The Echinoid Directory

Acrosalenia L. Agassiz, 1840, p. 38

[= Plesiosalenia Valette, 1906, p. 275 (subjective); = Perisalenia Valette, 1906, p. 276 (subjective).

See also Acrosalenia (Milnia) Haime, 1849]

Diagnostic Features
  • Apical disc not raised above the corona; smooth; hemicyclic (the posterior two oculars reaching the periproct).
  • Periproct displaced towards posterior along anterior-posterior axis. One or more suranal plates incorporated into the disc.
  • Ambulacral plating trigeminate adorally and usually throughout; granulation developed between the two columns of primary tubercles.
  • Single primary tubercle to each interambulacral plate; all tubercles perforate and crenulate. In type species primary tubercles decrease in size adapically.
  • Primary spines relatively stout and fusiform, with cortex.
Distribution
Lower Jurassic (Hettangian-Sinemurian) to Lower Cretaceous (Valanginian); Europe, Former Soviet Republic, North Africa; Middle East.
Name gender feminine
Type
 Acrosalenia spinosa L. Agassiz, 1840, by original designation.
Species Included
Classification and/or Status

Calycina, Salenioida (stem group).

Presumed paraphyletic.

Remarks

This genus, as redefined here, is presumed to represent the earliest stem group members of the Salenioida. Milnia is separated here as a monophyletic subclade distinguished by having a very slender, strongly U-shaped posterior genital plate (genital plate 5). Metacrosalenia differs in having simple ambulacral plating from the ambitus adapically. Eodiadema has a similar tuberculation, and a hemicyclic apical disc, but the disc has a smoothly rounded periproctal opening and there is no evidence for there having been suranal plates.

A. chartroni has a hemicyclic apical disc and integrated suranal plates that give the inner edge of the apical disc an angular appearance.

A. lycetti Wright, 1851 differs from true Acrosalenia in having a monocyclic rather than hemicyclic apical disc. It deserves separation at generic level.

Agassiz, L. 1840. Description des Échinodermes fossiles de la Suisse. Partie 2, Cidarides. Mémoires de la Société helvétique des Sciences naturelles, 4, 107 pp., 11 pls

Vadet, A. 1985. Oursins fossiles du Boulonnais. Memoires de la Societe academique du Boulonnais 1, 60 pp.