The Echinoid Directory

Stereopyga Pomel, 1883, p. 102

Diagnostic Features
  • Test flattened below and above; ambitus rounded.
  • Apical disc small (less than one-third test diameter); rounded; plating dicyclic, the posterior oculars insert; Genital plates pentagonal, G2 distinctly larger. Periproct subangular, plating unknown.
  • Ambulacra straight, plating trigeminate throughout; pore-pairs uniform and undifferentiated; more or less uniserial, except adorally where there are short phyllodes. Primary ambulacral tubercle to each plate; plate compounding acrosaleniid, with all three elements reaching the perradius two of the three elements overlapped by the primary tubercle.
  • Interambulacral plates wider than tall; plates with a single large tubercle, adradially placed. Wide perradial band of granulation at ambitus, with a naked interradial band developed adapically.
  • Ambulacral and interambulacral tubercles more or less similar in size; perforate and crenulate.
  • Peristome about half test diameter; buccal notches very deep, giving the peristome a crenulated appearance. No sphaeridial pits.
  • Spines and lantern unknown.
Distribution
Upper Triassic (Rhaetian) to Lower Jurassic (Toarcian), western Europe.
Name gender feminine
Type
Pseudodiadema mooreii Wright, 1854, p. 108, by monotypy.
Species Included
  • S. mooreii (Wright, 1857); Toarcian, UK.
  • S. gauthieri (Cotteau, 1885); Upper Pliensbachian, France.
  • S. prisciniacense (Cotteau, 1856); Upper Pliensbachian, France [probably synonymous with S. moorei].
  • S. silbinense Stefanini,1924; Rhaetian, Italy
Classification and/or Status
Acroechinoidea, Carinacea, Pseudodiadematidae.

Presumed paraphyletic by exclusion of Pseudodiadema
Remarks
Very close to Pseudodiadema, from which it differs only in having finer tuberculation and better developed granular zones in its interambulacra aborally.

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.