INTRODUCTION
Sphaerodoridae are mostly small benthic polychaetes with macrotubercles and papillae scattered across their body. They are commonly considered as belonging to Phyllodocida (Rouse & Fauchald, Reference Rouse and Fauchald1997; Pleijel, Reference Pleijel, Rouse and Pleijel2001; Aguado & Rouse, Reference Aguado and Rouse2006). The position of the family within Phyllodocida, however, is uncertain (Aguado & Rouse, Reference Aguado and Rouse2006). The present definition of the genera is based on the review of Fauchald (Reference Fauchald1974) who distinguished the various genera by the shape of macrotubercles and falcigers. Although the generic definitions are accepted by most authors, a plea for a revision, especially for the genus Sphaerodoropsis Hartman & Fauchald, Reference Hartman and Fauchald1971, has been expressed (Borowski, Reference Borowski1994). With 47 species described to date, Sphaerodoropsis is the most speciose of the sphaerodorid genera. As a first step towards a revision, Borowski (Reference Borowski1994) divided the genus into four groups based on number and arrangement of macrotubercles, emphasizing the heterogeneity of the genus. Group 1 is defined as having 1 transverse row with 4 macrotubercles per segment, Group 2 as having 1 transverse row with more than 4 macrotubercles per segment, Group 3 as having 2 transverse rows, an anterior row that is in line with the parapodia (herein referred to as segmental row) and a posterior row that is situated in between the segmental rows (herein referred to as inter-segmental row), and Group 4 as having macrotubercles randomly scattered over the dorsum, resulting in 3–4 transverse rows per segment.
The genus is found worldwide and is well presented both in Arctic and Antarctic waters. In our study, samples from the deep sub-Antarctic south-west Pacific, i.e. the Challenger Plateau in the Tasman Sea and the Campbell Plateau south-east of New Zealand, from depths between 924 and 1526 m, were examined.
In his review of Sphaerodoridae, Fauchald (Reference Fauchald1974) presented a key for Sphaerodoropsis comprising 20 species. Meanwhile, many new species have been described for this genus with S. solis sp. nov. as the 47th species. Therefore, it seemed appropriate to present an updated key for the genus Sphaerodoropsis.
MATERIALS AND METHODS
The specimens examined in this study have been collected during cruise So 136 (TASQWA) (Thiede et al., Reference Thiede, Nees, Altenbach, Andresen, Findlay, Hill, Howard, Jellinek, Jurkschat, Laurent, v.d. Lingen, Müller, Neil, Probert, Rehder, Reijmer, Rendle, Roth, Rueggeberg, Runze, Schulz, Schumann, Sturm, Swanson and Willamowski1999) with the German research vessel RV ‘Sonne’ to the Challenger Plateau and the Campbell Plateau in the south-west Pacific. Samples were taken using an epibenthic sledge (EBS) and sieved on board. Specimens were fixed in 10% formaldehyde–seawater solution and later transferred to 70% ethanol. Preserved specimens were examined using the stereo microscopes Wild Heerbrugg M5 and Zeiss Stemi 2000-C and the compound microscope Olympus BH-2. Drawings were made using a camera lucida and finalized according to the method described by Coleman (Reference Coleman2003). Schematic illustrations were made using Adobe Illustrator 10.0. Illustrations were assembled using Adobe Photoshop CS2.
TYPE SPECIES
Sphaerodoropsis sphaerulifer (Moore, Reference Moore1909)
GENERIC DIAGNOSIS (FROM AGUADO & ROUSE Reference Aguado and Rouse2006)
Four or more rows of dorsal sessile macrotubercles without terminal papillae. Anterior end with a median antenna and a pair of lateral antennae. A pair of ventral palps, similar to antennae present. A pair of papillae similar in length to antennae and palps may also be present. Chaetae compound.
