Ophiocamacidae O’Hara, Stöhr, Hugall, Thuy & Martynov, 2018

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 : 29-30

Family Ophiocamacidae O’Hara, Stöhr, Hugall, Thuy & Martynov, 2018

Type genus

Ophiocamax Lyman, 1878 . (No other genera)

Description

ARM. Arm shape unbranched; length more than 4× disc diameter; covering tubercles grown out of scales/plates. 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) 0.9–1. Arm spines cylindrical; 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; slightly longer than wide; shorter than the spine nearby; cross section oval. Position of lateral arm plate (LAP) only lateral. Dorsal and/or ventral edge(s) of LAPs without constriction. Ventral position of LAP projecting ventro-proximalwards. Ventrodistal tip of LAP projecting ventralwards. Arm spine articulation with dorsal and ventral lobes; without 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 circular; flat (about same level as arms). Integument not obscuring plates. Dorsal disc without granules; with concealed primary plates; with scales; with spines. Dorsal disc scale/plate without tubercles. Radial shield present; without granules/spines; length between one third and half of the disc radius; scalene (oblique) triangular.

VENTRAL DISC. Gonads restricted to the disc. Ventral interradii with 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; multiple rows of lateral papillae; spiniform. Adoral shield spine present. Lyman’s ossicle present. Oral shield covering more than one third of the length of an interradius; much wider than long. Madreporite one; 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 absent. Dental plate of equal width all over; entire (single plate). Dental sockets slit-shaped and circular; equal to or more 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 a single row on ⅔ and a cluster of tooth papillae on ⅓ of dental plate.

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