Cirrophorus furcatus

Cirrophorus furcatus (Hartman, 1957)

(Fig. 4)

Aricidea (Cirrophorus) furcata Hartman, 1957: 324 –325, pl. 43, fig. 6.

Cirrophorus furcatus.— Hartman 1969: 68 –69, fig. 1; Strelzov 1973: 118 –120, fig. 50A–E; Katzmann & Laubier 1975: 584 – 586, fig. 6; Hartley 1981: 145; Blake 1996: 40, fig. 2.5.

Material examined. 3940 Arenaria A1–04; 72.6234°N–24.9163°E; 264 m; 24.6.2007; one specimen. 3940 Snøhvit SD–09; 71.5960°N–21.2675°E; 340 m; 20.06.2007 D9–5; one specimen. 4664 Ormen Lange OL–18; 63.3778°N–5.3299°E; 815 m; 17.06.2009 18–1; three specimens. 5000 Regional IX Reg.9–01; 71.6395°N– 25.0941°E; 278 m; 25.05.2010; two specimens.

Description. All specimens incomplete, largest one 14.5 mm long, 0.8 mm wide for 60 chaetigers. Body dorsoventrally flattened, more conspicuously in branchial region; characteristically rusty brown pigmented. Prostomium conical, two and a half times as long as wide (Fig. 4A); median antenna lanceolate, short, not reaching posterior margin of prostomium (Fig. 4A); apical sensory organ absent; pair of nuchal organs as deep, oblique nuchal slits (Fig. 4A). Posterior buccal lip as four folds extending through chaetiger 1. First two notopodial postchaetal lobes short and triangular (Fig. 4A); on chaetiger 3 and in branchial region, progressively longer, digitiform, distally acute, up to five times as long as wide (Fig. 4A, B); on postbranchial region, much shorter, slender and tapering point (Fig. 4C). Branchiae from chaetiger 4, 17–19 pairs, not ciliated, cirriform and long, up to six times as long as wide, tapering to a thin tip on posterior branchial chaetigers (Fig. 4A, B). Noto- and neurochaetae as geniculate bilimbated capillaries in prebranchial and branchial regions (Fig. 4A); in postbranchial region as thin, straight capillaries, clearly less numerous (Fig. 4C); from chaetiger 4–8, with 1–3 forked notopodial chaetae with tines similar in thickness but slightly differing in length, with inner edges bearing long and dense spinulation (Fig. 4D); modified neurochaetae absent.

Remarks. Within the genus, only C. furcatus (Hartman, 1957) and C. americanus Strelzov, 1973 possess forked modified notochaetae in combination with digitiform notopodial postchaetal lobes in branchial chaetigers and with more than 15 pairs of branchiae, thus both species are very similar (Strelzov 1973). However, the author states that in the latter species the notopodial postachetal lobes are long and digitiform in postbranchial chaetigers, whereas in C. furcatus they become shorter. This difference was useful to refer our specimens to C. furcatus. Cirrophorus furcatus also has fewer branchiae (up to 33 pairs instead of up to 45) (Strelzov, 1973; Katzmann & Laubier 1975; Blake 1996). This feature was also present in our specimens, which bear 16–21 pairs of branchiae.

Distribution. California (Hartman 1957, 1969). Western Atlantic, off New England (Strelzov 1973). Eastern Atlantic, from Celtic Sea (Hartley 1981) to Portugal (Gil & Sardà 1999). Mediterranean (Katzmann & Laubier 1975). First record for Norway and adjacent waters.