Laonice norgensis Sikorski, 2003

Bick, Andreas, Guggolz, Theresa & Götting, Miriam, 2014, Spionidae (Polychaeta: Canalipalpata: Spionida) from seamounts in the NE Atlantic, Zootaxa 3786 (3), pp. 201-245 : 232-235

Laonice norgensis Sikorski, 2003

(Figure 15)

Laonice norgensis Sikorski, 2003: 333 –338, figures 9–10, table 3.— Dagli et al. 2011: 57 –58, figures 6A–E.

Material examined. Holotype: North Atlantic Ocean: Norwegian Sea: Oseberg-C Field, 60°36.19’N 2°45.64’E, Stn 19, grab 3, depth 110 m, fine sand, 5-May-1998, 1 complete ( ZMUM Pl 1818); Paratypes: North Atlantic Ocean: Norwegian Sea: Nordøstflanken Field Field, 61°22.44’N 1°55.39’E, Stn 11, grab 3, depth 161 m, fine sand, 18-May-1998, 1 af ( ZMUM Pl 1837).

Non– type material. NE Atlantic Ocean, Expedition DIVA 3, cruise METEOR ME 79-1: Irving Seamount: 31°56.98'N 027°56.67'W, station 684, grab, depth 280.8 m, 21-Aug-2003, formalin, 1 af (ZMH-P27548); 31°56.94'N 027°55.90'W, station 678, grab, depth 283.2 m, 21-Aug-2003, formalin, 2 af (ZSRO-P2291), 1 af ( SMF 23325); Hyères Seamount: 31°26.40'N, 028°56.13'W, station 669, grab, depth 290.8 m, 20-Aug-2009, formalin: 1 af (ZMH-P27549); 31°26.40'N, 028°56.27'W, station 671, grab, depth 288 m, 20-Aug-2009, formalin: 1 af ( SMF 23326); 31°26.40'N 028°56.31'W, station 672, grab, depth 286.2 m, 20-Aug-2003, formalin, 2 af (ZSRO-P2290). Great Meteor Seamount: 30°00.04'N 028°30.05'W, station 660, grab, depth 287.2 m, 19-Aug-2003, formalin, 1 af ( SMF 23324); 30°00.04'N 028°30.05'W, station 661, grab, depth 287.4 m, 19-Aug-2003, formalin, 1 af (ZSRO- P2289); 30°00.04'N 028°30.05'W, station 664, grab, depth 287.9 m, 19-Aug-2003, formalin, 3 af (ZMH-P27547); 30°00.00'N 028°29.99'W, station 659, epibenthic sledge, depth 287.7 m, 19-Aug-2003, 96% ethanol, 1 af ( SMF 23331); 29°44.24'N 028°24.54'W, station 657, epibenthic sledge, depth 285.5 m, 18-Aug-2003, 96% ethanol: 3 af (ZSRO-P2296), 1 af (ZSRO-P2297); 29°44.13'N 028°24.91'W, station 656, epibenthic sledge, depth 283.3 m, 18- Aug-2003, 96% ethanol: 2 af ( SMF 23330), 2 af (ZSRO-P2295); 29°42.17'N 028°22.96'W, station 650, grab, depth 289.2 m, 18-Aug-2003, formalin, 1 af ( SMF 23323); 29°42.16'N 028°22.99'W, station 649, grab, depth 289 m, 18- Aug-2003, formalin, 1 af ( SMF 23322); 29°42.09'N 028°22.76'W, station 647, grab, depth 289.9 m, 18-Aug-2003, formalin, 1 af (ZMH-P27546); 29°41.97'N 028°22.62'W, station 646, grab, depth 292 m, 18-Aug-2003, 96% ethanol, 1 af ( SMF 23329), formalin, 2 af (ZMH-P27545); 29°41.72'N 028°22.39'W, station 644, grab, depth 300.4 m, 18-Aug-2003, formalin: 1 af ( SMF 23320), 2 af (ZSRO-P2288), 1 af ( SMF 23321); 29°41.59'N 028°22.41'W, station 643, grab, depth 299.5 m, 18-Aug-2003, formalin, 1 af (ZMH-P27544); 29°41.46'N 028°22.14'W, station 641, grab, depth 313.3 m, 18-Aug-2003, formalin, 1 af (ZSRO-P2287). Little Meteor Seamount: 29°38.19'N 028°59.07'W, station 632, grab, depth 271.7 m, 17-Aug-2003, 96% ethanol, 1 af (ZSRO-P2294), formalin, 1 af (ZMH-P27543); 29°38.19'N 028°58.98'W, station 631, grab, depth 272.3 m, 17-Aug-2003, formalin, 1 af ( SMF 23319); 29°36.29'N 028°59.68'W, station 624, grab, depth 274.2 m, 17-Aug-2003, 96% ethanol, 1 af ( SMF 23328); 29°36.29'N 028°59.34'W, station 622, grab, depth 267.5 m, 17-Aug-2003, 96% ethanol: 1 af (ZSRO-P2293), 1 af ( SMF 23327); 29°36.27'N 028°58.81'W, station 619, grab, depth 268.2 m, 17-Aug-2003, 96% ethanol, 1 af (ZSRO-P2292), formalin, 1 af (ZMH-P27542).

