On the phanerobranch dorids of Angola (Mollusca, Nudibranchia): a crossroads of temperate and tropical species

This paper presents descriptions of a collection of phanerobranch dorids collected from Angola. The following species are reported for the first time in that area: Okenia amoenula (Bergh, 1907), Okenia digitata (Edmunds, 1966), Polycera hedgpethi Marcus, 1964, Polycera aurantiomarginata García-Gómez & Bobo, 1984, Thecacera pennigera (Montagu, 1815) and Kaloplocamus ramosus (Cantraine, 1835). Only three of them have been previously collected from the tropical west coast of Africa, P. aurantiomarginata in the Cape Verde Islands (under the junior name Polycera xicoi Ortea & Rolán, 1989), T. pennigera in Ghana, and O. digitata also in Ghana (as belonging to the genus Teshia, here synonymized with Okenia). In addition, the new species Limacia annulata is described. This species is characterized externally by having five branchial leaves, a red ring near the apex of the lateral papillae, and lacking tubercles on the dorsum. Internally, L. annulata has a rachian plate in the radula. The patterns of distribution of several species and the hypothesis that Angola is a transition area between western and southern Africa are discussed.