Aglaophamus pulcher ( Rainer, 1991 )

Ravara, Ascensão, Cunha, Marina R. & Pleijel, Fredrik, 2010, Nephtyidae (Annelida, Polychaeta) from southern Europe 2682, Zootaxa 2682 (1), pp. 1-68 : 17-20

Aglaophamus pulcher ( Rainer, 1991)

Figures 2 , 5

Nephtys pulchra Rainer, 1991: 83 , fig. 1A–F; Hartmann-Schröder 1996: 232; Arvanitidis 2000: 79; Dnestrovskaya and Jirkov 2001: 210, fig.; Laborda 2004: 410, fig. 150C–D.

Nephthys hystricis McIntosh 1900b: 259 (partim); McIntosh 1908: 27 (partim).

Nephtys incisa Fauchald 1963: 15 , figs. 1H, 2C, 3B (partim).

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

Aglaophamus rubella Hartmann-Schröder 1974: 205 (partim) (not Michaelsen 1896).

Type locality. Norway .

Material examined. Atlantic Ocean. Norway: 1 complete spm, holotype ( NHM 1921.5 .1.794 as Nephtys pulchra ). North Sea , Sweden, Skagerrak, Bohuslän: 58º07.726’– 58º07.909’N, 10º48.698’– 10º48,074’E, 212– 250 m, Aug 2006, 1 incomplete spm ( MB36000160 ) ; 58º19.728’– 58º20.116’N, 10º26.550’– 10º26,849’E, 333–370 m, Aug 2006, 4 incomplete spms, ( DBUA 01136-01 ) . Portugal, Nazaré canyon: 64PE252 cruise, RV Pelagia , 39º35.80’N, 9º24.25’W, 897 m, box-corer, 11 Sep 2006, 1 complete spm ( DBUA 00867-01 ) and 1 incomplete spm ( MB36000129 ) ; 39º35.80’N, 9º24.24’W, 897 m, box-corer, 11 Sep 2006, 2 complete and 1 incomplete spm, ( DBUA 00867-02 ) ; Cascais Canyon : 64PE252 cruise, RV Pelagia , 38º27.89’N, 9º28.51’W, 935 m, box-corer, 18 Sep 2006, 2 complete spms, ( DBUA 00868-01 ) and 1 incomplete spm, ( MB36000130 ) ; 38º27.86’N, 9º28.49’W, 1014 m, box-corer, 18 Sep 2006, 4 complete and 2 incomplete spms, ( DBUA 00868- 02 ) ; 38º27.90’N, 9º28.50’W, 1020 m, box-corer, 18 Sep 2006, 1 complete spm ( DBUA 00868-03 ) ; Setúbal Canyon : 64PE252 cruise, RV Pelagia , 38º17.10’N, 9º05.98’W, 970 m, box-corer, 17 Sep 2006, 1 incomplete spm ( DBUA 00869-01 ) ; 38º17.10’N, 9º06.00’W, 970 m, box-corer, 17 Sep 2006, 2 incomplete spms, ( DBUA 00869-02 ) ; Open slope off Sines : 64PE252 cruise, RV Pelagia , 37º49.99’N, 9º28.50’W, 1001 m, box-corer, 16 Sep 2006, 1 complete spm ( DBUA 01055-01 ) ; 37º49.98’N, 9º28.49’W, 1001 m, box-corer, 16 Sep 2006, 2 complete spms ( DBUA 01055-02 ) ; Open slope south of Nazaré Canyon : 64PE252 cruise, RV Pelagia , 39º10.36’N, 10º15.23’W, 1030 m, box-corer, 6 Sep 2006, 1 incomplete spm ( MB36000145 ) . Gulf of Cadiz, Mercator mud volcano: MSM01-03 cruise, RV M.S. Merian, 35º17.918’N, 6º38.717’W, 353 m, box-corer, 6 May 2006, 1 incomplete spm ( MB36000131 ) ; Pen Duick Escarpment : M2007 cruise, RV Pelagia , 35º10.29’N, 6º47.28’W, 750 m, box-corer, May 2007, 1 incomplete spm ( DBUA 00872-01 ) .

Description. Examined specimens up to 52 mm long for up to 96 chaetigers. See Fig. 2 for length and width measurements. Body small, slightly wider anteriorly, gradually tapering posteriorly. Poor dorsal delineation between anterior segments, strong on middle and posterior segments. Colour in ethanol cream, some specimens with light brown area dorsally on anterior region; chaetae white, glistening; tip of aciculae dark. Eyes not visible. Pharynx distal region with 10 pairs of terminal bifid papillae, separated by a low, conical dorsal and ventral simple papilla ( Fig. 5A ); middorsal and midventral papillae absent; subdistal region with 14 well defined rows of 10–15 conical and long subterminal papillae, extending to base of pharynx, plus several distal ones that do not necessarily fit within the rows; proximal region otherwise smooth. Jaws conical. Prostomium pentagonal, anterior margin slightly convex, tapered, forming a membrane between antennae, posterior margin V-shaped extending over first chaetiger ( Fig. 5B ); antennae conical, with broad base and cirriform tip; palps conical, similar to antennae but longer and with broader base ( Fig. 2C ), inserted ventrolaterally in anterior region of prostomium. Nuchal organs rounded. Parapodia biramous; interramal space “U-shaped” anteriorly and medially, “V-shaped” posteriorly; moderately ciliated. Parapodia of chaetiger 1 directed anteriorly, parallel to prostomium; notopodial acicular lobes conical, prechaetal lamella poorly developed, rounded, postchaetal lamella well developed but not extending beyond acicular lobes, rounded; neuropodial pre- and postchaetal lamellae forming a cylinder around acutely pointed acicular lobes; dorsal cirri conical, small ( Fig. 2D ); ventral cirri with broad bases and cirriform tips. Acicular lobes of following parapodia acutely pointed; prechaetal lamellae shorter than acicular lobes, rounded in notopodia, conical in neuropodia, becoming poorly developed posteriorly; postchaetal lamellae extending beyond acicular lobes in anterior parapodia, rounded, becoming shorter than acicular lobes in posterior parapodia; dorsal cirri long and conical, with bulbous bases and tapering tips; ventral cirri conical ( Fig. 5C–L ). In some middle parapodia, the notopodial postchaetal lamellae gradually shift to a more dorsal position giving the lamellae a bilobed appearance ( Fig. 5G–H ). This effect is more appearent in smaller specimens ( Fig. 5K–L ). Branchiae recurved, cirriform, long and thin, moderately ciliated; present from chaetigers 5–7 to near posterior end; occupy all interramal space when fully developed. Neuropodial superior lobe conical and small (difficult to observe), present in anterior and middle parapodia. Chaetae long and thin, of three kinds: barred chaetae in preacicular position ( Fig. 5N ), minutely spinulated chaetae in postacicular position ( Fig. 5M ), and capillary chaetae in neuropodia of chaetiger 1. One acicula with curved tip per ramus ( Fig. 5O ).

