Syllidia armata Quatrefages, 1866

Ruta, Christine & Pleijel, Fredrik, 2006, A revision of Syllidia (Psamathini, Hesionidae, Polychaeta), Journal of Natural History 40 (9 - 10), pp. 503-521 : 505-513

Syllidia armata Quatrefages, 1866

( Figures 1–6 )

Syllidia armata Quatrefages 1866, p 13 –15, Plate 8, Figures 10–15; Grube 1880, p 222; Langerhans 1880, p 305, Plate 16, Figure 40; Czerniavsky 1882, p 174–175; Saint- Joseph 1888, p 317; Fage 1906, p 326; Ehlers 1913, p 467–468; Chamberlin 1919, p 186; Augener 1918, p 227–229; Day 1953, p 412; 1960, p 307; 1967, p 226–227, Figures 2.1M , 11.1H–L; Hartman 1959, p 193; Hartmann-Schröder 1971, p 126–128, Figure 40A–D; 1974, p 110; 1982, p 8; 1996, p 138–139, Figure 57; Cazaux 1970, p 112–116, Plate 34, Figures 1–5 , Plate 35, Figures 1 , 2 ; Ben-Eliahu 1972, p 202; Rasmussen 1973, p 69–70; Rullier 1974, p 25; San Martin et al. 1981, p 67; Campoy 1982, p 212–213; Sordino 1990, p 41–44; Kirkegaard 1992, p 217–218, Figure 106; Mackie et al. 1995, p 185; Pleijel 1998, p 126; Pleijel and Rouse 2004, Figure 4 .

Magalia perarmata Marion and Bobretzky in Marion 1874, p 399; Marion and Bobretzky 1875, p 54–56, Plates 6, 7, Figure 16A–H; Langerhans 1880, p 305 (uncertain identity; see below); Saint-Joseph 1888, p 318–320, Plate 13, Figures 197, 198; McIntosh 1908, p 136–137, Plate 59, Figures 1 , 2 , Plate 65, Figure 10, Plate 69, Figure 18, Plate 78, Figure 8 ; 1924, p 16; 1925, p 41–42; Ehlers 1912, p 17; Rioja 1918, p 36–37; 1925, p 18; Chamberlin 1919, p 186; Fauvel 1923, p 246–247, Figure 92; Abeloos 1950a, p 477– 478; 1950b, p 1009–1110; Casanova 1954, p 155–162, Plates 1, 2, Plate 3, Figures 1–7 ; Rasmussen 1956, p 48; Marine Biological Association 1957, p 117; Banse 1959, p 427; Hartman 1959, p 188; Amoureux 1976, p 11; Amoureux and Gantès 1976, p 193; Pleijel 1998, p 126.

Pseudosyllidia armata Czerniavsky, 1882, p 174 –175; Pleijel 1998, p 126.

Castalia arctica sensu McIntosh 1908 [non Castalia arctica Malmgren, 1867 ], p 125–126, Plate 58, Figure 14, Plate 69, Figure 15, Plate 78, Figure 3, 3a .

Psammate [sic] britannica Chamberlin, 1919, p. 13 , new synonymy.

Megalia [sic] assimilis Pryde, 1914, p 273 –275, Plate 11, Figures 1–3 .

Magalia assimilis McIntosh 1924, p 16 ; 1925, p 42; Hartman 1959, p 188; Pleijel 1998, p 126.

Syllidia assimilis Hartman 1959, p 193 ; Pleijel 1998, p 126.

Magalia capensis McIntosh, 1924, p 16 ; 1925, p 41–42, Plate 5, Figure 2 , Hartman 1959,

p 188; new synonymy. Syllidia capensis Hartman 1959, p 193 ; Day 1967, p 226–227, Figure 11.1M; Pleijel 1998,

p 126.

