Hard parts in the female system of Syndesmis longicanalis (Platyhelminthes, Rhabdocoela, Umagillidae) are basement membrane derivatives

Abstract

Data are presented on the ultrastructure of the sclerotised parts in the female system of the symbiotic turbellarian (Platyhelminthes) Syndesmis longicanalis. The bursal canal, in- semination canal, and bursal valve are basement membrane derivatives. These structures are compared with hard parts derived from basement membrane in other turbellarians. The taxo- nomic value of the bursal valve in Umagillidae is rejected.