Nephtys longosetosa Örsted, 1842

Ravara, Ascensão, Cunha, Marina R. & Pleijel, Fredrik, 2010, Nephtyidae (Annelida, Polychaeta) from southern Europe 2682, Zootaxa 2682 (1), pp. 1-68 : 57-58

Nephtys longosetosa Örsted, 1842

Figure 13 , 22

Nephthys longosetosa Örsted, 1842: 123 ; Örsted 1843b: 195, pl. VI, figs. 75 and 76; Saint-Joseph 1894: 20, pl. I, fig. 19; Fauvel 1923: 367, fig. 143f–h; Ditlevsen 1937: 20; Uschakov 1955: 219, fig. 68C–E; Southward 1956: 264.

Nephthys longisetosa [misspelling of longosetosa ] Johnston 1865: 172, fig. 5 (partim); not Malmgren 1865: 106, tab. XII, fig. 20; Verrill 1881: 295, 319; Michaelsen 1896: 24; Heinen 1911: 26, fig. 7; Augener 1913: 193; Okuda 1939: 231; not McIntosh 1908: 29, pl. LVII, figs. 10–12, pl. LXVI, fig. 11, pl. LXXVII, fig. 8.

Nephthys johnstoni Ehlers, 1874: 293 ; Ehlers 1875: 38, pl. III, figs. 1–4; McIntosh 1908: 34 (partim).

Nephthys emarginata Malm, 1874: 77 , pl. I, fig. 1 (partim).

Nephthys ciliata Augener 1913: 193 (partim) (not Müller 1776).

Nephthys ciliata form. longosetosa Augener 1939: 137 .

Nephtys longosetosa Hartman 1944: 339 , pl. XV, fig. 7; Pettibone 1954: 268, fig. 301; Pettibone 1956: 558; Imajima 1961: 87, fig. 3; Fauchald 1963: 8, figs. 1C, 3F; Pettibone 1963: 204, fig. 47A; Imajima and Hartman 1964: 157; Hartmann-Schröder 1971: 221, figs. 71C, 73A–B; Wolff 1968: 4, fig. 8; Kirkegaard 1969: 52, figs. 24–26; Paik 1973: 125, pl. I, figs. E and F; Garwood and Olive 1981: 195, figs. 1, 2, 4B, 5A and 6; Imajima and Takeda 1987: 60, figs. 10A–I, 14; Jirkov 1989: 78, Figs. 16.10 and 16.11 ; Rainer 1991: 80, fig. 3D; Kirkegaard 1992: 339, fig. 166; Hartmann-Schröder 1996: 229, fig. 102; Böggemann 1997: 80, fig. 58; Dnestrovskaya and Jirkov 2001: 205,1 fig.

Nephtys longesetosa [misspelling of longosetosa ] Laborda 2004: 406, fig. 149D.

Type locality. Greenland, Arctic .

Material examined. Arctic Ocean. Greenland: 2 incomplete spms ( NHM 1921.5.1.704 as N. caeca ).

Atlantic Ocean. Kattegat, Anholt: 1 incomplete spm ( GNHM Polych. 49, syntype of N. emarginata ); Anholt- Lysegrund: Jan 1873, 1 complete and 3 incomplete spms ( GNHM Polych. 1231, syntypes of N. emarginata ) and 5 incomplete spms ( GNHM Polych. 1232, syntypes of N. emarginata ). North Sea, Scotland, off Shetland Islands: 1 complete spm ( NHM: 1865.3.9.18 as N. longisetosa ). Belgium, Oostend: 2 complete spms ( NHM 1928.4.26.559/560).