Material examined

Denmark: two specimens ( ZMUC), Isefjord , soft bottom, 4–8 m, collector E. Rasmussen, July 1943 . England: one specimen ( BMNH 1921.5.1.1104), Plymouth, 1 May 1921 . France: one specimen ( BMNH 1928.4.26.589), Iles Glénans , 26 April 1928 ; seven specimens ( FP), Dinard , La Rance, collector FP, 17 May 1989 ; one specimen ( FP), Ile Grosse, Banyuls-sur-Mer , 42 ° 29.09N, 03 ° 08.29E, 10 m, coarse sand and shells, scuba, collector FP, 13 October 1991 ; four specimens ( FP), same locality data, scuba, collector FP, 18 October 1991 ; two specimens ( FP), Cap d’Osne, Banyuls-sur-Mer , 42 ° 29.809N, 03 ° 08.489E, 24 m, collector FP, 18 October 1991 ; two specimens ( FP), Cap Oullestrell, Banyuls-sur-Mer , 42 ° 29.789N, 03 ° 08.439E, 24 m, coarse sand and shells, dredge, collector FP, 8 October 1993 ; one specimen ( FP), Banyuls-sur-Mer , 42 ° 29.759N, 03 ° 09.009E, 30 m, sandy mud with detritus, dredge, collector FP, 12 May 1997 . Ireland: two specimens ( BMNH 1921.5 .1.1098, lectotype and paralectotypes of Psamathe britannica ; see Remarks), 50 miles west of Valencia, 160–230 m, collector G. Jeffreys; six specimens ( BMNH 1914.12.12.18), Galway Bay , dredge, 4 November 1928 . Italy: one specimen ( FP), Brucoli , Sicily, 37 ° 16.89N, 15 ° 11.79E, 0–5 m, among Posidonia seagrass, scuba, collector FP, 21 May 1990 ; one specimen ( FP), Capo Mulini, Accitrezza , Sicily, 37 ° 34.49N, 15 ° 11.79E, 30 m, scuba, collector FP, 12 June 1990 ; one specimen ( FP), Pantano Piccolo, Messina , Sicily, 0–5 m, lagoon, snorkelling, collector FP, 25 May 1992 ; one specimen ( FP), Castello, Ischia off Naples , 48 ° 42.89N, 13 ° 57.859E, 1–2 m, snorkelling, collector FP, 8 September 1993 . NE Atlantic, Seamounts off Portugal: one specimen ( FP), SEAMOUNT 1 DW04 , Gorringe Bank , 36 ° 32.59N, 11 ° 34.49E, 93–96 m, coralligenous substratum, dredge, collector FP, 22 September 1987 . South Africa: eight specimens ( BMNH 1961.9.846–854), 401 m, September 1961 ; 58 specimens ( BMNH 1961.9.8 –61), 68 m, September 1961 . Spain: ca 10 specimens ( FP), Blanes harbour, dredge, collector FP, May 1997 . Sweden: one specimen ( FP), Klinken, Koster area , 58 ° 51.79N, 11 ° 11.199E, 6–8 m, among Pomatoceros tubes, sand and gravel, scuba, collector FP, 23 September 1989 ; seven specimens ( FP), same locality data, scuba, collector FP, 4 October 1989 ; two specimens mounted for SEM ( FP), same locality data, scuba, collector FP, 14 April 1990 ; two specimens ( FP), same locality data, scuba, collector FP, 14 April 1990 ; 30 specimens ( FP), same locality data, scuba, collector FP, 26 June 1990 ; one specimen ( FP), Gåsö Ränna, Gullmarsfjorden , west coast of Sweden, 30–40 m, dredge, collector FP, 24 July 1990 ; 26 specimens, Klinken, Koster area , 58 ° 51.79N, 11 ° 11.199E, 6– 8 m, among Pomatoceros tubes, sand and gravel, scuba, collector FP, 17 August 1990 ; 30 specimens ( FP), same locality data, scuba, collector FP, 20 August 1990 ; 20 specimens ( FP), same locality data, scuba, collector FP, 21 August 1990 ; seven specimens ( FP), same locality data, scuba, collector FP, 1 March 1991 ; 30 specimens ( FP); same locality data, scuba, collector FP, 15 June 1991 ; 36 specimens ( FP), same locality data, scuba, collector FP, 22 June 1991 ; four specimens ( FP), same locality data, scuba, collector FP, 25 May 1992 ; 10 specimens preserved for DNA analyses ( FP), five specimens preserved for TEM ( FP), same locality data, scuba, collector FP, 3 August 2004 ; six specimens preserved for DNA analyses ( FP), same locality data, scuba, collector FP, 4 April 2005 .

Apomorphies

None currently known (see Remarks for S. hongkongensis ).

