Phylo norvegicus

Phylo norvegicus (M. Sars in G.O. Sars, 1872)

Figures 41–42

Aricia norvegica M. Sars in G.O. Sars, 1872: 408; 1873: 236, p. 16, figs. 1–8; McIntosh 1910: 506; Fauvel 1927: 17, fig. 75. Phylo norvegica: Støp-Bowitz 1948: 66.

Phylo norvegicus: Hartman 1957: 261–262; 1959: 367; 1965: 130–131.

Orbinia (Phylo) norvegica: Pettibone 1963: 281–282, fig. 75c; Hartmann-Schr̂der 1974: 224; 1996: 295–296, fig. 131. Orbinia sp. 1: Blake et al. 1987: C-4; Maciolek et al. 1987b: D-3; Hilbig 1994: 942.

Material examined. (15 specimens) Off New England, US North Atlantic ACSAR program, coll. G.W. Hampson, Chief Scientist. Sta. 2: Cruise NA-2, Rep. 2, 25 Apr 1985, 40°57.16′N, 66°13.70′W, 2100 m (1, USNM 1622314). Sta. 3: Cruise NA-1, Rep. 3, 09 Nov 1984, 41°01.41′N, 66°20.22′W, 1338 m (1, USNM 1622315). Sta. 15: Cruise NA-2, Rep. 1, 05 May 1985, 39°40.08′N, 70°54.26′W, 2150 m (1, USNM 1622316).— Southeastern USA, U.S. South Atlantic ACSAR program, coll. J.A. Blake, Chief Scientist. Off Cape Hatteras, North Carolina, Sta. 10: Cruise SA-4, Rep. 2, 24 May 1985, 35°26.34′N, 74°41.57′W, 1988 m (2, USNM 1622317). Hatteras Canyon, Sta. 6: Cruise SA-1, Rep. 4, 19 Nov 1983; 34°48.87′N, 75°15.94′W, 1950 m (1, USNM 1622318). Off Cape Lookout, North Carolina, Sta. 1: Cruise SA-2, Rep. 2, 26 Mar 1984, 34°15.81′N, 74°46.012′W, 583 m (1, USNM 1622319); Rep. 3, 27 Mar 1984, 34°156.81′N, 75°45.78′W, 593 m (1 juv., USNM 1622320); Cruise SA-3, Rep. 2, 15 Jun 1984, 34°15.20′N, 75°45.60′W, 599 m (1, USNM 1622321). Sta. 2: Cruise SA-2, Rep. 2, 27 Mar 1984, 34°14.46′N, 75°43.85′W, 1019 m (1, USNM 1622322). Sta. 4: Cruise SA-1, Epibenthic sled tow No. 1, 17 Nov 1983, 34°13.06′N, 75°39.04′W to 34°13.46′N, 78°37.68, 1910–2050 m (1, USNM 1622323). Off Cape Fear, North Carolina, Sta. 11: Cruise SA-5, Rep. 1, 23 Sep. 1985, 33°04.83′N, 76°25.17′W, 896 m (1, USNM 1622324). Off Charleston, South Carolina, Sta. 14: Cruise SA-5, Rep. 2, 19 Sep 1985, 32°23.73′N, 77°01.24′W, 799 m (1, USNM 1622325). Sta. 15: Cruise SA-5, Rep. 2, 18 Sep 1985, 32°11.94′N, 76°42.23′W, 1991 m (1, USNM 1622326).

Description. A large species, with 75 setigers and a length of 58 mm for an incomplete specimen (Hartmann- Schr̂der 1996). Present collection with all specimens incomplete; longest nearly complete (USNM 1622324) with 120 setigers, 55 mm long, 1.5 mm wide across thorax; a large anterior fragment (USNM 1622317) with 53 setigers, 24 mm long, 3 mm wide across thorax (Fig. 42A). Body elongate, with all segments short (Fig. 42A); thoracic segments about 10 times wider than long, flattened dorsally (Fig. 41 A–B), rounded ventrally; abdominal segments

strongly rounded on venter, flattened dorsally due to parapodial shift dorsally. No dorsal or ventral grooves along body. Branchiae from setiger 6 (Fig. 41A). Present specimens light tan in alcohol with no other pigmentation.

Pre-setiger region short, wider than long; as long as first two setigers dorsally (Fig. 41A) but extending ventrally over setiger 1 due to nature of oral lips (Figs. 41B, 42B). Prostomium short, conical, tapering to rounded tip, with no obvious separation from peristomium (Figs. 41 A–B, 42A–B); eyespots absent; nuchal organs narrow slits on posterior lateral margin, difficult to observe. Peristomium a single ring, triangular-shaped dorsally, distinctly separated from setiger 1 (Fig. 41A); ventrally forming large lateral swellings around mouth (Figs. 41B, 42 B); mouth with conical posterior oral lip arising from anterior margin of setiger 2 (Figs. 41B, 42B); anterior oral lips not developed, instead anterior margin of mouth a shallow vestibule (Fig. 41B). Proboscis observed partially everted as 1–3 narrow lobes within mouth; fully everted proboscis with 2–3 large, inflated lobes.

