Nephtys incisa Malmgren, 1865

Ravara, Ascensão, Cunha, Marina R. & Pleijel, Fredrik, 2010, Nephtyidae (Annelida, Polychaeta) from southern Europe 2682, Zootaxa 2682 (1), pp. 1-68 : 52-53

Nephtys incisa Malmgren, 1865

Figures 19 , 20

Nephthys incisa Malmgren, 1865: 105 , pl. XII, fig. 21; Michaelsen 1896: 58 (partim); Nordgaard 1905: 162; McIntosh 1908: 38; Heinen 1911: 23, fig. 6 (partim); Augener 1913: 203 (partim); not Treadwell 1914: 193; not Fauvel 1914: 198, pl. XVIII, fig. 3; not Fauvel 1923: 369, fig. 144A–B (= N. hystricis ).

Nephthys sp. nr. incisa McIntosh 1900b: 262 .

Nephthys hystricis McIntosh 1908: 27 , pl. LVII, figs. 8 and 9; pl. LXVI, figs. 10 and 10A (partim); Fauvel 1914: 200; Fauvel 1923: 373, fig. 146A–E.

Nephtys incisa? Hartman 1944: 340 , pl. XV, fig. 9;? Hartman, 1950: 108; Eliason 1962: 249; Fauchald 1963: 15, figs. 1H, 2C and 3B (partim); Pettibone 1963: 198, fig. 49A, B, 51A; not Wolff 1968: 4, fig. 10;? Foret-Montardo 1969: 814, pl. III, figs. 8–10; Kirkegaard 1969: 51, fig. 23 (partim); not Hartmann-Schröder 1971: 217, fig. 70D–E; Day 1973: 43; not Hartmann-Schröder 1974: 207; Gardiner 1976: 154, fig. 16C, D; Campoy 1982: 516; Hartmann- Schröder 1982: 11; not Taylor 1984: 35-7, figs. 35-3 and 4A–D; Rainer 1990: 366, fig. 2A–E; Rainer 1991: 76, fig. 3G; not Kirkegaard 1992: 338, fig. 165 (= N. hystricis ); Hartmann-Schröder 1996: 225, fig. 100; Böggemann 1997: 80, fig. 57; Dnestrovskaya and Jirkov 2001: 202, 1 fig; Laborda 2004: 405, fig. 148C–D.

Nephtys (Nephtys) hystricis Day 1967: 345 .

Nephtys hystricis Wolff 1968: 6 , fig. 11;? Foret-Montardo 1969: 816, pl. III, figs. 1–4; Campoy 1982: 514.

Aglaophamus malmgreni Hartmann-Schröder 1974: 205 (partim) (not Théel, 1879).

Type locality. Väderöarna and Koster , Bohuslän, Sweden, Skagerrak, in 36–146 m depth .

Material examined. Atlantic Ocean. Sweden, Skagerrak, Bohuslän : 58º10.856’– 58º11.049’N, 10º53.439’– 10º53,024’E, 162–191 m, Aug 2006, 1 incomplete spm ( MB36000158 ) ; Koster: 127–146 m, 2 complete and 1 incomplete spms, paralectotypes (SMNH-type-2460); Väderöarna : 36–127 m, 5 complete and 2 incomplete spms, paralectotypes (SMNH-type-2461); 109 m, 1 complete spm, paralectotype (SMNH-type- 2459); 106,88 m, 1 complete spm, paralectotype ( NHM 1865.9.23.8). England, off Northumberland: 90 m, Apr 2008, 1 incomplete spm ( MB36000150 ) . Portugal, off Cascais : 38º39’– 38º42’N, 9º25’– 9º30’W, 40 m, 1997, 1 incomplete spm ( DBUA 00065-01 ) ; off Cape Sagres: Porcupine expedition, 4 incomplete spms ( NHM 1921.5.1.769-770 as N. hystricis ). NE USA, off Cape Cod : 10–50 fms, 1 complete and 6 incomplete spms ( NHM 1890.8.23.21/22); off Vineyard Sound: 10–20 fms, 1 incomplete spm in very poor condition ( NHM 1880.9.27.57); Hudson Canyon: RV Chain, 39º35.363’N, 72º24.9255’W, 360–380 m, Feb 1973, 1 complete and 4 incomplete spms ( MCZ 37133) ; 39º31’N, 72º18’W, 855 m, Feb 1973, 2 incomplete spms ( MCZ 37299) ; Massachusetts: 41º29.2’N, 70º53.8’W, 15 m, Jan 1966, 41 complete and 6 incomplete spms (4 adults) ( MCZ 57201) ; Florida: 2 complete spms in poor condition ( MCZ 1424 ) .

