Ultrastructure of sperm morphology of Trilobodrilus axi and T. heideri (Dinophilidae, Polychaeta)

Abstract

The ultrastructure of the sperm of the dinophilids Trilobodrilus axi and Trilobodrilus heideri was investigated. The sperms are extremely modified and show an elongated head, middle piece, and tail region, which are overlapping. This condition is a synapomorphous feature for the dinophilids. The sperm structure has to be related to the specialized mode of sperm transfer by hypodermal injection in these species. © 1986 Biologische Anstalt Helgoland.