Description

Longest, complete observed specimen 10 mm long for 38 segments; for further measurements, see Figure 1 . Body short, cylindrical, excluding parapodia, anteriorly truncate, posteriorly tapered ( Figure 2 ); venter flattened without distinct median longitudinal furrow. Prostomium rounded quadrangular, anteriorly straight, posterior incision weakly developed, sometimes not visible ( Figures 3 , 4A ). Small facial tubercle present ( Figure 4B, D ). Palpophores cylindrical, as long as palpostyles; palpostyles tapered ( Figure 4A ). Paired antennae as long as palps but thinner, tapered. Anterior pair of eyes reniform, slightly larger than posterior pair and situated farther apart, posterior pair rounded, both pairs with lenses. Nuchal organs lateral, mid-dorsally well separated ( Figure 4A ). Presence or absence of lip glands uncertain; weakly developed or absent. Noneverted proboscis reaching segment 8 or 9, with 10 terminal papillae ( Figure 4C ), ventral incision present ( Figure 4C ). Jaws large, dark, visible through body wall ( Figure 3 ), especially from ventral side, with two basal pointed shafts and serrated edges with about seven or eight teeth ( Figure 6B ); small unpaired stylet ( Figure 6B ) situated between jaws (often difficult to detect). Segment 1 not dorsally visible, segment 2 narrower than following segments. Dorsal cirri and cirrophores segments 1–5 enlarged and prolonged compared to following segments. Ventral cirri segments 1–3 much longer than on following segments, with well-developed cirrophores. Cirrophores of all cirri segments 1–3 with single acicula. Neuropodial lobes and neurochaetae absent on segments 1–3. Dorsal cirri on segments 5, 8, 10, 12, 15, 17, 20, 22, 25, and every third segment thereafter dorsally orientated and elongated, dorsal cirri of other segments shorter and more laterally orientated. All dorsal cirri distinctly annulated with basal rings as long as wide, distal rings usually shorter. Neuropodia with one or two aciculae and 20–30 compound chaetae ( Figures 5A , 6A ). Median neurochaetae with longer blades than dorsal and ventral ones; ventralmost ones shortest, length less than half of longest median ones. Chaetal shafts internally camerated. Several median chaetal blades with prolonged teeth ( Figure 5B ). Blades with unidentate tips. Ventral cirri subdistally inserted on neuropodium, tapered, indistinctly annulated, cirrophores absent ( Figure 6A ). Pygidium with pair of cirri, similar to dorsal cirri. Small medio-ventral pygidial papilla present ( Figure 5C ).

Colour

Live specimens opaque to transparent, unpigmented except for dark brown ventral longitudinal midline, usually on posterior part of body ( Figure 2 ). Gut yellowish, gut wall of last six or seven segments with white pigment speckles. Eyes red. Jaws dark brown, median stylet yellowish. Preserved specimens white to yellowish, eyes dark red, ventral longitudinal pigmentation usually retained.

Reproduction and deυelopment

Syllidia armata has an extended reproductive period, Cazaux (1970) recorded mature specimens from early summer to November in Arcachon near Bordeaux in France, and Rasmussen (1956) from May to October in Denmark. The eggs are 50–60 mm and colourless and the larvae are planktotrophic; the different stages were described in detail by Casanova (1954) and Cazaux (1970). They settle at a stage when they have about eight segments, and jaws start to develop at 10–14 segments. In contrast to the closely related Nereimyra punctata (O. F. Müller, 1776) (see Schram and Haaland 1984; Pleijel 1998), there are no traces of a median antenna in any early stages. The development described by Cazaux is in full agreement with observations from early stages from Sweden, with the exception that Cazaux reported the presence of a few capillary notochaetae in the late planktonic and newly settled stages; this requires further examination.

Habitat

Syllidia armata occurs in sand, gravel, and rocky substrata, 0–230 m depth; it is also recorded from mud bottoms in the literature ( McIntosh 1924; Hartmann-Schröder 1962).

Distribution

As seen from examined specimens, S. armata occurs in South Africa, Italy, Spain, Mediterranean and Atlantic coasts of France, and up to Sweden and Denmark in the north. Additional records from the literature include Amoureux (1976) and Amoureux and Gantès (1976) from Morocco, Langerhans (1880) from Madeira, Augener (1918) from Senegal, Hartmann-Schröder (1982) from Guinea-Bissau, Day (1967) from South Africa, Ben Eliahu (1972) from Suez, and Rullier (1974) from Florida. See also Figure 9.

Remarks

Quatrefages, in his original description of S. armata , reported the presence of capillary notochaetae. As his description in all other respects agrees well with the description above, and as no notochaetae have been observed in any European specimens, we believe this was an error.

