Spermatozoan morphology of 19 species of prosobranch limpets (Patellogastropoda) with a discussion of patellid relationships

Abstract

The spermatozoon morphology of 19 species of Indo-Pacific, East Atlantic and M editerranean patellid limpets was examined by transmission electron microscopy. All nine species of Patella and Helcion from the South Atlantic (southern Africa) and the Indo-Pacific, as well as three species from the North Atlantic, have sperm which correspond to one of the sperm groups I, II or III, previously described for patellacean limpets from southern Africa (Hodgson & Bernard 1988). With the exception of P. safiana and P. canescens , all 7 Patella species from the N.E. Atlantic/Mediterranean have sperm morphologies which closely resemble one another but are distinctly different from the sperm types of species in the southern hemisphere. These N.E. Atlantic/Mediterraean limpets have been assigned to a new sperm group, group VI. On the basis of sperm structure it is suggested that patellid limpets had three main centres of radiation: a N.E. Atlantic/Mediterranean centre; an East Atlantic centre with its focal point on the S.W. coast of southern Africa; an Indo-Pacific centre with its focal point on the S.E. coast of South Africa. Despite similarities between the species within groups, each has a unique sperm. An examination of spermatozoa of one patellid from Namibia and one from S. Angola (both initially identified as Patella miniata ), has revealed that their sperm are distinctly different, as well being different from that of P. miniata from South Africa. Subsequently, the species from Namibia was identified as P. adansonii . Furthermore, P. cf. miniata from S. Angola had a sperm which is remarkably similar to that of P. safiana from N.W. Africa and the two may be conspecific.