The Echinoid Directory

Eucidaris Pomel, 1883, p. 109

[= Gymnocidaris A. Agassiz, 1863, p. 17 [non Gymnocidaris L. Agassiz, 1838, p. 3] ]

Diagnostic Features
  • Test moderately thick.
  • Apical disc usually monocyclic but occasionally with one or more oculars exsert. Generally slightly smaller than peristome. Genital plate 2 significantly larger than other genital plates.
  • Tubercles perforate and non-crenulate; areoles hardly incised. Scrobicular tubercles differentiated; not contiguous. Extrascrobicular tuberculation rather heterogeneous. Adoral areoles confluent.
  • Ambulacra almost straight with pore-pairs horizontal and separated by raised interporal partition that is as wide as an individual pore. Perradial tuberculation comprises a marginal primary tubercle and an inner secondary tubercle.
  • Peristome with ambulacral plates becoming biserially arranged in each column in outer part (not in all species).
  • Primary spines short, stout cylinders with blunt termination with a central button. Neck and collar short; the shaft ornamented by dense beaded ribs. Cortical hairs well developed.
  • Secondary spines short and apressed.
?Oligocene, Miocene to Recent; Indo-Pacific, central Atlantic and Caribbean.
Name gender feminine
Cidaris metularia Lamarck, 1816, p. 56, by subsequent designation of Clark & Bather, 1909, p. 88.
Species Included
  • E. metularia (Lamarck, 1816); Pliocene to Recent, Indo-Pacific.
  • E. thouarsii (Agassiz & Desor, 1847); Recent, East Pacific.
  • E. tribuloides Desmoulins, 1835; Miocene-Recent; Atlantic and Caribbean.
  • E. clavata Mortensen, 1928; Recent, Central Atlantic.
  • ?E. strombilata Fell, 1954; Oligocene; Australia and New Zealand.
Classification and/or Status

Cidaroida, Cidaridae, Cidarinae.

Presumed monophyletic.


This taxon is characterised by its short stout spines with their beaded ornamentation and blunt crown.

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

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.