The Echinoid Directory

• Test ovate with shallow anterior sulcus at ambitus; base flat; upper surface low and weakly domed.
• Apical disc with four gonopores; ethmolytic.
• Anterior ambulacrum narrow with simple pore-pairs.
• Paired ambulacra petaloid; slightly depressed and parallel-sided; extending to ambitus; open distally, without occluded end plates.  Only a narrow perradial zone between columns of pore-pairs.
• Peristome subcentral; pentagonal in outline, wider than long. Ambulacra on oral surface in shallow grooves with extensive phyllodes; phyllode pores extending two-thirds of the distance to the ambitus.
• Plastron plating shown as biserial in Cotteau\'s original figure, but this is erroneous. Plastron expanding to rear and not indented by ambulacra.
• Periproct large, just supramarginal on short, steeply sloping posterior face.
• Test badly abraided so presence of fascioles cannot be discerned.
• Aboral tuberculation heterogeneous, scattered small tubercles over all interambulacral zones.

Eocene, Spain.

Stomaporus hispanicus Cotteau, 1888, p. 977, by original designation.

• Only the type species.

Spatangoida, Asterostomatidae.

Monotypic.

The position of this taxon has been much debated, with Mortensen (1950) aligning it with Heterolampas and Fisher (1966) with the Brissidae. However, the clear development of adoral ambulacral grooves with greatly extended phyllodes, subcentral peristome and posteriorly expanding interambulacrum 5 on the oral surface clearly align it with Asterostoma. It differs from Asterostoma in having the periproct slightly supramarginal rather than inframarginal, and in having somewhat less extensive phyllodes (if Cotteau\'s drawings are to be believed). It also has a shallow frontal groove.

Cotteau, G. 1888. Compte Rend. Acad. Sci. 107, p. 977.

Cotteau, G. 1888. Bull. Soc. Geol. France (3) 16, p. 552.