REMARKS
The interpretation of the anterior appendages by Aguado & Rouse (Reference Aguado and Rouse2006) as homologous to those of other taxa considered as belonging to Phyllodocida is in line with Pleijel (Reference Pleijel, Rouse and Pleijel2001) who considered the inferior lateral antennae as palps. However, studies of their innervation are contradictory (Orrhage, Reference Orrhage1990). Aguado & Rouse (Reference Aguado and Rouse2006) also argue that the additional 3rd pair of lateral antennae that occur in some of the species are prolonged papillae, although antennae differ histologically from papillae (Fauchald, Reference Fauchald1974). Albeit further research is needed to confirm both hypotheses, we follow Aguado & Rouse (Reference Aguado and Rouse2006) and refer to the ‘inferior lateral antennae’ as palps and the ‘3rd pair of antennae’, if present, as antenna-like papillae.
Sphaerodoropsis arctowskyensis Hartmann-Schröder & Rosenfeldt Reference Hartmann-Schröder and Rosenfeldt1988: 49–50, figures 40–44.—Borowski, Reference Borowski1994: table 2.—Moreira et al., Reference Moreira, Cacabelos and Troncoso2004: 999–1000, figure 4c, f.
EXAMINED SPECIMENS
1 male specimen (tubercle-like structure on chaetiger 6 absent), complete. (So 136, Station 2 EBS; south-west Pacific, Tasman Sea, Challenger Plateau, 42°17.99′S 170°00.00E; 937–945 m) (SMF 17639). Collected by T. Jellinek, 17 October 1998. 1 male specimen (tubercle-like structure on chaetiger 6 absent), complete. (So 136, Station 45 EBS; south-west Pacific, East Campbell Plateau, 50°07.77′S 174°40.65′E; 924–927 m) (SMF 17635). Collected by T. Jellinek, 23–24 October 1998.
DIAGNOSIS
1 pair of lateral antennae, 1 median antenna, 1 pair of palps. 2 transverse rows of macrotubercles per segment; segmental row with 6 macrotubercles, inter-segmental row with 7 macrotubercles. Lateralmost macrotubercles somewhat smaller, lacking in first two and last two inter-segmental rows. Parapodia with prechaetal lobe and ventral cirrus, postchaetal lobe lacking. 6 dorsal and 10 ventral papillae per segment in a non-random pattern (see Moreira et al., Reference Moreira, Cacabelos and Troncoso2004 for details). Females with tubercle-like structure ventral to parapodia of chaetiger 6. Blades of falcigers slightly spinulated.
REMARKS
Sphaerodoropsis arctowskyensis has been extensively studied and compared by Moreira et al. (Reference Moreira, Cacabelos and Troncoso2004). Both specimens studied here are males, since they lack a ventrolateral tubercle in chaetiger 6 and sperm is visible in the posterior part of the smaller specimen (SMF 17635). The specimen from the East Campbell Plateau is completely translucent showing its internal anatomy. One pair of nephridia is present, opening into the inflated ventral cirri of chaetiger 6.
DISTRIBUTION
Antarctic: Bransfield Strait, King George Island; 50–458 m (Hartmann-Schröder & Rosenfeldt, Reference Hartmann-Schröder and Rosenfeldt1988). Newly recorded from the south-west Pacific: East Campbell Plateau and Challenger Plateau, 924–945 m.
Sphaerodorum parvum Ehlers Reference Ehlers1913: 504–507, pl. 35, figures 7–12.
Sphaerodoropsis parva Fauchald Reference Fauchald1974: 276, figure 3.8 & 3.9.—Hartmann-Schröder & Rosenfeldt, Reference Hartmann-Schröder and Rosenfeldt1988: 48–49, figure 39.—Borowski, Reference Borowski1994: table 2.—Aguado & Rouse, Reference Aguado and Rouse2006: table 1.
EXAMINED SPECIMENS
6 specimens, complete. (So 136, Station 2 EBS; south-west Pacific, Tasman Sea, Challenger Plateau 42°17.99′S 170°00.00′E; 937–945 m) (SMF 17638). Collected by T. Jellinek, 17 October 1998. 1 specimen, complete. (So 136, Station 12 EBS; south-west Pacific, Tasman Sea, Challenger Plateau, 43°25.15′S 167°50.15′ E; 1523–1526 m) (SMF 17640). Collected by T. Jellinek, 18 October 1998. 21 specimens, complete. (So 136, Station 45 EBS; south-west Pacific, East Campbell Plateau, 50°07.77′S 174°40.65′E; 924–927 m) (SMF 17641). Collected by T. Jellinek, 23–24 October 1998.
