Eunoe nodosa M. Sars 1861

Eunoe nodosa (M. Sars, 1861)

(Fig. 2 A–K)

Polynoe nodosa M. Sars, 1861: 58.

Eunoe nodosa: Pettibone (1954): 217, fig. 26c; Uschakov (1955 Russ./1965 Engl.): 152/128, figs. 34F–G, 35A–B; Uschakov (1982): 176, pl. 65 figs. 6–7.

Harmothoe (Eunoe) nodosa: Pettibone (1963): 44, fig. 9a–c.

(for further synonymy see Pettibone 1954).

Type material. Polynoe nodosa: 1 syntype (cs in 2 fragments, elytra all free in vial), ZMO C5244, NE Atlantic, N Norway, Vadsø, Varangerfjord, 30–50 fathoms. Syntype (s) (several elytra mounted on needles), ZMO C5243, NE Atlantic, N Norway, Havøsund, near Nordcap.

Additional material. 1 spm. (af), SMF 17442, "Johan Ruud" 2006, St. 477 ES, NE Atlantic, N Norway, Varangerfjord, NE Korsnes, 69°55.85' N, 30°30.02' E, 10 May 2006, epibenthic sledge, 408 m, leg. & ded. C. d'Udekem d'Acoz. 1 spm., SMF 17445, "Johan Ruud" 2006, St. 482, NE Atlantic, N Norway, Varangerfjord, 69°52.36' N, 30°08.09' E, 10 May 2006, epibenthic sledge, 251 m, leg. & ded. C. d'Udekem d'Acoz. 5 spms., SMF 17475, 17524, 17526; " Jan Mayen " St. 195, 78 °54.2’N 22°12.2’E, Arctic Ocean, Svalbard, Hinlopen, 23 September 2003, Agassiz trawl, 139 m, leg. & ded. C. d'Udekem d'Acoz. 3 spms., SMF 17518, " Jan Mayen " St. 196, 78 °52.2’N 22°13.4’E, Arctic Ocean, Svalbard, Hinlopen, 23 September 2003, Sneli sledge, 120 m, leg. & ded. C. d'Udekem d'Acoz. 1 spm. (af), SMF 17494, "Johan Ruud" 2004 St. 284, 68 °00’N 16°13’E, NE Atlantic, N Norway, Hellemofjorden Styrneset, 0 5 May 2004, Agassiz trawl, 380 m, leg. & ded. C. d'Udekem d'Acoz. 1 spm. (af), SMF 17497, "Johan Ruud" 2004 St. 294, 68 °76’N 16°11’E, NE Atlantic, N Norway, Tysfjord Bekkenesholmen, 0 6 May 2004, RP-sledge, 182 m, leg. & ded. C. d'Udekem d'Acoz. 1 spm., SMF 17914, "Johan Ruud" 2005 St. 285, 70 °18.21’N 22°16.71’E, NE Atlantic, N Norway, Stjernsund Øksfjordklubbe, 11 April 2005, dive, 20 m, leg. & ded. C. d'Udekem d'Acoz. 2 spms., SMF 18842-18843, St. NUN-118; Arctic Ocean, Canada, Nunavut region, Devon Island, Thomas Lee Inlet; 75°42.42'N 88°17.16'W, dive, 11 August 2001, leg. J. DeWaard, ded. C. Carr. 1 spm., SMF 18859, St. NUN-262; Arctic Ocean, Canada, Nunavut region, Resolute Bay; 74° 41.084'N 94°51.42'W, 1 August 1999, leg. M. Pasquali, ded. C. Carr.

Diagnosis. Elytra at outer lateral margin with long, at posterior margin with more scattered, short papillae; microtubercles usually low, semi-globose, distally with nodular papillae; macrotubercles in a row near posterior margin, usually conical to cylindrical, distally with nodular papillae.

Description (based on syntype ZMO C5244). Body with 36 segments. At anterior end (Fig. 2 A), prostomium bilobed, with rather inconspicuous cephalic peaks; ceratophore of median antenna in anterior notch, style missing; lateral antennae inserted ventrally, styles papillate, tapering; anterior pair of eyes situated dorsolaterally at widest part of prostomium, posterior pair dorsally near hind margin of prostomium; palps distinctly papillate, tapering.

Tentaculophores inserted laterally to prostomium, each with two notochaetae and a dorsal and ventral tentacular cirrus, styles of cirri papillate, tapering. Second segment with first pair of elytra, biramous parapodia, and long buccal cirri. Following segments with short, tapering, slightly papillate ventral cirri.

Fifteen pairs of elytra, covering dorsum, on segments 2, 4, 5, 7, then on every second segment to 23, 26, 29, 32; last four segments cirrigerous; elytra at outer lateral margin with long, at posterior margin with more scattered, short papillae; microtubercles usually low, semi-globose, distally with nodular papillae; macrotubercles in a row near posterior margin, usually conical to cylindrical, distally with nodular papillae; at outer lateral margin few micro- and macrotubercles distally with spiny papillae; tubercles on first elytra also distally spiny (Fig. 2 B–D). Cirrigerous segments with distinct dorsal tubercles; dorsal cirri with cylindrical cirrophore, style papillate, tapering.

Parapodia biramous; notopodia with elongate acicular lobe; neuropodia with elongate prechaetal acicular lobe with short, digitiform supra-acicular process; neuropodial postchaetal lobe shorter than prechaetal lobe, rounded; tips of noto- and neuroacicula penetrating epidermis (Fig. 2 E). Notochaetae stouter than neurochaetae, with distinct rows of spines and blunt tip (Fig. 2 F,G); neurochaetae all unidentate with distinct rows of spines, leaving rather long bare part distally, tip slightly falcate (Fig. 2 H–K).

Measurements. Syntype (ZMO C5244): cs in two fragments, L 21 mm, W 7 mm (excl. chaetae) for 36 segments (Fig. 2 A–K).

Especially in Arctic waters specimens of Eunoe nodosa are known to get very large. According to D. Eibye-Jacobsen (pers. comm.) one of the largest specimens found reached a length of 47 mm and a width of 21.6 mm (excl. chaetae). In Pettibone (1963) the maximum size given for the species is even more impressive: up to 90 mm long and 39 mm wide (incl. chaetae) for up to 37 segments.

Remarks. Eunoe nodosa might be confused with Harmothoe globifera, but in E. nodosa the neurochaetae are exclusively unidentate versus uni- and bidentate in H. globifera and the elytral tubercles are papillate only distally in the former versus completely covered by papillae in the latter (Figs. 1, 2; see also remarks related to H. globifera).

Distribution and habitat. Arctic Ocean, North Atlantic and North Pacific; from shallow waters to 1250 m (see Pettibone 1963).