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Plesiocorys (Sternotaxis) Lambert, 1893, p. 95

[= Aurelianaster Lambert & Thiery, 1925, p. 589 (type species Leiocorys valettei Lambert, 1913 [= S. planus Mantell, 1822]; =Leiocorys Lambert 1913, p. 10 (type species Leiocorys valettei Lambert, 1913); = Cardiotaxis Lambert, 1917, p. 212(22) (type species Cardiotaxis peroni Lambert in Peron, 1887, p. 412(268) [= S. planus Mantell, 1822]); = Cardiataxis Lambert, 1917, p. 215(25) (pro errore); = Valettaster Lambert & Thiery, 1920, non Lambert, 1914 (type species Leiocorys valettei Lambert, 1913)]

Diagnostic Features
  • Test ovate with flat base, domal upper surface and weak anterior sulcus.
  • Apical disc subcentral with four gonopores.
  • All ambulacra with simple, rounded pore-pairs adapically.
  • Plastron plating uniserial with 2 to 4 post labral plates arranged uniserially.
  • Peristome small and circular; facing downwards.
  • Periproct on short truncate posterior face.
  • Aboral tuberculation uniform and fine.
  • Marginal fasciole may be present in small individuals of the type species.
Distribution
Upper Cretaceous (Turonian to Maastrichtian).
Name gender feminine
Type
Spatangus planus Mantell, 1822, p. 192, by original designation.
Species Included
  • P. (S.) plana (Mantell, 1822); Turonian, Europe.
  • P. (S.) aequituberculata (Cotteau, 1876); Coniacian-Santonian, western Europe.
  • P. (S.) heberti (Cotteau, 1860); Campanian-Maastrichtian, western Europe.
Classification and/or Status

Holasteroida, Cardiasteridae.

Monophyletic.
Remarks

Differs from Holaster and Offaster in having plastron plating uniserial over most of the oral surface. Distinguished from Plesiocorys (Plesiocorys) by having a distinct anterior sulcus and the periproct positioned much higher on the posterior face.

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.