The Echinoid Directory

Diplotagma Schluter, 1870, p. 132

Diagnostic Features
  • Test flattened below, tall domal above.
  • Apical disc small, monocyclic. Periproct relatively large, with angular plates indenting the apical circlet.
  • Ambulacra polygeminate throughout. Approximately six pore-pairs to compound plate, arranged biserially throughout. Plate compounding style not clear but likely to be phymosomatid. Remainder of plate densely covered in uniform small secondaries and granules.
  • Interambulacral plates wider than tall. A small primary tubercle on each. The interradial zone covered in rather dense, small secondaries only.
  • Ambulacral and interambulacral tubercles of similar size; imperforate and non-crenulate with small mamelon.
  • No aboral naked interradial zone, lines of interambulacral tubercles converging adapically.
  • Peristome small, flush; buccal notches very feeble, hardly indenting.
  • Spines and lantern unknown; no primordial interambulacral plate.
Distribution
Upper Cretaceous, Germany.
Name gender neuter
Type
Dipolotagma altum Schluter, 1870, p. 64, by monotypy.
Species Included
  • Only the type species.
Classification and/or Status

Euechinoidea, Phymosomatoida, Phymosomatidae.

Monotypic.

Remarks

The small, monocyclic apical disc separates it from most taxa other than Acanthechinus which is easily distinguished by its much flatter shape and larger primary tubercles. Pliocyphosoma is very similar in tuberculation and ambulacral plating, but is much flatter in profile and lacks a distinct field of adradial secondary interambulacral tubercles.

Schluter, C. 1870.  Verhandlungen des Naturforschenden Vereins der Preussischen Rheinlande und Westfalens, 27, p. 132.

Schluter, C. 1883. Die Regularen Echiniden der norddeutschen Kreide. 1. Glyphostoma (Latistella). Abhandlungen zur geologischen Specialkarte von Preussen und den Thuringischen Staaten 41-72, pls 1-7 (pl. 4).