The Echinoid Directory

• Test low hemispherical in profile with rounded ambitus.
• Apical disc small, firmly bound to coronal, dicyclic, with anterior genital plates larger than the posterior one. Periproct relatively large and with a smooth, rounded margin.
• Ambulacral zones narrower than interambulacral zones; plating trigeminate with plate compounding diadematid style (all three elements reach the perradius on ambital and adapical plates); with one element becoming a demiplate on adoral plates. Each compound plate with a primary tubercle, adjacent to the pore zone leaving a broad perradial granular zone.
• Pore-pairs in offset arcs of 3, expanding adorally slightly to form short phyllodes.
• Interambulacral plates wide, each with a central primary tubercle. At the ambitus and adorally there is a smaller adradial flanking scondary tubercle. The remainder of the plate is covered in dense granulation.
• Primary tubercles imperforate and non-crenulate; increasing in size beneath the ambitus.
• Narrow but distinct interradial naked zone developed adapically.
• Peristome moderate, hardly sunken; buccal notches deep and sharp.
• Spines and lantern unknown.

Middle Jurassic (Bathonian), Middle East.

Leioechinus namus Kier, 1972, p. 48 by original designation.

• L. namus Kier, 1972; Bathonian, Saudi Arabia.
• L. amplus Kier, 1972; Callovian, Saudi Arabia.

Euechinoidea, Echinacea, Stomechinidae.

Subjective junior synonym of Echinotiara Pomel, 1883.

Although Kier (1972) compared this taxon with Polycyphus and Psephechinus when erecting it, he surprisingly made no comparison with Echinotiara.

Kier, P. M. 1972. Tertiary and Mesozoic echinoids of Saudi Arabia. Smithsonian Contributions to Paleobiology 10, 1-242.