Additional material examined. Laonice appellöfi Söderström, 1920 : Holotype (cut into two halves in sagittal plane): Hjeltefjord, 60°32’N 4°34.5’E, coll. A. Appellöf, Stn 30. Right half dissected into 27 separate parapodia kept in four permanent slides (UPSZTY 2444, 347a–d); left half as af of 12 chaetigers and mf of 14 chaetigers ( ZMBN nr. 18649). Non-type material: Sognefjord S. for Raudberg lokt., 3-May-1966, 1248- 1228 m, 61°03’N 5°24’E, Stn S1, coll. T. Brattegard, det. K. Fauchald, 1 af, 1 mf ( ZMBN nr. 53367).

Laonice maciolekae Aguirrezabalaga & Ceberio, 2005 : Holotype: North Atlantic Ocean, Bay of Biscay, Capbreton Canyon, CB 88/DI-26, depth 984-1029 m, 8-Jul-1988, af of ~24 chaetigers (MNCN 16.01/9242). Paratype: same locality as holotype, 1 af of ~19 chaetigers (MNCN 16.01/9243).

Description (of specimens from the Atlantic seamounts, expedition DIVA 3). Specimens all anterior fragments, of 39 chaetigers at maximum, between 0.36–0.9 mm wide (measured at chaetiger 7), and 3–7 mm long. Palps lost in all specimens.

Prostomium bell-shaped, anteriorly broadly rounded, sometimes with small median incision, posteriorly extended into caruncle. Digitiform occipital antenna present at the posterior end of the prostomium. Prostomium of formalin fixed specimens with pair of rather large, reddish-brown eyes without clear demarcation, anteriorly to and not far from the occipital antenna, sometimes lost. In specimens originally fixed in ethanol two pairs of red eyes usually present, anterior pair as small dots in about the middle of the prostomium, posterior pair of eyes crescent shape, anterior to occipital antenna.

Peristomium separated from the prostomium, moderately developed. Nuchal organ as two long parallel ciliary bands along the middle of the dorsum, length of the nuchal organ correlates with specimen size, extending to chaetiger 13 in smallest specimens and up to chaetiger 19 in largest specimens.

