POPULATION DIFFERENTIATION AND TAXONOMIC STATUS OF THE EXPLOITED LIMPET PATELLA-CANDEI IN THE MACARONESIAN ISLANDS (AZORES, MADEIRA, CANARIES)

There has been considerable confusion in the taxonomy of limpets of th e North East Atlantic Ocean and Mediterranean Sea, particularly those from the Macaronesian islands. The present study compared populations of the intertidal limpet Patella candei d'Orbigny from the Azores, Mad eira and the Canaries with those of P. caerulea Linnaeus and P. depres sa Pennant from the European and African continental coasts. No major differences in radular morphology were detected between the three spec ies. However, electrophoretic analysis of 15 enzyme loci gave overall genetic identity (I) values of similar to 0.5 between the three specie s, indicating that they cannot be regarded as conspecific as previousl y thought, and suggesting that P. candei is endemic to the Macaronesia n islands. Comparisons of P. candei within these islands showed that, although populations did not differ with respect to radular morphology and soft-body parts, populations from the Azores were distinct from t hose in Madeira and the Canaries in shell shape and gene frequencies. Individuals from the Azores had, on average, taller shells and longer radulae, while those in Madeira and the Canaries had a shallow, depres sed and stellate shell form. This was interpreted as being due to the wider habitat distribution of the species in the Azores compared to Ma deira and the Canaries. Electrophoretic results showed that P. candei from the Azores differed from P. candei in Madeira and the Canaries by almost 40% of the loci investigated (I = 0.660), suggesting that the former is a separate endemic species. An I value of 0.969 between popu lations in Madeira and the Canaries was typical of conspecific populat ions.