Synelmis sergi, Glasby, Christopher J. & Marks, Shona, 2013

Glasby, Christopher J. & Marks, Shona, 2013, Revision of the genus Synelmis Chamberlin, 1919 (Annelida: Phyllodocida: Pilargidae) in Australia, Zootaxa 3646 (5), pp. 561-574 : 568-573

Synelmis sergi sp. nov.

( Fig. 3 A–D; 4; 5A–D; 6A–D)

Synelmis cf. rigida Hocknull & Glasby, 2009: 544 –545.

Type locality. Arafura Sea, northern Australia, 147 m.

Material examined. HOLOTYPE: Arafura Sea, CSIRO RV Southern Surveyor, Stn GR046, 9º 15.48’S, 133º 48’E, 147 m, mud, coll. 12 May 2005, NTM W21992 (1 specimen). PARATYPES: Arafura Sea, CSIRO RV Southern Surveyor, Stn GA282/001BS001, 9º 54.01’S 134º 30.04’ E, 74 m, greenish grey mud with calcareous particles, coll. K. Gowlett-Holmes, 1 May 2005, NTM W21066 (1 specimen); Stn BS001, 9º 54.01’S 134º 30.04’E, 74 m, greenish grey mud with calcareous particles, coll. 1 May 2005, NTM W21989 (1 specimen); Stn GR013, 9º 49.933’S 135º 19.656’E, 83 m, muddy fine sand; some calcareous gravel, 4 May 2005, NTM W21990 (1 specimen); Stn GR048, 9º 22.87’S 133º 39.89’E, 112 m, muddy sand, 13 May 2005, NTM W21991 (1 specimen); Stn GR069, 9º 5.365’S 133º 25.09’E, 226 m, muddy grit, 19 May 2005, NTM W21993 (1 specimen); Stn GR080, 9º 10.54’S 133º 29.672’E, 112 m, muddy gravel, 21 May 2005, NTM W21994 (1 specimen).

NON-TYPES: Joseph Bonaparte Gulf, Solander cruise 5117, Stn 54GR102, 10º 34.208’S 129º 28.886’E, 96 m, coll. Geosciences Australia, 20 Aug 2010, NTM W25211 (1 specimen). Gulf of Carpentaria, CSIRO RV Southern Surveyor cruise 03-2005, E of Vanderlin Island, Stn 60, 15º 31.4946’S 137º 59.5236’E, NTM W21987 (1 specimen); N of Groote Eylandt, Stn 64, 13º 20.67’S 136º 50.6556’E, coll. CSIRO RV Southern Surveyor, NTM W21988 (1 specimen); Stn 76, 15º 35.5014’S 137º 56.4756’E, coll. 9 Mar 2005, 46.6 m, QM G 230662 (1 specimen); Stn 81, 13º 09.5124’ 136º 56.4756’, coll. 15 Mar 2005, 45.6m, QM G 230663 (1 specimen); Stn 73, 15º 25.3668’S 137º 423.5864’E, coll. 17 Mar 2005, 46.2 m, QM G 230664 (1 specimen).

Southern Ocean, off Tasmania, Southern Surveyor Cruise 404, coll. K. Gowlett-Holmes, R. Wilson et al., 16– 21 Apr 2004, Stn 52, Ling Hole, 41º 19.80’S, 144º 20.00’E, 163 m, MV F124080 (2 specimens), MV F192523 (9 specimens); Stn 25, King Island Canyons (39º 49.53’S, 143º 16.00’E), 196 m, MV F124082 (1 specimen); Stn 30 King Island Canyons (39º 51.32’S, 143º 10.35’E), 249 m, MV F124083 (4 specimens); Stn 65, 41º 46.65’S, 144º 34.50’E, 226 m, MV F124084 (3 specimens); Stn 35, King Island Canyons, 39º 48.68’S, 143º 08.80’E, 348 m, MV F192524 (2 specimens).

South China Sea, East Natuna, Indonesia, Stn NT06A, 4º 11.02’N 108 º 24.04’E, 70m, soft mud (grey coloured), coll. Inayat Al Hakim, 30 Jul 2001, NTM W18523 (2 specimens); West Natuna, Indonesia, Stn NB15B, 3º 49.43’N 107º 55.61’E, 40 m, soft mud, coll. Inayat Al Hakim, 2 Aug 2001, NTM W18609 (2 specimens).

Description. The following description is based on the holotype (values given first) and variability assessed based on paratypes and other specimens. Size ranged from 135 (16.5–35.5) mm long, 1.9 (0.40–0.60) mm wide at widest point (including parapodia) for 186 (85–114) chaetigers.

Body subcylindrical, slender, width similar throughout, body, pink-white, surface smooth and shiny ( Fig. 3 A). Lateral subdermal pigmented glands absent ( Fig. 3 C).

