Pseudocrypthelia apoma Cairns, 2015

Periasamy, Rengaiyan, Kurian, Palayil John & Ingole, Baban, 2025, Deep-sea corals from the seamounts of Central and Southwest Indian Ridges, Zootaxa 5620 (2), pp. 278-294 : 281-283

2. Pseudocrypthelia apoma Cairns, 2015

( Figs. 2F–J )

Pseudocrypthelia apoma Cairns, 2015 Figs., 178I, 192D, K–L, 194 A–N, 195.

Material examined: One colony (NCPOR/HYD-CIR/0045), Central Indian Ridge: R/V MGS Sagar, stn. MGS35A_ BD9, 23°10' 01''S, 69° 31' 49'' E, 2103 m, 20 th April 2020 .

Description: Colony uniplanar with 9.23 mm tall and 1.5 mm wide, delicate anastomosing branches. Distal branches 0.42 mm in diameter; base of branch 0.9 mm diameter. Coenosteal texture linear-imbricate strips width of 37–51 µm; ridged and rough platelets. Circular-shaped cyclosystems, with 1–1.4 mm in diameter; 13–16 dactylopores per cyclosystem. Cup-shaped upper gastropore tube about 0.28 µm in diameter covered with linear-imbricate coenosteum. Ring constraint about 0.12–0.14 mm in diameter and tubular; about 80 µm in length; with a crescent-shaped lower chamber about 0.40 mm wide. Tip projects through ring constriction in the center of lower chamber as a triangular gastrostyle. Most cyclosystems have no lid, but many have an abcauline pseudoseptum enlarged to 2–3 times width of a typical pseudoseptum. Narrow dactylotomes, not descending into gastropore very far; broad and concave pseudosepta; uniformly white colour ( Fig. 2F ).

Remarks: Pseudocrypthelia is closely related to the genus Crypthelia but is distinguished by having a rudimentary gastrostyle. The genus Pseudocrypthelia comprises P. pachypoma ( Hickson & England 1905) and P. apoma , both native to the New Caledonian region. While P. apoma and P. pachypoma are similar in terms of their colony shape, coenosteal texture, nematopore placement, and pseudoseptal shape ( Cairns 2015), they differ in several key aspects: P. apoma lacks a cyclosystem lid. P. apoma has a markedly different placement of its female and male ampullae. The placement of the female efferent pores also differs significantly between the two species. These differences in reproductive structures and the presence or absence of the cyclosystem lid are the primary distinguishing characteristics between the two species within the genus Pseudocrypthelia .

Substrate type: The specimen was collected from the medium-grained basalt in the CIR ridge system.

Distribution: Pseudocrypthelia apoma is distributed in several regions around New Caledonia, including the Grand Passage, Loyalty Islands, and Northern Norfolk Ridge, at depths ranging from 235 to 502 m ( Cairns 2015). Herein, we register this species to the CIR at a much greater depth of 2103 m, significantly extending its known range.

Figures

FIGURE 2. A. colony of genus Crypthelia Milne Edwards & Haime, 1849; B. Cyclosystem; C. triangular pseudosepta; D. Brittle star associated with distal branch; E. coenosteal texture; F. colony of Pseudocrypthelia apoma Cairns, 2015; G. Cyclosystem; H and I. pseudoseptum; J. coenosteal texture.