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The Echinoid Directory

Angusticlypeus Vadet, 1997, p. 48

Diagnostic Features
  • Test large, circular, inflated, domed to subconical in profile, greatest height at apical disc, adoral surface depressed towards peristome with interambulacra slightly raised and ambulacra depressed.
  • Apical system subcentral, tetrabasal, posterior ocular plates posteriorly prolonged and extending to periproct. No accessory plates.
  • Petals open, extending two-thirds of the way to margin, outer pore slit-like, all ambulacral pores double beneath the petals.
  • Periproct close to apex, in contact with posterior oculars; opening into deep and sharp anal sulcus that runs from the apex to the posterior margin.
  • Peristome pentagonal, small, slightly anterior to centre, higher then wide; opening sunken with vertical-walled entrance.
  • Bourrelets weakly developed.
  • Phyllodes double pored, with pore-pairs arranged in arcs of three forming a broad, but not bowed, band.
  • No buccal pores.
Distribution
Middle Jurassic (Bathonian-Callovian) of England and France.
Name gender masculine
Type
Clypeus angustiporus L. Agassiz in Agassiz & Desor, 1847, p. 156; by original designation of Vadet, 1997, p. 48.
Species Included
  • Vadet (1997) included the following species in this genus:
  • Angusticlypeus angustiporus L. Agassiz in Agassiz & Desor, 1847; Callovian, France.
  • Angusticlypeus rostratus L. Agassiz in Agassiz & Desor, 1847; Bathonian, UK, France.
  • Angusticlypeus babeaui Cotteau, 1870; Callovian, France.
Classification and/or Status
Irregularia; Neognathostomata; 'clypeids'.

Subjective junior synonym of Clypeus Leske, 1778
Remarks

Vadet (1997, p. 48) distinguished this genus from Clypeus based on a slight difference in the distance of the periproct from the 'bivium'. Such a feature is distinctly size/age related. However Angusticlypeus does not possess the broad poriferous zones within the petals that Clypeus does. Furthermore, the bourrelets are generally better developed in Clypeus than in Angustiporous.

A. Vadet. 1997. Echinides du Callovien de la Sarthe et de l'Orne. II. A les echinides irregulies: analyse et evolution. Memoiures de la Societe Academique du Boulonnias Serie Histoire Naturelle, 18 (1), 1-72.