The Echinoid Directory

Plococidaris Mortensen, 1909, p. 51

Diagnostic Features
  • Test relatively thick.
  • Apical disc monocyclic; genital plates similar in size. Plates sparsely tuberculate.
  • Interambulacra with large primary tubercle; tubercles perforate and non-crenulate with lightly incised areoles.
  • Scrobicular tubercles differentiated and forming continuous circles on ambital plates; areoles coalesced close to the peristome.
  • Extrascrobicular zones very narrow with relatively few secondaries.
  • A narrow naked zone runs down the interradial and perradial zones.
  • Ambulacra weakly sinuous. Pore-pairs non-conjugate with interporal partition about as large as a single pore. Marginal tubercle on each plate, the rest of the narrow perradial zone being naked and furrowed.
  • Peristome similar in diameter to apical disc; 9-10 ambulacral plates, uniserially arranged in each series. Interradial plates confined to outer part of membrane.
  • Primary spines stout and bearing three or four whorls; the shaft in between the whorls is ornamented in dense granules, not aligned. Cortical hairs well developed.
Miocene to Recent, Madagascar, India, East Africa, Indo-Pacific.
Name gender feminine
Cidarites verticillata Lamarck, 1816, p. 56, by original designation.
Species Included
  • Only the type species.
Classification and/or Status

Cidaroida, Cidaridae, Cidarinae.



Close to Phyllacanthus in test form, but readily distinguished by its unmistakable spine morphology. Clark (1946) and Hoggett & Rowe (1986) synonymize this genus with Prionocidaris despite the very different spine morphology.

Mortensen, T. 1909. Die Echinoiden. Report on the Deutschen Südpolar-Expedition 1901-1903, 3 (3), 113 pp., 19 pls.

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

Hoggett, A.K. & Rowe, F. W. E. 1986. South-West Pacific cidarid echinoids (Echinodermata) including two new species. Indo-Malayan Zoology 3, 1-13.