Prostomium wider than long, anteriorly subacute ( Fig. 3 B). Eyes absent (though a faint outline maybe present – appear to fade easily in present material). Palps biarticulated, free from each other making deep anterior notch, palpostyles button-like. Ventrolateral palpal papilla present, longer than wide ( Fig. 4 ). Paired lateral antennae present, located on mid-prostomium; subulate. Median antenna present, subulate, 1 times as long as lateral antennae (approx.), extends back to chaetiger 1. Proboscis smooth lacking tooth-like structures, distal ring papillae and subdistal proboscideal papillae ( Fig. 3 C). Nuchal organs not visible. Tentacular cirri present, 2 pairs, same length as dorsal cirri.

Parapodia sub-biramous. Notopodial lobe low, indistinct. Dorsal cirri present, subulate, similar in size and shape throughout; ventral cirrus similar in length to dorsal cirrus in anterior parapodia but relatively longer than dorsal cirrus in mid and posterior chaetigers ( Figs 5 A–D). Dorsal cirrus of chaetiger 1 similar length to mid-body dorsal cirri. Notochaetal spines emerge at dorsal base of dorsal cirrus, present from chaetiger 15 (9–20), straight. Notoaciculae present, 2–3 per parapodium, tapering or knob-tipped, possibly a result of wear ( Fig. 6 A, B). Neuropodial lobe low, indistinct, about same width as base of dorsal and ventral cirri in mid-body chaetigers (rectangular and more emergent in non-type material). Ventral cirri present from chaetiger 1, basal, subulate. Neurochaetae comprise finely denticulate capillary chaetae ( Fig. 6 C) and short, asymmetrical furcate chaetae with blades between tines ( Fig. 6 D). Neuroacicula present, tapering. Last 4 (1–7) chaetigers prior to pygidium lacking neuropodia and neurochaetae.

Pygidium spherical, tapered. Lateral anal cirri present, filiform, located on outside margin of pygidium ( Fig. 3 D). Mid anal cirri absent. Anus opening dorsally.

Remarks. Synelmis sergi sp. nov. is most similar to S. sinica Sun & Chen, 1990 . The holotype and paratypes of S. sinica are lodged in the museum of the Institute of Oceanology, Chinese Academy of Sciences. Although they are not available to loan (email from Dr Xinzheng Li, 2 Dec 2011), Li assisted us with a comparison of the parapodia of the two species. The key difference between the two species is the relative length of the parapodial cirri along the body: in S. sinica , the dorsal and ventral cirri of anterior and posterior parapodia are much longer (1.5–2.0x) than those of mid-body parapodia, whereas in the new species the relative length of the dorsal and ventral cirri along the body is fairly constant. Also, we noted that S. sinica was described as having ‘brown spots on the lateral sides’ which may be the pigmented subdermal glands, which are common in many Synelmis and other pilargids; our specimens lacked these glands. Finally, the furcate chaetae of S. sergi sp. nov. have two unequal tines: the larger of the two tines has a blade on the inner surface, like those seen in Pseudoexogone (Salazar-Vallejo et al. 2007). The blades on the furcate chaetae appear to be real and not an artefact of observation angle, but this feature should be investigated further using SEM. Differences between S. sergi sp. nov. and all other 16 species of Synelmis are documented in Table 1.

Distribution. Continental shelf and slope sediments of Australia and SE Asia in 40– 348 m. Co-occurs with S. knoxi in northern and southern Australia, and co-occurs with S. gibbsi in the Joseph Bonaparte Gulf, NW Australia.

Etymology. The new species is named after our friend and colleague Dr Sergio (Serg) Salazar-Vallejo who initiated the recent revival in systematic studies of the family Pilargidae .

Figures

FIGURE 3. Synelmis sergi sp. nov., holotype, NTM W 21992, A, entire animal, head end upper right; B, head end and anterior region, dorsal view; C, head end and anterior region, lateral view of left side; D, tail end, dorsolateral view, right side. p = proboscis; la = lateral antenna; tc = tentacular cirrus; ma = median antenna; pp = palpophore; vpp = ventrolateral palpal papilla.

FIGURE 4. Synelmis sergi sp. nov., holotype, NTM W 21992, head end, lateral view of right side. vpp = ventrolateral palpal papilla; ps = palpostyle.

FIGURE 5. Synelmis sergi sp. nov., holotype, NTM W 21992, A, right side parapodium, chaetiger 5; B, right side parapodium, chaetiger 11; C, right side midbody parapodium; D, Left side posterior body parapodium.

FIGURE 6. Synelmis sergi sp. nov., holotype, NTM W 21992, A, midbody acicula, lateral view; B, midbody acicula, front view; C, midbody capillary chaeta; D, midbody furcate chaeta.