Remarks. Nephtys pulchra was erected by Rainer (1991), based on specimens from the Norwegian region that were previously included in four other species: N. hystricis , N. incisa , A. malmgreni and A. rubella . Recently, Laborda (2004) included N. pulchra in the Iberian Fauna and provided a brief description for specimens reported from the Gulf of Biscay. The present study updates the previous descriptions and extends the species distribution further south, to Portugal and Gulf of Cadiz. Nephtys pulchra was formally transferred to Aglaophamus , as A. pulcher , by Ravara et al. (2010), according to the results of a phylogenetic analysis based on morphological and molecular data. The morphological similarity between N. pulchra and Aglaophamus species was previously noted by Rainer (1991) in that N. pulchra has only 14 rows of subterminal papillae on the pharynx and a neuropodial superior lobe on anterior and middle parapodia. However, the recurved branchiae conditioned its inclusion in the genus Nephtys . The value of branchiae shape as a distinctive character for genera is discussed below, in the discussion section.

The description presented herein includes some minor differences from the original description given by Rainer (1991), such as the number of subterminal papillae per row on the pharynx (10–15 instead of 14–16), the postacicular chaetae, which are in fact minutely spinulated instead of smooth, and the notopodial postchaetal lamellae that have a bilobed appearance in some middle parapodia ( Fig. 4G–H, K–L ). In the smaller specimens examined (with less than 34 chaetigers) branchiae begin further posteriorly (chaetigers 18– 20) or are absent, and postchaetal lamellae are poorly developed ( Table 2). Variations on the chaetigers where branchiae occur, in smaller specimens, were already observed in A. elamellatus , a deep-water species also common in the Portuguese canyons (see above). In this later species, branchiae always start on the same chaetigers but extend further posteriorly according to the specimen size and are absent in the smallest ones. Despite the clearly larger dorsal cirri in A. pulcher than in A. elamellatus , the distinction between smaller specimens of these species is not easy and requires the examination of the pharynx papillae (see Table 3 for differences in the number of rows of pharynx papillae).

A comparison between A. pulcher and the other Aglaophamus species is summarized in Table 3. A . pulcher is close to A. malmgreni from which it can be distinguished by the branchiae shape and starting chaetiger, the number of subterminal papillae in the pharynx, and the bilobed postchaetal lamellae of notopodia, which occur further posteriorly and only in a few chaetigers of A. pulcher . Also the notopodial postchaetal lamellae of posterior chaetigers are dorsally oriented in A. malmgreni and directed laterally in A. pulcher .

Distribution. Atlantic Ocean ( Norway, Oslofjord, Skagerrak, NW Spain, Portugal and Gulf of Cadiz); Mediterranean Sea (abyssal plains and canyons of the western Mediterranean, Aegean Sea) ( Rainer 1991; Arvanitides 2000; Laborda 2004; J. Gil pers. com.; this study).

Habitat. Mud and clay, 200–1000 m depth ( Rainer 1991; Laborda 2004).

Figures

FIGURE 2. Relationships between: A. Number of segments and body length. B. Body length and body width. C. Antennae and palps length. D. Length of ventral cirri (VC) and dorsal cirri (DC) of chaetiger 1. Aglaophamus elamellatus. - A. malmgreni. A. pulcher. A. rubellus. Minute dorsal cirri were scored as 0.01. A. elamellatus, A. malmgreni and A. pulcher plots include measurements from the original description (Théel, 1879; Eliason, 1951; Rainer, 1991).

FIGURE 4. Aglaophamus malmgreni. A. Pharynx and prostomium, dorsal view. B. Detail of pharynx subterminal papilla. C. Jaw. D. Right parapodium of chaetiger 10, anterior 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 from chaetiger 20.

FIGURE 5. Aglaophamus pulcher. A. Dissected pharynx, dorsal view. B. Prostomium, dorsal view. C. Right parapodium of chaetiger 10, 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. Same, posterior view. I. Right parapodium of chaetiger 80, anterior view. J. Same, posterior view. K. Right parapodium of chaetiger 30 of a smaller specimen, anterior view. L. Same, posterior view. M. Postacicular chaetae from chaetiger 20. N. Preacicular chaeta from chaetiger 20. O. Acicula from chaetiger 20.