SPHAERODORIDS (POLYCHAETA, SPHAERODORIDAE) FROM THE CONTINENTAL MARGIN OFF THE NW IBERIAN PENINSULA, WITH FIRST RECORD OF SPHAERODOROPSIS SIBUETAE AND S. AMOUREUXI SINCE THE ORIGINAL DESCRIPTION

J. Moreira, Y. Lucas & J. Parapar. 2011. Sphaerodorids (Polychaeta, Sphaerodoridae) from the continental margin off NW Iberian Peninsula, with first record of Sphaerodoropsis sibuetae and S. amoureuxi since original description. Graellsia, 67(1): 23-33. Knowledge of the Sphaerodoridae (Annelida, Polychaeta) is still scarce in many parts of the world, including deep-sea waters around the Iberian Peninsula. Study of samples collected between 100-2000 m depth during several oceanographic expeditions done at the Galician Continental Margin (NW Iberian Peninsula) from 2003 to 2009 revealed the presence of six species of sphaerodorid polychaetes. Two species are reported for the first time since the original description, namely Sphaerodoropsis sibuetae Desbruyères, 1980 and S. amoureuxi Aguirrezabalaga & Ceberio, 2005; these records extend the known distribution of these species to the West of the Atlantic Ocean. All species collected are reported including distribution and ecological data as well as a key to all species known from the Iberian Peninsula.


Introduction
Sphaerodorids (Polychaeta, Sphaerodoridae) are small-sized polychaetes mostly distinguishable by having tubercles and papillae on the dorsum, sometimes arranged in a definite, non-random pattern (Fauchald, 1974).Systematics of the Sphaerodoridae have traditionally been confusing and problematic (Lützen, 1961;Fauchald, 1974) and their position within the Phyllodocida has not been resolved yet (Aguado & Rouse, 2006).In addition, there is a need for a full revision of the taxonomic status of the genera, mostly Sphaerodoropsis Hartman & Fauchald, 1971(Borowski, 1994;Aguado & Rouse, 2006).Indeed, descriptions of many species are inaccurate and brief, not giving much relevant information of characters such as the distribution of body papillae and the shape of the proventricle or whether there are special structures on the parapodia and spinulation on chaetae (but see, for example, Kudenov, 1987b;Moreira et al., 2004;Aguado & Rouse, 2006;Böggemann, 2009;Reuscher & Fiege, 2011).On the other hand, the taxonomy, distribution, biology and ecology of sphaerodorids are still poorly known in many geographic areas; this is related, in part, to the fact that they can easily be overlooked due to their small size when using mesh of coarse size or during the processing of samples (Borowski, 1994).Recent papers have, however, shown that sphaerodorids can be collected in numbers in soft bottoms when using sampling gear such as the Epibenthic Sledge of Brenke (2005) or the Macer-GIROQ Epibenthic Sledge (see Moreira & Parapar, 2007, 2011;Schüller & Ebbe, 2007;Böggemann, 2009;Reuscher & Fiege, 2011).
To date, five sphaerodorid genera have been reported from the Iberian Peninsula, comprising ten species in total (Campoy, 1982;Sardá, 1983Sardá, , 1987;;Aguirrezabalaga & Ceberio, 2005;Moreira et al., 2004;Moreira & Parapar, 2007).In general, many records of sphaerodorids around the Iberian Peninsula come from intertidal or shallow-water areas.In the last years, examination of samples from the continental shelf and deep-sea areas have revealed the presence of several new taxa and provided new records as well (Aguirrezabalaga & Ceberio, 2005;Moreira & Parapar, 2007).Thus, Aguirrezabalaga & Ceberio (2005)  Examination of further sphaerodorid material collected during 2003, 2004, 2008 and 2009 cruises along the Galician coast (projects DIVA-Artabria I & II and Vertidos 2004), at depths between 100-2000 m, has revealed the presence of six sphaerodorid species.These include two species of Sphaerodoropsis which had not been reported after their original description, namely Sphaerodoropsis sibuetae Desbruyères, 1980 andS. amoureuxi Aguirrezabalaga &Ceberio, 2005.In this paper, specimens of the two aforementioned taxa are described and figured and a full list of all sphaerodorids collected is provided, also including the available ecological data.

Material and Methods
The material examined was obtained during the following expeditions: DIVA- Artabria I 2003(September 2003), Vertidos 2004(September 2004), DIVA-Artabria II 2008(September 2008) and DIVA-Artabria II 2009 (October 2009), conducted along the western Galician Continental Margin, from the Ártabro Gulf in the North to off the Ria de Vigo in the South.Benthic samples were taken at depths of 100-2000 m (Table 1).A total of 498 sphaerodorid specimens were collected, mostly by means of an Epibenthic Sledge (EBS; Brenke, 2005); additional specimens were obtained by means of a Naturalist Dredge (DRN).Sampling methodology with both sampling gears and pro-cessing of samples is described in detail in Parapar & Moreira (2009).

