Spermatophores in Dermopristis cairae Whittington et Kearn, 2011 (Monogenea, Microbothriidae)

Spermatophores are described in the microbothriid monogenean Dermopristis cairae from the giant shovel-nosed ray, Glaucostegus typus (Elasmobranchii, Rhinobatidae). Each spermatophore consists of a fusiform capsule containing sperm and a hollow stalk. The proximal ends of the stalks of fully formed spermatophores were open and located in a recess on the ventral surface close to, but not inside, the vagina and the male reproductive opening. Three adult parasites carried spermatophores attached externally to the ventral surface. One individual carried 3 spermatophores and 2 others a single spermatophore. In addition, in 2 adults, short lengths of what appeared to be stalk remnants were observed attached near the reproductive openings. With regard to spermatophore exchange, the evidence in support of the following 2 possibilities is discussed. (1) Adult specimens of D. cairae carrying fully formed spermatophores ventrally are recipients not donors, having received their spermatophores singly during mating events. (2) Spermatophore carrying adults are donors, their spermatophores being freshly made and on offer to a potential mate. The evidence points to the first of these alternatives as the most likely but this is not conclusive and requires observations on mating between living parasites.