Marion and Bobretzky (in Marion 1874) introduced the new species Magalia perarmata from Marseille in southern France. They did not compare it to or mention Quatrefages’ description of S. armata , possibly due to Quatrefages statement of the presence of capillary notochaetae. There is no extant type or other original material accompanying either of the two species names, but at present we see no need to designate neotypes. We agree with previous studies that the two are synonymous (e.g. Day 1967; Kirkegaard 1992; Pleijel 1998) as only one species is known from European waters. For the same reason we consider Pryde’s (1914) species M. assimilis from the North Sea, also without extant types, as a junior synonym of S. armata . Pryde (1914), in his original description of Magalia assimilis , noted the presence of prolonged teeth on the blades, but then incorrectly assumed them to be absent from M. perarmata since they had not been described by Marion and Bobretzky (1875). All examined specimens, from the Mediterranean and elsewhere, have some chaetal blades with prolonged teeth. Pryde, similarly to Marion and Bobretzky, did not make any reference to Quatrefages’ species.

Chamberlin (1919) introduced Psamathe britannica . Although he had examined no specimens and did not provide any description of the species, he named it for the specimen from Ireland that McIntosh (1908) had referred to Castalia arctica Malmgren, 1867 (junior synonym of Nereimyra aphroditoides Fabricius, 1780 cf. F. Pleijel and A. Nygren, in preparation). According to McIntosh’s (1908) original description, there was only one specimen, but re-examination of his material shows at least two specimens to be present (two anterior ends, one median part, and one posterior end). Although not previously recognized as such, these specimens (or minimally one of them) are actually the types for Chamberlin’s species P. britannica . Of these specimens at least one anterior end clearly belongs to Syllidia , as seen from the everted proboscis with paired jaws and a median, ventral stylet. This is also the same specimen that was used for McIntosh’s illustration Figure 14 on Plate LVIII, and we here designate it as lectotype. We therefore agree with Chamberlin that McIntosh’s specimen was misidentified, but disagree with him on both the generic assigment and on the erection of a new species; instead we regard P. britannica as a junior synonym of S. armata . This is a new synonymy.

Syllidia capensis was described by McIntosh (1924; as Magalia capensis ) from South Africa based on a single, incomplete specimen. McIntosh did not mention any depository and his type is not present at BMNH, at the National Museum of Scotland, or at the South African Museum, and it is therefore here considered lost. The new species was justified by the presence of chaetae with tips possessing long, delicate, and hair-like terminal pieces. However, examination of other South African specimens revealed no chaetal, parapodial, or other consistent morphological differences from S. armata , and we therefore here treat the name S. capensis as a junior synonym of S. armata . This is a new synonymy as well.

Several authors ( Day 1967; Kirkegaard 1992; Hartmann-Schröder 1996) have reported more than 10 papillae on the terminal proboscis ring. Nevertheless, all examined specimens where the proboscis was examined (ca 50) were provided with 10 papillae, as is the case also in closely related taxa, including Nereimyra Blainville, 1828 and Sirsoe Pleijel, 1998 .

Figures

Figure 1. Relationships between number of segments and length in Syllidia armata (n) from Sweden and southern France and S. hongkongensi, new species (©) from the type locality.

Figure 2. Micrograph of mature female of Syllidia armata from the Koster area, Sweden, dorsal view. Exact scale unknown but whole animal, excluding cirri, is about 9 mm long.

Figure 3. Anterior end of Syllidia armata (after Marion and Bobretzky 1875).

Figure 4. SEM micrographs of Syllidia armata from Sweden. (A) Anterior end, dorsal view; (B) anterior end, ventral view of subadult specimen (22 segments) with neuropodial lobes and chaetae on segment 3; (C) distal part of everted proboscis, ventral view, with papillae embedded in cilia. The two visible folds (arrows) will extend to form the ventral incision in the fully everted proboscis; (D) anterior end, ventro-lateral view of same specimen as in (B). Scale bars: 100 mm (A); 150 mm (B, C); 120 mm (D).

Figure 5. SEM micrographs of Syllidia armata from Sweden. (A) Chaetae from median parapodium; (B) close-up of chaetae with prolonged teeth; (C) posterior end, ventral view. Scale bars: 60 mm (A); 15 mm (B); 120 mm (C).

Figure 6. LM micrographs of Syllidia armata from Sweden. (A) Median parapodium; (B) jaws. The inset shows the median stylet (not to scale). Scale bars: 250 mm.

Figure 8. LM micrographs of Syllidia hongkongensis, new species. (A) Median parapodium; (B) jaws and median stylet. Scale bars: 200 mm (A); 100 mm (B).