Mediterranean Sea. France, off Banyuls: RV Nereis , 42º29.35’N, 03º11.16’E, 70 m, Apr 2001, dredge, 2 incomplete spms ( DBUA 01047-01); 42º29.55’N, 03º09.90’E, 45 m, dredge, Jul 2004, 2 complete and 2 incomplete spms ( DBUA 01046-01), and 1 incomplete spm ( MB 36000141). Israel: Dec 1924, 1 incomplete spm ( NHM 1926.11.12.123 as N. hystricis ). Suez: Suez Canal expedition, 7 incomplete spms ( NHM 1955.10.12.35/39 as N. hystricis ).

Description. Examined specimens up to 50 mm long for up to 71 chaetigers. See Fig. 19 for length and width measurements. Body small, slightly wider anteriorly, gradually tapering from middle region to pygidium. Poor dorsal delineation between anterior segments. Colour in ethanol cream; chaetae amber; tip of aciculae dark. Eyes not visible. Pharynx distal region with 10 pairs of very small terminal bifid papillae, separated by dorsal and ventral gap; middorsal papilla cirriform, very long ( Fig. 19D ); midventral papillae absent; subdistal region with 20 rows of 1–5 very small subterminal papillae, extending over 1/3 length of pharynx ( Fig. 20A ); proximal region smooth. Jaws conical ( Fig. 20B ). Prostomium subpentagonal, anterior margin slightly concave, posterior margin rounded ( Fig. 20A ); antennae and palps conical, equal in length; palps inserted ventrolaterally on anterior region of prostomium. Nuchal organs rounded, inconspicuous. Parapodia biramous; interramal space “U-shaped” anteriorly and “V-shaped” posteriorly, heavily ciliated. Parapodia of chaetiger 1 slightly smaller than subsequent ones, directed anteriorly, obliquely to prostomium; notopodial acicular lobes conical, prechaetal lamellae rudimentary, postchaetal lamellae well developed but not extending beyond acicular lobes, rounded; neuropodial pre- and postchaetal lamellae forming a cylinder covering acicular lobes; dorsal cirri rounded, foliaceous; ventral cirri conical, with broad base and tapering distally, similar in size to dorsal cirri ( Fig. 19C ). Acicular lobes of following parapodia conical; pre- and postchaetal lamellae of both rami well developed, as long as acicular lobes (or slightly smaller, in posterior parapodia), rounded; dorsal and ventral cirri flattened, triangular ( Fig. 20C–G ). Branchiae recurved, cirriform, heavily ciliated; present from chaetiger 9 or 10, absent in posterior parapodia; occupy half of interramal space when fully developed. Chaetae short, of three kinds: distally barred chaetae in preacicular position ( Fig. 20H ), finely spinulated chaetae in postacicular position ( Fig. 20I ), and capillary chaetae in neuropodia of chaetiger 1. One acicula per ramus, posterior ones with curved tips ( Fig. 20J ).

Remarks. Nephtys incisa and N. hystricis are morphologically very similar, and are often confused. Rainer (1990) re-examined much of the older material and provided a re-description of these two species. The main differences between them are summarized in the remarks on N. hystricis . Both species occur in the same geographical regions although N. incisa seems to have a wider distribution in the eastern and western Atlantic. Rainer (1990) advised caution regarding the western Atlantic records, and stated that they likely refer to N. hystricis . In this study some material from several localities in the NW Atlantic were examined, and some differences from the typical N. incisa or N. hystricis specimens were found, indicating that these records are in need of revision.

Distribution. Atlantic Ocean (from Iceland to off NW Africa, including the North Sea, Skagerrak, Kattegat and the coasts of Spain and Portugal); Mediterranean Sea (as far as the Bosphorus) ( Rainer 1990, 1991; Laborda 2004). There are further reports of this species from the western Atlantic ( Rainer 1990, 1991), but these records require revision.

Habitat. Gravel and mud to soft silts (most common in silty sand and/or mud), from the shallow subtidal to 930 m depth, but also reported from depths to 1700 m in the western Atlantic ( Rainer 1990, 1991; Laborda 2004).

Figures

FIGURE 19. 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 hystricis. N. incisa.

FIGURE 20. Nephtys incisa. A. Pharynx, prostomium and anteriormost chaetigers, dorsal view. B. Jaw. C. Right parapodium of chaetiger 11, anterior view. D. Same, posterior view. E. Right parapodium of chaetiger 20, anterior view. F. Same, posterior view. G. Right parapodium of chaetiger 40, anterior view. H. Preacicular chaeta from chaetiger 20. I. Postacicular chaeta from chaetiger 20. J. Acicula of chaetiger 40.