Sperm transfer and fertilization in the marine planarian<i>Sabussowia dioica</i>(Platyhelminthes, Tricladida, Maricola)

Abstract

Summary It has been established that in the gonochoristic marine planarian Sabussowia dioica (Claparède, 1863), the male animal produces sclerotic spermatophores that are deposited onto the body wall of the female. Sperm contained in these capsules penetrate the parenchyma and eventually enter the ovaries and the anterior vitellarian follicles. External deposition of spermatophores is unique within the triclads, while formation of spermatophores is unique within the marine planarians.