DIAGNOSIS
1 pair of lateral antennae, 1 median antenna, 1 pair of palps, and one pair of antenna-like papillae. 1 dorsal transverse row of 4 macrotubercles per segment. Parapodia with prechaetal lobe and ventral cirrus, postchaetal lobe lacking. Numerous dorsal and ventral papillae, randomly distributed. Blades of falcigers spinulated.
REMARKS
A record from the north-east Atlantic (Desbruyères, Reference Desbruyères1980: Plateau de Meriadzek, 2906 m) is considered doubtful since Sphaerodoropsis parva appears to have an Antarctic to sub-Antarctic distribution (see also Aguado & Rouse, Reference Aguado and Rouse2006).
DISTRIBUTION
Antarctic, sub-Antarctic Islands, Falkland Islands, southern South America, Australia; 56–4758 m (Fauchald, Reference Fauchald1974; Hartmann-Schröder & Rosenfeldt, Reference Hartmann-Schröder and Rosenfeldt1988). Newly recorded from the south-west Pacific: East Campbell Plateau and Challenger Plateau, 924–1526 m.
Sphaerodoropsis solis sp. nov. holotype (SMF 17636), lateral view.
Sphaerodoropsis solis sp. nov. (a–e: holotype, SMF 17636; f: paratype, SMF 17637). (a) Anterior end, dorsal view; (b) anterior end, ventral view; (c) parapodium, anterolateral view; (d) pygidium, ventral view; (e) ventral macrotubercle, lateral view; (f) chaetigers 5–8 (from left to right), dorsolateral view, with additional tubercle (arrow) of female specimen (paratype). DA, dorsal anal cirrus; LA, lateral antenna; M, mouth; MA, median antenna; OS, orange spot; P, palps; PC, peristomial cirrus; PL, prechaetal lobe; PP, parapodial papilla; VA, ventral anal cirrus; VC, ventral cirrus.
Sphaerodoropsis solis sp. nov. (a) Scheme of arrangement of dorsal macrotubercles, chaetigers 1–3 and 20–22, dorsal view; (b) scheme of arrangement of ventral macrotubercles and papillae, chaetigers 1–3 and 20–22, ventral view.
TYPE MATERIAL
Holotype: male (tubercle-like structure of chaetiger 6 absent) 4 mm, complete. (So 136, Station 12 EBS; south-west Pacific, Tasman Sea, Challenger Plateau, 43°25.15′S 167°50.15′E; 1523–1526 m) (SMF 17636). Collected by T. Jellinek, 18 October 1998.
Paratype: female (tubercle-like structure of chaetiger 6 present) 4 mm, complete. (So 136, Station 2 EBS; south-west Pacific, Tasman Sea, Challenger Plateau, 42°17.99′S 170°00.00′E; 937–945 m) (SMF 17637). Collected by T. Jellinek, 17 October 1998.
DIAGNOSIS
2 transverse rows of macrotubercles per segment; segmental rows with 6 macrotubercles, inter-segmental rows with 7 macrotubercles. Lateralmost macrotubercles somewhat smaller, lacking in first two and last two inter-segmental rows. 2 rows of ventrolateral, inter-segmental macrotubercles present, of same size as lateralmost dorsal macrotubercles, lacking in first and last segment. 6 ventral papillae per segment in a non-random pattern, dorsal papillae lacking. Females with tubercle-like structure ventral to parapodia. Blades of falcigers not spinulated.
