Cephalaspidea s. l (Mollusca: Opisthobranchia) of the Madeira archipelago and Selvagens Islands, Northeast Atlantic, Portugal

A total of 37 species of cephalaspidean opisthobranchs have been recorded in the literature from the Madeira Archipelago and the Selvagens Islands. More than half of these records date from the 19th century. In this paper, two new records are added: Chelidonura africana Pruvot-Fol, 1953 and Chelidonura sabadiega Ortea, Moro and Espinosa, 1996; the latter recently described from El Hierro, Canary Islands. Anatomical data on Bulla mabillei are provided. The radula of this species and those of Ringicula conformis, Haminoea hydatis and Haminoea orteai are illustrated using scanning electron microscopy. Morphological details of the shells of six species (Ringicula conformis, Bulla mabillei, Philine catena, Retusa truncatula, Retusa mammillata, and Retusa sp.) are also described. The presence of Haminoea orteai (previously recorded twice from the eastern Atlantic, both as Haminaea cf. orteai) allows us to expand the range of this species. The faunistic affinities of the cephalaspideans from Madeira are studied by cluster analysis. This analysis shows a high affinity between Madeira and the Canary Islands, within a group formed by Mauritania, Senegal, and Cape Verde, and suggests the existence of a "boundary" between the Azores and Madeira that makes those archipelagoes more similar to the Lusitanian and Mediterranean regions, respectively, than to each other.