The Echinoid Directory

Taphropygus Pomel, 1883, p. 59

Diagnostic Features
  • Test of small to medium size, ovate with posterior truncation, flattened aborally, oral surface sunken towards peristome.
  • Apical system tetrabasal, slightly anterior, with four gonopores, posterior oculars elongate and genital plate 2 enlarged, no catenal plating (advanced form).
  • Petals small, parallel, open distally, inner pore rounded, outer pore weakly elongated transversely; all ambulacral plates with double pores.
  • Periproct aboral, opening into deep sulcus that extends to the posterior margin. Far removed from the apical disc.
  • Peristome anterior, pentagonal, depressed, wider than high.
  • Bourrelets absent.
  • Phyllodes slightly widened, double pored, with two series of pore-pairs in each half-ambulacrum.
  • No buccal pores.
  • No naked zone in posterior interambulacrum orally.
Valanginian, Early Cretaceous of Switzerland.
Name gender masculine
Nucleolites subquadratus L. Agassiz, 1839, p. 41; by subsequent designation of Kier, 1962, p. 63.
Species Included
  • Pomel (1883) included two species, subquadratus and placentula, when erecting this genus.
Classification and/or Status

Irregularia; Neognathostomata; 'nucleolitid'.

Subjective junior synonym of Nucleolites Lamarck, 1801.


Pomel (1883) distinguished this from Clitopygus by its more deeply sunken periproct and the shape of the anal groove. In reality there is little to separate the two. Kier (1962) synonymized it with Nucleolites.

P. M. Kier. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections, 144 (3) 262 pp.