The Echinoid Directory

Cystechinus A. Agassiz, 1879. p. 207

Diagnostic Features
  • Test large, ovate; paper-thin shell.
  • Apical disc with anterior genital plates fused. Three or four gonopores.
  • Ambulacra all similar with minute pore-pairs only; all flush.
  • Peristome subcentral and a little depressed; subcircular.
  • Plastron plating orthosternous. Episternal plates opposite; subsequent plating biserial.
  • Scattered primary tubercles uniformly distributed over the entire aboral surface.
  • Periproct submarginal to oral.
  • No fascioles.
Recent; north and central Pacific and Antarctic.
Name gender masculine
Cystechinus wyvillei A. Agassiz, 1879, p. 207, by original designation.
Species Included
  • C. wyvillei A. Agassiz, 1879; Recent, south eastern Pacific.
  • C. loveni A. Agassiz, 1898; Recent, central East Pacific.
  • C. giganteus (A. Agassiz, 1904); Recent, East Pacific.
Classification and/or Status

Holasteroida, Meridosternata, Urechinina, Urechinidae.



Differs from Urechinus A. Agassiz in having fused anterior genital plates. Mooi & David (1996) provide a detailed analysis of this genus.

Agassiz, A. 1879. Preliminary report on the echini of the exploring expedition of HMS Challenger. Proceedings of the American Academy of Arts and Sciences 14, 190-212.

Agassiz, A. 1904. Reports on an exploration off the west coasts of Mexico, central and south America and off the Galapagos Islands. Memoirs of the Museum of Comparative Zoology at Harvard University 31.

Mooi, R. & David, B. 1996. Phylogenetic analysis of extreme morphologies: deep-sea holasteroid echinoids. Journal of Natural History 30, 913-953.