Taxonomy and phylogeny of the ‘football stars’ (Asteroidea, Sphaerasteridae)

The phylogenetic relationships of spherical and sub-spherical asteroids, belonging to the valvatidan family Sphaerasteridae (Early Jurassic–Recent), are revised in the light of abundant new fossil material from Europe and North Africa. The family had radiated by the Early Jurassic and the family Stauranderasteridae is its sister group. Morphological changes involved the formation of a domed body, the absence of differentiated marginal ossicles and the transformation of dorsal abactinal ossicles into a tessellation of large, thin plates. The family Podosphaerasteridae is placed in synonomy with the Sphaerasteridae. New taxa include Eosphaeraster amellagensis gen. et sp. nov., Bulbosphaeraster valettei gen. et sp. nov., Pouzaster pocknotata gen. et sp. nov., Rugosphaeraster rugenensis gen. et sp. nov., Echinosphaeraster gen. nov. (type species: Asterias scutata Goldfuss, 1833) and Valettaster thuyi sp. nov. It is suggested that the morphology of Sphaerasteridae is related to their close association with sponges.