The Echinoid Directory

• Test tall with sides subvertical.
• Apical disc unknown.
• Interambulacra with approximately 12 plates in a series. Primary tubercles perforate and noncrenulate throughout. Areoles ovate and incised; separated.
• Scrobicular circles strongly differentiated from extrascrobicular tubercles; confluent on adoral plates. Extrascrobicular zones developed adradially and especially interradially where granulation is dense, uniform and arranged in horizontal lines; more heterogeneous on adradial side and without strong alignment.
• No pits or naked zones; sutures not incised.
• Ambulacra straight and wide. Pore zones about same width as perradial tuberculate zone. Pore-pairs strongly conjugate, the two pores widely separated and linked by a well-developed furrow.
• Ambulacral tuberculation consisting of a marginal primary tubercle plus two smaller perradial tubercles forming a horizontal row; granulation also present.
• Primary spines long and relatively slender.

Upper Cretaceous, (Turonian) to Eocene, North Africa, Pakistan.

Pomel (1883) included four species when proposing this genus, Rhabdocidaris sanctae-crucis, venulosa, pouyannei and subvenulosa; no type has ever been designated. Here I select Rhabdocidaris subvenulosa Peron & Gauthier, 1880, p. 90, as the type species. Syntypes of R. subvenulosa are J06076 (2 specimens), Museum National d'Histoire Naturelle, Paris.

• It is not certain that the four species originally referred to this genus by Pomel have any close relationship.

Cidaroida, Cidaridae, Cidarinae.

Subjective junior synonym of Prionocidaris Agassiz, 1863.

Both Mortensen (1928) and Fell (1966) chose to ignore this taxon. However, Pomel's original designation was sound, although he did not designate a single type species, and the genus is valid. The strongly congugate pore-pairs and dense aligned interradial granulation distinguish this genus.

The non-crenulate nature of the primary tubercles and the dense homogeneous extrascrobicular granulation distinguish this taxon from Rhabdocidaris and its relatives. However, there are no significant differences in test morphology that distinguish it from Prionocidaris.

Pomel, A. 1883. Classification méthodique et Genera des Échinides vivante et fossiles. Thèses présentées a la Faculté des Sciences de Paris 503, A. Jourdan, Alger, 131 pp.

Mortensen, T. 1928. A monograph of the Echinoidea. 1, Cidaroidea. C. A. Reitzel, Copenhagen.

Fell, H. B. 1966. Cidaroida, in R. C. Moore (ed.) Treatise on Invertebrate Paleontology Part U, Echinodermata 3. Geological Society of America and University of Kansas Press, Boulder.