The Echinoid Directory

Antrechinus Mooi & David, 1996, p. 946

Diagnostic Features
  • Test small, ovate; thin-shelled.
  • Apical disc in males standard, with four gonopores. In females, highly modified for brooding (see David & Mooi 1990).
  • Ambulacra all similar with minute pores only; all flush.
  • Peristome subcentral and a little depressed; subcircular.
  • Plastron plating orthosternous; first sternal plate enlarged and followed by a pair of nearly symmetrical episternal plates.
  • Scattered tubercles uniformly distributed over the entire aboral surface.
  • Periproct marginal to supramarginal.
  • Subanal fasciole present, starting on Interambulacral plates 5b2/5a3.
  • Sphaeridia with ribbed ornament.
Distribution Recent, Antarctic.
Type Urechinus mortenseni David & Mooi, 1990, p. 207, by original designation.
Species Included
  • A. mortenseni (David & Mooi 1990); Recent, Antarctic.
  • A. nordenskjoeldi (Mortensen, 1905); Recent, Antarctic.
  • ? A. drygalskii (Mortensen, 1905); Recent, Antarctic.
Classification and/or Status

Holasteroida, Meridosternata, Urechinina, ?Urechinidae.



Differs from Cystechinus and Urechinus in having apical disc with four distinct genital plates, each with a gonopore. Unique in having a sunken test adapically in females associated with brooding, and ribbed sphaeridia. Periproct position and presence of a subanal fasciole similar to juveniles of Urechinus. Mooi & David (1996) provide a detailed analysis of this genus.

David, B. & Mooi, R. 1990. An echinoid 'gives birth', morphology and systematics of a new Antarctic species, Urechinus mortenseni (Echinodermata, Holasteroida). Zoomorphology 110, 75-89.

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