Laonice lemniscata, Greaves, Elizabeth & Wilson, Robin, 2011

Greaves, Elizabeth & Wilson, Robin, 2011, New Laonice species (Polychaeta: Spionidae) from western and northern Australia, Zootaxa 2903, pp. 1-20 : 4-6

Laonice lemniscata sp. nov.

Figures 3–4

Material examined. Holotype: Australia: Indian Ocean, Albany region, T6 200, Stn SS07/2005 183, 35º21.5ʹ S 118º17.4ʹ E, 9 Jan 2005, 193 m, MV F167370. Paratypes: Indian Ocean, Two Rocks region, T4 200, Stn SS07/ 2005 134, 31º38.9ʹ S, 115º1.267ʹ E, 4 Jan 2005, 196 m, 1 specimen, MV F 111057; Indian Ocean, Bald Island region, T7 100, Stn SS07/2005 195, 35º10.65ʹ S, 118º37.917ʹ E, 10 Jan 2005, 102 m, 1 specimen, MV F158711; Indian Ocean, Bunbury region, L13 100, Stn SS07/2005 213, 33º2.3ʹ S, 114º48.483ʹ E, 14 Jan 2005, 102 m, 1 specimen, MV F 110637; Indian Ocean, Albany region, T6 200, Stn SS07/2005 183, 35º21.5ʹ S, 118º17.4ʹ E, 9 Jan 2005, 193 m, 1 specimen, MV F167372.

Description. All specimens anterior fragments, 18–35 chaetigers except nearly complete holotype (MV F167370) with 61 chaetigers, 2.3–15 mm long (holotype 15 mm), 0.3–0.8 mm wide.

Prostomium blunt, anteriorly rounded, entire or very slightly indented; without frontal or lateral horns. Caruncle present, continuous with prostomium, narrowing at about level of chaetiger 2, then extending back to chaetiger 9 or 10 (difficult to determine due to split dorsum). Long, finger-like occipital antenna present on posterior part of prostomium, behind eyes. Eyes present as one pair, each a dark brown to reddish patch edged anteriorly and laterally by lighter brown crescent. Peristomium separate from prostomium, approximately half the length of prostomium. Palps lost from all specimens. Nuchal organ long, U-shaped, extending posteriorly to about chaetiger 15 or 16 (difficult to determine due to split dorsum) ( Fig. 3 A).

Dorsal branchiae present from chaetiger 2 to near posterior end of body. Branchiae free, separate from notopodial lamellae throughout; all simple, distinctly ciliated on inner margin; longest on anterior third of specimen, first branchiae approximately same length as notopodial lobe, by about chaetiger 7 approximately twice length of notopodial lobe, and in posterior half up to three times length of lobes (due in part to the smaller size of the notopodial lobe).

Notopodial postchaetal lobes reduced to small subtriangular projection on chaetiger 1; then leaf-like and slightly pointed until about chaetiger 4, then becoming more rounded and gradually reduced to small round lobes. Neuropodial postchaetal lobes leaf-like from chaetiger 1; dorsally rounded and ventrally pointed until about chaetiger 15, then rounded and reduced in size; small by about chaetiger 25( Fig. 3 B–D). Dorsal crests present from chaetiger 10, initially separated by nuchal organ/caruncle, full, ciliated crests from chaetiger 13 and on all remaining chaetigers. Additional transverse ciliation present on segmental margins. Interparapodial pouches on chaetigers 9– 61; starting from chaetiger 9–11 and continuing posteriorly to end of fragment ( Fig. 3 E).

Anterior capillaries in two rows in both noto- and neuropodia, anterior row generally stout and short. Posterior neuropodial capillaries narrower and fewer than anterior. Neuropodial hooded hooks begin from chaetiger 17–22, 4–5 per fascicle, bi- or tridentate (tooth above main fang may or may not have smaller apical tooth) ( