Ophiolycus Ophioscolex Mortensen, 1933b: 315 Reassessment of the classification of the Ophiuroidea (Echinodermata), based on morphological characters. I. General character evaluation and delineation of the families Ophiomyxidae and Ophiacanthidae 2697 Martynov, Alexander Zootaxa 2010 2010-12-03 2697 1 154 7PQY8 Mortensen, 1933 Mortensen 1933 [238,591,1586,1612] Ophiuroidea Ophioscolecidae Ophiolycus Animalia Ophioscolecida 102 103 Echinodermata genus   Figures 27Q–U; 71–74     Ophiolycus(as subgenus of  Ophioscolex):  Mortensen, 1933b: 315   Typespecies:  Ophioscolex dentatus Lyman, 1878, by original designation   Diagnosis.The disk is covered with numerous small, uniform scales, conspicuous when dried, covered by a thin skin layer. The radial shields are moderately developed, elongated, visible in dried specimens. The adradial genital plate is well developed, tightly articulating with the radial shield, proximally slightly curved. The abradial genital plate is short and externally only slightly conspicuous. The articulation surface of the adradial genital plate is an elongate elevation with a small pit dorsally. The articulation surface of the radial shield is a slightly prominent elevation with distinct proximal groove. The genital slits are long; genital plates bordering about two thirds of the slits. The jaw bears numerous spiniform oral papillae, similar in shape to the cluster of the 3–4 ventralmost teeth. Two adoral shield papillae and one adjacent oral papilla of each jaw are spiniform, approximately 2 times as long as the oral papillae, placed around the second tentacle pore. The half-jaws are slightly elongated. The adradial sides of the jaws bear a few sharp straight folds distally. The dental plate is small, elongated, entire, without folds and with few rounded sockets, alternately placed. The teeth are spiniform and few in number (besides the apical papillae there are 4–5 teeth). All teeth are of similar shape. The oral shield is rhomboidal, almost devoid of a distinct distal lobe. The adoral shields have distal bilobed wings and are proximally very narrow bars. Dorsal arm plates are moderately developed in some segments but fragmented proximally. Ventral arm plate is well defined. The arm spine articulations are placed almost parallel in relation to the lateral plate. The muscle and nerve openings are similar in size. A low perforated lobe occupies the dorsal part of the articulations. The sigmoidal fold is absent. The spines are relatively long, flattened, solid over almost their entire length, containing only a small lumen. Distally the dorsal and middle arm spines transform into hooks. One small spiniform tentacle scale is placed on the lateral arm plate. The vertebrae have a broad dorsal keel, with a blunt end; the dorsal medial suture is indistinct. The articulation is zygospondylous. The podial basins are large.   Material studied.  Ophiolycus dentatus( Lyman, 1878),  ZMUC, 3 specimens( Figs 71–72);  Ophiolycus purpureus, ZMMUD-845, 11 specimens; Mareano, 3 specimens( Figs 73–74);  Ophiolycus nutrix Mortensen, 1936, ZMMUD-818, 2 specimens( Figs 27S–U).   Remarks.One of the characteristic external features of the genus  Ophiolycuswas the presence of hooks on the distal arm segments ( Mortensen 1933b; 1936) ( Figs 71H; 73J), whereas the typespecies of the genus  Ophioscolex,  O. glacialisdoes not possess hook-shaped spines on the distal segments. However, well-defined hooks on the distal arm segments are apparently widely distributed within various distantly-related taxa of the family Ophiomyxidae. In the present study, true distal hooks were detected in the genera  Ophiomyxaand  Ophiobyrsa( Figs 1L; 79J).  Ophiosyzygus disacanthusH.L. Clark, 1911, also has on the distalmost segments small hook-shaped spines ( Figs 71I; 75J), somewhat different from the typical hooks of  Ophiomyxaand  Ophiobyrsa. Thus, the hooks or hook-shaped spines are clearly a convergent feature. Besides hook-shaped spines, the genus  Ophiolycusis well distinguished from the genus  Ophioscolex, and the restricted diagnosis of both genera are given above.   FIGURE 72.  Ophiolycus dentatus( Lyman, 1878), ZMUC, details. A–B, arm spine articulations, proximal segments; C. same, dorsalmost articulation details; D. same, ventralmost articulation details; E. arm spine articulation, distal segments; F. dorslamost spine; G. spine; H. proximal vertebra, dorsal view; I. same, ventral view; J. same, proximal view; K. same, distal view; L. spine, ventral view; M. solid proximal spine, sectioned transversally showing only small cavities. Scale bars: A, F, G–K, 300 µ; B–E, L, M, 100 µ; Photos: Alexander Martynov O’Hara (pers. comm.) suggested that  Ophiolycus farquhari McKnight, 2003may be a synonym of  Ophiologimus quadrispinusH.L. Clark, 1925.  Ophiolycus farquhariis externally similar to  Ophiologimus quadrispinusin general appearance of the disk and arms, elongate radial shields and absence of the long adoral shield papillae. The latter feature is diagnostic for all species of the genus  Ophiolycus. McKnight (2003)mentioned the distalmost spines as “weakly hooked at the tip”. Both the typespecies of the genus  Ophiologimus,  O. hexactis( Fig. 48F), and other studied material of  O. quadrispinusreveal the presence of well-defined hooks. “  Ophiolycus”  farquharitherefore is not included into the genus  Ophiolycushere, but until a complete revision of the genus  Ophiologimuswill be performed, it is retained as a species of doubtful status.  Number of species:3. ZMUC, ZMMU 103 104 19