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

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Synelmis sergi

sp. nov.

Synelmis sergi  sp. nov.

( Fig. 3View FIGURE 3 A –D; 4; 5 A –D; 6 A –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, 9 º 15.48 ’S, 133 º 48 ’E, 147 m, mud, coll. 12 May 2005, NTM W 21992 (1 specimen). PARATYPES: Arafura Sea, CSIRO RV Southern Surveyor, Stn GA 282 /001BS001, 9 º 54.01 ’S 134 º 30.04 ’ E, 74 m, greenish grey mud with calcareous particles, coll. K. Gowlett-Holmes, 1 May 2005, NTM W 21066 (1 specimen); Stn BS001, 9 º 54.01 ’S 134 º 30.04 ’E, 74 m, greenish grey mud with calcareous particles, coll. 1 May 2005, NTM W 21989 (1 specimen); Stn GR013, 9 º 49.933 ’S 135 º 19.656 ’E, 83 m, muddy fine sand; some calcareous gravel, 4 May 2005, NTM W 21990 (1 specimen); Stn GR048, 9 º 22.87 ’S 133 º 39.89 ’E, 112 m, muddy sand, 13 May 2005, NTM W 21991 (1 specimen); Stn GR069, 9 º 5.365 ’S 133 º 25.09 ’E, 226 m, muddy grit, 19 May 2005, NTM W 21993 (1 specimen); Stn GR080, 9 º 10.54 ’S 133 º 29.672 ’E, 112 m, muddy gravel, 21 May 2005, NTM W 21994 (1 specimen).

NON-TYPES: Joseph Bonaparte Gulf, Solander cruise 5117, Stn 54 GR102, 10º 34.208 ’S 129 º 28.886 ’E, 96 m, coll. Geosciences Australia, 20 Aug 2010, NTM W 25211 (1 specimen). Gulf of Carpentaria, CSIRO RV Southern Surveyor cruise 03- 2005, E of Vanderlin Island, Stn 60, 15º 31.4946 ’S 137 º 59.5236 ’E, NTM W 21987 (1 specimen); N of Groote Eylandt, Stn 64, 13º 20.67 ’S 136 º 50.6556 ’E, coll. CSIRO RV Southern Surveyor, NTM W 21988 (1 specimen); Stn 76, 15º 35.5014 ’S 137 º 56.4756 ’E, coll. 9 Mar 2005, 46.6 m, QM G 230662 (1 specimen); Stn 81, 13º 09.5124’ 136 º 56.4756 ’, coll. 15 Mar 2005, 45.6m, QM G 230663 (1 specimen); Stn 73, 15º 25.3668 ’S 137 º 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, 41 º 19.80 ’S, 144 º 20.00’E, 163 m, MV F 124080 (2 specimens), MV F 192523 (9 specimens); Stn 25, King Island Canyons (39 º 49.53 ’S, 143 º 16.00’E), 196 m, MV F 124082 (1 specimen); Stn 30 King Island Canyons (39 º 51.32 ’S, 143 º 10.35 ’E), 249 m, MV F 124083 (4 specimens); Stn 65, 41º 46.65 ’S, 144 º 34.50 ’E, 226 m, MV F 124084 (3 specimens); Stn 35, King Island Canyons, 39 º 48.68 ’S, 143 º 08.80’E, 348 m, MV F 192524 (2 specimens).

South China Sea, East Natuna, Indonesia, Stn NT06A, 4 º 11.02 ’N 108 º 24.04 ’E, 70m, soft mud (grey coloured), coll. Inayat Al Hakim, 30 Jul 2001, NTM W 18523 (2 specimens); West Natuna, Indonesia, Stn NB 15 B, 3 º 49.43 ’N 107 º 55.61 ’E, 40 m, soft mud, coll. Inayat Al Hakim, 2 Aug 2001, NTM W 18609 (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. 3View FIGURE 3 A). Lateral subdermal pigmented glands absent ( Fig. 3View FIGURE 3 C).

Prostomium wider than long, anteriorly subacute ( Fig. 3View FIGURE 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. 4View FIGURE 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. 3View FIGURE 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 5View FIGURE 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. 6View FIGURE 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. 6View FIGURE 6 C) and short, asymmetrical furcate chaetae with blades between tines ( Fig. 6View FIGURE 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. 3View FIGURE 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  .