Bathypolaria undetermined

Bonifácio, Paulo & Menot, Lénaïck, 2019, New genera and species from the Equatorial Pacific provide phylogenetic insights into deep-sea Polynoidae (Annelida), Zoological Journal of the Linnean Society 185, pp. 555-635 : 593-594

BATHYPOLARIA SP. 608

( FIG. 10B–D, F; TABLES 1, 2)

Polychaeta sp. NB-Po581 (GenBank KJ736683) Janssen et al. (2015).

Material examined: Specimen 1, MNHN-IA-PNT 66 ( IFR608 ), complete, length 3.80 mm, width 0.80 mm, 15 segments (including tentacular segment), Equatorial Eastern Pacific Ocean , Clarion-Clipperton Fracture Zone , APEI#3 , station 192, collected 21 April 2015, epibenthic sledge epi-net, start 18°44.807′N, 128°21.874′W, end 18°45.338′N, 128°20.418′W, 4821– 4820 m depth, 2799 m trawling distance. Specimen 2, MNHN-IA-PNT 67 ( IFR658-1 ), complete, length 3.73 mm, width 0.74 mm, 15 segments (including tentacular segment), Equatorial Eastern Pacific Ocean , Clarion-Clipperton Fracture Zone, APEI#3 , station 192, collected 21 April 2015, epibenthic sledge epi-net, start 18°44.807′N, 128°21.874′W, end 18°45.338′N, 128°20.418′W, 4821– 4820 m depth, 2799 m trawling distance. Specimen 3, MNHN-IA-PNT 68 ( IFR658-2 ), incomplete, length 3.84 mm, width 0.80 mm, ten segments (including tentacular segment), Equatorial Eastern Pacific Ocean , Clarion-Clipperton Fracture Zone, APEI#3 , station 192, collected 21 April 2015, epibenthic sledge epi-net, start 18°44.807′N, 128°21.874′W, end 18°45.338′N, 128°20.418′W, 4821– 4820 m depth, 2799 m trawling distance. Specimen 4, MNHN-IA-PNT 69 ( IFR624 ), incomplete, length 0.43 mm, width 0.74 mm, not possible to count the number of segments, Equatorial Eastern Pacific Ocean, Clarion-Clipperton Fracture Zone, APEI#3 , station 210, collected 24 April 2015, epibenthic sledge supranet, start 18°49.271′N, 128°25.804′W, end 18°49.926′N, 128°24.401′W, 4700–4740 m depth, 3399 m trawling distance. Specimen 5, MNHN-IA-PNT 70 ( IFR625 ), complete, length 0.38 mm, width 0.75 mm, not possible to count the number of segments, Equatorial Eastern Pacific Ocean, Clarion-Clipperton Fracture Zone, APEI#3 , station 210, collected 24 April 2015, epibenthic sledge supra-net, start 18°49.271′N, 128°25.804′W, end 18°49.926′N, 128°24.401′W, 4700–4740 m depth, 3399 m trawling distance .

Description (based on all specimens): Fragile worms, all damaged; parapodia, prostomial and parapodial appendages often missing. Body dorsoventrally cylindrical; live specimen with body surface translucent to milky, prostomium whitish, pharynx red; ethanol-preserved specimens with body surface pale white, prostomium white, pharynx internally red, longitudinal ventral whitish line ( Fig. 10B).

Prostomium bilobed, wider than long, lobes slightly pronounced, anteriorly rounded; frontal filaments absent; median notch between prostomial lobes moderately wide and deep ( Fig. 10B); eyes absent. Median antenna present, lateral antennae absent; ceratophore of median antenna small (not surpassing anterior end of prostomial lobes), inserted near median notch, style missing. Palps missing.

Tentacular segment fused to prostomium, with a pair of short lobes, inserted laterally and slightly below prostomium; tentaculophores distinct, small; dorsal tentacular style very short (reaching segment 2), smooth, tapering. Pharynx everted, with seven pairs of distal subtriangular papillae, equal sized ( Fig. 10B); two pairs of jaws, each one with one main fang, outer margin with a secondary very small tooth (pointed or blunt; Fig. 10D). Lips of mouth in a bulbous projection when pharynx not everted.

Probably eight knob-like elytrophores present (all elytra missing).

Cirrigerous segments with distinct, cylindrical dorsal cirrophores ( Fig. 10C); elongated, and anteriorly directed on segment 3, not seen in subsequent segments; styles missing; dorsal tubercles absent.

Ventral cirri smooth, tapering; inserted basally on neuropodia of segment 2, style short (much shorter than tip of neuroacicular lobe); in subsequent segments inserted subdistally on neuropodia, styles short (approaching tip of neuroacicular lobe).

Parapodia subbiramous; notopodia shorter than neuropodia ( Fig. 10C). Notopodia tapering into long acicular lobe, tip of notoacicula not penetrating epidermis. Neuropodia rectangular, tapering into long acicular lobe, tip of neuroacicula not penetrating epidermis.

Notochaetae flattened, short, few (two observed), with spines on convex side, smooth on straight side, with pointed tips. Neurochaetae long, slender, distally flattened, serrated along both margins, with pointed tips ( Fig. 10F).

Nephridial papillae not seen. Anal cirri lost, scars not seen. Ventral keel present on last segments.

Remarks: See Remarks on Bathypolaria sp. 173 for more details.

Genetic data: DNA sequencing for this species was successful for COI, 16S and 18S, respectively sharing at least 99.6, 99.5 and 99.9% of genetic material between the specimens.The average K2P distance for intraspecific variation was 0.2% for COI and 0.1% for 16S.

Distribution: Based on the material examined (five specimens), this species has a restricted distribution within the Clarion-Clipperton Fracture Zone, being sampled at two stations in APEI#3 area.