Freyastera stet. CCZ_201

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

Freyastera stet. CCZ_201

Fig. 26

Material.

Clarion-Clipperton Zone • 1 specimen; APEI 1; 11.2518°N, 153.6059°W; 5204 m deep; 10 Jun. 2018; Smith & Durden leg.; GenBank: ON400730 (COI); NHMUK 2022.81; Voucher code: CCZ_201 .

Comparative material.

Pacific Ocean • 1 specimen, holotype of Freyella benthophila Sladen, 1889; mid-South Pacific; 39.6833°S, 131.3833°W; 4663 m deep; Challenger Expedition, Stn. 289; NHMUK 1890.5.7.1078. Atlantic Ocean • 1 specimen, syntype of Freyella tuberculata Sladen, 1889; between west coast of Africa and Ascencion Islands ; 22.3°N, 22.0333°W; 4389 m deep; Challenger Expedition, Stn. 346; NHMUK 1890.5.7.1077. • 1 specimen, syntype of Freyella tuberculata ; between Canary Islands and Cape Verde Islands; 2.7°S, 14.6833°W; 4298 m deep; Challenger Expedition, Stn. 89; NHMUK 1890.5.7.1076 .

Description.

Single specimen, with very small disc and six long, slender, tapered arms (R = 190 mm, r = 5 mm; Fig. 26A ). Specimen before preservation has a slightly orange adoral disc surface, white arms, and bright orange tube feet discs (Fig. 26A-D ). Disc is somewhat rounded, covered with short, scattered spines covered by a membrane bearing pedicellariae (Fig. 26B ). Arms with long, slender lateral spines, also covered with a membrane bearing pedicellariae (Fig. 26C ). Each abactinal plate on the genital area bears a one to few spinelets, completely covered with a membrane with pedicellariae. Each mouth plate has two oral spines covered by a clear membrane bearing pedicellariae; one located on the adoral margin of the mouth plate and the suboral spine located above the centre of the mouth plate.

Remarks.

The COI sequence is 4% divergent from the two specimens of Freyastera cf. tuberculata reported herein, and hence considered a separate species. It is also divergent (> 4% K2P distance) to sequences of other species of Freyastera , but forms a monophyletic clade with those, confirming its placement within the genus (Fig. 24 ). Morphologically it resembles Freyastera cf. tuberculata , but differ in having slightly shorter and more scattered spinelets on the abactinal surface of the disc. Also, the spinelets on the abactinal plates on the genital area are more numerous, and completely covered by a membrane bearing pedicellariae, instead of having a membrane that does not cover the spine all the way down to the base as in F. cf. tuberculata . In addition, the genetic distance with specimens of that species corresponds to the genetic distance between morphologically distinct species and hence considered a separate species.

Ecology.

The specimen was collected on the sedimented abyssal plain of APEI 1 at 5204 m depth, with arms curled up like a basket (Fig. 26A ).

Comparison with image-based catalogue.

Freyastera spp. are commonly found in image-based megafauna assessments across the CCZ (e.g., Amon et al. 2016; Amon et al. 2017b), abyssal areas of the Kiribati EEZ, and other areas of the Pacific abyss (e.g., Peru Basin: Simon-Lledó et al. 2019a), both in nodule fields and in seamount areas. The relatively large size of adult specimens facilitates the detection of these brisingids even upon imagery collected at high altitudes (> 5 m) above the seabed. However, only one Freyastera sp. morphotype (e.g., Freyastera sp. indet., AST_002) has been catalogued so far, as differences in structure of the abactinal armament and/or the suboral spines are not visible from seabed images.

Order Forcipulatida Perrier, 1884

Family Zoroasteridae Sladen, 1889

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 26. Freyastera stet. CCZ _ 201 A in situ image B whole specimen C dorsal disc surface D ventral disc surface. Scale bars: 2 cm (A); 2 mm (B); 1 cm (C); 2 mm (D). Image attribution: Durden and Smith (A); Wiklund, Durden, Drennan, and McQuaid (B-D).