FIGURE 15. Light microscopy and SEM studies of neuropodial hooded hooks of Laonice spp. based on type material: L. norgensis Sikorski, 2003 : A. Hook from 25th last chaetiger, anterior oblique view. B. Hook from posterior chaetiger, lateral view. C. Hook from middle body region, sheath partially removed, view from above. (A, C ZMUM-Pl 1818, holotype; B ZMUM-Pl 1837, paratype). L. maciolekae Aguirrezabalaga & Ceberio, 2005 : D. Hook from 22nd chaetiger, lateral oblique view ( MNCN 16.01/9242, holotype). L. appellöfi Söderström, 1920 : E. Hook from 26th chaetiger, anterior oblique view. F. Hooks at 25th chaetiger, lateral-oblique view (both UPSZTY 2444, 347d).—A, D, E with schematic illustration of species-specific hook arrangement as seen from anterior: large circle for main fang, smaller circles for apical teeth. Abbreviations in figure C: sh = sheath, at = apical teeth, mf = main fang. Scales: A, B, D 10 µm, C 3 µm, E, F 5 µm.

Dorsal branchiae from chaetiger 2, usually present throughout the body (until the end of the fragment); branchiae cirriform with long finely tapered tip, separate from notopodial lamellae throughout; on chaetiger 2 shorter than the notopodial postchaetal lobe of the same chaetiger, on chaetiger 3 and sometimes also 4 as long as notopodial lobe, afterwards longer than notopodial lobe.

Postchaetal lamellae as described and illustrated by Sikorski (2003, figure 16). Praechaetal lamellae in neuropodia low, discernable only with methyl green staining.

Interparapodial lateral pouches first present from chaetigers 8–10, usually present throughout until the end of the fragment. Low transversal dorsal ciliated crests present in chaetigers towards the end of the nuchal organ and thereafter; only observable in well-preserved specimens.

Capillary chaetae in some anterior chaetigers arranged in more than 2 rows in both rami: chaetiger 1 with 2 rows in both rami or irregular bundle of capillaries in notopodium, chaetigers 2–3 usually with 2 rows of capillaries in both rami, sometimes 3, chaetigers 4–8 with up to 4 rows, but mostly 3, chaetigers 9–11 with 2 rows in both rami, from chaetiger 12 neuropodium with 1 row and notopodium with 2 rows of capillaries, afterwards reduced to 1 row in both rami. Juvenile specimens with only 2 rows of capillaries in anterior chaetigers. Capillaries in anterior chaetigers granulated near the tips, with narrow sheaths, in middle and posterior chaetigers capillaries simple, without granulations and sheaths. Neuropodial hooded hooks first present from chaetiger 16–22 (start of hooks positively correlated with body width), 5–7 hooks per neuropodium, hooks bidentate with small apical teeth above main fang (Figure 15A–C), some hooks tridentate, either with pair of apical teeth above main fang or two apical teeth in tandem, hooks accompanied by simple capillaries. Sabre chaetae first present from 9–13, starting with 2–3 long, stout, granulated chaetae in inferiormost position, later single sabre chaeta present.

Pygidium not observed (all specimens are anterior fragments).

Pigmentation. Pigmentation visible in some specimens fixed in ethanol: inconspicuous greyish or brownish pigment on ventral side of anterior body half. Pigmentation usually completely lost in specimens fixed in formalin.

Methyl green staining pattern. Inconspicuous. Sometimes methyl green not rapidly removed from anterior part of prostomium after returning specimen to ethanol and thus causing the appearance of a horizontal band across the prostomium.

Ecology. Laonice norgensis was found on seamounts in coral and crushed shell gravel in about 250–300 m of depth during the DIVA 3 cruise. Sikorski (2003) found the species in 106–298 m of depth in sandy and mixed bottom.

Geographical distribution. Northern North Sea and on the Norwegian shelf north to 63°30’ N, Great and Little Meteor Seamounts, Irving Seamount, Hyères Seamount, Turkish coast of the Aegean Sea (Mediterranean).

