Quarterly Journal of Microscopical Science, Vol s3-101, 407-432, Copyright © 1960 by Company of Biologists

The Spermatophores of Dolops ranarum (Crustacea, Branchiura): their Structure, Formation, and Transfer

¹ East African Fisheries Research Organization, Jinja, Uganda. Present address: Freshwater Biological Association, Ambleside, Westmorland

Sperm transfer in the genus Dolops involves the employment of spermatophores. In this respect the genus is unique within the Branchiura.

Proteinaceous wall material is secreted by arborescent spermatophore glands located in the carapace lobes of the male and is passed into a pair of long canals which terminate posteriorly as a pair of spermatophoric vesicles, part of whose walls are glandular. Spermatozoa from the vasa deferentia are injected into these vesicles and become surrounded by wall material. During the mating process the contents of each vesicle are squeezed out through the common genital orifice, where they become confluent and form a single, globular spermatophore. While its walls are still soft this is pressed against the base of the abdomen of the female, where it is pierced by two perforated spines at the end of the spermathecal ducts. The spermatophore hardens and remains attached to the female, thus giving the spermatozoa opportunity to migrate through the spermathecal ducts to the spermathecae. Not until after a moult of the female, however, during which the spermatophore is shed with the old cuticle, are the spermatozoa free to enter the eggs, each of which is believed to be pricked bythe spermathecal spines during oviposition.

By virtue of the fact that it involves quite different organs and processes in the two groups, spermatophore formation indicates that the Branchiura and Copepoda are not closely related. On the other hand, the process is in no way suggestive of a close relationship of the Branchiura and Branchiopoda, and the isolated position of the Branchiura is emphasized.