Ophiotrichidae 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 : 48-49

Family Ophiotrichidae Ljungman, 1867

Type genus

Ophiothrix Müller & Troschel, 1840 .

Other genera

Gymnolophus Brock, 1888 ; Lissophiothrix H.L. Clark, 1938 ; Macrophiothrix H.L. Clark, 1938 ; Ophiocnemis Müller & Troschel, 1842 ; Ophiogymna Ljungman, 1866 ; Ophiolophus Marktanner- Turneretscher, 1887; Ophiomaza Lyman, 1871 ; Ophiophthirius Döderlein, 1898 ; Ophiopsammium Lyman, 1874 ; Ophiopteron Ludwig, 1888 ; Ophiothela Verrill, 1867 ; Ophiotrichoides Ludwig, 1882 .

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 longer than two segments long. Tentacle scales present; pores visible along most of the arm; more than two times as long as wide; as long as the spine nearby; cross section round. 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; without sigmoidal fold; arranged over entire distal LAP edge; larger in middle of arm. Distance between spine articulations dorsalwards increasing. Nerve and muscle openings separated by small ridge if at all. Nerve opening approximately as large as 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; with spines; length more than 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 single or with several tooth papillae ( O’Hara et al. 2018). Infradental papillae on oral plate absent. Buccal scales on OP present. Accessory oral papillae on OP absent. Lateral oral papillae on OP absent. Adoral shield spine absent. Lyman’s ossicle absent. Oral shield covering less than one third of interradius; much wider than long. 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 ventral half widest; entire (single plate). Dental sockets slit-shaped and circular; less than 50% of the width of to equal to or more than 50% of the width. At least one socket on DP as perforation with septum. Teeth flat (with round or slightly pointed tip, but never spine-like). Teeth on DP arranged as a single row on half of dental plate and other half with a cluster of tooth papillae (ventral cluster).

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