Descriptions of the larvae of six species of monocotylid monogeneans from Himantura fai (Dasyatididae) and Rhinobatos typus (Rhinobatidae) from Heron Island, Great Barrier Reef, Australia

The oncomiracidia of the following six species of monocotylids are described: Monocotyle helicophallus and M. spiremae from the gills and Merizocotyle australensis from the nasal fossae of Himantura fai; Neoheterocotyle rhinobatidis and Troglocephalus rhinobatidis from the gills and Merizocotyle icopae from the nasal fossae of Rhinobatos typus. With these descriptions, larvae from 17 described monocotylids representing 11 genera from five subfamilies are now known. The distribution, types of secretions, and possible functions of the anteromedian, lateral and posterior gland-cells are discussed. The distribution of flame-cells and other characters which may help distinguish between oncomiracidia of monocotylids are also tabulated and discussed.