The Echinoid Directory

Bolbaster Pomel, 1869, p. 15

[=Psephoaster McNamara, 1987, p. 347, type species Psephoaster klydonos McNamara, 1987 ]

Diagnostic Features
  • Test globular in outline and profile; no anterior sulcus.
  • Apical disc ethmophract with four gonopores; central.
  • Anterior ambulacrum weakly sunken adapically; pore-pairs enlarged and presumably originally associated with funnel-building tube-feet. Interporal zone narrow.
  • Paired ambulacra petaloid; petals cruciform, with anterior pair much longer than posterior pair. Petals straight, weakly depressed and with a narrow and smooth interporal zone.
  • Ambulacral zones only narrowing a little as it passes through the peripetalous fasciole immediately beneath the petals.
  • Peristome small, kidney-shaped, facing obliquely forwards.
  • Labral plate longitudinally elongate - flask-shaped; widening to posterior and extending almost to the rear of second ambulacral plate. Sternal plates triangular, paired, symmetrical, with near vertical median suture; episternal plates and subsequent plating biserially alternate.
  • Periproct small and circular, near top of posterior face.
  • Peripetalous fasciole present; not indented interradially.
  • Aboral tubercles fine, dense, uniform and sunken.
Distribution
Upper Cretaceous to Upper Miocene; Europe, Australia.
Name gender masculine
Type
Spatangus prunella Lamarck, 1816, p. 33; by original designation.
Species Included
  • B. prunellla Lamarck, 1816; Maastrichtian, western Europe.
  • B. subidus McNamara 1987; Upper Eocene, Australia.
  • B. dolosus McNamara, 1987; Lower Oligocene, Australia.
  • B. verecundus McNamara, 1987; Lower Miocene, Australia.
  • B. planedeclivis Gregory, 1890; Early-Middle Miocene, Australia.
  • B. callidus McNamara, 1987; Upper Miocene, Australia.
  • Probably many others.
Classification and/or Status

Spatangoida, Hemiasterina, Hemiasteridae.

unknown.

Remarks

McNamara (1987), like others before, differentiate Bolbaster from Hemiaster sensu stricto by its spherical or subspherical shape and the almost complete absence of a frontal notch. It was supposedly distinguished from the very similarly-shaped Psephoaster by its more bowed and better developed petals. However, the type species of Bolbaster and Psephoaster have very similar petal development and no clear distinction between these two genera can be drawn.

Here Bolbaster is distinguished from Hemiaster by its more or less symmetrical sternal plating. In Hemiaster the two sternal plates are unequally developed and the median suture between them runs obliquely.

McNamara, K. J. 1987. Taxonomy, evolution and functional morphology of southern Australian Tertiary hemiasterid echinoids. Palaeontology 30, 319-352.

Pomel, A. 1869. Revue des échinoderms et de leur classification pour servir d’introduction à l’étude des fossiles, 67 pp. Deyrolle, Paris.