Comparative sperm morphology of 15 species of limpet (Mollusca: Patellogastropoda: Lottioidea) and correlation with current systematics and phylogenies

The spermatozoa of 14 species (four genera) of Lottiidae and one species of Acmaeidae are described by transmission electron microscopy. All have ect-aquasperm, which are relatively small, morphologically simple, free-swimming sperm produced by species with external fertilization. Based on the size, shape and structure of the nucleus and acrosome, as well as features of the mid-piece, several morphological sperm ‘types’ are recognized within the species of Lottioidea described by the present and several previous studies. Sperm morphology largely supports current taxonomy as well as systematic and phylogenetic relationships. However, the morphology of the sperm of Lottia dorsuosa suggests that its generic status should be re-examined. The sperm morphology of Niveotectura pallida (formerly Acmaea pallida) is more similar to that of species of Tectura than of Acmaea mitra, supporting the current placement of N. pallida in the Lottiidae. This result is at odds with the close relationship between N. pallida and A. mitra indicated by recent phylogenies based on molecular data.