On the number of Patella species in south-west England

Abstract

Limpet populations of the genus Patella from the south-west coast of England were examined by means of gel electrophoresis in order to settle debate on the specific status of the three Patella forms. Populations varied morphologically along an east-west gradient, from three distinct forms in the west to continuous intergradation in the east, in accord with earlier studies. Patella collected were divided into three groups on the basis of a complex of external features described by earlier workers, corresponding to the morphologically defined taxa P. vulgata Linn., 1758, P. aspera Röding, 1798, and P. depressa Pennant, 1777. These groups were electrophoretically distinct in five of seven enzyme systems examined, with no hybrids or intermediates. Incomplete speciation and hybridization can be ruled out as possible causes of the observed morphological variation.