Fig. 2. SEM images of various brittle star ossicles. A–E. Disc structures. A. Dorsal disc, radial shield with tubercles (Ophiomusa lymani (Wyville-Thomson, 1873)). B. Dorsal disc (Ophiolimna bairdi (Lyman, 1883)). C. Ventral disc (Ophionereis porrecta Lyman, 1860), the interradius is assumed as a triangle and H gives its height. D. Dorsal disc, triangular radial shield (Ophiactis savignyi (Müller & Troschel, 1842)). E. Ventral disc, mouth (Ophioderma sp.). – F–H. Atypical arm spines. F. Umbrella-shaped arm spine (Ophiotholia spathifer (Lyman, 1879)). G. Hook-shaped arm spine (Asteronyx loveni Müller & Troschel, 1842). H. Bristle spines (Ophiernus vallincola Lyman, 1878). – I–L. Lateral arm plates (LAP). I. LAP with constriction (Ophioscolex glacialis Müller & Troschel, 1842). J. Dorsal and ventral part of LAP without constriction (Ophiura ophiura (Linneaus, 1758)). K. Ventral part of LAP projecting ventro-proximalwards (Ophiopallas paradoxa Koehler, 1904). L. Ventral part of LAP not projecting ventro-proximalwards (Ophiosphalma fimbriatum (Koehler, 1922)).

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 page 9, DOI: 10.5852/ejt.2021.766.1483, http://zenodo.org/record/5514587