The Echinoid Directory

Diademopsis Desor, 1855, p. 79

[=Hecistocyphus Pomel, 1883, p. 99, type species Diademopsis bonissenti Cotteau, 1976 ]

Diagnostic Features
  • Test generally rather small (<40 mm diameter); plating tesselate.
  • Apical disc dicyclic but usually with plating lost, thus not firmly bound to the corona.
  • Ambulacra more or less straight; trigeminate throughout with non-conjugate pore-pairs. Adoral triads with single large primary tubercle, adapical plates with primary tubercle uniting just two of the three elements. All three elements extending to the perradial suture.
  • Interambulacral plates wider than tall; dominated by large primary tubercle with a massive mamelon. In some species secondary tubercles on interradial side approach the size of the primary tubercle.
  • Primary interambulacral tubercles non-crenulate and perforate; areoles not sunken and contiguous on ambital and adoral plates.
  • Perignathic girdle of small peg-like auricles.
  • Lantern with broad, grooved teeth.
  • Spines long and slender, with solid core of stereom meshwork.
Distribution
Late Triassic (Rhaetian) to early Jurassic (Sinemurian); western Europe and South America (Peru). Possibly younger.
Name gender feminine
Type
Echinus serialis L. Agassiz, 1840, by subsequent designation of Bather, 1909, p. 109.
Species Included
  • D. serialis (L. Agassiz, 1840); Early Jurassic (Hettangian, Sinemurian) of Europe.
  • D. michelini (Cotteau, 1858); Upper Triassic (Rhaetian) and Early Jurassic (Hettangian) of western Europe and possibly Peru. [includes D. tomesii (Wright, 1857); Rhaetian, UK]
  • Diademopsis bonissenti Cotteau, 1976;
  • Several other nominal species in need of revision.
Classification and/or Status

Acroechinoidea, Pedinoida, Pedinidae.

Presumably paraphyletic by exclusion of Pedina and others.

Remarks

One of the commonest echinoids in the early Jurassic of western Europe. Distinguished from Hemipedina by having primary interambulacral tubercles contiguous within each column. Differs from Pedina in having uniserial pore-pairs and from Caenopedina in having wider interambulacral plates and simpler ambulacral plating adapically.

Desor, E. 1855-1858. Synopsis des échinides fossiles. Reinwald , Paris, lxviii+490 pp., 44 pls.

Vadet, A. 1995. Note sur les genres Diademopsis et Hemipedina. Memoires de la Societe Academique du Boulonnais 16, 89-97.

Smith, A. B. 1981. Implications of lantern morphology for the phylogeny of post-Palaeozoic echinoids. Palaeontology 24, 779-801 (description of lantern).