Euryalidae Gray 1840
Creators: name: Goharimanesh, Mona
name: Stöhr, Sabine
name: Mirshamsi, Omid
name: Ghassemzadeh, Fereshteh
name: Adriaens, Dominique
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Ophiuroidea
Euryalida
Euryalidae

description: Family Euryalidae Gray, 1840
Type genus
Euryale Lamarck, 1816.
Other genera
Asteromorpha Lütken, 1869; Asteroschema Örstedt & Lütken, 1856; Asterostegus Mortensen, 1933; Astrobrachion Döderlein, 1927; Astroceras Lyman, 1879; Astrocharis Koehler, 1904; Ophiocreas Lyman, 1869; Squamophis Okanishi Okanishi, O'Hara & Fujita, 2011; Sthenocephalus Koehler, 1898; Trichaster Agassiz, 1836.
Description
ARM. Arm shape branched; length more than 4× disc diameter; covering with granules. Arm combs absent. Dorsal arm plate absent. Accessory dorsal arm plate absent. Ventral arm plate present or absent. Accessory ventral arm plate absent. Girdle of tiny hooks on the arms absent. Spines not all similar in shape.Atypical arm spines are hook-shaped.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; at proximal segments only on ventral side of arms; predominantly erect, standing perpendicular to arm axis. Longest arm spines shorter than half a segment. Tentacle scales present; pores visible along the arm; nearly as long as wide; shorter than the spine nearby; cross section round. Position of lateral arm plate (LAP) only lateral. Dorsal and/or ventral edge(s) of LAPs without constriction (Fig. 2J). Ventral position of LAP not projecting ventro-proximalwards. Ventro-distal tip of LAP not projecting ventralwards. Arm spine articulation without dorsal and ventral lobes; restricted to (the ventral or central) portion of the distal edge; all similar. Distance between spine articulations not applicable (two spine articulation). Nerve and muscle openings separated by large, prominent ridge or regular stereom. Nerve opening approximately as large as muscle opening (Fig. 3A–B).
DORSAL DISC. Disc pentagonal; flat (about same level as arms). Integument not obscuring plates. Dorsal disc with granules; with concealed primary plates; without scales; without spines. Dorsal disc scale/plate without tubercles. Radial shield present; with tubercles grown out of plate; length more than half of the disc radius; bar-like.
VENTRAL DISC. Gonads not restricted to the disc (extending into the basal portion of the arms) or restricted to the disc (Asteroschema). Ventral interradii without granules/spines. Scales on ventral interradii absent. Ventral teeth single. Infradental papillae on oral plate present. Buccal scales on OP absent. 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; about as long as wide. Madreporite multiple; with one pore, or 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 shorter than half interradius. Genital papillae absent. Dental plate of equal width all over; fragmented. Dental sockets slit-shaped; 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 hourglass-shaped (streptospondylous); beyond segment 5 non-keeled; with oral bridge (Fig. 3E).
description: Published as part of 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, pp. 1-63 in European Journal of Taxonomy 766 (1) on pages 20-21, DOI: 10.5852/ejt.2021.766.1483, http://zenodo.org/record/5514587