Revision of Decacotylinae Chisholm, Wheeler & Beverley!Burton, 1995 (Monogenea&COLFAML; Monocotylidae), including the synonymy of Papillicotyle Young, 1967 with Decacotyle Young, 1967 and a description of a new species from Australia

Close examination of type and new material of Decacotyle lymmae Young, 1967 revealed the presence of two unsclerotised structures on the dorsal surface of the haptor which were overlooked in the original description. We demonstrate that Papillicotyle Young, 1967, distinguished previously from Decacotyle Young, 1967 in part by the presence of unsclerotised accessory structures on the dorsal surface of the haptor, is synonymous with Decacotyle. D. tetrakordyle n. sp, is described from the gills of Pastinachus sephen (Forsskal) collected from Heron Island, Great Barrier Reef, Australia. D. tetrakordyle n. sp. is distinguished from the other four species in the genus by the presence of four accessory structures on the dorsal surface of the haptor and a complex male copulatory organ. Additional specimens of D. lymmae Young, 1967 from the gills of Taeniura lymma (Forsskal) and D. floridana (Pratt, 1910) n. comb and D. octona (Young, 1967) n. comb from the gills of Aetobatus narinari (Euphrasen) were also collected from the Queensland coast, Australia in the present study: D. youngi (Timofeeva, 1983) n. comb. is also transferred to Decacotyle from Papillicotyle. The Decacotylinae Chisholm, Wheeler & Beverley-Burton, 1995 is revised based on examination of type material, material of the new species and additional material of three previously described species. The oncomiracidium of D. floridana is described. A key to species is given and a description is provided of anterior glands containing needle-like secretion located lateral to the pharynx not described previously in D. lymmae. The discovery of D. floridana at Heron Island and D. octona in Moreton Bay represent new locality records for these species.