Key to the species of the Antennablennius (adapted after Bath 1983 and Williams & Springer 2022)

1a No spots on cheeks and underside of head...................................................... A. ceylonensis

1b Cheeks and underside of head with various patterns of small dark and/or pale spots................................. 2

2a Opercle with oval ocellated spot with dark grey centre, ringed with orange then yellow or white; head with few scattered white spots; males with bilateral pair of crests on head.................................................... A. simonyi

2b Opercle without ocellated spot; head without white spots, if spots present, they are very small and numerous; males without crest or with single fleshy crest on head................................................................... .. 3

3a Pair of long cirri on nape............................................................................... 4

3b Nape cirri short...................................................................................... 5

4a Dorsal-fin rays XII,19–20; anal-fin rays II,20; body below spinous portion of dorsal fin with six narrow white bars but without white spots; head with one black bar at corner of mouth.............................................. A. persicus

4b Dorsal-fin rays XII,17–18; anal-fin rays II,18–19; body below spinous portion of dorsal fin with white spots and white bars restricted to ventral half; head ventrally with three black bars.......................................... A. bifilum

5a Nasal cirrus very long, reaching to or below mouth in adults................................................... 6

5b Nasal cirrus usually short, not reaching or just reaching to mouth............................................... 7

6a Dorsal-fin rays usually XII,18–19; anal-fin rays II,20; head with row of tiny black spots below eye, and occasionally on cheek; males with simple crest on nape................................................................. A. hypenetes

6b Dorsal-fin rays usually XII,20; anal-fin rays II,21–22; head with numerous small orange-red spots; no crest on nape in either sex.................................................................................. A. variopunctatus

7a Upper jaw teeth 37–45, lower jaw teeth 29–36; posterior part of body with row of irregular dark spots and scattered small white spots; head with orange-red spots and numerous white spots.......................................... A. adenensis

7b Upper jaw teeth 26–30, lower jaw teeth 23–28; dorsal half of posterior part of body with numerous close-set white spots or vermiculations preceded by 2–3 white bars above anal-fin origin; head with many small dark orange spots..... A. australis