Ophiuridae Müller & Troschel, 1840

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 : 24-25

Family Ophiuridae Müller & Troschel, 1840 , restricted sensu O’Hara et al. (2017)

Type genus

Ophiura Lamarck, 1801 .

Other genera

Ophiocrossota H.L. Clark, 1928 ; Ophiocten Lütken, 1855 ; Ophioctenella Tyler, Paterson, Sibuet, Guille, Murton & Segonzac, 1995 ; Ophionotus Bell, 1902 .

Description

ARM.Arm shape unbranched; length 3× disc diameter; covering without granules/spines/tubercles. Arm combs present. 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 round. The ratio of thickness of distal ⅓ of arm spine to maximum thickness (in a given cross-sectional plane) 0.6–0.9. Arm spines pointed; mainly lateral and at proximal segments only on ventral side of arms; predominantly parallel to arm axis (adpressed). Longest arm spines between half and one segment long, or between one and two segments long ( Ophiura sarsii Lütken, 1855 ). Tentacle scales present or absent; pores visible along most of the arm; slightly longer than 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 not projecting ventroproximalwards. Ventro-distal tip of LAP not projecting ventralwards. Arm spine articulation without dorsal and ventral lobes; restricted to (the ventral or central) portion of the distal edge; all similar. Distance between spine articulations ventralwards increasing. Nerve and muscle openings separated by large, prominent ridge or regular stereom. Nerve opening approximately as large as muscle opening.

DORSAL DISC. Disc circular; flat (at arm level). Integument not obscuring plates. Dorsal disc without granules; with obvious primary plates; with scales; without spines. Dorsal disc scale/ plate without tubercles. Radial shield present; without granules/spines; length between one third and half of the disc radius; isosceles (mirror-symmetric) triangular to pear-shaped.

VENTRAL DISC. Gonads restricted to the disc. Ventral interradii without granules/spines. Scales on ventral interradii covering the whole area of an interradius. The number of scales on H line of an interradius fewer than 7, or 7–14 ( Ophiocten ). Ventral teeth several (tooth papillae). Infradental papillae on oral plate present. Buccal scales on OP present. Accessory oral papillae on OP absent. Lateral oral papillae on OP absent. Adoral shield spine present. Lyman’s ossicle absent. Oral shield covering more than one third of the length of an interradius; much longer than wide or about as long as wide ( Ophiocten ). Madreporite one; with one pore or with numerous pores. Adoral shield meeting in front of the oral shield. Abradial genital plate not twisted. Number of genital slits one per bursa. Genital slit longer than half the length of an interradius. Genital papillae present. Dental plate of equal width all over, or ventral half widest ( Ophiura sarsii , Ophiocten ); entire (single plate). Dental sockets circular; equal to or more than 50% of the width. At least one socket on DP as depression or perforation without septum. Teeth flat (with round or slightly pointed tip, but never spine-like). Teeth on DP arranged as a single row on ⅔ and a cluster of tooth papillae on ⅓ of dental plate (two rows in Ophiocten ).

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