Callozostron mirabile Wight, 1885

6. Callozostron mirabile Wight, 1885 View in CoL

( Figs. 5A–F View FIGURE 5 )

Callozostron mirabile Wright, 1885: 691 View in CoL , fig. 234, 235

Callozostron mirabilis View in CoL — Wright & Studer 1889: 48, 280, Pl. 10, fig. 1–6, Pl. 20, fig. 1.

Callozostron horridum Kükenthal 1909: 49 View in CoL ;— Kükenthal 1912: 331, Text fig. 38–42, Pl. 22, fig. 12–13.

Callozostron mirabile View in CoL — Bayer 1996: 152–159, fig. 1 (left), 2–6 (complete synonymy);— Cairns & Bayer 2009: 27, fig. 5 O– X;— Cairns 2016; 31, figs 1E, 19, 11.

Material examined: One colony ( NCPOR/HYD-CIR/0047 ), Central Indian Ridge : R/V MGS Sagar, stn. MGS35A-BD22), 23° 11' 14'' S, 69° 33' 9'' E, 2005 m, 23 rd April 2020 GoogleMaps .

Description: Colony unbranched, flagelliform (whip-like or bottlebrush), and up to 15.3 cm in length and 1.4 mm in width; central axis hard and golden in color. Polyps stand perpendicular polyps to the stem, arranged in a spiral, many polyps with cylindrical about 3.2–3.5 mm in height including spines, arranged in whorls of four or five polyps, the lesser number toward the branch tip.

Marginal, opercular, body wall, and coenenchymal scales have a smooth outer, inner surfaces covered by tuberculate. Marginal and submarginal scales cover a polyp and those closest to the operculum, an elongated apical spine that does not fold over the operculum. Opercular scales blunt, elongated apical spines, tongue-shaped, highly concave in the outer surface, blunt tip without non-spinose, 0.8–0.95 mm in length, base scales 0.32–0.54 mm in width. Body wall scale arranged in eight longitudinal rows, with each row having 7–10 scales. Coenenchymal scale smaller, smooth outer surface, more irregular in shape and like those of body wall, arranged in one thin layer, inner surface covered with a thick layer of tuberculate on base region 0.15–0.35 mm in diameter ( Figs. 5A–F View FIGURE 5 ).

Remark: The CIR specimen features tightly compressed whorls with well-developed axes, as described by Bayer (1996), Cairns & Bayer (2009), and Cairns (2016). Callozostron contains six species and is commonly found in deep water (bathyal abyss). Bayer (1996) identified the four Callozostron species that existed at the time, whereas Cairns (2015, 2016) described two new species. C. mirabile was found to be deeper than 3000 m in the CIR.

Substrate type: The specimen collected from highly altered basalt in the ridge system indicates a geological environment where the original basalt has undergone significant changes due to weathering, hydrothermal alteration, or chemical reactions with seawater.

Distribution: This species is previously known from the Southern Ocean, Antarctic Oates coast (2836 to 2864), South Atlantic Ocean (2653 to 2941), and North Island ( New Zealand) (1354 to 3876). Notably, it has now been identified for the first time in the CIR at a depth of 2005 m.

Molecular data: The pairwise distance between Callozostron mirabile from the CIR ( OM472571 View Materials ) and New Zealand ( MG986927 View Materials ) is 0.9 to 1.0% with other Callozostron species. The low pairwise distance suggested closely related species, indicating a relatively close evolutionary relationship.