The Echinoid Directory

• Test small; coronal plating non-imbricate.
• Apical disc large and not bound to the corona; plating unknown.
• Ambulacra narrow and almost straight; composed of simple plates throughout.
• Pore-pairs small and non-conjugate. Perradial tuberculate zone very narrow (equal to pore-pair width); without primary tubercle but with three subequal granules.
• Interambulacral zones wide with about 5 pentagonal plates in a column.
• Single large primary interambulacral tubercle on each plate surrounded by small uniform granules that enlarge in size towards the plate periphery.
• No scrobicular circle of enlarged tubercles.
• Primary interambulacral tubercles crenulate; imperforate adorally and at the ambitus but with small rudimentary perforation adapically; mamelon very large and areole minimal.
• No buccal notches.
• Small lantern supports (apophyses) on first interambulacral plates.

Late Triassic (Carnian); Italy.

Cidaris montanaro Zardini, 1973, p. 12, by original designation.

• Only the type species.

Cidaroida (stem group).

Monotypic.

Differs from  miocidarids and most stem and crown cidaroids in having imperforate tubercles and no scrobicular circles or primary ambulacral tubercles. Only psychocidarids have imperforate tubercles, and they are always non-crenulate. Psychocidarids also have scrobicular circles surrounding primary interambulacral tubercles, and have differentiated primary ambulacral tubercles.

Kier, P.M. 1977. Triassic echinoids. Smithsonian Contributions to Paleobiology 30, 1-88.