired pore ω present; body with scarce ctenoid scales covering at caudal peduncle......................... C. hasseltii

9b. Lacking paired pore ω; ctenoid scales covering anteriorly till D1 base........................................... 10

10a. Anterior oculoscapular canal present; markings behind eye interrupted.................................... C. aquilus

10b. Anterior oculoscapular canal absent; markings behind eye not interrupted................................... C. sheni