DESCRIPTION
Holotype male, 4 mm long and 0.7 mm wide. Body grub-like, with 22 chaetigers (Figure 1). Anterior end bluntly rounded. Prostomium fused to peristomium. Eyes absent. One pair of lateral antennae and one median antenna present (Figure 2a). Lateral antennae slender, digitiform with broadened bases and blunt ends. Median antenna short and broad, spherical. One pair of palps and one pair of peristomial cirri, each similar to lateral antennae in shape. Mouth opening encircled by lip-like ridge. Numerous prostomial and peristomial papillae (Figure 2a, b). Parapodia uniramous with ventral cirrus and a slightly shorter prechaetal lobe (Figure 2c). Postchaetal lobe absent. Parapodia with one papilla on anterior face. Composite falcigers numbering up to ten per fascicle. Blades of chaetae straight or slightly convex with curved tips. No spinulation visible in light microscope, even under highest magnification (1000×). Pygidium with one digitiform ventral cirrus and two spherical dorsolateral cirri, reminiscent of macrotubercles, with a single orange spot each (Figure 2d). Three papillae between spherical anal cirri. Dorsum densely covered with sessile macrotubercles, spherical in shape, without terminal papilla (Figure 2e). Macrotubercles basally filled with brown granulate. Few of them with single orange spot. Macrotubercles arranged in two alternating (segmental and inter-segmental) transverse rows, per segment, resulting in a typical zigzag pattern (Figure 3a). Segmental rows with six dorsal macrotubercles per segment. Inter-segmental rows with five dorsal tubercles on first two and last two chaetigers and seven dorsal tubercles on intermediate chaetigers (Figure 3a). Lateralmost macrotubercles slightly smaller than remaining ones. All chaetigers, except for first and last one, with one additional ventrolateral macrotubercle on each side. Macrotubercles of ventral side situated in line with inter-segmental rows of dorsal tubercles. Ventral macrotubercles of same size as lateralmost ones of dorsal inter-segmental rows and with more brown pigment than dorsal ones, but without distinctive differences visible under compound microscope. Overall, both first and last chaetiger with 11 dorsal macrotubercles, arranged 6 + 5, both second and second to last chaetiger with same set of dorsal macrotubercles plus 2 ventrolateral ones, remaining segments with 13 dorsal macrotubercles, arranged 6 + 7, plus 2 ventrolateral ones. Dorsal papillae absent. Six ventral papillae per segment, consistently arranged in a non-random pattern (Figure 3b).
VARIATION
Paratype 4 mm long and 0.4 mm wide; specimen presumably female with an additional pair of tubercles situated dorsally to ventrolateral tubercles of chaetiger 6. Additional tubercles with distal opening (Figure 2f).
REMARKS
With its high number of macrotubercles in two transverse rows per segment, arranged in a zigzag pattern, this new species belongs to Group 3 sensu Borowski (Reference Borowski1994). Within this group Sphaerodoropsis arctowskyensis, S. bisphaeroserialis and S. garciaalvarezi, extensively studied and compared by Moreira et al. (Reference Moreira, Cacabelos and Troncoso2004), are morphologically similar to S. solis sp. nov. according to number and arrangement of dorsal macrotubercles and shape of parapodia. Additionally, S. solis sp. nov. shows the same sexual dimorphism with respect to the ventrolateral tubercles of chaetiger 6 in the female specimen as shown by Moreira et al. (Reference Moreira, Cacabelos and Troncoso2004) for the three related species mentioned above. Sphaerodoropsis solis sp. nov. can be distinguished from these species by the presence of two regular, longitudinal rows of ventrolateral macrotubercles, the different arrangement of ventral papillae, and the lack of dorsal papillae. The only other species of this genus showing regular, longitudinal rows of ventral macrotubercles are S. malayana (Augener, Reference Augener1934) and S. spissum (Benham, Reference Benham1921). While S. malayana has only four longitudinal rows of dorsal, and one median row of ventral macrotubercles, S. spissum has five rows of ventral macrotubercles and its parapodia lack ventral cirri.
ETYMOLOGY
The species is named after the research vessel RV ‘Sonne’.
DISTRIBUTION
South-west Pacific: Challenger Plateau, 937–1526 m.
KEY TO SPECIES OF SPHAERODOROPSIS
1. Ventral macrotubercles present………2
– Ventral macrotubercles absent………4
2. 4 longitudinal dorsal rows and 1 longitudinal ventral row of macrotubercles present………S. malayana (Augener, Reference Augener1934)
– More than 4 longitudinal dorsal rows and more than 1 longitudinal ventral row of macrotubercles present………3
3. 5 longitudinal rows of ventral macrotubercles present………S. spissum (Benham, Reference Benham1921)
– 2 longitudinal rows of ventral macrotubercles present………S. solis sp. nov.
