Ophiobyrsidae Matsumoto, 1915

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 : 29

Family Ophiobyrsidae Matsumoto, 1915

Type genus

Ophiobyrsa Lyman, 1878 .

Other genera

Ophiobyrsella Verrill, 1899 ; Ophiophrixus H.L. Clark, 1911 ; Ophiosmilax Matsumoto, 1915 .

Description

ARM.Arm shape unbranched; length more than4×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 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; predominantly erect, standing perpendicular to arm axis. Longest arm spines between half and one segment long. Tentacle scales absent. Position of lateral arm plate (LAP) arched (wrapped around the arm). Dorsal and/or ventral edge(s) of LAPs with constriction. Ventral position of LAP projecting ventro-proximalwards. Ventro-distal tip of LAP projecting ventralwards. Arm spine articulation with dorsal and ventral lobes; without sigmoidal fold; arranged over entire distal LAP edge; ventralwards increasing in size. Distance between spine articulations equal. Nerve and muscle openings separated by large, prominent ridge or regular stereom. Nerve opening smaller than muscle opening.

DORSAL DISC. Disc circular; flat (about same level as arms). Integument obscuring plates. Dorsal disc with granules; with concealed primary plates; without scales; with spines. Dorsal disc scale/plate without tubercles. Radial shield present; with granules.

VENTRAL DISC. Gonads restricted to the disc. Ventral interradii without granules/spines. Scales on ventral interradii absent. 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. Adoral shield spine present. Lyman’s ossicle present. Oral shield covering less than one third of interradius; about as long as wide. Madreporite no data. 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 absent. Dental plate of equal width all over; entire (single plate). Dental sockets circular; less than 50% of the width. At least one socket on DP as depression or perforation without septum. Teeth spine-shaped. Teeth on DP arranged as covering the entire dental plate evenly.

VERTEBRAE. Vertebrae hourglass-shaped (streptospondylous); beyond segment 5 with short keel; without oral bridge.