Monostephanostomum nolani sp. n. and M. krusei Reimer, 1983 (Digenea: Acanthocolpidae) from carangid fishes from coral reef waters off Australia.

Monostephanostonum nolani sp. n. is described from Carangoides plagiotaenia Bleeker, off Lizard Island, Great Barrier Reef, Queensland, Australia. It differs from all other species in the genus except M. manteri Kruse, 1979 in that the vitellarium reaches into the forebody. It differs from M. manteri in the ventral hiatus in the circum-oral spine row, the extent of the vitellarium in the forebody, where it is not confluent, its elongate pharynx and its smaller eggs. Monostephanostoinum krusei Reimer, 1983 is redescribed from Pseudocaranx dentex (Bloch et Schneider) from Ningaloo Reef off Western Australia. It is considered similar to M. nolani, differing in the vitellarium being restricted to the hindbody, but sharing with M. nolani an unusual arrangement of small body-spines on the antero-ventral surface. It is also morphologically very similar to Monostephanostomum roytmani (Parukhin, 1974), which apparently lacks the diminutive antero-ventral body-spines. A key to eight recognized species in the genus is presented.