Systematics and biodiversity of South African sea urchins

Master Thesis


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University of Cape Town

The South African Echinoidea (Echinodermata) were last reviewed by Clark & Courtman Stock (1976) and numerous unidentified specimens and records have accumulated since that time, plus there have been many taxonomic changes within the group. Therefore this study, which forms the first of its kind in 37 years, aims to update knowledge on the diversity and distribution patterns of South African echinoids and to provide a user-friendly, well-illustrated guide to the group. Dry and wet specimens, particularly those within the extensive collections of the Iziko South African Museum, were morphologically examined and identified, and the associated data were added to a database. Other data considered in this study include; historic data from the South African Museum and University of Cape Town catalogues, imagery data from the EchinoMapVM open-online database, trawl by-catch data from the Department of Forestry and Fisheries, and data from published literature. These resulted in 19 new records for the region, of which 84.2% were Indo-Pacific, 5.3% introduced, and the remaining 10.5% non-endemic, raise the total number of known species to 71. All species were photographically illustrated and a field guide is presented which included synonomy and previous literature for each species, one of more photographic illustrations, a distribution map, description and notes on global distribution. In terms of biogeography the regional echinoid fauna comprises 26.8 % endemics, 1.4 % introduced, and 71.8 % non-endemics; across 14 orders and 29 families. As expected, species richness pattern increased from west to east coast. However , the east coast displayed the lowest number of records; as compared to the South coast, which had the highest. Endemism peaked on the south coast and the west and east coast both supported the same level of endemics. The only introduced species, Tetrapygus niger, was from the west coast region. In terms of depth; species richness was highest in<500m and lowest in>500m.This maybe a result of the deep-seas (>500m) being severely under-sampled. The lack of full-time taxonomists and lack of expertise to review this group, may have contributed to the high number of new records.

Includes bibliographical references.