Amphilimnidae 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 : 41-42

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

Type genus

Amphilimna Verrill, 1899 . (No other genera)

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 oval. 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 flat; mainly lateral; predominantly erect, standing perpendicular to arm axis. Longest arm spines between one and two segments long. 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 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 ventroproximalwards. 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 dorsalwards increasing. Nerve and muscle openings separated by small ridge if at all. Nerve opening approximately as large as muscle opening.

DORSAL DISC. Disc pentagonal or circular; flat (about same level as arms). Integument 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 or bar-like.

VENTRAL DISC. Gonads restricted to the disc. Ventral interradii with spines. Scales on ventral interradii covering the whole area of an interradius. The number of scales on H line of an interradius about 14–21. Ventral teeth single. Infradental papillae on oral plate present. Buccal scales on OP present. Accessory oral papillae on OP absent. Lateral oral papillae on OP present; single row of lateral papillae; rounded and spiniform. 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 twisted. Number of genital slits one per bursa. Genital slit longer than half the length of an interradius. Genital papillae absent. Dental plate dorsal half widest; 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 flat (with round or slightly pointed tip, but never spine-like). Teeth on DP arranged as single row.

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