Synelmis rigida (Fauvel, 1919)

Glasby, Christopher J. & Marks, Shona, 2013, Revision of the genus Synelmis Chamberlin, 1919 (Annelida: Phyllodocida: Pilargidae) in Australia, Zootaxa 3646 (5), pp. 561-574 : 567-568

Synelmis rigida (Fauvel, 1919)

( Fig. 2 A, B)

Ancistrosyllis rigida Fauvel, 1919: 337 –339, fig. 1a–e.

Synelmis simplex Chamberlin, 1919: 177 –179, pl. 28, figs 1–5.

Kynephorus inermis Ehlers, 1920: 27 –29, pl. 3, figs 1–9.

Synelmis rigida . – Salazar-Vallejo, 2003: 34–36, fig. 11a–g. (see this reference for full synonymy).

Type locality. Djibouti, Red Sea; shallow coastal.

Material examined. Papua New Guinea, Madang, Channel between Pik & Kranket Is., Stn RH91/101, 5º 9.6’S 145º 49.7’E, 3–8 m, rubble buried in sand/silt, coll. R. Hanley, 21 Oct 1991, SCUBA, NTM W7484 (1 specimen); Coral Sea, Chesterfield Reef, Stn RH88/72, 19º 46.95’S 158º 13.34’E, 28–52 m, coral rubble on floor of the lagoon, coll. R. Hanley, 1 Aug 1988, NTM W6242 (1 specimen); Great Barrier Reef, Heron Island, North Wistari Reef, Stn HI10–041, 15 m, 23º 27.0318’S 151º 53.0579’E, coll., CReefs Heron 2010 team, 21 Nov. 2010, NTM W25209 (1 specimen).

Description. The following description is based on NTM W7484, and variability assessed based on 2 other specimens. Size ranged from 33 (6.1–42) mm long, 1.2 (0.4–1.6) mm wide at widest point (including parapodia) for 159 (56–125) chaetigers.

Body red-brown, subcylindrical, robust, width similar throughout, body surface smooth and shiny, intersegmental grooves visible dorsally and ventrally ( Fig. 2 A). Lateral subdermal pigmented glands absent.

Prostomium wider than long, anteriorly subacute. Eyes present, one pair, at ventral base of lateral antennae. Palps biarticulated, free from each other making deep anterior notch, palpostyles button-like. Ventrolateral palpal papilla present, as long as wide. Paired lateral antennae present, located on mid-prostomium; fusiform. Median antenna present, fusiform, 1 times as long as lateral antennae (approx). Pharynx smooth, lacking tooth-like structures, distal ring papillae, and subdistal papillae. Nuchal organs not visible. Tentacular cirri present, 2 equal pairs, slightly shorter than dorsal cirri ( Fig. 2 B).

Parapodia sub-biramous. Notopodial lobe low, indistinct. Dorsal cirri present, subulate, similar in size and shape throughout. Dorsal cirri of chaetiger 1 similar length to mid-body dorsal cirri. Notochaetal spines emerge at dorsal base of dorsal cirrus, present from chaetiger 13–20, straight. Notoaciculae present, 2 per parapodium, tapering. Neuropodial lobe rectangular, about same width as base of dorsal and ventral cirri in mid-body chaetigers. Ventral cirri present from chaetiger 1, basal, subulate. Neurochaetae comprise capillary chaetae and short, symmetrical furcate chaetae; 9 capillary neurochaetae per neuropodium.

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

Remarks. The Australian material matches well the redescription of this species by Salazar-Vallejo (2003). Characteristic features of this species are the dark body (in ethanol-preserved specimens) and the late start of notospines.

Distribution. Subtidal coralline sediments, tropical Indo-west Pacific. New record for the Great Barrier Reef, Australia, Chesterfield Reef and Papua New Guinea.

Figures

FIGURE 2. Synelmis rigida, NTM W 7484, A, entire animal, head upper left; B, head end and anterior region, lateral view.