RESEARCH ARTICLE

Review of the Indo-Pacific labrid fish genus Hemigymnus

John E. Randall

Abstract

The labrid fish genus Hemigymnus Günther consists of three relatively large coral-reef species: the wide-ranging Indo-Pacific H. fasciatus (Bloch) and H. melapterus (Bloch), and H. sexfasciatus (Rüppell) of the Red Sea and Gulf of Aden, usually regarded as a synonym of H. fasciatus. It is treated here as a species, distinguished by color pattern, longer pelvic fins of the terminal male, and fewer gill rakers. These three fishes are generally found as solitary individuals over sand or sand-and-rubble substrata adjacent to sheltered coral reefs within the depth range of 1-30 m. Their principal mode of feeding consists of taking a mouthful of sand and detritus, releasing sand from the gill opening as they swim from the bottom, sorting the fossorial prey within the mouth and pharynx, and ejecting the larger inorganic fragments from the mouth. They also feed opportunistically on larger benthic prey. A maximum total length of 90 cm has been claimed for H. melapterus, but the largest specimen reliably reported is only 37 cm long. No specimens of H. fasciatus are known that are larger than 30 cm, and the largest H. sexfasciatus measures 36.5 cm in total length. A key, literature survey, table of gill-raker counts, and color photographs are provided for the three species.