Docosaccus sp. CCZ_021

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

Docosaccus sp. CCZ_021

Fig. 58

Material.

Clarion-Clipperton Zone • 1 specimen; APEI 7; 5.1043°N, 141.8867°W; 4860 m deep; 25 May. 2018; Smith & Durden leg.; GenBank: ON400684 (COI), ON406635 (18S), ON406612 (16S), ON406598 (28S), ON411255 (ALG11); NHMUK 2022.6; Voucher code: CCZ_021 .

Description.

Single specimen; lophophytous sponge. Plate-like, flat, subcircular body; 8.7 cm at its longest axis, 1 mm thick (Fig. 58A ). Colouration is yellowish. Atrial surface facing up (Fig. 58C ), and dermal surface almost in contact with the seafloor, with basalia protruding from it and anchoring it to the sediment (Fig. 58B ).

Remarks.

External morphological characters are concordant with the description of D. maculatus ( Kahn et al. 2013). However, sequences for the 16S and COI genes from the holotype are 2.4% and 3.9% divergent (K2P distance), respectively, from the western CCZ specimen. Sequences from 18S and 28S do not match to sequences from D. maculatus . The species was described from Station M, off California, in the Pacific Ocean at depths of 3,953-4,000 m, but the genus was originally thought to be restricted to Antarctica ( Kahn et al. 2013). This species has been recorded in the CCZ, in the eastern IFREMER contract area and in APEI 3, from 4905-4998 m depth ( Kersken et al. 2019). The specimen collected in the western CCZ differs from the holotype of D. maculatus in having more parietal oscula, and is smaller, and therefore considered a different species. External morphological characters also differ from the other species reported for the CCZ, D. nidulus Kersken, Janussen & Martínez Arbizu, 2019.

Ecology.

This specimen was found anchored to abyssal sediments of APEI 7 at 4860 m depth.

Comparison with image-based catalogue.

A very similar Docosaccus sp. morphotype (i.e., Docosaccus maculatus sp. inc., HEX_015) has been very frequently encountered in seabed image surveys conducted across nodule fields areas of the eastern CCZ and in abyssal areas of the Kiribati EEZ.

Figures

Figure 58. Docosaccus sp. CCZ _ 021 A in situ image B dermal surface C and atrial surface. Scale bars: 1 cm (A, B, C). Image attribution: Durden and Smith (A); Wiklund, Durden, Drennan, and McQuaid (B, C).