New observations on the genus Hypocreadium Ozaki, 1936 (Digenea: Lepocreadiidae) in the Indo-West Pacific region, including the description of one new species

Abstract

The following members of the genus Hypocreadium are described or redescribed: Hypocreadium cavum from the starry triggerfish, Abalistes stellatus, Swain Reefs, Great Barrier Reef; Hypocreadium patellare ‘Typical form’ from Abalistes stellatus, Swain Reefs, the masked triggerfish, Sufflamen fraenatum, Ningaloo, Western Australia and off New Caledonia and the titan triggerfish, Balistoides viridescens, off Lizard Island, Great Barrier Reef; Hypocreadium patellare ‘Atypical form A’ from the black-bar triggerfish, Rhinecanthus aculeatus, off Lizard Island and Palau and blackbelly triggerfish, R. verrucosus, off Palau; Hypocreadium patellare ‘Atypical form B’ from the yellow-spotted triggerfish, Pseudobalistes fuscus off Lizard Island; Hypocreadium picasso n. sp. from Rhinecanthus aculeatus, off Lizard Island and Palau, characterised by its broadly pyriform shape and lack of an anterior notch. A key to the species of Hypocreadium is presented. The similarity of the genus Lutianotrema to Hypocreadium is pointed out, but both known species of Lutianotrema are described with ‘dorsal’ oral suckers.