Ophiotrichidae Ljungman, 1867

Stöhr, Sabine, Hugall, Andrew F., Thuy, Ben & Martynov, Alexander, 2018, Morphological diagnoses of higher taxa in Ophiuroidea (Echinodermata) in support of a new classification, European Journal of Taxonomy 416, pp. 1-35 : 22-23

Family Ophiotrichidae Ljungman, 1867

Type genus

Ophiothrix Müller & Troschel, 1840 (type species: O. rosula (Forbes, 1839) = O. fragilis (Abildgaard in O.F. Müller, 1789)) . Original type designation O. rosula by Lyman (1865). H.L. Clark (1915) synonymized O. rosula with O. pentaphyllum ( Pennant, 1777) which may have caused later authors to accept the latter (older) name for the type species for some time but it was then replaced by O. fragilis for unknown reasons. Indeed, the name O. pentaphyllum has priority over the name O. fragilis and the proposal by A.M. Clark (1967) to suppress it appears never to have been decided. Prevailing usage cannot be applied because the name O. pentaphyllum was used as a valid species name after 1899 (ICZN article 23.9.1.1). However, to change the name of the well-known O. fragilis after a century of usage would not serve the purpose of nomenclatural stability. A ruling by the commission is needed.

Other genera

Gymnolophus Brock, 1888 , Lissophiothrix H.L. Clark, 1938 , Macrophiothrix H.L. Clark, 1938 , Ophiocnemis Müller & Troschel, 1842 , Ophiogymna Ljungman, 1866 , Ophiolophus Marktanner- Turneretscher, 1887, Ophiomaza Lyman, 1871 , Ophiophthirius Döderlein, 1898 , Ophiopsammium Lyman, 1874 , Ophiopteron Ludwig, 1888 , Ophiothela Verrill, 1867 , Ophiotrichoides Ludwig, 1882 .

Diagnosis

Dorsal disc with thorny spines or granules, arm spines thorny. Ventral half of dental plate with numerous papilliform teeth, at the outer edge as column of larger papillae, in the centre as lower granules. Dorsal teeth block-shaped. On dental plate ventral half an outer column of small holes at each edge, indistinct small depressions in the centre, dorsal half with fenestrations with septum. Infradental papillae and lateral oral papillae absent. Arm spine articulation diagonal to almost vertical, with two thick lobes, connected by thin proximal bridge, diagonal. Outer surface of lateral arm plates generally without tubercles. Inner side of lateral arm plates with three knobs. Vertebrae with narrow dorsal keel protruding distalwards far beyond vertebra edge, matching large dorsal groove proximally.

Remarks

The Ophiotrichidae forms a large, but genetically and morphologically coherent, family-level taxon. Genetic data ( O’Hara et al 2017) indicates that Ophiothrix is polyphyletic and suggests that Hoggett (1991) was correct in transferring Ophiothrix species with wide dorsal arm plates into an expanded Macrophiothrix .