Ophiolepis Müller & Troschel, 1840

Okanishi, Masanori & Fujita, Yoshihisa, 2018, First finding of anchialine and submarine cave dwelling brittle stars from the Pacific Ocean, with descriptions of new species of Ophiolepis and Ophiozonella (Echinodermata: Ophiuroidea: Amphilepidida), Zootaxa 4377 (1), pp. 1-20 : 3

Ophiolepis Müller & Troschel, 1840

Type species: Ophiolepis superba H. L. Clark, 1915 (see Pineda-Enríquez et al. (in press) for background of this name)

Diagnosis. Arms 5 in number, not branching; disc covered by scales; larger disc scales surrounded by smaller scales on aboral surface; lacking arm combs; 2nd tentacle pore opening inside of oral slits; supplementary arm plates beside laterally to each dorsal and sometimes ventral arm plates.

Remarks. Ophiolepis is morphologically related to Ophiozonella ( Stöhr 2011) . These genera were previously in the family Ophiolepididae ; Ophiozonella was polyphyletic and split across Ophiolepididae and Hemieuryaldae Verrill, 1899 as a result of a molecular phylogenomic study (O’Hara et al. 2017). Ophiozonella species with 1 or 2 arm spines were in the Hemieuryalidae and species with more than 3 arm spines were in the Ophiolepididae . Ophiozonella cavernalis n. sp. should belong to the latter family because it has 3 arm spines ( Fig. 9A, B, D, E, G, H ). Ophiozonella longispina ( H. L. Clark, 1908) , which is the type species of Ophiozonella , was included in the Hemieuryalidae (O’Hara et al. 2017) , therefore a new genus should be established for the Ophiozonella species in the Ophiolepididae , with more than 3 arm spines. However, we refrain from establishing the new genus because we did not take into account all species of Ophiozonella in this study and any DNA sequences of O. cavernalis n. sp. have not obtained. In this study, we refer the Ophiozonella of Ophiolepididae to Ophiozonella s. str.

For the purposes of this study, we compare and contrast Ophiolepis and Ophiozonella s. str. in terms of morphology. Main taxonomic characters of Ophiolepis and Ophiozonella s. str. are as follows: On the aboral disc surface, larger scales are surrounded by smaller scales in Ophiolepis , while the disc scales of Ophiozonella s. str. are almost uniform in size. Ophiolepis has supplementary plates on the lateral side of the dorsal plates, whereas Ophiozonella s. str. lacks the supplementary plates (e.g. Fell 1960). However, the value of these characters has been questioned because specimens with variations of these characters have been observed in both genera (e.g. Devaney 1974; Cherbonnier & Guille 1978; Stöhr 2011).

In this study, we define Ophiolepis as follows: two supplementary plates lateral to each dorsal arm plate; larger disc scales are regularly surrounded by smaller ones on aboral surface.

Figures

FIGURE 9. Ophiozonella cavernalis n. sp. holotype (RUMF-ZE-02008).A, aboral proximal portion of arm; B, aboral middle portion of arm; C, aboral distal tip of arm; D, oral proximal portion of arm; E, oral middle portion of arm; F, oral distal tip of arm; G, lateral middle portion of arm; H, lateral distal tip of arm. Arrow heads indicate tentacle scale. Abbreviation: ASP, arm spine; DAP, dorsal arm plate; LAP, lateral arm plate; VAP, ventral arm plate.