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.