Gosliner, T. M. (1987). Biogeography of the Opisthobranch gastropod fauna of Southern Africa. American Malacological Bulletin. 5: 243-258.
Gosliner, T. M.
Biogeography of the Opisthobranch gastropod fauna of Southern Africa
American Malacological Bulletin
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In temperate Atlantic and Indian Ocean waters of southern Africa, endemic and Atlantic opisthobranch mollusks are predominant, while in tropical waters of the region these are replaced by Indo-Pacific and circumtropical species. Well-defined boundaries, previously described for southern African biogeographical provinces, are blurred when opisthobranchs are considered. However, distinct temperate and tropical faunas are present. Most of the Indo-Pacific species present in southern Africa extend well across the Indian Ocean, and a majority of species are also found on the non-marginal portions of the Pacific Plate.
Sister group relationships suggest that are southern African opisthobranch fauna is phylogenetically and biogeographically linked to three primary regions: sub-Antarctic, North Atlantic and Indo-Pacific. Links with sub-Antarctic species appear to be the oldest and may be related to cold water present during the Pliocene. Relationships with North Atlantic species are more recent (Pleistocene) and also appear to be related to major oceanographic and climatic changes.
Levels of endemism in different taxa are simply systematic artifacts, these discrepancies could actually represent challenges to simplistic vicariant hypotheses. The notion that sister species relationships of endemic species provide the only meaningful biogeographical data is discussed and challenged.