Chrysogorgia ramificans Xu, Li, Zhan & Xu, 2019

Xu, Yu, Zhan, Zifeng & Xu, Kuidong, 2023, Studies on western Pacific gorgonians (Anthozoa: Octocorallia, Chrysogorgiidae). Part 1: a review of the genus Chrysogorgia, with description of a new genus and three new species, Zootaxa 5321 (1), pp. 1-107 : 76

Chrysogorgia ramificans Xu, Li, Zhan & Xu, 2019

Figs. 46 , 47

Chrysogorgia ramificans Xu, Li, Zhan & Xu, 2019: 94–97 , figs. 2–3.

Material examined. MBM286861 , station FX-Dive 223 (10°4′42″N, 140°15′12″E), a seamount (tentatively named as M7) on the Caroline Ridge, 1047m, 11 June 2019 .

Description. Colony typical bottlebrush-shaped and attached to a rocky substrate ( Fig. 46 A ). Specimen about 36 cm long and 15 cm wide in maximum with the holdfast not recovered ( Fig. 46 B ). Main stem about 1.5 mm in diameter at base and brown to yellow with metallic luster. Branching sequence 1/ 3L. Branches subdivided dichotomously, up to five orders with branching angle 80°–100°. Distance between adjacent branch 6–12 mm, orthostiche intervals 17–34 mm, the first internode of branch 8–27 mm and the terminal branchlets up to 31 mm. Polyps cylindrical, some of them curved, usually perpendicular to the branches, 1.0– 2.5 mm tall average 2 mm, and 0.5–1.0 mm wide ( Fig. 46C, E, F ). Polyps up to three and became very small on the first internode, up to four in medial internodes and up to five in terminal branchlets. Polyps absent in stem internodes and verruae absent. Tentacular part 0.5–1.0 mm long with tentacle rachis forming eight obvious columns ( Fig. 46E ).

Rods and spindles in polyp body wall longitudinally or obliquely arranged, large and thick, rarely branched with many large and coarse warts, occasionally with irregular edges and shape, measuring 115–529 × 49–141 μm ( Fig. 47D ). Rods and spindles in tentacle rachis longitudinally arranged extending to the polyp neck, all covered with many large and coarse warts, some of them branched with irregular shape, measuring 135–459 × 23–106 μm ( Fig. 47A ). Scales in pinnules transversely arranged, small with finely toothed ends and sparse warts on surface, some of them curved or twisted with a medial contraction, occasionally nearly smooth, measuring 114–148 × 21–60 μm ( Figs. 46D , 47B ). Scales in coenenchyme arranged along to the branch, elongated and flat with dentate edges and a few large warts, some of them smooth and thick, measuring 223–671 × 35–118 μm ( Figs. 46G , 47C ).

Distribution and habitat. The Kocebu Guyot in Magellan Seamounts, 1831 m ( Xu et al. 2019); a seamount on the Caroline Ridge in the Western Pacific, 1047 m.

Remarks. The colony of the Caroline specimen has a single bottlebrush-shaped branching part and smaller polyps compared with the holotype, and these differences may be caused by different growth stage or environment, and we treat as the intraspecific variation.

Figures

FIGURE 46. The external morphology and polyps of Chrysogorgia ramificans Xu, Li, Zhan & Xu, 2019. A, B. The same specimen in situ and after collection. C, E. Single non-terminal polyps under a light microscope and SEM, respectively. D. Pinnular part under SEM. F. A single terminal polyp under SEM. G. A part of branch under SEM. Scale bars: 10 cm (B); 1 mm (C, E, F); 500 μm (G); 100 μm (D).

FIGURE 47. The sclerites of Chrysogorgia ramificans Xu, Li, Zhan & Xu, 2019. A. Sclerites in tentacle rachis. B. Sclerites in pinnules. C. Sclerites in coenenchyme. D. Sclerites in polyp body wall. Scale bars: 300 μm (A, C and D in the same scale); 100 μm (B).