Article: A reappraisal of the phylogenetic relationships of somaliasterid echinoids

Taxa assigned to the family Somaliasteridae (Atelostomata: Echinoidea) possess a combination of the characters usually considered diagnostic for placement in either Holasteroida or Spatangoida. Thus, the affinity of the somaliasterids to one or other of these orders has long been a subject of debate. A cladistic analysis of somaliasterid echinoids with unequivocal representatives of both holasteroids and spatangoids using characters that have commonly been applied in traditional evaluations of atelostomate phylogeny demonstrates that the somaliasterids are spatangoids. Descriptions of the somaliasterid taxa included in the analysis are given, and a new species, Iraniaster omanensis, is erected for previously undescribed somaliasterid material from Oman.