Genetic variation and biochemical systematics in the marine bryozoan Alcyonidium mytili

For many years the taxonomic position of the marine ctenostome bryozoan Alcyonidium mytili Dalyell (1848) has been in doubt, with some authorities regarding it as being conspecific with A. polyoum (Hassall). We have set out to resolve this problem using enzyme electrophoresis to examine the genetics of the population structure in the two species. The results show beyond reasonable doubt that sympatric populations of the two species are indeed from quite separate and non-interbreeding gene pools. An examination of various allopatric populations shows a new species of A. mytili to exist sympatrically with the other at Langstone Harbour, Hampshire, England. This species can be readily distinguished on morphological as well as genetic ground. Samples of A. mytili from Guernsey also show substantial genetic differences from other populations examined. It is tentatively concluded that this population also represents a separate gene pool and consequently should be recognised as a third species of A. mytili.