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Holaster Agassiz, 1836, p. 183

Diagnostic Features
  • Test cordiform; anterior sulcus shallow without carina; posterior truncate; base flat.
  • Apical disc with four gonopores.
  • Paired ambulacra subpetaloid with circumflexed pore-pairs. Columns in anterior paired ambulacra markedly narrower than those in posterior column.
  • Frontal groove continuous from apex to peristome; mouth facing directly downwards.
  • Plastron plating meridosternous plating biserial after the sternal plate.
  • Row of enlarged primary tubercles in all interambulacral columns aborally.
  • No fascioles.
Distribution
Lower Cretaceous (Hauterivian) to Upper Cretaceous (Cenomanian).
Name gender masculine
Type
Spatangus nodulosus Goldfuss, 1829, p. 149, by subsequent designation of Savin, 1905, p. 26.
Species Included
  • H. intermedius (Goldfuss, 1829); Hauterivian, Europe.
  • H. laevis (Brongniart, 1822); Albian and Cenomanian, Europe.
  • H. nodulosus (Goldfuss, 1829); Cenomanian, Europe.
  • H. trecensis Leymerie, 1842; Cenomanian, western Europe.
  • H. gregoryi Lambert in Valette, 1913; Lower Cenomanian, UK.
Classification and/or Status

Holasteroida, Meridosternata, Holasteridae.

Paraphyletic as currently construed by exclusion of Cibaster, Offaster and possibly other genera.
Remarks

Differs from Sternotaxis in having biserial plastron plating rather than uniserial plating, and in lacking a marginal fasciole. Cibaster and Offaster differ primarily by possessing a marginal fasciole and a better developed anterior sulcus. Crassiholaster has a much thicker test, smaller, more anterior peristome opening into a shallow frontal groove, and more rounded lower surface but is otherwise identical in plate architecture.

Agassiz, L. 1836. Prodrome d'une monographie des Radiaires ou Échinodermes. Mémoires de la Société des Sciences naturelles de Neuchâtel, 1, 168-199.

Smith, A. B. & Wright, C. W. 2003. British Cretaceous echinoids. Part 7, Atelostomata, 1. Holasteroida. Palaeontographical Society Monographs, London. Pp. 440-568, pls 139-182.

Smith, A. B., Paul, C. R. C., Gale, A. S. & Donovan, S. K. 1988. Cenomanian and Lower Turonian echinoderms from Wilmington, south-east Devon, England. Bulletin of the British Museum (Natural History) Geology series 42, 1-244.