Synoptic Keys to the Genera of Ophiuroidea
Family Gorgonocephalidae Ljungman, 1867, emend. Mortensen, 1933
Family Gorgonocephalidae Ljungman, 1867, emend. Mortensen, 1933
1 (39) |
Arms forked. |
2 (3) |
Seven arms, bifurcating once about halfway out: girdle hooklets minute, without secondary teeth: reproducing by transverse fission. . . . Schizostella A. H. Clark, 1952. *bifurcata A. H. C., 1952. Caribbean. Littoral. |
3 (2) |
Five arms. |
4 (7) |
More than 30 arm-joints before the first fork. |
5 (6) |
Disc and arms with transverse ridges. . . . Astrocnida Lyman, 1872. *Trichaster isidis Duchassaing, 1850. Caribbean. 100 fms. |
6 (5) |
Disc and arms without transverse ridges. . . . Astroclon Lyman, 1879. *propugnatoris Lyman, 1879. Indonesia. 100 fms. |
7 (4) |
Less than 20 arm-joints before the first fork. |
8 (38) |
Primary plates inconspicuous: radial shields elongate, bar-like. |
9 (17) |
Five madreporites of similar size. |
9a (10) |
Hooklets with a secondary tooth. . . . Astroglymma Doederlein, 1927. Syn.: Astrodactylus Doederlein, 1911 (preoccupied). *Astrophyton sculptum Doed., 1896. Indonesia. |
10 (9a) |
Hooklets with no secondary teeth. |
11 (14) |
Armspines occurring below the disc before the first or second fork. |
12 (13) |
Radial shields without transverse ridges: arm-spines occurring before the first fork. . . . Astrogordius Doederlein, 1911. *Astrophyton cacaoticum Lyman, 1874. Caribbean. Littoral. |
13 (12) |
Radial shields with transverse ridges. . . . Astrocyclus Doederlein, 1911. *Astrophyton caecilia Ltk., 1856. Caribbean. 100 fms. |
14 (11) |
Armspines lacking before the fourth fork. |
15 (16) |
Disc and arms with transverse rows of spines. . . . Astrocaneum Doederlein, 1911. (Synonym Astrocynodus A. H. Clark, 1918.) *Astrophyton spinosum Lym., 1875. Panama, Pearl Is. Littoral. |
16 (15) |
Disc and arms without spines. . . . Astrodictyum Doederlein, 1927. *Astrophyton panamense Verr., 1867. Panama, Pearl Is. Littoral. |
17 (9) |
One madreporite (exceptionally 2 or 3 of different sizes). |
18 (27) |
Arm-spines present before the first fork. |
19 (20) |
Madreporite placed at the proximal border of the soft interbrachium. page 8 |
20 (19) |
Madreporite separated by accessory plates on the soft interbrachium: mouth in a crater-like depression. . . . Astracme Doederlein, 1927. *Astrophyton mucronatum Lyman, 1869. Caribbean. 100 fms. |
21 (24) |
Disc and arms covered with large tubercles or spines. |
22 (23) |
Radial shields conspicuously separated. . . . Astroconus Doederlein, 1911. *Astrophyton australe Verrill, 1876. Tasmania. Littoral. |
23 (22) |
Radial shields scarcely separated. . . . Conocladus H. L. Clark, 1909. *oxyconus H. L. C., 1909. E. Australia. 50 fms. |
24 (21) |
Disc and arms bearing only small spinules or granules, or else naked. |
25 (26) |
Disc with a zone of calcareous plates at the margin. . . Gorgonocephalus Leach, 1815 This genus, originally intended to embrace all ophiuroids with branching arms, has successively been restricted by Lyman, 1882, and Doederlein, 1911. *Asterias caputmedusae L., 1758. N. Europe. Littoral. |
26 (25) |
Disc-margin without calcareous plates. . . . Astrodendrum Doederlein, 1911. *Gorgonocephalus sagaminus Doed., 1902. Japan. 100 fms. |
27 (18) |
Arm-spines absent before the first fork. |
28 (33) |
Arm-spines beginning at the edge of the disc, after the first or second fork. |
29 (30) |
Madreporite at the inner border of the soft interbrachium; warts or tubercles usually present on disc. . . . Astrocladus Verrill, 1899. *Asterias euryale Retzius, 1783. S. Africa. Littoral. |
30 (29) |
Madreporite separated from the soft interbrachium by accessory plates. |
31 (32) |
Disc and arms smooth. . . . Astrospartus Doederlein, 1911. *Euryale mediterraneus Risso, 1826. Mediterranean. Littoral. |
32 (31) |
Disc and arms with warts. . . . Astroplegma Doederlein, 1928. *expansum Doed., 1928. Indonesia. 100 fms. |
33 (28) |
Arm-spines beginning at some distance from the disc, not before the fourth fork. |
34 (35) |
The arms near the disc nearly as high as broad, with a narrow ventral side. |
35 (34) |
Free arms near the disc conspicuously broader than high, with flat, broad ventral surfaces. . . . Astrochalcis Koehler, 1905. *tuberculosus Koehler, 1905. Indonesia. Littoral. |
36 (37) |
Radial shields with a longitudinal series of tubercles or spines: hooklets without any secondary teeth. . . . Astrophyton Mueller & Troschel, 1842. As originally proposed Astrophyton was an absolute synonym of Gorgonocephalus: the current usage is derived from Lyman, 1882. *Euryale muricatum Lmk., 1816. Caribbean. 200 fms. |
37 (36) |
Radial shields without tubercles or spines: hooklets with a secondary tooth. Astroboa Doederlein, 1911. Syn.: Astrorhaphis Doederlein, 1911. *Astrophyton clavatum Lyman, 1861. Indian O. Littoral. |
38 (8) |
