Flabelligera pergamentacea Ehlers 1913

Flabelligera pergamentacea Ehlers, 1913

Figure 11

Flabelligera pergamentacea Ehlers 1913:533–534, Pl. 40, Figs. 1–6; Günther 1912:13; Hartman 1966:39–41, Pl. 11, Figs. 7–9; Hartwich 1993:127.

Type material. Antarctic Ocean. Antarctica. Syntypes of Flabelligera pergamentacea, all dried-out [ZMB-6774 (1 syntype), ZMB-5887 (many smaller syntypes)], off Kaiser-Wilhelm Land, Deutsche Tiefsee Expedition, R /V Valdivia, 14 Apr. 1902, 385 m, 17 Dec. 1902, Brutnetz, 385 m, Twist, 12 Jan. 1903, 380 m, 24 Jan. 1903, 380 m, 31 Jan. 1903, 380 m, 8 Feb. 1903, 350 m.

Additional material. Antarctica. One specimen (ZMH-8592), dried-out, German South Pole Expedition 1901–1903, Wilhelm II Land, 31 Jan. 1903, 389 m. One specimen (ZIRAS-16343; used for description), near Cape Möbius, Davis Sea, Antarctica, XI Soviet Antarctic Expedition, R / V Ob, Station G, 43 m, rock, 28 Jan. 1966, Pushkin, diver, coll.

Description. Non-type specimen (ZIRAS-16343), complete, white, truncate anteriorly, swollen medially, tapering posteriorly, with some parapodia previously removed (Fig. 11A); 21 mm long, 5 mm wide, cephalic cage 2 mm long, 26 chaetigers. Tunic thick, smooth, especially in swollen region, very pleated towards anterior (Fig. 11B–D) and posterior ends, without abundant sediment, but containing thin layer of very fine particles (Fig. 11E) making it shiny. Papillae very long, subdistally swollen, mucronate (most lost), forming well-defined noto- and neurochaetal lobes, without exposing individual papillae, unless eroded.

Cephalic hood not exposed. Prostomium low cone; four dark eyes, anterior ones larger. Caruncle well developed, separating branchiae into two lateral groups (other details not observed to avoid further damage). Palps thick, pale, about as long as branchiae. Lateral lips well developed; ventral and dorsal lips not seen (to avoid further damage to the specimen).

Branchiae in two lateral groups, each with branchiae arranged in rows, each group with about 40 filaments. Nephridial lobes not examined to avoid further damage.

Cephalic cage chaetae as long as 2/5 body width. Chaetiger 1 involved in the cephalic cage, about 26 noto- and about 30 neurochaetae per side. Anterior dorsal margin of chaetiger 1 papillated. Chaetigers 1–3 decreasing in size posteriorly. Chaetal transition from cephalic cage to body chaetae abrupt; chaetiger 2 with multiarticulated neurohooks. Gonopodial lobes not seen.

Parapodia well developed, lateral. Median neuropodia ventrolateral. Notopodial lobes low, foliose, covered by flat lobe, completely covering notochaetae, made by long, subdistally swollen, clavate papillae, many notopodial lobes entire, not eroded. Neuropodial lobes conical, covered by a similar chaetal lobe, but not covering entire neurohook, made of similar papillae. Noto- and neuropodia widely separated.

Median notochaetae arranged in short, transverse rows; all notochaetae multiarticulated capillaries, as long as 1/3 body width, nine per fascicle, basal articles poorly defined, medial- and distally with long articles, slightly longer distally. Neurochaetae multiarticulated capillaries in chaetiger 1; single multiarticulated neurohooks from chaetiger 2 (Fig. 11F). Handle articulation medially placed, articles of about the same length; two articles, long. Other articles anchylosed, small, continued to bending region. Crest slightly wider than handle, dark brown along body, pigmentation extending towards base; width:length ratio 1:5–6.

Posterior end tapered, markedly contracted; pygidium with anus terminal, short, muscular ring; no anal cirri.

Remarks. Flabelligera pergamentacea (Ehlers, 1913) n. comb. resembles F. vaginifera (Rathke, 1843) n. comb. because both have opaque tunics with sediment particles. They differ because in F. pergamentacea the tunic is smooth, the sediment particles do not form any pattern and the neurohook crests are slightly longer (width:length ratio 1:5–6), whereas in F. vaginifera the tunic is rough with sediment particles forming areoles and neurohook crests are slightly shorter (width:length ratio 1:4–5).

Distribution. Antarctic Ocean, in shallow to deep water (43–389 m).