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Synoptic Keys to the Genera of Ophiuroidea

Subfamily Ophiolepidinae Matsumoto, 1915

Subfamily Ophiolepidinae Matsumoto, 1915

1 (28)

Tentacle-pores well developed throughout arm.

2 (5)

No tentacle-scale.

3 (4)

Disc thin and flat covered by scales and large radial shields, and bordered by a row of marginal plates which are erect and movable, being attached only by their proximal margins. . . . Ophiophyllum Lyman, 1878.

*petilum Lyman, 1878. Kermadec Is., N.Z. 600 fms.

4 (3)

Disc and sides of arms covered by fine scales, which are swollen and resemble coarse granules: radial shields inconspicuous or hidden: upper arm-plates separated more or less widely by intervening small platelets: lowermost arm-spine sometimes serving as a tentacle-scale. . . . Ophiopenia H. L. Clark, 1911.

*disacantha H. L. C., 1911. Bering Sea. 50 fms.

5 (2)

Tentacle-scales present.

6 (27)

Tentacle-scales well-developed throughout the arm.

7 (20)

Dorsal arm-plates entire, not fragmented nor divided into supplementary plates.

8 (9)

A row of papillae skirting the outer borders of the gential scales and radial shields: a pair of plates wedged between the radial shields: arm-spines minute. . . . Ophiothyreus Ljungman, 1872.

*goesi Ljung., 1872. Cuba. 200 fms.

9 (8)

No papillae skirting genital scales or radial shields.

page 33
10 (11)

Adoral shields entirely separated by the oral shield, not meeting within, 1 tentacle scale.

10a (10b)

Primary plates and radial shields large and conspicuous and, together with a radial series of plates, covering the entire disc; no granulation. . . . Ophioceramis Lyman, 1865.

*Ophiolepis januarii Lütk., 1856. Caribbean. Littoral.

10b (10a)

Primary plates inconspicuous; radial shields the only large plates on dorsal side of disc, all other plates reduced to small scales, with fine granulation between them. . . . Ophiocrates Koehler, 1904.

*lenta Koehler, 1904. Indonesia. 1,100 fms.

11 (10)

Adoral shields meeting on midline proximad to oral shield, 1 or 2 tentacle scales.

12 (13)

First lateral arm-plate conspicuously enlarged: 1 tentacle-scale: radial shields conspicuous, triangular, tumid, at the arm bases. . . . Ophiomidas Koehler, 1904.

*alatus Koehler, 1904. Indonesia. 700 fms.

13 (12)

First lateral arm-plate not enlarged.

14 (15)

Marginal plates of disc greatly swollen, forming a rampart about the periphery: 2 tentacle scales. . . . Ophioteichus H. L. Clark, 1938.

*parvispinum H. L. C., 1938. Tasman Sea (Lord Howe Is.). Littoral.

15 (14)

Marginal plates not swollen.

15a (15b)

Oral shield divided transversely into 1 proximal plate and 1 distal plate. Aboral side of disc covered by regularly arranged plates which carry tubercles. About 4 short, thick arm-spines. Oral papillae distinct, conspicuous. . . . Ophiocypris Koehler, 1931.

*tuberculosus Koehler, 1931. Kei Is., 150 fms.

15b (15a)

Not so.

16 (17)

Disc covered with numerous small plates and scales, the larger ones surrounded by the smaller: radial shields small, widely separated by intervening plates and scales: three conspicuous plates lie between, and distal to, the shields: 4 or 5 short arm-spines: 2 tentacle-scales: dorsal and ventral arm-plates broadly contiguous throughout. . . . Ophiozona Lyman, 1865 (restr. Matsumoto, 1915).

*Ophiolepis impressa Lütk., 1859. Caribbean. 50–200 fms.

17 (16)

Disc covered by a limited number of stout plates, including radial shields, and some smaller plates: 2 to 4 short arm-spines: dorsal and ventral arm-plates contiguous only at arm-base becoming progressively distant on the distal parts of arms.

18 (19)

Primary plates very conspicuous, covering the central half of disc: radial shields small, separated by three plates between and distal to them: 1 tentacle scale. . . . Ophiozonoida H. L. Clark, 1915.

