Paramphinome sp. NHM_6022E

Neal, Lenka, Wiklund, Helena, Gunton, Laetitia M., Rabone, Muriel, Bribiesca-Contreras, Guadalupe, Dahlgren, Thomas G. & Glover, Adrian G., 2022, Abyssal fauna of polymetallic nodule exploration areas, eastern Clarion-Clipperton Zone, central Pacific Ocean: Amphinomidae and Euphrosinidae (Annelida, Amphinomida), ZooKeys 1137, pp. 33-74 : 33

Paramphinome sp. NHM_6022E

Figs 11A-C , 12A-I

Material examined.

NHM_1167D, NHMUK ANEA 2022.638, coll. 26/02/2015, EBS, 12.11550, -117.16450, 4100 m, OMS, http://data.nhm.ac.uk/object/fd4902df-aef2-44cf-991f-31905434c2a1; NHM_4044, NHMUK ANEA 2022.639, coll. 06/03/2020, box core, 13.27406, -116.69997, 4185 m, UK-1, http://data.nhm.ac.uk/object/56235559-3f2c-426e-b4cd-37462593a4ba; NHM_6022E, NHMUK ANEA 2022.640, coll. 13/11/2020, box core, 10.35780, -117.15931, 4284 m, NORI-D, http://data.nhm.ac.uk/object/bd4b405d-3e56-4671-909e-fdf9c3e7fbcf.

Diagnosis

(after Fauchald (1977)). All very small, poorly preserved and posteriorly incomplete specimens (Fig. 11A-C ). Specimen NHMUK ANEA.2022.638, 1.65 mm long and 0.35 mm wide for ca. 7 discernible chaetigers. Prostomium broad, rounded, slightly longer than wide; with a pair of palps and lateral antennae and posteriorly with median antenna; all prostomial appendages tiny and globular to ovoid (Fig. 12A, B ). Two pairs of tiny reddish eyes (Fig. 12A ) in trapezoidal arrangement, plus a pair of tiny, pigmented spots present posteroventrally on prostomium (Fig. 12B ). Caruncle as a low-lying lobe, reduced, difficult to observe.

Parapodia biramous. Dorsal cirri small and ovoid (Fig. 12F ), ventral cirri not observed. Two pairs of branchiae present on chaetiger 4 and 5, comb-shaped with two main stalks branching into 4 terminal lobes (Figs 11A, B , 12C, D ). Stout, distally strongly curved hook present in each notopodium of chaetiger 1 (Fig. 12E ). Other observable chaetae include stout spines, slightly subdistally swollen (Fig. 12G ); slender bifurcate chaetae, their prongs significantly differing in length, the long prong marginally serrated (Fig. 12H ) and slender, long, smooth chaetae (Fig. 12I ). Posterior segments and pygidium not observed.

Molecular information.

Only one specimen, NHMUK ANEA.2022.640, was successfully sequenced for 16S and 18S (Table 1 ). There were no identical sequences for 16S on GenBank. In the phylogenetic tree this species falls as a sister taxon to Paramphinome jeffreysii and an unidentified specimen, Amphinomidae sp. RG-2014 (Fig. 5A ).

Remarks.

Three very small posteriorly incomplete specimens were collected in CCZ samples. They differ from known species by its very small size and low number of branchial pairs (only two pairs) and undeveloped prostomial appendages, which are tiny and globular. While body size, number of segments and number of branchial pairs were previously linked to developmental stages (e.g., Kudenov 1993; Barroso and Paiva 2008), we believe that the three specimens presented here, collected during three different cruises up to eight years apart, represent a small-bodied species rather than juveniles.

Of the known deep-sea Paramphinome species, none were described from the abyssal depths. Paramphinome pacifica Fauchald & Hancock, 1981 has been described from NE Pacific Ocean: off central Oregon (USA), 1800-2900 m; (type locality: Cascadia Abyssal Plain, 2860 m). Paramphinome australis Monro, 1930 has type locality off Signy Island, South Orkney Islands, Southern Ocean in depths between 244-344 m, although it has been widely reported from the Southern Ocean ( Kudenov 1993) and also the abyssal Atlantic ( Böggemann 2009). Paramphinome posterobranchiata Barroso & Paiva, 2008 has type locality in South Atlantic, off Brazil at 1600 m depth. Finally, P. jeffreysii has type locality in St. Lawrence estuary (shallow depths), but has been widely reported, even from great depths (e.g., Gunton et al. 2015) and specimens ascribed to this taxon likely represents different species (see Fig. 5A ).

It is likely that the CCZ-collected specimens represent a new species; however, their tiny size and poor morphological preservation prevent its formal description, therefore the specimens are assigned to morphospecies only.

Distribution.

Central Pacific Ocean, Eastern CCZ, the exploration contract areas UK-1, OMS, and NORI-D (Fig. 1 ).

Figures

Figure 1. Map of CCZ of exploration areas and areas of particular interest, with targeted areas where samples of this study were collected highlighted in colours (see legend for explanation).

Figure 5. Majority-rule consensus trees from the Bayesian analyses with posterior probability values on nodes. Taxon names highlighted in blue are news species or new sequences for already known species. A Amphinomidae phylogenetic tree using a combined datasets for COI, 16 S, and 18 S with 26 terminal taxa of which Euphrosine foliosa (Euphrosinidae) was used as a root B Euphrosinidae phylogenetic tree using a combined datasets for 16 S and 18 S with nine terminal taxa of which Paramphinome jeffreysii (Amphinomidae) was used as a root.

Figure 11. Paramphinome sp. NHM _ 6022 E A, B preserved specimen NHMUK ANEA. 2022.638 in dorsolateral view, branchiae (br) of chaetigers 4 and 5 marked by arrows C preserved specimen, NHMUK ANEA. 2022.639, in dorsal view. Scale bars: 500 µm.

Figure 12. Paramphinome sp. NHM _ 6022 E (specimen, NHMUK ANEA. 2022.638) A anterior end in lateral view, with eyes and median antenna B prostomium in ventral view with palps and pigmented spots C detail of branchiae from chaetiger 4 in dorsolateral view D branchiae and dorsal lobe from chaetiger 4 in lateral view E notopodial hook from chaetiger 1 F dorsal lobe from chaetiger 2 G protruding acicular spine (ac) H spinose bifurcate chaeta I long spinose neurochaeta. Scale bars: 100 µm (A-C); 50 µm (D-I). Abbreviations: e - eyes, ma - median antenna, p - palps, ps - pigmented spots, ac - acicular spines.