The Echinoid Directory

Leiostomaster Lambert, 1920, p. 138 (20)

[=Vomeraster Lambert, 1920, 27, type species Hemiaster verrucosus Coquand, 1862 ]

Diagnostic Features
  • Test inflated with circular outline; posterior face obliquely truncate. Test slightly wedge-shaped in profile.
  • Apical disc ethmophract with four gonopores; central.
  • Strong sexual dimorphism, with females having wide, deeply sunken petals, and males narrower weakly depressed petals.
  • Anterior ambulacrum narrow and sunken adapically. Pore-pairs differentiated and presumably associated with funnel-building tube-feet.
  • Petals strongly bowed; sunken with pores elongate and slit-like; closing distally. Pinched where they cross the peripetalous fasciole.
  • Peristome small, pentagonal with lip; downward-facing.
  • Labral plate flask-shaped; extending to near the rear of the second ambulacral plate. Sternal plates almost symmetric, with slightly oblique median suture. Episternal plates offset.
  • Periproct small, circular, near top of posterior obliquely truncate face.
  • Well developed peripetalous fasciole; not indented interradially.
  • Aboral tuberculation uniform but rather coarse, with little granulation.
Upper Cretaceous (Senonian), North and central Africa, Antarctica to Recent.
Name gender masculine
Leistomaster gentili Lambert, 1920, p.162, by original designation.
Species Included
  • L. gentili Lambert, 1920; "Senonian superieur" (?Campanian), Algeria.
  • L. bignoti Cotteau, 1888; "Senonian superieur" (?Campanian), Algeria (possibly a synonym), Angola.
  • L. verrucosus (Coquand, 1862); "Senonian superieur" (?Campanian), Algeria.
  • L. subverrucosus (Gauthier, 1892); "Senonian superieur" (?Campanian), Tunisia.
  • L. vomer (Lambert, 1910); Upper Cretaceous, Antarctica.
Classification and/or Status

Spatangoida, Hemiasterina, Hemiasteridae.



Differs from Palaeostoma in having episternal plates biserial rather than following one another alternately. Sexual dimorphism in Leistomaster is marked and it is likely that Vomeraster, which was established on individuals with narrow, weakly sunken petals, represent males of this taxon.

Close to Holanthus in architecture but differing in having interambulacral plates swollen and with much coarser tuberculation.

Lambert, J. 1920. , p. 138Etude de quelques formes primitives de spatangoides. Bulletin de la Societe des sciences de l'Yonne 73, 107-147.