The Echinoid Directory

Contributed by Andreas Kroh, June 2011

Promechinus Vadet, Nicolleau & Reboul, 2010, p. 34

Diagnostic Features

From Vadet et al. (2010)

  • Test circular, in profile flattened below and above.
  • Apical disc small, dicyclic with relatively large and regularly circular periproct. Apical firmly bound to corona and usually preserved.
  • At the ambitus and below ambulacra polygeminate, with 5 to 6 (?) elements to a compound plate. Plate compounding appears to be of diademaoid style with all elements reaching the perradius, but united in a single perradial wedge. Pore-pairs biserial aborally and at the ambitus, expanding into moderately well developed phyllodes adorally. Adapically ambulacral plating simple.
  • Ambulacral plates with single large tubercle. At the ambitus secondary tubercles present perradially. Adapically tubercles dimish in size rapidly.
  • Interambulacral plates with single large tubercle; centrally placed and set in a groundmass of coarse secondary tubercles. Plates wider than tall.
  • Ambulacral and interambulacral tubercles of similar size.
  • No well defined aboral naked interradial zone.
  • Primary tubercles weakly crenulate; some are perforate, some imperforate.
  • Peristome large, almost flush; buccal notches shallow but distinct.
  • Spines and lantern unknown; no primordial interambulacral plate.
Distribution Bajocian, High Atlas, Morocco.
Name gender masculine
Type Promechinus taferdoutensis Vadet, Nicolleau & Reboul, 2010, by original designation.
Species Included Only the type.
Classification and/or Status Euechinoidea, Echinacea, Stomopneustoida, Stomopneustidae.
Remarks Originally placed in Atopechinidae by Vadet et al. (2010), a taxon not recognized herein. Based on the morphology of the type species Promechinus seems to fit best within the Stomopneustidae. Differs from the similar Phymechinus by its crenulate and partially perforate tubercles.

Vadet, A., Nicolleau, P. & Reboul, R. 2010. Les Echinides de l'Atlas marocain: Bajocien Bathonien. Premiere partie: les reguliers. Annales de la Societe d'Histoire Naturelle du Boulonnais 9/1, 1-40.