On the morphology and life-history ofPodocotyle Reflexa(Creplin, 1825) Odhner, 1905, and a Comparison of its developmental stages with those ofP. Atomon(Rudolphi, 1802) Odhner, 1905 (Trematoda, Opecoelidae)

Abstract

Abstract The life-cycle of the digenetic trematode Podocotyle reflexa (Creplin, 1825) Odhner, 1905 (fam. Opecoelidae) is shown experimentally. The cotylomicrocercous cercaria of P. reflexa, C. buccini Lebour, 1911, develops in sporocysts in Buccinum undatum L. and Neptunea antiqua (L.) (Gastropoda, Prosobranchia). The cercariae encyst in muscles of various crustaceans. Crangon crangon (L.) was used as experimental intermediate host. The metacercariae developed into P. reflexa in cod, Gadus morhua L. given shrimps with two to four months old metacercariae. The cercaria, metacercaria and adult of P. reflexa are redescribed and compared with similar developmental stages of P. atomon (Rudolphi, 1802) Odhner, 1905. P. reflexa has been considered a synonym of P. atomon. The tegument and suckers of the cercaria of P. reflexa were studied in the transmission electron microscope. All developmental stages of P. reflexa and P. atomon were studied in the stereoscan electron microscope. The surface of the cercaria of P. reflexa is smooth apart from a microvillous fringe which surrounds the suckers, whereas the whole surface of the cercaria of P. atomon is covered with microvilli. The microvilli of both cercarial species are shed a few hours after penetration into the crustacean host. A few days after encystment the metacercariae of both species develop short microvillus-like projections all over the body. These projections disappear about one month after encystment, and the metacercariae do not grow further.