Chrysogorgia sp. CCZ_112

Bribiesca-Contreras, Guadalupe, Dahlgren, Thomas G., Amon, Diva J., Cairns, Stephen, Drennan, Regan, Durden, Jennifer M., Eleaume, Marc P., Hosie, Andrew M., Kremenetskaia, Antonina, McQuaid, Kirsty, O'Hara, Timothy D., Rabone, Muriel, Simon-Lledo, Erik, Smith, Craig R., Watling, Les, Wiklund, Helena & Glover, Adrian G., 2022, Benthic megafauna of the western Clarion-Clipperton Zone, Pacific Ocean, ZooKeys 1113, pp. 1-110 : 1

Chrysogorgia sp. CCZ_112

Fig. 16

Material.

Clarion-Clipperton Zone • 1 specimen; APEI 4; 7.2874°N, 149.8578°W; 4125 m deep; 04 Jun. 2018; Smith & Durden leg.; GenBank: ON400711 (COI), ON406602 (16S); NHMUK; Voucher code: CCZ_112 .

Description.

Wide, long, sparsely branched colony, ~ 30 cm tall from the base (Fig. 16A, B ). Polyps constricted basally on the neck (Fig. 16C-E ), placed on internodes and absent from the main stem (Fig. 16A, B ). Polyps are light orange when alive (Fig. 16C, D ) and white after preservation (Fig. 16E ). Sclerites near the polyp base are scale-like, but throughout the body and along the tentacle rachis are all elongate flat rods; sclerites are absent from the tentacle pinnules.

Remarks.

The sequence for the COI gene is 0% divergent from a sequence of a specimen of Chrysogorgia abludo Pante & Watling, 2011 (specimen NAS102-3, GenBank accession number GQ180138) collected at Nashville Seamount, New England Seamounts at 2246 m depth (Station 102; 34.5828°N, 56.8433°W) included as comparative material during the species description ( Pante and Watling 2011). In octocorals, it has been found that COI evolves very slowly and therefore it is not suitable for species discrimination, with different species having the same haplotype ( McFadden et al. 2011). Chrysogorgia abludo is distributed in the Atlantic Ocean, and morphological characters of the specimen collected in this study differ from the original description of C. abludo , as well as other species within the genus and hence considered a potentially new species In the phylogenetic tree (Fig. 15 ) the specimen was also recovered along with another specimen of Chrysogorgia , supporting its placement within the genus.

Comparison with image-based catalogue.

No similar Alcyonacea morphotypes have been catalogued so far from seabed imagery in the eastern CCZ or in abyssal areas of the Kiribati EEZ. Consequently, the in situ image of Chrysogorgia sp. CCZ_112 was catalogued as a new morphotype (i.e., Chrysogorgia sp. indet., ALC_017).

Ecology.

The specimen was attached to polymetallic crust on the slope of a seamount in the APEI 4, at 4124 m depth.

Family Mopseidae Gray, 1870

Mopseidae sp. CCZ_088

Fig. 17

Material. Clarion-Clipperton Zone • 1 specimen; APEI 4; 7.0089°N, 149.9109°W; 5018 m deep; 02 Jun. 2018; Smith & Durden leg.; GenBank: ON400705 (COI), ON406603 (16S); NHMUK XXX; Voucher code: CCZ_088.

Description. Single specimen, with white axis and polyps; polyps standing perpendicular to the axis when alive (Fig. 17A ). Colony is long, ~ 45 cm tall, and unbranched (Fig. 17A, B ). Polyps are tall, ~ 2 mm, clavate, and standing parallel to the branch (Fig. 17C ).

Remarks. Both 16S (0.3% K2P) and COI (0.6% K2) sequences are very similar to Mopseinae sp. NHM_330 ( Dahlgren et al. 2016), which morphologically resembles the genus Primnoisis . The specimen from the western CCZ likely belongs to the same genus but based on genetic and morphological differences represents a different species from that of the eastern CCZ.

Ecology. The specimen was found attached to a nodule in abyssal sediments of APEI 4 at 5018 m depth.

Comparison with image-based catalogue. No similar Alcyonacea morphotypes had been catalogued so far from seabed imagery in the eastern CCZ or in abyssal areas of the Kiribati EEZ. Consequently, the in situ image of CCZ_088 was catalogued as a new morphotype (i.e., Mopseidae gen. indet., ALC_018). However, it is often not possible to determine whether such small and abundant polyps are arranged in pairs or not, or the actual orientation of these with regards to the axis from seabed images.

Family Primnoidae Milne Edwards, 1857

Figures

Figure 15. Rooted Bayesian phylogeny of Octocorallia. Concatenated (16 S, COI, mtMutS, NADH 2) median consensus BEAST tree with posterior probability (PP) and bootstrap (BS) values indicated. Only values of PP> 0.70 and BS> 50 are shown, with values of PP> 0.95 and BS> 90 indicated with a circle. Nodes not recovered on the RAxML tree are indicated with a hyphen. Sequences generated in this study are highlighted in violet.

Figure 16. Chrysogorgia sp. CCZ _ 112 A, B in situ images of colony C closed polyp on live specimen D opened polyp on live specimen showing light orange colouration E closed polyp of preserved specimen. Scale bars: 2 cm (A); 0.5 mm (C-E). Image attribution: Durden and Smith (A, B); Wiklund, Durden, Drennan, and McQuaid (C, D); Bribiesca-Contreras (E).

Figure 17. Mopseidae sp. CCZ _ 088 A in situ image B whole colony attached to a nodule C detail of polyps before preservation. Scale bars: 5 cm (A); 2 cm (B); 5 mm (C). Image attribution: Durden and Smith (A); Wiklund, Durden, Drennan, and McQuaid (B, C).