The Echinoid Directory

Pseudholaster Pomel, 1883, p. 45

[=Labrotaxis Casey, 1960, p. 260, type species Labrotaxis cantianus Casey, 1960 ]

Diagnostic Features
  • Test cordate with deep anterior sulcus with sharp carina. Lower surface flat but with keeled plastron.
  • Apical disc subcentral with four gonopores.
  • Paired ambulacra petaloid with elongate and conjugate pore-pairs Columns of pore-pairs of unequal size, the posterior column being 1.5 to 2 times as wide as the anterior column.
  • Frontal groove present from apex to peristome.
  • Peristome oval, typically facing slightly anterior.
  • Plastron plating protosternous: labral plate with horn that extends to meet second sternal plate.
  • Enlarged primary tubercles line the margin of the anterior sulcus and are also developed adapically and along the posterior interambulacral ridge aborally.
  • No fascioles.
Cretaceous (Valanginian to Campanian) to Palaeocene, widespread.
Name gender masculine
Holaster bicarinatus Agassiz, in Agassiz & Desor 1847, p. 29 , by subsequent designation of Lambert, 1917, p. 20.
Species Included
  • P. bicarinatus (Agassiz, 1847); Albian, Cenomanian of France and UK.
  • P. cantianus (Casey, 1960); Albian, UK.
  • P. depressus Smith & Wright, 2003; Upper Albian, UK.
  • P. blackdownensis Smith & Wright, 2003; Albian, UK.
  • P. latissimus (Agassiz, in Agassiz & Desor, 1847); Albian, western Europe.
  • P. suborbicularis (Brongniart, 1822); Albian-Cenomanian, western Europe.
  • P. cenomanensis (d'Orbigny, 1855); Cenomanian, western Europe.
  • P. prestensis Desor, in Jaccard, 1869; Aptian, Europe.
  • P. benstedi (Forbes, 1852); Aptian, UK.
  • P. caseyi Smith & Wright, 2003; Aptian, UK.
  • P. sequanicus (Bucaille, 1883); Albian-Cenomanian, western Europe.
  • P. declivus (Lambert, 1881); Albian, UK.
  • P. boulei (Lambert, 1896); Campanian, Madagascar.
  • P. tenuiporus (Cotteau); Santonian, France.
  • P. faxensis (Hennig, 1898); Palaeocene, Denmark.
Classification and/or Status

Holasteroida, Cardiasterina stem group.

Paraphyletic by exclusion of Cardiaster  and the cardiasterids.


A currently undivided grade group that contains early members of the holasteroid that retain the primitive protosternous plastron plating. Cardiaster has a rather similar appearance, but has a marginal fasciole and labrum in contact with just one sternal plate. Giraliaster is also very similar in appearance, differing in having a submarginal fasciole. Differs from Protocardiaster only in lacking a marginal fasciole.

Pomel, A. 1883. Classification méthodique et Genera des Échinides vivante et fossiles. Thèses présentées a la Faculté des Sciences de Paris pour obtenir le Grade de Docteur ès Sciences Naturelles 503, Aldolphe Jourdan, Alger, 131 pp.

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.