Observations on the ultrastructure of the spermatozoon of two mytilids from the south-west coast of England

Abstract
Two forms of the genus Mytilus, M. edulis L. and M. galloprovincialis Lmk inhabit the rocky shores of Devon and Cornwall (Hepper, 1957). According to Gosling (1984), controversy has existed since 1860 as to whether M. galloprovincialis is a separate species or a subspecies of M. edulis. In a review of the systematic status of M. galloprovincialis, Gosling (1984) analysed the criteria used to identify and classify this form of Mytilus. Gosling did not reach any firm conclusion on the systematic status of these mytilids, but did suggest that the evidence favoured placing M. galloprovincialis as a variety, ecotype or even subspecies of M. edulis.