The Echinoid Directory

Echinoneus Leske, 1778, p. 173

[=Echinonaus Gray, 1825, p. 7, [non Echinonaus de la Beche, 1822) type species Echinoneus cyclostomus Leske, 1778 (objective); =Echinanaus Gray, 1825 (nomen vanum) ]

Diagnostic Features
  • Test of moderate size, ovoid, margin broadly rounded, oral surface sunken towards the peristome.
  • Apical disc central, tetrabasal with four genital pores.
  • Ambulacra narrow, petals undeveloped, pores double throughout and arranged uniserially.  Ambulacral plating trigeminate with every third element a tiny adradial demiplate.; the other two elements subequal and reaching the perradius.
  • Tubercles imperforate. Glassy tubercles common (in the type-species).
  • Periproct oral, very large, longitudinally elongate, close to the peristome.
  • Peristome large, central or slightly anterior, oblique, depressed.
  • Bourrelets absent.
  • Phyllodes undeveloped.
  • No buccal pores.
  • No naked sternal area.
Oligocene to Recent, worldwide distribution.
Name gender masculine
Echinoneus cyclostomus Leske, 1778, p. 38; by subsequent designation of H. L. Clark, 1917, p. 101.
Species Included
  • E. cyclostomus Leske, 1778; Recent, Indo-Pacific, Caribbean, West Indies.
  • E. melitensis (Wright, 1864), Lower Miocene, Malta
  • E. dennanti Hall, 1907; Miocene, Australia

Lambert & Thiery (1909-1925) list 11 species within this genus.

Classification and/or Status
Irregularia; Echinoneioida, Echinoneidae.

Young Echinoneus have been found with an Aristotle's lantern. Mortensen (1948, p. 74) regarded Echinoneus as a direct descendant of Pyrina, belonging to the holectypoids, while A. Agassiz (1872-1874, p. 332) points out the close structural resemblance between the young Echinolampas and Echinoneus.

Echinoneus is very similar to Micropetalon. The two genera can be distinguished by the orientation of the periproct. This appears to be oblique in the type species of Micropetalon, while in Echinoneus only the peristome is oblique, the periproct being longitudinally ovate.

J. Lambert & P. Thiery. 1909-1925. Essai de nomenclature raisonnee des echinides. Libraire Septime Ferriere, Chaumont, 607 pp., 15 pls.

T. Mortensen. 1948. A monograph of the Echinoidea: 4 (1): Holectypoida, Cassiduloida. Reitzel, Copenhagen, 363 pp., 14 pls.