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 (rarely more) large suranal plate incorporated into the centre of 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	A. spinosa L. Agassiz, 1840; Bathonian of western Europe A. jauberti (Cotteau, 1881); Bajocian of western Europe. Most other species currently assigned to Acrosalenia belong elsewhere. The following are poorly known and are tentatively retained here pending further information. A. marratensis Kier, 1972; Toarcian, Saudi Arabia. ?A. radians Agassiz, in Agassiz & Desor, 1847); Callovian, France.
Classification and/or Status	Calycina, Salenioida (stem group). Presumed paraphyletic.
Remarks	This genus is a stem group members of the Salenioida. Milnia is separated here 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. Perisalenia has an apical disc with many more periproctal plates forming a pavement inside the apical ring, usually with the most anterior two or three plates enlarged, See discussion in Smith (2016). A. chartroni has a hemicyclic apical disc and integrated suranal plates that give the inner edge of the apical disc an angular appearance. Wrightechinus 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. Smith, A. B. 2016. British Cretaceous regular echinoids. Part 2 Carinacea. Monographs of the Palaeontographical Society (no. 646), pp. 69-176, pls 42-82. Vadet, A. 1985. Oursins fossiles du Boulonnais. Memoires de la Societe academique du Boulonnais 1, 60 pp.