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The Echinoid Directory

Allaster Nisiyama, 1968, p. 127

Diagnostic Features
  • Test small and circular in outline, depressed in profile with rounded margins. A little depressed towards centre on aboral surface.
  • Apical disc subcentral; presence of gonopores not determinable.
  • Internal partition arrangement unknown.
  • Petals distally open and rather wide.
  • Interambulacral plating unknown on oral surface.
  • Periproct marginal.
Distribution
Oligo-Miocene of Japan.
Name gender masculine
Type
Allaster rotundatus Nisiyama, 1968, p. 128, by original designation. Holotype IGPS 73768.
Species Included
  • Only the type species.
Classification and/or Status

Clypeasteroida; Scutellina; Scutelliformes; Incertae sedis.

Monotypic; possibly a junior synonym of Remondella Durham, 1955.
Remarks

Based on two specimens, neither of which show the oral surface. The marginal periproct, widely open, lyrate petals and thick margin suggest this may be a young Scaphechinus or Remondella. However, preservation is very poor and insufficient information is available to place this taxon. Best treated as a nomen dubium.

S. Nisiyama 1968. The echinoid fauna from Japan and adjacent regions. Part II Palaeontological Society of Japan Special Papers 13, 1-491 [Text]. Illustrations of the species appear in S. Nisiyama 1967. The echinoid fauna from Japan and adjacent regions. Part I. Palaeontological Society of Japan Special Papers 11, 1-227.