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Synoptic Keys to the Genera of Ophiuroidea

Family Euryalidae Gray, 1840 — (Syn. Trichasteridae sensu Mortensen, 1933)

Family Euryalidae Gray, 1840
(Syn. Trichasteridae sensu Mortensen, 1933)

1 (6)

Arms simple.

2 (5)

Arms with a prominent dorso-lateral ridge of spines or granules on either side: arm-spines short, of equal size.

3 (4)

Dorso-lateral ridges carrying numerous, very prominent tubercles: additional interradial plates lying distal to the adoral shields. . . . Asterostegus Mortensen, 1933.

*tuberculatus Mrtsn., 1933. S. Africa. 200 fms.

4 (3)

Dorso-lateral ridges with scattered tubercles or spines: no additional interradial plates distal to the adoral shields, interredius naked ventrally. . . . Astroceras Lyman, 1879.

For a review of this genus see Mortensen, 1933a.

*pergamena Lyman, 1879. Japan. 100 fms.

5 (2)

Arms rounded above, without dorsolateral ridges: inner arm-spine usually longer than the outer. . . . Asteromorpha Lütken, 1869.

Synonym Ophiogelas Koehler.

*Asteroschema rousseaui Michelin, 1862. Indian O. 100 fms.

6 (1)

Arms forking several times: arm-spines short, both of equal size.

7 (10)

More than 18 arm-joints occurring before the first fork.

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10 (7)

Less than 10 arm-joints before the first fork: arms forking repeatedly over most of their length: gonads entering the arms. . . . Euryale Oken, 1815.

Euryale is usually attributed to Lamarck, 1816: however, Oken's usage appears to have priority. The current employment of Euryale stems from Lyman, 1882; previously it was an absolute synonym of Gorgonocephalus: for discussion, see Verrill, 1899.

*asperum Lmk., 1816. Indonesia. Littoral.

8 (9)

Arms with dorso-lateral ridges, often set with spines or granules: lateral plates widely separated on ventral surface of arm: arms branching only in their distal halves: gonads entering arms. . . . Trichaster Agassiz, 1836.

*Euryale palmiferum Lmk., 1816. Indian O. 100 fms.

9 (8)

Arms symmetrically rounded above, without dorso-lateral ridges: lateral plates meeting on ventral midline of arm: gonads confined to disc. . . . Sthenocephalus Koehler, 1898.

*indicus Koehler, 1898. Indonesia. 30 fms.