Key to batfishes of the genus Halicmetus

1A. Peritoneal membrane uniformly light brown, grayish or black.................................................. 2

1B. Peritoneal membrane pale with scattering of darker peppery dots................................................ 5

2A. Body uniformly dark, blackish or gray; tubercles on body surface mainly trifid or bifurcate; rostrum extended well beyond mouth........................................................................... H. niger (western Pacific)

2B. Dorsal surface uniformly pale or with a light brown marble pattern; rostrum usually not extended beyond mouth (with few exception)........................................................................................... 3

3A. Dorsal surface uniformly pale; dark pigmentation on nostrils, upper roof of illicial trough, both jaws, pelvic fin, and distal portions of pectoral and anal fins................................................... H. ruber (eastern Indian Ocean)

3B. Dorsal surface with light brown marble pattern (often faded after preservation); body uniformly pale elsewhere........... 4

4A. Body mainly covered with bifurcate tubercles; peritoneal membrane light brown....... H. cf. ruber (western North Pacific)

4B Body mainly covered with simple tubercles; peritoneal membrane greyish or black........ H. drypus sp. nov. (Tasman Sea)

5A. White reticulate pattern on dorsal surface (often faded after preservation).............. H. reticulatus (Indo–West Pacific)

5B. Marble pattern on dorsal surface (often faded after preservation)................................................ 6

6A. Rich brown marble pattern on dorsal surface (often faded after preservation); simple tubercles covering dorsal surface.............................................................................. H. marmoratus (Indo–West Pacific)

6B. Dorsal surface uniformly pale or sometimes with light brown smoky pattern (often faded after preservation); dorsal surface covered with both bifurcate and simple tubercles.......................... H. westraliensis sp. nov. (Western Australia)