Suborder Ophiopsilina Matsumoto, 1915 Superfamily Ophiopsiloidea Matsumoto, 1915

Diagnosis

As for Ophiopsilidae stat. nov.

Family Ophiopsilidae Matsumoto, 1915 stat. nov. (raised to family rank)

Type genus

Ophiopsila Forbes, 1843 (type species: O. aranea Forbes, 1843).

Diagnosis Dorsal disc fully scaled, neither spines nor granules. Extremely long, flat tentacle scales that cross on the mid-line of the ventral arm. Ventral tooth sockets shallow and indistinct, dorsalwards increasing in size and penetrating with septum. Oral plate (half-jaw) higher than long, with large dorsodistal muscle flange (similar to Amphiuridae). Arm spine articulations with two smooth, parallel, straight lobes, in the proximal space between them a short ridge (similar to Amphilimna). Inner side of lateral arm plates with two merged knobs instead of a ridge.

Remarks

The position of this family is variable in our molecular analyses with some trees supporting a sister relationship to the Ophionereidina and others to the Gnathophiurina (O’Hara et al. 2017) . The morphological analysis supports a relationship within Gnathophiurina, close to Amphiuridea (Thuy & Stöhr 2016).