Family
Genus Sphaerodoridium Lützen, 1961 Sphaerodoridium fauchaldi Hartmann-Schröder, 1993  DISTRIBUTION AND ECOLOGY.North Sea (Hartmann-Schröder, 1993), Capbreton Canyon, Bay of Biscay (Aguirrezabalaga & Ceberio 2005), Ártabro Gulf (Moreira & Parapar, 2007).Examination of samples collected during the expeditions reported here indicates that this species is frequent in sandy-muddy sediments along the Galician western continental shelf, from the Ártabro Gulf in the north to off the Ría de Vigo in the South, at depths of 102-495 m.
Dorsal macrotubercles sessile, spherical to pearshaped.Two macrotubercles on chaetiger 1; from chaetiger 2 backwards four macrotubercles on each chaetiger in a transverse row.Dorsal body surface covered with rounded papillae arranged in four irregular transversal rows per chaetiger.Ventral body surface covered with papillae similar to those on dorsal surfaces, arranged in about five irregular transversal rows per chaetiger.
REMARKS.The specimen collected in the Galician Continental Margin agrees well with the original description by Desbruyères (1980), mostly regarding the number and arrangement of the parapodial papillae.In fact, the number of parapodial papillae of S.  Moreira, Lucas & Parapar sibuetae is much higher than that of the other eastern Atlantic species of Sphaerodoropsis provided with four dorsal macrotubercles per segment, namely S. parva (Ehlers, 1913) sensu Desbruyères, 1980, S. laureci Desbruyères, 1980, S. longipapillata Desbruyères, 1980, S. martinae Desbruyères, 1980, S. stellifer Aguirrezabalaga & Ceberio, 2005 and S. artabrensis Moreira & Parapar, 2007.In addition, S. laureci and S. martinae differ from the aforementioned species in the particular shape of their macrotubercles; S. stellifer has body papillae which are star-shaped distally instead of rounded; the parapodia of S. longipapillata bear one long, erect papilla just behind the prechaetal lobe.On the other hand, the presence of S. parva in the north-east Atlantic should be reviewed (Desbruyères, 1980;Reuscher & Fiege, 2011).This species was originally described from Antarctica and later reported from other localities in the Southern Ocean.However, descriptions of this species differ in the number and arrangement of parapodial papillae (e.g.Fauchald, 1974;Desbruyères, 1980;Hartmann-Schröder & Rosenfeldt, 1988) which suggests that perhaps those records might actually refer to several similar species.DISTRIBUTION AND ECOLOGY.Banc Le Danois, Bay of Biscay (Desbruyères, 1980), continental slope off Galicia (NW Iberian Peninsula) (this work).Muddy sediments, 1913-2034 m.This record extends the known distribution of S. sibuetae to the West.Aguirrezabalaga & Ceberio, 2005 (Fig. 2) DESCRIPTION.Three complete specimens, measuring 1.1.-3.5 mm long, 0.2-0.5 mm wide (excluding parapodia), with 17-22 chaetigers.Prostomium anteriorly rounded, somewhat contracted in specimens examined (Fig. 2A-B).Eyes not observed.Median antenna short, distally rounded.Dorsal antenniform papillae not distinguished, probably contracted.One pair of intermediate antennae and one pair of palps, digitiform, longer than median antenna, provided with papillar spurs (palps with 4-5 spurs; intermediate antennae with up to 6).Several papillae encircled by lateral paired prosto-mial appendages.Peristomial cirri digitiform, enlarged at base, with 4-5 papillar spurs; about 4-6 papillae dorsally to peristomial cirri, digitiform or apparently contracted.
REMARKS.The examined specimens correspond well to the original description of the species, mostly regarding appearance of lateral prostomial appendages and parapodia, and number and distribution of dorsal macrotubercles and papillae.The only minor differences among specimens from the NW Iberian Peninsula and those of the type series were the possession of one postchaetal lobe instead of 1-2 and 2 parapodial papillae instead of 2-4, respectively.In addition, the dorsal antenniform papillae and a third pygidial papilla were not clearly distinguished in Galician specimens; this could, however, be due to state of contraction of the examined specimens.The only species of the genus previously reported from the area which is provided with more than 4 macrotubercles per segment arranged in a single transversal row is Sphaerodoropsis minuta (Webster & Benedict, 1887).This species may easily be distinguished from S. amoureuxi by bearing between 10-14 macrotubercles per segment.DISTRIBUTION AND ECOLOGY.Capbreton Canyon, Bay of Biscay (Aguirrezabalaga & Ceberio, 2005), Galician western continental shelf (this work).Soft bottoms, 102-1029 m.This record extends its known distribution to the West.Moreira & Parapar, 2007 Sphaerodoropsis artabrensis Moreira & Parapar, 2007. Cah. Biol. Mar., 48 DISTRIBUTION AND ECOLOGY.This recently described species shows a pattern of distribution similar to that of S. fauchaldi (see above); both species were frequently found co-occurring in the same samples (9 out of 14) and constituting 97% of sphaerodorid specimens collected by means of the EBS.Sandy-muddy sediments, 148-264 m.

