Iridogorgia verrucosa Xu, Zhan & Xu, 2021

Figs. 11, 12

Iridogorgia verrucosa Xu, Zhan & Xu, 2021: 11–13, Figs 5, 6.

Material examined: MBM286361, station FX-Dive 57 (21°11.80′N, 118°04.00′E), Northeast of South China Sea, depth 1641 m, 5 March 2016 .

Diagnosis (redefined on the basis of Xu et al. 2021): Colony relatively short with closely coiled helices and branches producing nearly from the bottom to top. Polyps with an expanded body base. Rods in the tentacles relatively sparse with many small warts, some of them with a slight medial contraction. Flat rods and needles in the polyp body wall and coenenchyme often with a slight medial contraction, some of them wide with irregular shape. Sclerites in coenenchyme abundant at the base of polyps and rare to absent in inter-polyps.

Description: Colony grown in a rocky bottom in situ (Fig. 11A). Specimen bright orange after collection and became white after fixation, about 43.5 cm long, with the holdfast not recovered (Fig. 11B, C). The direction of growth clockwise. Axis closely coiled spiraling upward and with an iridescent metallic luster, about 5 mm in diameter at base. Branching part including 14 helical turns, each turn about 3 cm in height and 1 cm in diameter (Fig. 11C). Branches up to 200 mm long, producing nearly from the colony base to top and arranged on one side of the axis, about 2 mm apart. Polyps with an expanded body base, about 3 mm wide and 1 mm from the branches to the tentacle bases, 5–7 mm apart (Fig. 11D, E, G–I). Tentacles up to 3 mm when spread out. The proximal polyps usually with a more expanded body base, shorter tentacles, and longer inter-polyp distance. Polyps and branches with a few low verrucae (Fig. 11I).

Rods in the tentacle bases longitudinally arranged, sparse and large with two rounded ends, usually covered with many small warts and a slight middle constriction, some of them with a rugged surface, and measuring 200–487 × 19–63 (Figs. 11J, K; 12A). Flat rods and needles in the polyp body wall transversely or obliquely arranged, nearly smooth, some of them with a slight middle contraction and sharp ends, occasionally crossed, wide and irregular, measuring 96–407 × 12–106 µm (Figs. 11J, K; 12B). Sclerites rare to absent in inter-polyp coenenchyme (Fig. 11F). Flat rods and needles in coenenchyme at the base of polyps nearly smooth, some of them with two sharp ends, occasionally branched, and measuring 174–419 × 19–49 µm (Fig. 12C).

Distribution: A seamount located on the Caroline Ridge, 1397 m (Xu et al. 2021); South China Sea, 1641 m.

Remarks: This specimen matches well with the holotype in relatively tightly coiled central axis, sclerites rare to absent in the coenenchyme between the polyps, rods in tentacles and flat rods and needles in polyp body wall and coenenchyme. Moreover, their mtMutS-cox1 and 28S gene sequences showed they are identical with the intraspecific differences (see the genetic analysis before). Thus, we identified them as the same species. This specimen differs from the holotype by deeper color when alive, longer branches, less verrucae and relatively regular sclerites in polyp body and coenenchyme (Xu et al. 2021). However, these differences may be caused by different environment or growth stage, and we thus treat as the conspecific variation.