Remarks. The most conspicuous character of L. norgensis is the presence of more than two rows of capillaries in the parapodia of anterior chaetigers. Among Laonice spp. this character is also described for L. appellöfi Söderström, 1920 , L. wedellia Blake, 1983 , L. blakei Sikorski & Jirkov, 1988 [in Sikorski et al. 1988], L. nuchala Blake, 1996 , L. maciolekae Aguirrezabalaga & Ceberio, 2005 , and L. pectinata Greaves , Meißner & Wilson, 2011. Laonice nuchala , reported from California, differs from all these species by possessing a triple nuchal organ. Laonice wedellia was reported from Antarctic and subantarctic waters ( Blake 1983), from southern Brazil ( Radashevsky & Lana, 2009), and specimens determined as L. cf. wedellia were found in the Indian Ocean off the coast of Western Australia ( Greaves et al. 2011). The species has up to three pairs of eyes, bi- and tridentate hooded hooks (in the case of the latter, the apical teeth are arranged in tandem, see Greaves et al. 2011, figure 11) from chaetiger 16–25, pouches starting between chaetigers 8–11 ( Blake 1983) or 6–11 ( Radashevsky & Lana 2009), and a nuchal organ extending to chaetigers 12–20. Laonice wedellia was discussed to be in need for reassessment by Radashevsky & Lana (2009) and Greaves et al. (2011). Laonice blakei and L. pectinata differ from other Laonice spp. in this group by the presence of multidentate hooded hooks in posterior neuropodia: 4–6 apical teeth above the main fang are present in hooks of L. blakei , whereas many accessory teeth and no discernable main fang have been observed in L. pectinata .

The remaining two species, L. appellöfi and L. maciolekae , are very similar to L. norgensis . In L. appellöfi and L. maciolekae the nuchal organs extend to chaetigers 8–13 or 14 opposed to an extension to chaetigers 15–28 in L. norgensis . Between L. appellöfi and L. maciolekae no differences can be observed regarding the start of interparapodial pouches, the start of sabre chaetae, and the start of neuropodial hooks. In L. norgensis the range of these three characters only partially overlaps with the two previous species but is usually shifted to slightly more posterior chaetigers. In the description of L. maciolekae by Aguirrezabalaga & Ceberio (2005) it is noted that the prostomial shape, the number of eyes and the number of apical teeth (quadridentate in L. maciolekae versus tridentate in L. appellöfi ) would be different from that in L. appellöfi . Since the authors did not examine the type material of L. appellöfi their information was probably based on the re-description of the types by Sikorski (2003). However, our examination of the type material revealed that both species possess quadridentate hooks (Figure 15D–F) and that the prostomial shape does not distinctly differ. The number of eyes is generally not accepted to be a reliable character (particularly in preserved material) and cannot be sufficiently observed in the type material. For this reason we regard L. maciolekae Aguirrezabalaga & Ceberio, 2005 to be a junior synonym of L. appellöfi Söderström, 1920 and formally synonymise the two species.

In the course of this study we also examined the type material of L. norgensis and studied the neuropodial hooks of the holotype and one paratype. According to the original description by Sikorski (2003) hooks were expected to be tridentate with a pair of apical teeth above the main fang. We dissected several parapodia from the holotype and from one paratype for light microscopy and SEM studies and found only bidentate hooks with one apical tooth above the main fang (Figure 15A–C). Dagli et al. (2011) also observed bidentate hooks in specimens from the Turkish coast of the Aegean Sea. The observation of hooks is difficult in Laonice due to the small size of the apical teeth and also hampered by the presence of the hood. The opening of the hood is usually exactly there where the apical teeth are located. Thus we assume that Sikorski (2003) was mistaken by the presence of the hood and erroneously stated the presence of two apical teeth instead of one. Interestingly, specimens from the Atlantic seamounts here assigned to L. norgensis exhibited mainly bidentate hooks but some single hooks possessed a “double” apical tooth (two tips in tandem position). Despite this observation we assign our specimens from the seamounts to L. norgensis for the time being. The availability of sequence data from other localities (sequences of COI and 18S gene fragments are presented with this study for specimens from the seamounts) will extend the discussion and might imply alternative conclusions.