Pectoral fin absent. Gill-opening roundish, subequal to eye, and located on mid-side of body. Total length 6.6〜6.8 times of head length. Anus situated in front of mid-body, total length 2.2〜2.3 times of preanal length. Dorsal origin on head. Mouth closes completely. Anterior nostril tubular near tip of snout; posterior nostril simple pore without raised rim situated above the anterior margin of eye. Teeth finely serrated. Blackish spots arranged on dorsal fin regularly spaced; anal fin with a series of black and white areas, and not uniform black; corner of mouth and gill-opening not black.
Distribution:
Coastal waters from northern part of Gulf of Mexico to Brazil.
Remarks:
G. nigromarginatus and G. saxicola are quite similar to the present species, but distinguishable by their uniform black anal fins (Ginsburg, 1951). (Uyeno and Sasaki)