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
Author
Martynov, Alexander
text
Zootaxa
2010
2010-12-03
2697
1
154
journal article
11755334
Genus
Ophiologimus
H.L.
Clark, 1911
Figures 4M
;
27
L-N; 40 I –J; 48; 49
Ophiologimus
H.L.
Clark, 1911: 252
Type
species:
Ophiologimus hexactis
H.L.
Clark, 1911
, by original designation
Diagnosis.
The disk is covered with numerous small, uniform scales, and a thin skin layer, evident when dried. The radial shields are completely concealed by skin, small rounded plates hardly conspicuous in dried specimens in most species (including the
type
species). The adradial genital plate is poorly developed and the abradial genital plate is absent in most species. The genital slits are long and conspicuous, genital plate(s) lining approximately half of the slits. The jaw bears numerous very short, square or rounded oral papillae, considerably different from the 2–3 ventralmost teeth. The adoral shield papillae are very short and do not differ from other oral papillae, placed around the second tentacle pore. The half-jaws are elongate, very low. The adradial sides of the half-jaws bear a few sharp straight folds distally. The dental plate is small, elongated, without folds, with few rounded sockets, alternately placed. The teeth are spiniform and few in number (besides apical papillae there are 4–5 teeth). All teeth are of similar shape. The oral shield is broadly triangular, without distinct distal lobe, except for the madreporite. The adoral shields have distal bilobed wings, proximally tapering. The dorsal and ventral arm plates are well developed. The arm spine articulations are placed distinctly at an angle or almost transversally in relation to the lateral plate. Muscle and nerve openings are similar in size. There is a prominent perforated lobe, occupying the dorsal and distal part of the articulations. The sigmoidal fold is absent. The spines are relatively long, flattened, hollow over almost their entire length, hooked distally. Two or one flattened tentacles scales with pointed ends are placed on the lateral arm plate. The vertebrae have a rounded distal keel, the dorsal medial suture is indistinct. The articulation is zygospondylous. The podial basins are large.
Remarks.
The genus
Ophiologimus
, traditionally placed within the family
Ophiacanthidae
externally similar to one of the ophiomyxid genus,
Ophyolycus
, which is in turn often considered as just a synonym of the genus
Ophioscolex
(see below).
Ophiologimus
distinguishes from the
Ophiolycus
by the short oral and oral shield papillae, all similar in size (
Ophyolycus
has long spiniform oral shield papillae), well defined dorsal arm plate throughout the arm length (
Ophyolycus
possesses well defined dorsal arm plates only proximally) and entirely hollow arm spines (
Ophiolycus
has almost solid spines with small holes).
FIGURE 45.
Ophiolimna
and
Ophioconis
, spine articulations and spines. A–C, G–J,
Ophiolimna diastata
(H.L.
Clark, 1911
)
, paratype USNM 26210, 6.7 mm dd. A. lateral arm plate showing spine articulation; B–C, details of spine articulations, proximal segments; G. proximal spine; H. proximal spine, sectioned transversally in the basal part showing semi-solid structure; I. same, hollow spine sectioned transversally in the middle part showing a ridge inside; J. same, ventral view; D, K–L,
Ophioconis cincta
USNM
E
42554, 3 mm dd. D. details of spine articulations, proximal segments; K. solid proximal spine showing distinct ribs; L. same, ventral view; E–F, M–O,
Ophioconis cupida
,
Koehler, 1905
, USNM
E 42555
, 5 mm dd, E. proximal lateral arm plate showing spine articulation; F. same; M. proximal spine, ventral view; N. solid spine sectioned transversally showing distinct ribs; O. proximal spines. Scale bars: A, G, 300. B, C, H–J, K, E–F, O, 100 µ; D, L, M–N, 30 µ. Photos: Alexander Martynov.
FIGURE 46.
Ophiolimna
and
Ophioconis
, vertebrae. A–D,
Ophiolimna diastata
(H.L.
Clark, 1911
)
, paratype USNM 26210, 6.7 mm dd. A. proximal vertebra, dorsal view; B. same, ventral view; C. same, proximal view; D. same, distal view. E–F,
Ophioconis cincta
USNM
E
42554, 3 mm dd. E. middle vertebra, dorsal view; F. distal vertebra, dorsal view; G–J,
Ophioconis cupida
, USNM
E
42555, 5 mm dd. G. proximal vertebra, dorsal view; H. same, ventral view; I. same, proximal view; J. same, distal view. Scale bars: A–D, G–H, 300 µ; E–F, I–J, 100 µ. Photos: Alexander Martynov.
Material studied.
Ophiologimus hexactis
H.L.
Clark, 1911
,
holotype
USNM
25724 (
Fig. 48
);
Ophiologimus quadrispinus
H.L.
Clark, 1925
,
USNM
E 06912,
4 specimens
,
USNM
E 06911,
one specimen
(
Fig. 49
);
Ophiologimus secundus
Koehler, 1914
,
4 syntypes
USNM
032302;
Ophiologimus
cf.
secundus
, ZMMU
D-814,
one specimen
,
ZMMU
D-814,
4 specimens
(
Figs 4M
;
27L–N
;
40I–J
)
Number of species:
4.