Chrysogorgia delicata Nutting, 1908

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 : 73-76

Chrysogorgia delicata Nutting, 1908

Figs. 44 , 45 ; Table 9

Chrysogorgia delicata Nutting, 1908: 589–590 , Pl. XLV, fig. 7.

Chrysogorgia sp. Versluys 1902: 78 , figs. 128–129.

Chrysogorgia delicata: Kükenthal 1919: 531 .

Material examined. MBM286859 , station FX-Dive 221 (10°3′6″N, 140°9′30″E), a seamount (tentatively named as M5) on the Caroline Ridge, 1966 m, 9 June 2019 .

Description. Colony attached to a rocky substrate in situ with a small bottlebrush shape ( Fig. 44A ). Specimen short about 10 cm long and 6 cm wide in maximum with the holdfast not recovered ( Fig. 44B ). Stem about 0.7 mm in diameter at base with golden metallic luster. Branching sequence 1/ 3L. Branches subdivided dichotomously, up to four orders with branching angle 70°–80°. Distance between adjacent branches 3–6 mm, orthostiche intervals 10– 17 mm, the first internode of branch 5–9 mm long and the terminal branchlets up to 12 mm long. Polyps on branch internode average 2 mm tall and 1–2 mm wide, usually with a small oval body, and became large with a cylindrical body in terminal and up to 4 mm tall ( Fig. 44C, D, F, G ). Polyps usually arranged one on first and medial internode and one or two on terminal branchlets. Polyps in stem internodes small with eight extended tentacles, 0.5–1.0 mm tall and often arranged one in each internode. Tentacular part with eight obvious tentacles, up to 2.5 mm in terminal polyps. Verrucae absent.

Scales in aboral face of tentacle rachis transversely and alternately arranged, thick and nearly smooth, forked and branched with irregular shape, some of them curved with sparse fine warts and toothed edges of ends, measuring 75–497 × 10–283 μm ( Fig. 45A ). Scales in pinnules longitudinally arranged, nearly smooth, usually a little curved with one end forked or broad and the other end narrow or sharp, some of them with many warts and finely toothed end surface, and branched with irregular shape, measuring 183–452 × 7–144 μm ( Fig. 45C, E ). Scales in polyp body wall irregularly arranged, elongate and nearly smooth with an obvious medial contraction, occasionally with sparse fine warts, measuring 130–314 × 14–107 μm ( Fig. 45B ). Its edges usually finely toothed on surface, forked or lobed with very irregular shape, occasionally protruding outward. Scales in coenenchyme longitudinally arranged, small and slender, nearly smooth and often with lobed edges, some of them forked or branched with irregular shape, measuring 190–419 × 17–95 μm ( Figs. 44E , 45D ).

Distribution and habitat. Off Menado, 1264– 1165 m ( Versluys 1902); Hawaii, 536–1463 m ( Nutting 1908); a seamount on the Caroline Ridge in the Western Pacific Ocean, 1966 m.

Remarks. The original description of Chrysogorgia delicata Nutting, 1908 is unclear. As described by Nutting, the polyp’s sclerites are same with Chrysogorgia sp. (described by Versluys 1902, p78). We compared our specimen with the descriptions of Versluys and Nutting, and found it matches well with them. Therefore, the characters of C. delicata can be summarized by having a bottlebrush-shaped colony, nearly smooth and more forked or lobed scales with various shape in polyp body wall, slender and nearly smooth scales often with lobed edges and irregular shape in coenenchyme, and nearly smooth scales usually curved with one end forked or branched and broad, and the other end narrow or sharp in pinnules. It is similar to C. axillaris ( Wright & Studer, 1889) and C. sibogae Versluys, 1902 , but differs from them by more irregular scales with more lobed and branched edges in polyp body wall and coenenchyme (vs. both relatively regular with less lobes) ( Table 9 ).

Figures

FIGURE 44. The external morphology and polyps of Chrysogorgia delicata Nutting, 1908. A, B. The same specimen in situ (the arrow) and after collection. C, F. Non-terminal polyps under a light microscope and SEM, respectively. D, G. Terminal polyps under a light microscope and SEM, respectively. E. A part of branch under SEM. Scale bars: 5 cm (B); 1 mm (C, D, F, G); 500 μm (H).

FIGURE 45. Sclerites of Chrysogorgia delicata Nutting, 1908. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C. Some warty sclerites in the proximal pinnules. D. Sclerites in coenenchyme. E. Sclerites in pinnules. Scale bars: 300 μm (A–E; A, B, D, E in the same scale).