Iridogorgia chewbacca Xu, Watling & Xu, 2025

Iridogorgia chewbacca Xu, Watling & Xu , sp. nov.

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Figs. 8–10 View FIGURE 8 View FIGURE 9 View FIGURE 10

Material examined: Holotype: MBM286365 View Materials , station FX-Dive 68 ( 139°17.86′N, 11°19.86′E), a seamount (temporarily named as M2) near the Mariana Trench in the tropical northwest Pacific, depth 672 m, 25 March 2016 . Paratype: BPBM D2954 About BPBM , MOL501-1 About BPBM , Dive P 5-670, ( 21° 14.644' N, 156° 48.401'W) off Molokai Is. in the Hawaiian Island chain, depth 663 m, 4 September 2006 GoogleMaps .

Diagnosis: Colony large with whip-like branches producing from the bottom to top. Axis coiled tightly and nearly straight with strong iridescent metallic luster. Polyps with an expanded body. Sclerites rods, usually thick with fine warts, some of them flattened and nearly smooth with rugged surface. Polyp and branch with a few verrucae.

Description: Holotype incomplete, about 510 mm long, with the holdfast not recovered ( Fig. 8C View FIGURE 8 ). Axis tightly coiled spiraling upward and nearly straight with strong iridescent metallic luster, about 6 mm in diameter at base. The direction of growth clockwise. Branches whip-like and very flexible, up to 40 cm long, arranged on one side of the axis, 2–3 mm apart, with approx.75 polyps counted, emanating from the bottom to top of the colony. Each helical turn about 3 cm in height. Polyp orange after collection and became light yellow to white after fixation ( Fig. 9A, C, D View FIGURE 9 ), with an expanded body, average 3 mm wide and 1 mm from the branch to the tentacle base. Polyps 1–3 mm apart at proximal part of the branches, up to 5 mm in distal. Tentacles 2–3 mm long when spread out. Some polyps and branches covered with a few verrucae ( Fig. 9G View FIGURE 9 ).

Sclerites all rods, usually thick with small warts, some of them flattened and nearly smooth with rugged surface ( Fig. 10 View FIGURE 10 ). Rods in tentacle base longitudinally arranged, usually with small warts and two rounded ends, some of them nearly smooth and crossed with a few large warts or a rugged surface, measuring 106–412 × 22–98 μm ( Fig. 10A View FIGURE 10 ). Rods in the polyp body wall transversely or obliquely arranged, usually with sparse fine warts, some of them flattened and nearly smooth with a slightly medial contraction, occasionally crossed and curved with a few large warts, and measuring 91–580 × 20–75 μm ( Fig. 10B View FIGURE 10 ). Rods in the coenenchyme arranged along to the branch, nearly smooth, occasionally with small warts and irregular shape, and measuring 123–820 × 26–94 μm ( Fig. 10C View FIGURE 10 ).

Type locality: An unnamed seamount (temporarily named as M2) near the Mariana Trench with water depth of 672 m.

Etymology: The species named according to its shape resembling the wookie in the Star Wars movies.

Distribution and habitat: Holotype found on a seamount near the Mariana Trench. Colony large and lush in situ and growing on a rocky bottom ( Fig. 8A, B, D View FIGURE 8 ). The water temperature was 6.0°C and the salinity 36.3. Paratype from off Molokai, Hawaiian Is. Additional specimens photographed in the western Pacific Ocean.

Remarks: Iridogorgia chewbacca sp. nov. is characterized by tightly coiled and nearly straight axis with short helix, long and whip-like branches producing from colony bottom to top and sclerites all rods. The nearly straight axis can be seen as a special wavy shape with a narrow helical turn in diameter. Iridogorgia chewbacca sp. nov. is most similar to I. superba Nutting, 1908 but differs by tentacles with abundant sclerites (vs. absent), and longer branches (up to 400 mm vs. up to 175 mm) ( Nutting 1908).