The Echinoid Directory

Contributed by Andrew Smith, September 2006

Heteropedina Michalet, 1895, p. 71

Diagnostic Features
  • Test small, depressed, weakly subconical in profile; thin-plated.
  • Apical large (40% of test diameter); plating lost; opening pentagonal.
  • Ambulacra narrow and straight aborally; composed of simple plates with small tubercle on every third; all plates similar in size. At ambitus plating becomes trigeminate, with all three elements reaching the perradial suture.
  • Primary ambulacral tubercle on plates at and below the ambitus; occupying all three elements; perforate and crenulate below the ambitus, imperforate and non-crenulate adapically.
  •  Interambulacral zones with just 7 plates in a series; the aboral plates very tall and with single primary tubercle centrally placed. This is surrounded by a small number of secondary tubercles and granules, but the majority of the plate is tubercle free. Immediately beneath the ambitus, interambulacral plates become lower and bear three or four subequal primary tubercles plus large secondary tubercles. Multiple tubercles are present on all adoral plates.
  • Interambulacral tubercles are perforate and crenulate below the ambitus.
  • Peristome slightly sunken, about 50% test diameter.
  • Buccal notches not deep but there are large, well developed tags that run from them along the adradial margin of interambulacral zones.
  • Spines and lantern unknown
Distribution Middle Jurassic (Upper Bathonian), France.
Name gender feminine
Type Heteropedina moteti Michalet, 1895, p. 73. Holotype: Museum National d'Histoire Naturelle, Paris J01693.
Species Included Only the type species.
Classification and/or Status Euechinoidea, Acroechinoidea, Diadematoida incertae sedis

Monotypic.
Remarks The thin plating, large apical disc and very marked difference between apical and adoral plating and tuberculation make this a very instantly distinguishable taxon. In the absence of lantern information it is not possible to place this taxon for certain; however, it is almost certainly an acroechinoid and is here tentatively placed in the diadematoid, on account of its ambulacral plating and crenulate tuberculation.

Michalet, M. A. 1895. Le Bathonien des environs de Toulon et ses echinides. Description d'un nouveau genre Heteropedina. Bulletin de la Societe geologique de France, serie 3 23, 50-75.