Ophiomyxidae Ljungman, 1867

Martynov, Alexander, 2010, Reassessment of the classification of the Ophiuroidea (Echinodermata), based on morphological characters. I. General character evaluation and delineation of the families Ophiomyxidae and Ophiacanthidae 2697, Zootaxa 2697, pp. 1-154 : 136-137

Family Ophiomyxidae Ljungman, 1867

Diagnosis. Disk usually soft, covered with a thick layer of naked skin, usually with a few, small, inconspicuous, embedded scales, but in some taxa disk scales are larger and skin reduced. Radial shields are small, placed at the disk edge. Genital plates in many taxa are poorly developed, in some genera the abradial plate is completely reduced. The articulation surface of the adradial genital plate has a more or less elevated condyle, quite evident in some taxa, but missing entirely in others. The articulation surface of the radial shield has a conspicuous excavation in some taxa, a distal groove or an elongated condyle. Oral papillae usually spiniform, but in Ophiomyxa they are clearly widened with a dentate edge. Apical papillae (ventralmost teeth) usually spiniform and forming a small cluster, but in Ophioplexa gen. nov. the cluster is composed of numerous papillae, and in Ophiomyxa there is a single wide apical papilla. The following teeth are also in most cases spiniform. The dental plate has usually several small, round, perforating sockets, but in Ophiomyxa they are elongated and non-perforating. Jaws are relatively short. Adoral shields are distinctively widened, wing-like distally in many taxa, including Ophioscolex and Ophioplexa gen. nov. Oral shields are variable in size.

Dorsal arm plates are usually either fragmented or absent and concealed by a thick skin, but in some genera, including Ophiocymbium and Ophioplexa gen. nov., they are entire, well-defined with a very thin skin layer. Arm spine articulations are never volute-shaped and lack the sigmoidal fold, and in most taxa, including Ophiomyxa and Ophiobyrsa , are of the double-opening type. Around the muscle opening there is often a ribbed or folded area. In some taxa, including Ophioscolex and Ophiogeron , articulations are of the singleopening type, with a large muscle opening and a massive border. Single-opening articulations are present also in some species of the genus Ophiocymbium . Arm spines in most taxa, including Ophiomyxa , Ophioscolex and Ophiobyrsa are solid, having a distinctive long base, flattened ventrally and devoid of condyles, but in some taxa, e.g. Ophiolycus and Ophiocymbium , this base is not evident. In most taxa the vertebrae have a zygospondylous articulation, but in Ophiobyrsa and related genera the articulation is streptospondylous.

The family includes the genera: Astrogeron Verrill, 1899 , Astrogymnotes H.L. Clark, 1914 , Neoplax Bell, 1884 , Ophiobyrsa Lyman, 1878 , Ophiobyrsella Verrill, 1899 , Ophioblenna Lütken, 1859 , Ophiobrachion Lyman, 1883 , Ophiocanops Koehler, 1922 , Ophiocymbium Lyman, 1880 , Ophiogeron Lyman, 1878 , Ophiohyalus Matsumoto, 1915 , Ophiohymen H.L. Clark, 1911 , Ophioleptoplax H.L. Clark, 1911 , Ophiologimus H.L. Clark, 1911 , Ophiolycus Mortensen, 1933 , Ophiomyxa Müller & Troschel, 1840 , Ophiophrixus H.L. Clark, 1911 , Ophiophrura H.L. Clark, 1911 , Ophioplexa gen. nov., Ophioprium H.L. Clark, 1915 , Ophiorupta gen. nov., Ophiosciasma Lyman, 1878 , Ophioscolex Müller & Troschel, 1840 , Ophiosmilax Matsumoto, 1915 , Ophiostiba Matsumoto, 1915 , Ophiostyracium H.L. Clark, 1911 , Ophiosyzygus H.L. Clark, 1911 and Ophiovesta Koehler, 1930 .