*picta H. L. C., 1915. New Zealand. Littoral. 50 fms.

Ophiotylos Murakami, 1943, appears to fall very close to Ophiozonoida, differing mainly in having rudimentary arm-spines whereas there are 3 short arm-spines in Ophiozonoida picta. The type of Ophiotylos is O. leucus Murakami, 1943, Caroline Island.

19 (18)

Primary plates either conspicuous or not so, but not large: radial shields large, either contiguous, or separated by only a single narrow row of plates, not by 3 distal intervening plates: 1 or 2 tentacle scales. . . . Ophiozonella Matsumoto, 1915.

*Ophiozona longispina H. L. C., 1908. Japan. 50–300 fms.

page 34
20 (7)

Dorsal arm-plates more or less sub-divided into supplementary plates or mosaic platelets.

21 (24)

Dorsal arm-plates quite distinct, but accompanied by a few supplementary plates.

22 (23)

Disc covered by irregular plates, not distinctly imbricating; usually small granules at or near the margins of the plates: radial shields small but distinct: primaries not distinct: one dorsal supplementary plate on each arm-joint, or on some arm-joints only. . . . Ophiolebella Mortensen. 1936.

*Ophiolebes biscutifer E. A. Smith, 1879. Antarctic. 100 fms. The type-species was overlooked in H. L. Clark's (1915) Catalogue.

23 (22)

Disc covered by scales in two sizes, the larger surrounded by the smaller: radial shields conspicuous: 2 tentacle scales: smaller supplementary dorsal plates on either side of and/or distal to, the dorsal plates. . . . Ophiolepis Mueller & Troschel, 1840.

*superba H. L. C., Indo-W. Pacific. Littoral.

See H. L. Clark (1915), p. 342, for discussion on name of type-species.

24 (21)

Dorsal arm-plates profoundly modified by extensive fragmentation and intercalation of small mosaic platelets: radial shields very small and in-conspicuous.

25 (26)

Three or four tentacle-scales: dorsal arm-plates subdivided into two widely separated lateral halves, between which lies a mosaic of small platelets. Ophioplocus Lyman, 1861.

*Ophiolepis imbricata M. & T., 1842. Indo-W. Pacific. Littoral.

26 (25)

One tentacle-scale: dorsal arm-plates subdivided into two lateral halves which are more or less widely separated at the base of the arm by a mosaic; but distally they lie close together, and one or two median plates intervene, or alternate, with them. Genital clefts not extending beyond the first arm-joint. . . . Ophioceres Koehler, 1922.

*incipiens Koehler, 1922. Antarctic. 0–100 fms.

27 (6)

A single well-developed tentacle-scale on the basal 3 or 4 joints, but beyond this the tentacle-pores have no scale. Disc covered by a few large plates and scales: radial shields large, contiguous. . . . Amphipholizona H. L. Clark, 1915.

*delicata H. L. C, 1915. Caribbean. 100 fms.

28 (1)

Tentacle-pores restricted to a few joints at the base of the arm.

29 (30)

Entire animal covered by thick smooth skin, more or less obscuring the plates: beneath the skin (and visible on its inner surface) are oval radial shields and other plates: dorsal arm-plates fragmented, comprising only thin, irregular fragments. . . . Ophiolipus Lyman, 1878.

*agassizii Lyman, 1878. Caribbean. 100 fms.

30 (29)

Disc and arm-plates distinct, not obscured by skin: disc covered by porcellanous regular plates and radial shields: dorsal and ventral arm-plates minute, and not developed in the outer part of arm: lateral arm-plates meeting in dorsal and ventral midlines.

31 (32)

A continuous ridge of fused oral papillae round jaw-edge: two to five tentacle-pores. . . . Ophiomusium (s.s.) Lyman, 1869.

Ophiomusa *ultima Hertz West Africa, Hertz 1927, established for spp. with only 2 pairs of tentacle-pores, is here regarded as falling within the definition of Ophiomusium.

*eburneum Lyman, 1869. Caribbean. 200 fms.

32 (31)

Oral papillae distinct. . . . Ophiosphalma H. L. Clark, 1941.

*Ophiomusium planum Lyman, 1878. Caribbean. 1,000 fms.