Hodor, 2019

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 : 600-602

HODOR ANDURIL GEN. NOV., SP. NOV.

( FIG. 13A–G; TABLES 1, 2)

Type material: Holotype, MNHN-IA-TYPE 1826 ( IFR655-2 - 3 ), complete, length 8.82 mm, width 1.50 mm, 23 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 . Paratype, MNHN-IA-TYPE 1827 ( IFR655-2 - 2 ), complete, length 6.03 mm, width 0.73 mm, 23 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 .

Description (based on holotype): Holotype complete, 8.82 mm long and 1.50 mm wide for 23 segments (including tentacular segment), dorsoventrally flattened, posteriorly tapering; colour of live animal not known; ethanol-preserved specimen pale white.

Prostomium bilobed, about as long as wide, lobes subtriangular, poorly developed, anteriorly tapering into blunt peaks, extending until superior lip; frontal filaments absent; median notch between prostomial lobes narrow and shallow ( Fig. 13A); eyes absent; a pair of internal white ganglia visible through translucent epidermis, dorsolaterally located on prostomium. Median and lateral antennae absent. Palps smooth, tapering, very short (reaching segment 2), inserted on large, rounded palpophores ( Fig. 13A). Facial tubercle absent.

Tentacular segment well developed, with a pair of short lobes, inserted laterally and slightly below prostomium; without acicula or chaetae; tentaculophores large, bulbous, equal sized ( Fig. 13A); tentacular styles missing. Second segment with elytrophores, subbiramous parapodia, chaetae and ventral cirri. Pharynx dissected, with seven pairs of subtriangular distal papillae, abruptly tapering, increasing in length gradually towards middle, with middle pair longest; two pairs of jaws with main fang, serrated margin (one pair of jaws with 15–16 teeth and the other with ten or 11 teeth; Fig. 13B).

Nine pairs of large, globular to cylindrical elytrophores ( Fig. 13A) present on segments 2, 4, 5, 7, 9, 11, 13, 15 and 17 (all elytra missing); with dorsal cirrophores on last segments.

Cirrigerous segments with large, bulbous dorsal cirrophores ( Fig. 13C), inserted subdistally on notopodia; styles smooth, thin, long (longer than tip of neuroacicula lobe).

Segments 6 and 8 with large, swollen dorsal structure ( Fig. 13C), located basally to cirrophores, interiorly whitish; similar in size. Dorsal tubercles absent.

Ventral cirri smooth, tapering, present from segment 2 to last segment; inserted basally on neuropodia of segment 2, style missing; in subsequent segments inserted medially on neuropodia ( Fig. 13C), style short (shorter than tip of neuroacicular lobe).

Parapodia subbiramous; notopodia reduced, much shorter than neuropodia ( Fig. 13C). Notopodia arising from the dorsum as two thickened ridges; narrow, subtriangular, tapering into long acicular lobe, tip of notoacicula not penetrating epidermis. Neuropodia large, rectangular to subtriangular, tapering into long acicular lobe, tip of neuroacicula not penetrating epidermis. Notochaetae variable in number (one to 13 observed), long, slender, slightly curved with distinct, faint spinous rows on convex side, with blunt tips preceded by smooth margin ( Fig. 13D); notochaetae more slender than neurochaetae. Neurochaetae of two types: (1) moderate in number (13–21 observed), long, distally flattened to concave, serrated along both margins, with pointed tips ( Fig. 13E); and (2) middle and lower group on segments 3–7 modified, moderate in number (16 observed), stouter, short to long, distally flattened to concave, with coarse spines along both margins, spines concentrated basally and well spaced later, middle part with smooth margins (most of or less of their length), subdistally smooth or with one or two spines, blunt tips, tip margin slightly lighter ( Fig. 13F, G).

Nephridial papillae present on segments 11, 12 and 13, small, globular. Last segment very reduced. Pygidium rounded, not enclosed by last segment; with terminal anus. Anal cirri lost, scars not seen.

Morphological variation: Holotype and paratype agree in many characters (e.g. number of segments, prostomium and parapodial shape, and form of chaetae) and their DNA (see Genetic data) but they show two important differences. In the holotype, the palps are very short (reaching segment 2), the segments 6 and 8 have swollen dorsal structure, and the nephridial papillae are present on segments 11–13, whereas in the paratype the palps are very long (reaching segment 11), the swollen dorsal structure is absent on segments 6 and 8, and the nephridial papillae are present on segments 10–13. These differences might be linked to sexual dimorphism.

R e m a r k s: D i f f e r e n c e s i n t h e f i r s t s e g m e n t with nephridial papillae have been observed in Branchipolynoe seepensis ( Jollivet et al., 2000) . They suggested that male specimens present one pair of nephridial papillae on segment 11, whereas female specimens present two pairs on segments 10 and 11. Thus, we believe that the differences observed between the holotype and paratype of Hodor anduril gen. nov., sp. nov. are linked to sexual dimorphism. In view of the morphological variation observed in this species, more attention needs to be paid to this genus. The long palps in the paratype resemble those of Hodor hodor gen. nov., sp. nov., but the first segment with nephridial papillae is different. In Hodor anduril gen. nov., sp. nov., nephridial papillae start on segment 10, whereas in Hodor hodor gen. nov., sp. nov. nephridial papillae start on segment 11. Furthermore, the presence of a swollen structure on anterior segments seems to indicate a reproductive feature, which is perhaps temporary.

Etymology: The species name is derived from the sword named ‘andúril’ meaning ‘Flame of the West’ and belonging to Aragorn in the novel ‘ The lord of the rings ’ by J. R. R. Tolkien. It refers to the sword-like modified neurochaetae present in this species.

Genetic data: DNA sequencing for this species was successful for COI, 16S and 18S. Holotype and paratype shared 100% of genetic material in COI, 16S and 18S. The average K2P distance for intraspecific variation was 0.0% for both COI and 16S.

Distribution: Only two specimens were sampled and both at a single station within the Clarion-Clipperton Fracture Zone in APEI#3 area (type locality).