Fungiacyathus (Fungiacyathus) cf. fragilis Sars, 1872

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

Fungiacyathus (Fungiacyathus) cf. fragilis Sars, 1872

Fig. 14

Material.

Clarion-Clipperton Zone • 1 specimen; APEI 4; 7.2647°N, 149.774°W; 3562 m deep; 03 Jun. 2018; Smith & Durden leg.; NHMUK 2021.26; Voucher code: CCZ_107

Description.

Single specimen, solitary, and unattached, ~ 27 mm in transverse diameter. Live specimen with tapered, transparent tentacles, longer than half the corallum diameter and arranged in two or three cycles (Fig. 14A ). Corallum is light brown distally and darker proximally on live specimen (Fig. 14B, C ). The base is flat and the lower cycle septa are strongly arched upward; septa are arranged in five cycles, those of the fifth are rudimentary.

Remarks.

No genetic sequences were obtained from this specimen. Morphological characters match the genus Fungiacyathus .

Ecology.

This free-living specimen was found on a sedimented area on a seamount in APEI 4, at 3561 m depth.

Comparison with image-based catalogue.

A very similar scleractinian morphotype (i.e., Fungiacyathus sp. indet., SCL_003) has been encountered in seabed image surveys conducted across the eastern CCZ but not in abyssal areas of the Kiribati EEZ, usually on sediment. As with other solitary scleractinians, this taxon could be confused with an anemone in seabed imagery (e.g., SCL_003 was originally catalogued as an Actiniaria from in situ images, which was addressed following the collection and analysis of the specimen collected in this study).

Subclass Octocorallia Haeckel, 1866

Order Alcyonacea Lamouroux, 1812

There are 131 records of Alcyonacea at> 3000 m depth in the CCZ, only eight of those representing preserved specimens ( OBIS 2022). We collected three specimens belonging to three different species, only one assigned to a previously described species. Genetic sequences for both 16S and COI genes were amplified for each specimen, and included in a concatenated alignment (16S, COI, mtMutS, NADH2) used to generate a phylogenetic tree of Octocorallia (Fig. 15 ). Classification of Alcyonacea specimens from seabed imagery is often constrained by the lack of visibility of polyp morphology, particularly when these are small (e.g., family Primnoidae ). Therefore, classification from in situ images is mostly based on broader features like the branching pattern, the length of the main stem, and/or the number, size, and positioning of polyps on branch nodes.

Suborder Calcaxonia Grasshoff, 1999

Family Chrysogorgiidae Verrill, 1883

Figures

Figure 14. Fungiacyathus (Fungiacyathus) cf. fragilis Sars, 1872. Specimen CCZ _ 107: A in situ image B dorsal view of live specimen C bleached skeleton. Scale bars: 1 cm (A); 3 mm (B, C). Image attribution: Durden and Smith (A); Wiklund, Durden, Drennan, and McQuaid (B); Bribiesca-Contreras (C).

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.