The Echinoid Directory

Polyechinus Mortensen, 1942, p. 231

Diagnostic Features	Test hemispherical; height ca. 50-60% diameter. Apical disc dicyclic. Ambulacra polygeminate, with mostly four pore-pairs to a plate (some with three or five); pore-pairs forming oblique lines; not expanded adorally. Primary tubercle to each ambulacral plate; tubercles imperforate and non-crenulate. Interambulacral plates with prominent primary tubercle and scattered and much smaller secondary tubercles. Granules generally rather sparse so that plates appear naked. Peristome relatively small; less than one-third test diameter. Globiferous pedicellariae with tubular blade and several lateral paired teeth.
Distribution	Recent; South Africa.
Name gender	masculine
Type	Paracentrotus agulhensis Doderlein, 1905, p. 623, by original designation.
Species Included	Only the type species.
Classification and/or Status	Camarodonta; Echinoida; Echinidae. Monotypic.
Remarks	Distinguished from Echinus and Parechinus by its polygeminate ambulacral plating. Distinguished from Paracentrotus by the prominence of its primary tubercles and the number of pore-pairs to a compound ambulacral plate. Mortensen, T. 1943. A monograph of the Echinoidea Part III, 3. Camarodonta II. C. A. Retzel, Copenhagen.