Discussion
To date, 11 species of sphaerodorids have been found off the Iberian Peninsula, including those reported here: S. gracile, E. abyssorum, Sphaerodoridium claparedii (Greeff, 1866), S. fauchaldi, S. minuta, S. sibuetae, S. garciaalvarezi Moreira, Cacabelos &Troncoso, 2004, S. amoureuxi, S. stellifer, S. artabrensis andEuritmia hamulisetosa Sardá, 1987.Of these species, S. gracile, E. abyssorum, S. claparedii and S. minuta are well distributed along European waters, from Arctic or Subarctic latitudes to the Mediterranean Sea; there are also records from other areas but some of those should be re-evaluated.For instance, reports of S. gracile from the southern Ocean turned out to actually refer to other, new taxa (Fauchald, 1974) and specimens initially identified as S. minuta from Alaska represented a new species (Kudenov, 1987a).In addition, S. gracile has been cited on a wide variety of substrata and at a range of depths, from the intertidal to the deep sea.It is also likely that records of these species from any given substratum or depth might refer to similar but different taxa, only distinguishable externally according to subtle characters which might have been overlooked in the past.In fact, recent work has shown that careful examination of shape and arrangement of parapodial and body papillae may constitute a reliable character to separate close species (see Kudenov, 1987b;Moreira et al., 2004;Reuscher & Fiege, 2011).For example, the second described European species of Ephesiella, i.e.E. ramosae Desbruyères, 1980 from deep-sea areas of the Bay of Biscay, may be distinguished from E. abyssorum and other Ephesiella species according to the number and disposition of parapodial papillae.Some sphaerodorid species seem to be restricted to a range of depths and/or substrata.For example, S. fauchaldi has only been found on soft bottoms at depths of between 100-500 m, in the North Sea, the Bay of Biscay and the Iberian Peninsula; Sphaerodoropsis artabrensis also shows a similar pattern of distribution (Fig. 3).On the other hand, S. stellifer and S. amoureuxi were originally described from soft bottoms at about 1000 m depth; the latter has also been found at the Galician continental shelf on soft bottoms but at shallower depths (102-264 m).Furthermore, the few known specimens of S. sibuetae were found at deeper bottoms than the aforementioned species (about 2000 m depth).Other species seem to be typical from subtidal areas, such as S. garciaalvarezi, which has been reported from soft bottoms not deeper than 30 m at the Galician rías (Moreira et al., 2004;Cacabelos et al., 2008).In the same way, E. hamulisetosa seems to be distributed from the Strait of Gibraltar to the northeastern Mediterranean coast of the Iberian Peninsula and has only been found at the intertidal zone and shallow subtidal (Martín, 1987;Sardá, 1987).
The sphaerodorid fauna from the soft bottoms of the Galician continental shelf (100-600 m depth) is dominated by S. fauchaldi and S. artabrensis; other species such as S. amoureuxi, S. gracile and E. abyssorum are less common and abundant at those depths and substrata, according to the results of sampling by means of the EBS.It can be expected that further sampling at deeper bottoms may reveal the presence of other deep-sea species previously reported from the Bay of Biscay, such as Clavodorum fauchaldi Desbruyères, 1980, E. ramosae, S. chardyi Desbruyères, 1980, S. laureci, S. longipapillata andS. martinae.In fact, S. chardyi has recently been reported from the southeastern Atlantic (Böggemann, 2009).Nevertheless, the actual distribution and ecological features of the aforementioned species cannot be properly assessed until more data are available from different substrata and depths.This will need an adequate processing of samples and the use of meshes finer than 1 mm due to the size of many of these polychaetes (Fauchald, 1974).Furthermore, an effective quantitative sampling in soft bottoms, whether they are in shallow or deep-sea areas, will also require the use of the appropriate sampling gear, such as the Epibenthic Sledge of Brenke (2005), as was demonstrated by Böggemann (2009) and Parapar & Moreira (2009).
describe two new species of Sphaerodoropsis from the Capbreton Canyon and provide the first record of Sphaerodoridium fauchaldi Hartmann-Schröder, 1993 since the original description.Later, Moreira & Parapar (2007) report again S. fauchaldi from the continental shelf off Galicia and further describe a new species of Sphaerodoropsis, both collected during the DIVA-Artabria I 2002 expedition.