A morphological study of Diplodiscus subclavatus (Pallas, 1760) (Trematoda: Diplodiscidae) adults from the accidental host, Viviparus contectus (Millet, 1813) (Caenogastropoda: Viviparidae)

摘要

A phenomenon of switching of the parasite in the food chain to an accidental host is commonly observed in nature. However, there is little available data concerning the morphological descriptions of parasites that passively get into the atypical hosts and are capable, at least to some degree, of somatic growth and development of reproductive structures. A morphological survey of Diplodiscus subclavatus (Pallas, 1760) adults isolated from a digestive tract of an accidental host, Viviparus contectus (Millet, 1813), was carried out. Diplodiscus subclavatus individuals identified in prosobranch snails were morphologically similar to adult forms of the parasite described from amphibians, typical final hosts in the life cycle of this paramphistomid. The observed forms of D. subclavatus had a fully developed reproductive system, sperm in the seminal vesicle and oocytes in the ovary. The number of eggs in the uterus ranged from 3 to 17. Our research indicates that D. subclavatus individuals reach the sexual maturity in the accidental, invertebrate hosts.