Ophiocomidae Ljungman, 1867

Goharimanesh, Mona, Stöhr, Sabine, Mirshamsi, Omid, Ghassemzadeh, Fereshteh & Adriaens, Dominique, 2021, Interactive identification key to all brittle star families (Echinodermata; Ophiuroidea) leads to revised morphological descriptions, European Journal of Taxonomy 766 (1), pp. 1-63 : 36-37

Family Ophiocomidae Ljungman, 1867

Type genus

Ophiocoma L. Agassiz, 1836 .

Other genera

Breviturma Stöhr Stöhr, Boissin & Hoareau, 2013 ; Ophiarthrum Peters, 1851 ; Ophiocomella A.H. Clark, 1939 ; Ophiomastix Müller & Troschel, 1842 .

Description

ARM. Arm shape unbranched; length 3–4× disc diameter; covering without granules/spines/tubercles. Arm combs absent. Dorsal arm plate present.Accessory dorsal arm plate absent. Ventral arm plate present. Accessory ventral arm plate absent. Girdle of tiny hooks on the arms absent. Spines all similar in shape. Arm spine cross section oval. The ratio of thickness of distal ⅓ of arm spine to maximum thickness (in a given cross-sectional plane) 0.6–0.9, or 0.9–1. Arm spines flat, or cylindrical, or pointed; mainly lateral; predominantly erect, standing perpendicular to arm axis. Longest arm spines longer than two segments. Tentacle scales present; pores visible along most of the arm; nearly as long as wide; shorter than the spine nearby; cross section oval. Position of lateral arm plate (LAP) arched (wrapped around the arm). Dorsal and/or ventral edge(s) of LAPs without constriction. Ventral position of LAP projecting ventro-proximalwards. Ventro-distal tip of LAP not projecting ventralwards. Arm spine articulation with dorsal and ventral lobes; with a fully developed sigmoidal fold; arranged over entire distal LAP edge; dorsalwards increasing in size. Distance between spine articulations dorsalwards increasing. Nerve and muscle openings separated by small ridge if at all. Nerve opening smaller than muscle opening.

DORSAL DISC. Disc pentagonal to circular; flat (about same level as arms). Integument obscuring plates. Dorsal disc with granules; with concealed primary plates; with scales; with smooth spines ( O’Hara et al. 2018) or without spines. Dorsal disc scale/plate without tubercles. Radial shield present; with granules; length less than one third of the disc radius; scalene (oblique) triangular.

VENTRAL DISC. Gonads restricted to the disc. Ventral interradii with granules. Scales on ventral interradii covering the whole area of an interradius. The number of scales on H line of an interradius more than 21. Ventral teeth several (tooth papillae). Infradental papillae on oral plate present. Buccal scales on OP absent. Accessory oral papillae on OP absent. Lateral oral papillae on OP present or absent; multiple rows of lateral papillae; rounded. Adoral shield spine present. Lyman’s ossicle present. Oral shield covering less than one third of interradius; about as long as wide. Madreporite one; with one pore. Adoral shield separated. Abradial genital plate not twisted. Number of genital slits one per bursa. Genital slit longer than half the length of an interradius. Genital papillae absent. Dental plate of equal width all over; entire (single plate). Dental sockets circular to heart-shaped; equal to or more than 50% of the width. At least one socket on DP as perforation with septum. Teeth block-like (with square tip). Teeth on DP arranged as a single row on half of dental plate and other half with a cluster of tooth papillae (ventral cluster), or a single row on ⅔ and a cluster of tooth papillae on ⅓ of dental plate.

VERTEBRAE. Vertebrae zygospondylous; beyond segment 5 with short keel; without oral bridge.