A study of the conjugate sperm of the dytiscid water beetles Dytiscus marginalis and Colymbetes fuscus

Abstract

Paired sperm in which the sperm are closely united by their heads leaving the tails more or less free occur regularly in some animals. Among the Coleoptera paired sperm occur in several species including Dytiscus marginalis. In another Coleopteran, Colymbetes fuscus, sperm occur in groups of 3 or more. The sperm in each group are united in the head region with the tails free. The ultrastructure of the mature sperm of Dytiscus and Colymbetes is described. The sperm of both species are very long (Dytiscus, 0.94 mm; Colymbetes, 0.53 mm). The sperm heads are short (Dytiscus, 3.3 μm; Colymbetes, 15 μm) and are hooded structures. The head of Dytiscus is unusual in the possession of a barb extending out from the base of the hood. The nature of the pairing and grouping of the sperm described has been investigated both ultrastructurally and histochemically, and its significance is discussed. © 1974 Springer-Verlag.