Laonice weddellia Hartman 1978

Laonice cf. weddellia Hartman, 1978

Figures 10–11

Material examined. Australia: Indian Ocean, Point Hiller region, L16 400, Stn SS07/2005 166, 35º22.85ʹ S, 117º13.267ʹ E, 8 Jan 2005, 436 m, 1 specimen, MV F167421; Indian Ocean, Bald Island region, T7 400, Stn SS07/ 2005 199, 35º12.55ʹ S, 118º39.533ʹ E, 10 Jan 2005, 414 m, 1 specimen, MV F158703.

Additional material examined. Laonice weddellia Hartman, 1978: Antarctica: Scotia Sea, cruise ANT 68/1 Walther Herwig, Stn 149, 61°09.0ʹ S, 56°07.2ʹ W, 24 Feb 1985, 208 m, box corer, 9 specimens, ZMH P- 20854; Stn 149, 60°57.1ʹ S, 55°55.2ʹ W, 25 Feb 1985, 246 m, box corer, 20 specimens, ZMH P- 20856; Stn 137, 61°18.5ʹ S, 54°40.3ʹ W, 21 Jan 1985, 370 m, box corer, 10 specimens, ZMH P- 20850.

Description. (based on Western Australian specimens of Laonice cf. weddellia). Two anterior fragments, 36 and 25 chaetigers respectively, 4.3–12 mm long, 1–1.5 mm wide.

Prostomium bell-shaped, anteriorly rounded, extending posteriorly to between chaetiger 1–2. Occipital antenna present, short; arising from posterior part of prostomium, well behind eyes. Eyes present, one or three pairs; specimen with three has one anterior pair, close to edge of prostomium and relatively deeply set, second and third pairs more posterior and close together, such that on one side two eyes appear almost as one; specimen with only one pair, eyes at posterior end of prostomium and potentially composed of two closely set pairs. Peristomium separate from prostomium, well developed. Palps lost from both specimens. Nuchal organ present, extending posteriorly until approximately chaetiger 13 (difficult to determine as specimen somewhat damaged) (Fig. 10 A).

Branchiae from chaetiger 2, continuing until end of fragments; initially short, similar length to notopodial lobe, approximately twice lobe length by about chaetiger 12, by end of longest fragment only just reaching beyond the lobe.

Chaetiger 1 notopodial lobes significantly smaller than those of chaetiger 2. Notopodial lobes initially rounded, gradually increasing in size, by chaetiger 4 pointed dorsally and rounded ventrally, by chaetiger 7 rounded dorsally and ventrally. Neuropodial postchaetal lobes ear-shaped, dorsal margin extending with lateral projection, becoming more triangular (Fig. 10 B–D). Dorsal crests first present chaetiger 24, continuing to end of fragments; crests less obvious on some chaetigers, appearing as mid-segmental ciliation. Interparapodial pouches present from chaetiger 9, continuing to end of fragment.

Anterior chaetigers with 4–5 dense rows of capillary chaetae, reduced to 1–2 rows by about chaetiger 15; from chaetiger 5 there is a neuropodial inferior fascicle of approximately six capillary chaetae directed ventrally; by chaetiger 13 capillaries stouter and reduced in number (2–4) and probably comparable to sabre chaetae. Neuropodial hooded hooks from chaetiger 22, with paired apical teeth above the main fang (Fig. 11A–B).

Pygidium unknown.

Colour. White (unpigmented) in ethanol.

Distribution. Southern Western Australia, 414–436 m (Figs. 1-2).

Remarks. The Western Australian material resembles Laonice weddellia based on original and subsequent descriptions (Blake 1983; Hartman 1978; Radashevsky & Lana 2009), with some variations noted: the anterior region of the Western Australian specimens has 4–5 rows of capillary chaetae for 11–12 chaetigers, rather than 14– 15; dorsal ciliation appears to be mid-segmental instead of inter-segmental. However these differences were also observed during this study in some specimens identified as L. weddellia from Antarctica. Specimens of Laonice weddellia from the Scotia Sea, Antarctica include some specimens in which the apical teeth above the main fang of the neuropodial hooks include a smaller tooth above the paired teeth (Fig. 11 C).

Laonice weddellia Hartman, 1978 was originally described from the Weddell Sea and redescribed by Blake (1983), who expanded the distribution into other areas of the Antarctic Seas, off southern South America and the South Orkney and South Shetland Islands in depths of 44–3111 m. Radashevsky & Lana (2009) further reported the species from Brazil and discussed the need for this species to be reassessed given the unusual distribution. More specimens, including material suitable for genetic analysis, will be required from widespread localities to determine if the specimens identified as Laonice weddellia and already encompassing a wide geographic and bathymetric range represent intraspecific variation or separate species in a widely-distributed species complex. Based on the variation noted above and the wide and disjunct distribution of our material, the latter explanation seems most likely to us and we prefer a conservative approach and refer the material from Western Australia to Laonice cf. weddellia.