4. 4 dorsal macrotubercles per segment, arranged in 1 transverse row………5
– More than 4 dorsal macrotubercles per segment, arranged in 1–4 transverse rows………24
5. First chaetiger with 4 macrotuberclesS………vittori Kudenov, Reference Kudenov1987b
– First chaetiger with 2 macrotubercles………6
6. Parapodia with dorsal cirri………S. longiparapodium………(Katzmann, Reference Katzmann1973)
– Parapodia without dorsal cirri………7
7. Prechaetal lobe present………8
– Prechaetal lobe absent………21
8. Postchaetal lobe present………9
– Postchaetal lobe absent………10
9. 1 pair of antenna-like papillae present………S. longipalpa Hartman & Fauchald Reference Hartman and Fauchald1971
– Antenna-like papillae absent………S. furca Fauchald, Reference Fauchald1974
10. Papillae on parapodia present………11
– Papillae on parapodia absent………20
11. 1 pair of antenna-like papillae present………12
– Antenna-like papillae absent………17
12. Macrotubercles with distal invaginations………S. discolis Borowski, Reference Borowski1994
– Macrotubercles without distal invaginations………13
13. Median antenna long and slender, similar to lateral antennae………S. anae Aguado & Rouse, Reference Aguado and Rouse2006
– Median antenna short and conical………14
14. Parapodia with only 2 big papillae, located on superior edge………S. triplicata Fauchald, Reference Fauchald1974
– Parapodia with more than two papillae………15
15. Median dorsal macrotubercles larger than lateral ones………S. philippi (Fauvel, Reference Fauvel1911)
– Median and lateral macrotubercles of same size………16
16. Parapodia with 1 papilla on each face and two papillae on superior edge………S. biserialis (Berkeley & Berkeley, Reference Berkeley and Berkeley1944)
– Parapodia with 10–15 papillae………S. sibuetae Desbruyères, Reference Desbruyères1980
17. Macrotubercles with distal invaginations………18
– Macrotubercles without distal invaginations………19
18. Median antenna bifurcate………S. laureci………Desbruyères, Reference Desbruyères1980
– Median antenna not bifurcate………S. stellifer Aguirrezabalaga & Ceberio Reference Aguirrezabalaga and Ceberio2005
19. Antenna-like papillae shorter than lateral antennae and palps………S. parva (Ehlers, Reference Ehlers1913)
– Antenna-like papillae, lateral antennae, and palps of same length………S. longipapillata Desbruyères, Reference Desbruyères1980
20. Median macrotubercles larger than lateral ones; aciculae straight………S. exmouthensis Hartmann-Schröder in Hartmann-Schröder & Hartmann, Reference Hartmann-Schröder and Hartmann1981
– Median and lateral macrotubercles of same size; aciculae curved………S. martinae Desbruyères, Reference Desbruyères1980
21. Papillae on parapodia and ventrum present………22
– Papillae on parapodia and ventrum absent………23
22. Postchatal lobe present………S. elegans Hartman & Fauchald, Reference Hartman and Fauchald1971
– Postchaetal lobe absent………S. corrugata Hartman & Fauchald, Reference Hartman and Fauchald1971
23. Papillae on prostomium present; postchatal lobe present………S. laevis Fauchald, Reference Fauchald1974
– Papillae on prostomium absent; postchaetal lobe absent………S. simplex, Amoureux, Rullier & Fishelson, Reference Amoureux, Rullier and Fishelson1978
24. Dorsal macrotubercles in one transverse row per segment………25
– Dorsal macrotubercles in two or more transverse rows per segment………34
25. One or two postchaetal lobes present………26
– Postchaetal lobe absent………32
26. One postchaetal lobe present………27
– Two postchaetal lobes present………30
27. Median segments with 10 macrotubercles………S. aestuarium Averincev, Reference Averincev1990
– All segments with less than 10 macrotubercles………28
28. 24–30 dorsal papillae per segment………S. amoureuxi Aguirrezabalaga & Ceberio Reference Aguirrezabalaga and Ceberio2005
