The Echinoid Directory

Urechinus A. Agassiz, 1879, p. 207

Diagnostic Features	Test ovate; thin-shelled. Apical disc with three gonopores (no gonopore in G2). Posterior ocular V separated from G4. Ambulacra all similar with minute pores only outside oral region; all flush. Peristome subcentral and a little depressed; subcircular. Plastron plating orthosternous; first sternal plate enlarged and followed by a pair of symmetrical episternal plates. Scattered tubercles uniformly distributed over the entire aboral surface. Periproct submarginal. Subanal fasciole variably present.
Distribution	Recent; central Pacific and Antarctic.
Name gender	masculine
Type	Urechinus naresianus A. Agassiz, 1879, p. 207, by original designation.
Species Included	U. naresianus A. Agassiz, 1879; Recent, Antarctic. U. antipodeanus McKnight 1974; Recent, New Zealand. U. reticulatus H. L. Clark, 1913; Recent Hawaii.
Classification and/or Status	Holasteroida, Meridosternata, Urechinina, Urechinidae. Monophyletic.
Remarks	Differs from Cystechi nus A. Agassiz in having unfused anterior genital plates with just three gonopores. Mooi & David (1996) provide a detailed analysis of this genus. The three species vary only in slight details of pedicellarial structure and may well prove conspecific. Agassiz, A. 1879. Preliminary report on the Echini of the exploring expedition H.M.S. Challanger. Proceedings of the American Academy of Arts and Science 14, 182-261. Mooi, R. & David, B. 1996. Phylogenetic analysis of extreme morphologies: deep-sea holasteroid echinoids. Journal of Natural History 30, 913-953.