Flabegraviera mundata ( Gravier, 1906 )

Jimi, Naoto, Tsujimoto, Megumu, Watanabe, Kentaro, Kakui, Keiichi & Kajihara, Hiroshi, 2017, A new species and the shallowest record of Flabegraviera Salazar-Vallejo, 2012 (Annelida: Flabelligeridae) from Antarctica, Zootaxa 4221 (4), pp. 477-485 : 481

Flabegraviera mundata ( Gravier, 1906)

Flabelligera mundata Gravier, 1906 , 537–538; Gravier 1907, 37–39, Pl. 4, Figs 31–32, Text figs 22–23; Gravier 1911, 110– 112, Pl. 8, Fig. 87; Benham 1921, 108–109; Monro 1939, 130; Hartman 1952, 233; Hartman 1953, 50; Hartman 1966, 37– 39, Pl. 11, Figs 1–4 ; Hartman 1967, 124; Hartman 1978, 170; Rozbaczylo 1985, 159; Hartmann-Schröder & Rosenfeldt 1989, 72; Knox & Cameron 1998, 72, Figs 137–139.

Flabegraviera mundata: Salazar-Vallejo 2012 , 43–44, Fig. 18.

(New Japanese name: Kibukure-habouki)

( Figs 3–4 )

Material examined. Nontype specimen. NSMT-Pol- 113161. Complete (some chaetae broken, dissected), sex undetermined, non-reproductive adult, Nishinoura (69°00.4´S, 39°34.5´E), 8 m depth, sandy mud, 16 Jan., 1981.

Description. Nontype (NSMT-Pol- 113161) 6.0 cm long, 1.1 cm wide, fusiform, covered by very thick tunic ( Fig. 3 A). Tunic transparent, gel-like, covering whole body and posterior portion of cephalic cage; sediment grains not attached. Body papillated; papillae long, clavate, forming sheath around base of chaetae. Lobe on dorsum of chaetiger 1 absent. Dorsal and ventral surface irregular.

Prostomium low cone. Branchiae 5–7 rows, about 120 filaments per side, 3 mm long, decreasing in size ventrally, colorless in ethanol. Branchial plate crescent-like, bisected by well-developed caruncle. Palps long (8 mm), cylindrical, grooved, pink in ethanol. Four black eyes present. Lateral and dorsal lips well developed, ventral lip reduced. Nephridial lobes present.

Chaetigers 30 in number; chaetiger 1 comprising cephalic cage. Cephalic cage 0.7 cm long, exposed for anterior 0.2–0.3 cm ( Fig. 3 B), about 1/10 body length (6/10 body width), comprising 36 notochaetae and 30 neurochaetae per side. Chaetal transition from cephalic cage to body abrupt.

Parapodia poorly developed, completely covered by tunic; notopodia and neuropodia widely separated. Gonopodial lobe absent.

Chaetal arrangement from chaetiger 1 (using “u” for upper, “m” for middle, and “l” for lower (cf. Salazar- Vallejo 2012)): ululumluml.... Notochaetae of single type, multiarticulated, 1.1–2.6 cm long, sickle-like, 4–6 per fascicle. Neurohooks in chaetigers 2–30 ( Fig. 4 A), 3 per fascicle, multiarticulated, 0.6–1.1 cm long, dark orange, covered by cylindrical shaft; handle anchylosed basally and distally, articulated in between, with 17 articles, progressively longer towards distal end ( Fig. 4 B); crest distinct, width: length = 1: 7.

Posterior end not exposed; pygidium simple; no anal cirri; anus without pigment.

Remarks. The syntype specimens of Flabegraviera mundata ( Gravier, 1906) were collected from 40 m and other specimens from a 20–385 m depth range ( Salazar-Vallejo 2012). Our specimen was collected from 8 m depth, making it the shallowest record of the species. The finding of this species and also F. fujiae sp. nov. in shallow water means good opportunities for future research on adaptation of annelids to extreme environments, since the locality can be sampled using SCUBA.

Figures

FIGURE 1. Flabegraviera fujiae sp. nov., holotype, NSMT-Pol-H- 609. A, Entire body, body twisted, anterior region in lateral view, posterior region in ventral view; head upper side; B, Head, frontal view; left half of branchial plate has been partly removed; branchiae and palps have been removed (BP, branchial plate; Ca, caruncle; LL, lateral lip; PS, palp scar); C, Posterior end, ventral view; arrow indicates ventral anal margin. Scale bars = 10 mm (A); 1 mm (B, C).

FIGURE 2. Micrographs of chaetae in Flabegraviera fujiae sp. nov., holotype, NSMT-Pol-H- 609. A, Chaetiger 29, tip of notochaeta; B, Same, base of notochaeta; black arrows indicate type 2 notochaetae; C, Chaetiger 6, tip of smaller neurohook; D, Chaetiger 27, tip of neurohook. Scale bars = 50 µm (A); 200 µm (B); 100 µm (C, D).

FIGURE 3. Flabegraviera mundata (Gravier, 1906), NSMT-Pol- 113161. A, Entire body, lateral view; B, Same, anterior end, ventral view; tunic has been removed on left side. Scale bars = 10 mm (A); 5 mm (B).

FIGURE 4. Micrographs of chaetae in Flabegraviera mundata (Gravier, 1906), NSMT-Pol- 113161. A, Chaetiger 27, distal region of neurohook; B, Same, middle area of neurohook, right top is distal side. Scale bars = 200 µm.