Thorax with 14–16 setigers and usually one transitional setiger. Thorax divided into anterior and posterior sections: anterior thorax with 1–12 setigers (Figs. 41A, 42A); posterior thorax with large spines beginning on setiger 13 continuing over setigers 14, 15 or 16 depending on specimen. Thoracic notopodia digitate, short at first (Fig. 41A, C), becoming long and narrow in middle and posterior thoracic setigers (Fig. 41A). Abdominal notopodia elongate digitiform lobes thickened basally, tapering to conical tip (Fig. 41D). Thoracic neuropodia thick, elongate, bearing six rows of uncini and capillaries. In largest specimens, setiger 1 with a single postsetal lobe, increasing to two lobes on setiger 2, four lobes on setiger 4, seven lobes on setigers 5–7, and nine lobes on setigers 11–12, thereafter decreasing in number with eight on setiger 13, five on setiger 15 and two on setiger 16. All neuropodial postsetal lobes short, stubby with a rounded tip (Figs. 41C, 42C). All postsetal lobes arranged in a row posterior to setae (Fig. 41C). Subpodial lobes or stomach papillae absent on thoracic and abdominal segments. Abdominal neuropodia elevated, divided apically into a rounded inner lobe and a pointed or digitiform lateral lobe (Figs. 41D, 42F). First 1–2 abdominal segments with 2–3 extra lobes or ventral cirri ventral to neuropodium; these reduced to a single cirrus in all subsequent abdominal neuropodia. Interramal cirri absent.

Branchiae from setiger 6 (Fig. 41A), one specimen (USNM 1622317) with a single small branchia on left side of setiger 5 and none on the right side. Branchiae near notopodia in both thoracic and abdominal segments. Each branchia triangular in shape with conical tip (Figs. 41C, 42C); some abdominal branchiae asymmetrical; all heavily ciliated (Figs. 41D).

Thoracic notosetae all crenulated capillaries in dense fascicle of 100 or more setae. Abdominal notosetae about 25 capillaries and 1–2 furcate setae initially, with numbers of capillaries reduced in 5–20 in middle and posterior setigers. Furcate setae with unequal tynes with rounded tips; each tyne with fine needles directed medially; shaft appearing smooth in light microscope (Fig. 41F). Thoracic neurosetae of setigers 1–12 numerous narrow spines in at least two anterior rows and four or more additional rows of long camerated capillaries (Fig. 41E); first row of spines continuing ventrally, then curving dorsally about one-third of distance up posterior side of neuropodium; these ventral spines longer and thicker than those of anterior rows; each spine tapering to a narrow pointed tip covered with a sheath extending well beyond tip of spine (Fig. 41E); shaft with transverse rows of minute ribs or barbs. From setiger 13, 4–5 large dark hastate or spear-like spines appearing in anterior row of neuropodia (Fig. 42E) with capillaries and sheathed spines still present but reduced in number. Most hastate spines imbedded with only spearlike point protruding; however, uppermost spine usually fully protruded (Fig. 42 D–E). Imbedded oval-shaped gland (“glandular pouch” of Hartman 1957) present on posterior thoracic neuropodia, gland with distinct swollen aperture on surface in close proximity to uppermost hastate spine. Abdominal neurosetae consisting of 12–15 long capillaries, reduced to 4–5 capillaries in middle and posterior setigers; flail setae not observed; 1–2 minute imbedded aciculae also present, usually not emergent.

Pygidium not observed.

Remarks. Phylo norvegicus is most similar to P. nudus (Moore, 1911), a Pacific species, in lacking a ventral fringe of subpodial papillae or stomach papillae. The two species differ in that P. nudus has branchiae from setiger 5, an anterior thoracic region of setigers 1–11 and a posterior thoracic region of setigers 12–15, whereas P. norvegicus has branchiae consistently from setiger 6, an anterior thoracic region of setigers 1–12, and a posterior region of setigers 13–16. Further, the posterior modified spines of posterior thoracic setigers are distinctly hastate or spear-like in P. norvegicus, whereas the posterior spines of P. nudus, while expanded apically, are not hastate or spear-shaped.

Distribution. Northeastern Atlantic, North Sea, subtidal; Western North Atlantic, off New England to the Carolinas, continental slope, 583–2150 m.