Ophiopyrgidae Perrier, 1893

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 : 25-26

Family Ophiopyrgidae Perrier, 1893

Type genus

Ophiopyrgus Lyman, 1878 .

Other genera

Amphiophiura Matsumoto, 1915 ; Aspidophiura Matsumoto, 1915 ; Dictenophiura H.L. Clark, 1923 ; Euvondrea Fell, 1961 ; Glaciacantha Fell, 1961 ; Gymnophiura Lütken & Mortensen, 1899 ; Ophiogona Studer, 1876 ; Ophiomages Koehler, 1923 ; Ophioperla Koehler, 1912 ; Ophiopleura Danielssen & Koren, 1877 ; Ophioplinthus Lyman, 1878 ; Ophiosparte Koehler, 1922 ; Ophiosteira Bell, 1902 ; Ophiuroglypha Hertz, 1927 ; Spinophiura Stöhr & Segonzac, 2006 ; Stegophiura Matsumoto, 1915 .

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 ( Amphiophiura , Ophioplinthus ), or oval ( Ophiosparte ). The ratio of distal 1/3 an arm spine to maximum thickness (in a given cross-sectional plane) 0.2–0.6, or 0.6–0.9 ( Amphiophiura ), or 0.9–1 ( Ophiosparte , Ophioplinthus ). Arm spines tapering (conical), or cylindrical ( Ophiosparte ), or pointed; mainly lateral; predominantly parallel to arm axis (adpressed). Longest arm spines shorter than half a segment ( Amphiophiura , Ophioplinthus , Ophiopleura ), or between half and one segment ( Ophiosparte ). Tentacle scales present; pores visible along most of the arm; more than two times 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 not projecting ventro-proximalwards. Ventro-distal tip of LAP not projecting ventralwards. Arm spine articulation without dorsal and ventral lobes; arranged over entire distal LAP edge; ventralwards increasing in size ( Amphiophiura ), or all similar ( Ophiosparte , Ophiopyrgus , Ophioplinthus ). Distance between spine articulations dorsalwards 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; high (above arm level). Integument not obscuring plates ( Amphiophiura , Ophiopyrgus , Ophioplinthus , Ophiopleura ), or skin obscuring plates ( Ophiosparte ). Dorsal disc without granules; with obvious primary plates ( Amphiophiura , Ophioplinthus ), or with concealed primary plates ( Ophiosparte , Ophiopleura ); with scales (the scales are covered by thickened skin in Ophiosparte and embedded in thickened skin in Ophiopleura ) without spines. Dorsal disc scale/plate without tubercles. Radial shield present; without granules/spines; length less than one third of the disc radius, or length between one third and half of the disc radius ( Ophiopyrgus ), or length more than half of the disc radius ( Ophiopleura ); 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, or absent ( Ophiosparte , Ophiosparte , Ophiopleura ). The number of scales on H line of an interradius about less than 7. Ventral teeth several (tooth papillae). Infradental papillae on oral plate present. Buccal scales on OP present. Accessory oral papillae on OP present. Lateral oral papillae on OP absent. Adoral shield spine present. Lyman’s ossicle absent. Oral shield covering less than one third of interradius; much longer than wide or about as long as wide (e.g., Ophioplinthus tessellata (Verrill, 1894) and Ophiopleura borealis Danielssen & Koren, 1877 ). 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 (or about equal). Genital papillae present. Dental plate ventral half widest; 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 a single row on ⅔ and a cluster of tooth papillae on ⅓ of dental plate ( Ophioplinthus ).

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