Abstract

This study analyzes the structure of the spermatozoa of Fissurella latimarginata and Fissurella cumingi, two sympatric keyhole limpet species from the coast of Chile. Observations were made using light and scanning and transmission electron microscopy. The spermatozoa of these species are of the ect-aquasperm type, typical of molluscs having external fertilization. They are composed of a conical acrosome, with a deep posterior subacrosomal invagination, a truncated conical nucleus, and a mid-piece containing a ring of five mitochondria, from which emerges a flagellum. The spermatozoa of the two species have quantitative and qualitative differences between different structural components. The total mean length of the head of F. latimarginata spermatozoa was significantly longer than that of F. cumingi. Components of the heads of the spermatozoa including the acrosomes and nuclei also showed interspecific differences. The morphology of the spermatozoa of these species constitutes a valid taxonomic character which supports the proposal that F. latimarginata and F. cumingi are valid species.