Description. Examined specimens up to 90 mm long for up to 118 chaetigers. See Fig. 13 for length and width measurements. Body long and slender, of about same width, slightly tapering posteriorly. Colour in ethanol cream; chaetae whitish; tip of aciculae brown. Eyes not visible. Pharynx distal region with 10 pairs of terminal bifid papillae, separated by dorsal and ventral small elevation; middorsal papilla cirriform, long ( Fig. 13D ); subdistal region with 22 rows of 4–7 long and conical subterminal papillae, extending over 1/2 length of pharynx; proximal region smooth. Jaws conical, brown. Prostomium subpentagonal, anterior margin slightly convex, tapering between antennae, posterior margin V-shaped ( Fig. 22A ); antennae and palps conical, subequal in length; palps inserted ventrolaterally on median region of prostomium. Nuchal organs rounded, somewhat hidden by a fold made by the anterior border of the first chaetiger. Parapodia biramous; interramal space “U-shaped”, heavily ciliated. Parapodia of chaetiger 1 similar in size to subsequent ones, directed anteriorly, parallel to prostomium; notopodial acicular lobes rounded; pre- and postchaetal lamellae well developed but not extending beyond acicular lobes, rounded; neuropodial pre- and postchaetal lamellae forming a cylinder covering acicular lobe; dorsal and ventral cirri well developed, subequal in length ( Fig. 13C ), conical to cirriform. Acicular lobes of following parapodia rounded or slightly bilobed; prechaetal lamellae poorly developed, rounded; notopodial postchaetal lamellae extending beyond acicular lobes, unequally bilobed, with dorsal lobe much larger than ventral one; neuropodial postchaetal lamellae extending well beyond acicular lobes, with a median ventral incision giving it a typical S-shaped appearence; dorsal cirri slender, with broad base and a cirriform tip; ventral cirri conical somewhat flattened ( Figs. 22B–C ). Branchiae recurved, heavily ciliated, with very small, rounded basal projection; present from chaetiger 3 to near posterior end; occupy 2/3 of interramal space when fully developed. Chaetae very thin and long, of three kinds: barred chaetae in preacicular position, coarsely spinulated chaetae in postacicular position, and capillary chaetae in neuropodia of chaetiger 1. One acicula per ramus, posterior ones with curved tips.

Remarks. Nephtys longosetosa has often been confused with other species, especially with N. caeca . Fauchald (1963) summarized the synonymy history for both species and Garwood and Olive (1981) provided a detailed comparison between them. The main differences between these two species were already mentioned in the remarks on N. caeca , and consist on start of branchiae, parapodial lamellae proportions and pharynx papillae patterns. All specimens of N. longosetosa examined have branchiae starting from chaetiger 3 and neuropodial postchaetal lamellae with a soft ventral incision, giving an “S” appearance to the lamellae. Pharynx of N. longosetosa differs from N. caeca in having a long middorsal papillae and a smooth proximal region. Both N. caeca and N. longosetosa are cold-water species, with overlapping geographical distributions, occurring more frequently in northern regions. Specimens from NW Spain, Mediterranean Sea and Pacific Ocean were not available for confirmation and therefore these records should be considered with caution. Nevertheless, the Spanish records are the reason why this species is included in this paper. Two examined specimens, from Panama (NHM 1928.9.13.22) and Alaska (CASIZ 22792), labelled as N. longosetosa do not belong to this species.

Distribution. Arctic Ocean ( Greenland); Atlantic Ocean ( Norway, North Sea, Skagerrak, Kattegat, western Baltic, NW Spain); Mediterranean Sea (as far as the Black Sea); Pacific Ocean (Bering Sea; Sea of Okhotsk; Japan; Yellow Sea; China Sea; Alaska to California) ( Imajima & Takeda 1987; Rainer 1991; Jung & Hong 1997; Laborda 2004). There is another report of this species from the Strait of Magellan ( Imajima & Takeda 1987), but this record requires confirmation.

Habitat. In a wide variety of sediments, most common in well-sorted fine or medium sands, from the lower intertidal to 1000 m depth ( Rainer 1991; Jung & Hong 1997; Laborda 2004).

Figures

FIGURE 13. Relationships between: A. Number of segments and body length. B. Body length and body width. C. Length of ventral cirri (VC) and dorsal cirri (DC) of chaetiger 1. D. Length of pharynx distalmost subterminal papillae and middorsal papilla. Nephtys caeca. N. ciliata. × N. longosetosa.

FIGURE 16. Relationships between: A. Number of segments and body length. B. Body length and body width. C. Length of ventral cirri (VC) and dorsal cirri (DC) of chaetiger 1. D. Length of pharynx distalmost subterminal papillae and middorsal papilla. Nephtys cirrosa. N. paradoxa. Minute dorsal cirri were scored as 0.01.

FIGURE 22. Nephtys longosetosa. A. Prostomium and first chaetigers, dorsal view. B. Right parapodium of chaetiger 39, anterior view. C. Same, posterior view.