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The Echinoid Directory

Nucleopygus L. Agassiz, 1840, p. 7, 16

[=Lychnidius Pomel, 1883, p. 55; type species Nucleolites scrobiculatus Goldfuss, 1829; = Porobrissus Lambert, 1916, p. 169; type species Echinobrissus angustatus Clark, 1915, p. 69.  Jolyclypus Lambert, 1918, p. 26, type species Galeropygus jolyi Gauthier, 1898, p. 837. ]

Diagnostic Features
  • Test small, low, generally oval; well-rounded margin; slightly depressed towards peristome.
  • Apical system tetrabasal, four gonopores; eccentric anteriorly.
  • Petals narrow, inconspicuous, usually open with subconjugate pores. Ambulacral pores beyond petals single pored.
  • Periproct supramarginal, longitudinal, opening into short groove that extends to posterior margin.
  • Peristome pentagonal or subpentagonal; anterior.
  • Bourrelet zones flush and confined to inward sloping walls of peristome.
  • Phyllodes single pored, narrow, very few or no occluded plates but every third plate insert.
  • Buccal pores present.
  • Adoral tubercles of same size or only slightly larger than adapical tubercles.
  • Very narrow finely granular zone following interradial suture of interambulacrum 5.
Distribution
Cretaceous (Albian-Maastrichtian) Europe, Africa.
Name gender masculine
Type
Nucleopygus minor Desor, 1842, p. 33, by subsequent designation of Lambert 1898, p. 165.
Species Included
  • N. minor Desor, 1842; Turonian, France.
  • N. coravium Agassiz & Desor; Maastrichtian, Netherlands and Belgium.
  • N. haydeni (Fourtau, 1917); Turonian, India.
  • N. magnus Smith; Maastrichtian, Oman.
  • N. madrugensis (Sanchez Roig, 1949); Maastrichtian, Cuba.
  • N. meslei (Peron & Gauthier, 1881); Maastrichtian, Tunisia.
  • N. carezi Lambert, 1907; Maastrichtian, France.
  • N. pseudominimus (Peron & Gaulthier, 1881); Maastrichtian, Libya.
  • N. pullatus (Stoliczka, 1873); Campanian-Maastrichtian, Madagascar.
  • N. scrobiculatus (Goldfuss, 1829); Maastrichtian of Europe.
  • N. angustatus (Clark, 1915); Albian-Cenomanian, USA.
  • N. (Jolyclypus) jolyi (Gauthier, 1898); Cenomanian, France.
Classification and/or Status
Irregularia; Cassiduloida; Apatopygidae.
Remarks

Nucleopygus is similar to Apatopygus in having a tetrabasal apical system (in young Apatopygus) with four gonopores, a supramarginal periproct with an anal sulcus, and simple phyllodes with only a well defined outer series of single pores.

Nucleopygus differs from Apatopygus and Porterpygus in lacking pyrinoid plating in the ambulacra beyond the petals.

Nucleopygus is superficially similar to the \'nucleolitids\', however, these genera are double pored beneath the petals and lack buccal pores.

Agassiz, A. 1840. Catalogus systematicus Ectyporum Echinodermatum fossilium Musei Neocomiensis, secundum ordinem zoologicum dispositus; adjectis synonymis recentioribus, nec non stratis et locis in quibus reperiuntur. Sequuntur characteres diagnostici generum novorum vel minus cognitorum. Oliv. Petitpierre, Neuchâtel. 20 pp.

E. Desor. 1842. Troisieme monographie des Echinites; Des Galerites. In L. Agassiz Monographies d\' Echinodermes vivans et fossiles p. 33, pl. 5, figs, 20-22.

P. M. Kier. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections 144 (3) 262 pp.

A. B. Smith & C. H. Jeffery. 2000. Maastrichtian and Paleocene echinoids: a key to world faunas. Special Papers in Palaeontology 63, 406 pp.