The elongated encased spermatophores of the capsalid (entobdelline) monogeneans Neoentobdella diadema (Monticelli, 1902) Kearn et Whittington, 2005 and N. apiocolpos (Euzet et Maillard, 1967) Kearn et Whittington, 2005 have been found attached by their proximal ends to the region of the vaginal opening, with the bulk of the spermatophore projecting from the vagina and therefore lying outside the body. In spite of previous reports, no spermatophores were found projecting from the common genital opening and if spermatophore exchange is as rapid as it is in the related entobdelline Entobdella soleae, then the chances of finding a spermatophore in this location are small. In N. diadema and N. apiocolpos it is likely that sperm enters the vagina through the open proximal end of an attached spermatophore, after which the empty spermatophore case is probably discarded. There is no evidence for a previous proposal that the whole spermatophore is engulfed by the vagina followed by digestion of the case to release the sperm. Three specimens of N. diadema were found each with two spermatophore cases projecting from the vagina and a specimen of N. apiocolpos carried three cases. Assuming that each parasite is able to donate or receive only one spermatophore at each mating, then the presence of one spermatophore does not prevent a further mating and acceptance of a fresh spermatophore. In spite of differences between the spermatophores of E. soleae and N. diadema/N. apiocolpos, the events of spermatophore exchange may be similar.
Two new species of entobdelline (capsalid) monogeneans are described from the skin of Australian dasyatid stingrays, namely Neoentobdella cribbi sp. n., a small parasite from the estuarine stingray, Dasyatis fluviorum Ogilby (Elasmobranchii: Dasyatidae) and Neoentobdella baggioi sp. n., a relatively large parasite from the porcupine ray, Urogymnus asperrimus (Bloch et Schneider) (Elasmobranchii: Dasyatidae). A striking feature of both of these new parasite species is a pad, possibly located within the genital atrium, armed with rows of closely spaced, rod-shaped microsclerites. Both species also possess a muscular papilla in the genital tract and a club-shaped structure near the common genital opening on the left lateral margin of the body. In N. cribbi, the latter feature is large and located anterior to the genital pad and in N. baggioi, it is small and located in a more posterior position. Similar embellishments in the genital area occur in N. natans Kearn et Whittington, 2005 and in N. parvitesticulata Kearn et Whittington, 2005, while other species (e.g. N. garneri Whittington et Kearn, 2009 and N. taiwanensis Whittington et Kearn, 2009) lack these features and differ also in functional aspects of the male copulatory apparatus and the haptor. Separate generic status for these two groupings is indicated, but must await a comparative and comprehensive review of all Neoentobdella spp.