Ophiura Lamarck, 1801 ( type species: O. ophiura (Linneaus, 1758)).
Ophiocrossota H.L. Clark, 1928, Ophiocten Lütken, 1855, Ophioctenella Tyler et al., 1995, Ophionotus Bell, 1902.
Flat disc, usually fully scaled but naked in some species. Genital papillae and arm combs present, although combs in Ophionotus reduced. Dental plate entire, sockets small round holes, not perforating, with low borders; single, offset column, ventral cluster. Lateral arm plates commonly divided in two halves by central, distalwards-pointing tentacle notch. Arm spine articulation with large, irregularly round muscle opening on an elevation, nerve opening at base of elevation.
Ophiura may be polyphyletic and needs to be revised (e.g., O. robusta (Ayres, 1852) has hooked spines on the distal arm, a character of Ophiopyrgidae Perrier, 1893). The subgenus Ophiuroglypha Hertz, 1927 is herein raised to genus-rank and referred to the Ophiopyrgidae. The available genus name Glaciacantha Fell, 1961b is used herein to contain two Southern Ocean species of Ophiocten ( dubium Koehler, 1901 and doederleini Hertz, 1927) with raised disc plates and hooked distal arm spines, and also transferred to the Ophiopyrgidae.