– 15 or less dorsal papillae per segment………29
29. 6–8 macrotubercles per segment; 13–15 dorsal papillae per segment………S. uzintunensis Kudenov, Reference Kudenov1987a
– 8–9 macrotubercles per segment; 11 dorsal papillae per segment………S. katchemakensis Kudenov, Reference Kudenov1987a
30. 10–14 macrotubercles per segment………S. minuta (Webster & Benedict, Reference Webster and Benedict1887)
– Less than 10 macrotubercles per segment………31
31. Parapodia with 2 papillae………S. octopapillata Hartmann-Schröder, Reference Hartmann-Schröder1965
– Parapodia with at least 6 papillae………S. balticum (Reimers, Reference Reimers1933)
32. Mid-body segments with 12–13 dorsal macrotubercles………S. polypapillata Hartmann-Schröder & Rosenfeldt, Reference Hartmann-Schröder and Rosenfeldt1988
– All segments with less than 10 dorsal macrotubercles………33
33. Ventral cirrus papilla-like not projecting beyond prechaetal lobe………S. benguellarum (Day, Reference Day1963)
– Ventral cirrus different from papillae, projecting beyond prechaetal lobe………S. sphaerulifer (Moore, Reference Moore1909)
34. Dorsal macrotubercles in 2 alternating transverse rows per segment………35
– Dorsal macrotubercles in 3–4 irregular rows per segment………S. multipapillata (Hartmann-Schröder, Reference Hartmann-Schröder1974b)
35. Two types of dorsal macrotubercles present: spherical and bell-shaped ones………S. campanulata Borowski, Reference Borowski1994
– Only spherical macrotubercles present………36
36. Palps with polyp-like accessory papillae………S. sexantenella Kudenov, Reference Kudenov1993
– Palps without polyp-like accessory papillae………37
37. 36–40 dorsal macrotubercles per segment………S. paracapense (Hartmann-Schröder, Reference Hartmann-Schröder1974a)
– Less than 20 macrotubercles per segment………38
38. Prechaetal lobe present………39
– Prechaetal lobe absent………S. chardyi Desbruyères, Reference Desbruyères1980
39. 9 dorsal macrotubercles per segment………S. distichum (Eliason, Reference Eliason1962)
– 10 or more dorsal macrotubercles per segment………40
40. Prechaetal lobe large and foliose………S. pycnos Fauchald, Reference Fauchald1974
– Prechaetal lobe digitiform………41
41. 5 dorsal macrotubercles in segmental rows………S. oculata Fauchald, Reference Fauchald1974
– More than 5 dorsal macrotubercles in segmental rows………42
42. 6 dorsal macrotubercles in segmental rows………43
– 8 dorsal macrotubercles in segmental rows………S. fauchaldi Hartmann-Schröder in Hartmann-Schröder & Hartmann, Reference Hartmann-Schröder and Hartmann1979
43. 7–12 dorsal macrotubercles in irregular inter-segmental rows………S. translucida Borowski, Reference Borowski1994
– 7 dorsal macrotubercles in regular inter-segmental rows………44
44. 6 ventral papillae per segment………S. garciaalvarezi Moreira, Cacabelos & Troncoso, Reference Moreira, Cacabelos and Troncoso2004
– 10 ventral papillae per segment………45
45. Lateral antennae short, globular; prechaetal lobes papilliform………S. arctowskyensis Hartmann-Schröder & Rosenfeldt, Reference Hartmann-Schröder and Rosenfeldt1988
– Lateral antennae and prechaetal lobes slender, digitiform………S. bisphaeroserialis………(Hartmann-Schröder, Reference Hartmann-Schröder1974c)
Sphaerodoropsis longesetosa (Averincev, Reference Averincev1972) was not included because of its insufficient description.
ACKNOWLEDGEMENTS
We thank Thomas Jellinek (University of Canterbury, New Zealand; formerly Forschungsinstitut Senckenberg) for collecting and making these samples available to us, Alexander Plotkin (University of Bergen) for his translation of Russian literature, and Christopher Cagle (Texas A&M University–Corpus Christi) for helping to prepare the figures.