Primary plates conspicuous, covering much of disc surface: radial shields ovate. . . . Ophiocrene Bell, 1894. Bell, 1894, himself points out that the type specimen of O. oenigma Bell may be a juvenile form. Should it prove to be the young stage of a genus described since 1894, Ophiocrene will take priority. H. L. Clark, 1915, has suggested it may be a young Astrochalcis. *oenigma Bell, 1894. Indian Ocean. Littoral. page 9 |
39 (1) |
Arms simple. |
40 (58) |
Disc covered by granulation, sometimes including small spinules or shallow scales, but without coarse projecting spikes or tubercles. |
41 (42) |
Arms annulated by alternating belts of granules and hooklets, and with the belts continued on to the disc, so that concentric ridges and furrows mark the dorsal surface: seen from above the animal looks "as if composed only of 5 arms, whose bases were thickened and wedged together" (Lyman, 1882). Hooklets with 1 secondary tooth. . . . Astroporpa Oersted & Lütken, 1856. *annulata Lütken, 1856. Caribbean. 100 fms. |
42 (41) |
No concentric furrows and ridges on disc. |
43 (46) |
Granulation of disc more or less covered, and partly obscured, by a soft skin. |
44 (45) |
About two arm-joints included within the disc: genital clefts shorter than 1 arm-joint: ventral arm-plates fragmented: 4 arm-spines. . . . Astrochlamys Koehler, 1911. (The type species, A. bruneus Koehler, is viviparous, and the females carry a dwarf-male clinging to the dorsal side of the disc: a second species, A. sol Mortensen, has 10 arms.) *bruneus K., 1911. W. Antarctica. 100 fms. |
45 (44) |
About six arm-joints included within the disc: genital clefts as long as 3 arm-segments: 4–5 arm-spines: girdle hooklets with 2 or 3 secondary teeth. . . . Astrochele Verrill, 1878. *lymani Verr., 1878. N. Atlantic. 300–1,000 fms. |
46 (43) |
Granulation not invested in skin. |
47 (48) |
A peripheral zone of stumpy granules demarcates the ventral margin of the disc, which is otherwise covered by a fine granulation: a zone of spinules surrounds the mouth: 3 or 4 conspicuous arm-spines, each about as long as an arm-joint. . . . Astrostephanus Doederlein, 1930. *Astrotoma vecors Koeh., 1904. Indonesia. 100 fms. |
48 (47) |
No peripheral zone of specialized granules. |
49 (50) |
A continuous mosaic of small platelets covers the ventral side of the arms and disc: the genital clefts small and restricted to the peripheral region, outside the mosaic: 6 arm-spines. . . . Astrozona Doederlein, 1930. *Astrogomphus munitus Koehler, 1904. Indonesia. 600 fms. |
50 (49) |
Not so. |
51 (52) |
Girdle-hooklets without secondary teeth: about 5 arm-spines. . . . Astrotoma Lyman, 1875. *agassizii Lyman, 1875. Antarctic. 100 fms. |
52 (51) |
Girdle-hooklets with secondary teeth. |
53 (54) |
Girdle-hooklets with 1 secondary tooth: 5 to 10 armspines. . . . Astrothorax Doederlein, 1911. *misakiensis Doed., 1911. Japan. Litt. |
54 (53) |
Girdle-hooklets with 2 to 6 secondary teeth. |
54a (55) |
Five arm-spines: disc uniformly covered by granules, and excavated inter-radially, so that radial lobes occur at the arm-bases: genital clefts short: hooklets with 2 secondary teeth. . . . Astrohelix Doederlein, 1930. *Astrotoma bellator Koehler, 1904. Indonesia. 150 fms. |
55 (54a) |
Two or three arm-spines. page 10 |
56 (57) |
Two or three secondary teeth: disc covered by larger rounded and smaller angular granules. . . . Astrothrombus H. L. Clark, 1909. *rugosus H. L. C., 1909. E. Australia. 50 fms. |
57 (56) |
Three to six secondary teeth: thorny granules occur among the disc granules. . . . Astrothamnus Matsumoto, 1915. *echinacea Matsumoto, 1912. Japan. Littoral. |
58 (40) |
Disc carrying coarse spikes or prominent tubercles. |
59 (64) |
Disc carrying coarse prominent tubercles, but no spikes. |
60 (63) |
Three or four arm-spines. |
61 (62) |
Scattered large tubercles on dorsal side of disc, and clusters of platelets on the ventral arm-bases around the mouth: arms annulated by bands of coarser granules, in 4 transverse rows, which alternate with bands of much more numerous and finer granules, in many transverse rows: girdle-hooklets with 1 or 2 secondary teeth. . . . Astrocrius Doederlein, 1927. *Astrotoma sobrinus Matsumoto, 1912. Japan. |
62 (61) |
Disc covered above and below by coarse granules and tubercles: arms annulated by double rows of granules, alternating with rows of hooklets which have one feeble secondary tooth. . . . Astrohamma Doederlein, 1930. *Astrothamnus tuberculatus Koehler, 1923. Antarctica. 70 fms. |
63 (60) |
One flat, scale-like arm-spine, some large tubercles on the dorsal side of disc resembling a cluster of pearls: hooklets of arm with 3 or 4 secondary teeth. . . . Ophiozeta Koehler, 1931. *turgida Koehler, 1931. Indonesia. 200 fms. |
64 (59) |
Disc with irregularly disposed conical spikes on dorsal surface, a mosaic of minute granules occupying the spaces between: oral papillae spiniform, similar to teeth: lateral plates meeting ventrally, and continued upward as double rows of nodules and hooks. . . . Astrogomphus Lyman, 1869. *vallatus Lym., 1869. N. Atlantic. 300 fms. |