Chrysogorgia midas, Cairns, Stephen D., 2018

Cairns, Stephen D., 2018, Deep-Water Octocorals (Cnidaria, Anthozoa) from the Galapagos and Cocos Islands. Part 1: Suborder Calcaxonia, ZooKeys 729, pp. 1-46 : 23

Chrysogorgia midas sp. n. Figures 3e, 14

Material examined.

Types. Holotype: colony and SEM stubs 2316-2319, 2350-2316, JSL-I-1915, USNM 1160575. Paratypes: Alb-2818, many denuded branches (dry), USNM 51464; JSL-I-1912, distal colony, USNM 1160579; JSL-I-1916, distal colony, USNM 1160578; JSL-I-1929, 1 colony, USNM 1160585; JSL-I-1933, 1 branch, USNM 1160582; JSL-I-3902, 1 branch, USNM 1405908.

Type locality.

1°17'12"S, 89°48'42"W (north of Española, Galápagos), 650-662 m deep.

Distribution.

Throughout Galápagos from Roca Redondo to Española, 560-816 m deep.

Description.

The colony is bottlebrush in shape (Figure 3e), the holotype measuring 26 cm tall and 12-13 cm in maximum diameter, having a basal branch diameter of 2.5 mm. The branching is sympodial, the branching formula being consistently 1/3L. The orthostiche interval is 12-18 mm. The length of the internodes of the branchlets ranges from 4.0-5.9 mm, up to nine nodes occurring on each branchlet; each internode supports one polyp. The polyps are about 1.1 mm in length, cylindrical (Figures 14a, b), and when preserved in alcohol tend to curve toward the branch surface, the tentacles often adhering to the surface branch. The axis is bronze in color.

The body wall sclerites (Figure 14 a–c) are slightly flattened, rotund rods 0.22-0.25 mm in length, having a L:W of 5-6. They are straight and longitudinally oriented. The tentacular sclerites (Figure 14d) are similarly shaped rods, but are slightly shorter (0.18-0.22 mm in length) and more elongate (L:W = 5-8), also longitudinally oriented along the tentacles. All of the rods bear low sparse granulation. The pinnular scales (Figure 14e) are 0.08-0.12 mm in length, about 0.005 mm in thickness, and have a L:W of 3.5-4.5. The coenenchymal scales (Figures 14a, f) are 0.13-0.17 mm in length, about 0.01 mm in thickness, and have a H:W of 3.5-5.0. They are longitudinally oriented along the branch axis.

Comparisons.

Having rods in its body wall and tentacles places C. midas in Chrysogorgia Group A, the largest of the four groups of Chrysogorgia , consisting of 38 species (Table 1). C. midas is the only species in this group to have a 1/3L branching formula, this formula being much more common in Group C and in one species of Group B (see Cairns 2001).

Etymology.

Named “midas” (from the Greek Midas, the mythical king at whose touch everything turned to gold) in allusion to the golden luster of the branch axis, characteristic of the genus.