Zoroaster stet. CCZ_065

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

Zoroaster stet. CCZ_065

Fig. 27

Material.

Clarion-Clipperton Zone • 1 specimen; APEI 7; 4.8877°N, 141.7569°W; 3132 m deep; 27 May. 2018; Smith & Durden leg.; GenBank: ON400691 (COI), ON406607 (16S); NHMUK 2022.78; Voucher code: CCZ_065 .

Description.

Single specimen (R = 16.6 cm, r = 1.3 cm). Actinal and abactinal surfaces are bright orange when alive, with ambulacrum slightly darker orange (Fig. 27A-D ). Small disc; with five long, slender arms, gradually tapering distally (Fig. 27B ). Carinal plates bear conical primary spines, forming a single longitudinal row that runs along the arm (Fig. 27A, C ).

Remarks.

Morphological characters are concordant with the description of the genus Zoroaster . The phylogenetic analyses also recovered the specimen in a well-supported clade with other species of the genus (Fig. 24 ). However, COI divergence between species in the genus is very low (K2P distance ≈ 1-2%) and species-level clades were not recovered in the phylogeny, preventing us from assigning it to any species based on COI sequences. The closest match to the COI sequence of the CCZ specimen is a sequence from the long-armed morphotype (K2P distance 0.6%, GenBank accession number AY225785.1) identified for Z. fulgens Wyville Thomson, 1873 in the Porcupine Seabight, Atlantic Ocean (50.1987°N, 14.6593°W; 4001 m depth; Howell et al. 2004). Although this value is concordant with intraspecific divergence in the genus, the 16S sequences divergence between the CCZ specimen and the long-armed morphotype (K2P 1.1%) is larger than between the long-armed morphotype and Z. spinulosus Fisher, 1906 (K2P 0.0%) and between Z. spinulosus and Z. ophiactis Fisher, 1916 (K2P 0.3%).

Ecology.

The specimen was found partially buried in the sediment on the seamount on APEI 7 at 3133 m depth.

Comparison with image-based catalogue.

No similar Zoroasteridae morphotypes have been catalogued so far from seabed imagery in the eastern CCZ nor in abyssal areas of the Kiribati EEZ. Consequently, the in situ image of Zoroaster stet. CCZ_065 was catalogued as a new morphotype (i.e., Zoroaster sp. indet., AST_025).

Class Crinoidea

To date, there are 66 records of crinoids occurring deeper than 3000 m in the CCZ, with only seven of these representing preserved specimens ( OBIS 2022). Three specimens, belonging to two species, were collected in the western CCZ. The barcoding gene COI was amplified for all specimens, and sequences were included in a concatenated alignment (16S, 18S, 28S, COI, and CytB) used to estimate a phylogenetic tree for the class (Fig. 28 ).

Subclass Articulata Zittel, 1879

Order Comatulida

Suborder Bourgueticrinina Sieverts-Doreck, 1953

Family Phrynocrinidae AH Clark, 1907

Subfamily Porphyrocrininae AM Clark, 1973

Figures

Figure 24. Rooted Bayesian phylogeny of Asteroidea. Concatenated (12 S, 16 S, 18 S, COI, and H 3) 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 27. Zoroaster stet. CCZ _ 065 A in situ image B abactinal view of whole specimen C detail of abactinal surface D detail of actinal surface before preservation. Scale bars: 3 cm (A); 2 cm (B); 5 mm (C, D). Image attribution: Durden and Smith (A); Wiklund, Durden, Drennan, and McQuaid (B-D).

Figure 28. Rooted Bayesian phylogeny of Crinoidea. Concatenated (16 S, 18 S, 28 S, COI, and CytB) 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.