Zoogeography of the southern African echinoderm fauna

Abstract

Pertinent features of the oceanography of southern Africa are reviewed and an analysis of the echinoderm fauna in relation to the general biogeographic regions and local faunistic provinces is given. The last such analysis appeared in 1923, based on fewer species (216) and long before Stephenson's comprehensive analysis of the distribution of the southern African marine biota. Over 400 species of echinoderms are currently known from southern African waters, south of the tropic of Capricorn. These comprise 17 crinoids, 99 asteroids, 124 ophiuroids, 59 echinoids and 108 holothuroids. The endemic component is the richest, accounting for at least 47% of the fauna, with the Indo-Pacific component, including those species restricted to the Indian Ocean, or specifically to the West Indian Ocean, making up 37% of the fauna. The remaining species are either cosmopolitan (3%), tropicopolitan (1 %), or shared with the Atlantic (6%) or Southern Oceans (2%), or are ‘Other Foreign’ species (4%). The distribution pattern along the coast supports the division of the southern African marine region into three faunistic provinces-tropical, subtropical and temperate. The echinoderm fauna appears to have had mostly an Indo-Pacific origin but evidence indicates that, once it became well established and isolated, there was a secondary development of an active evolutionary centre.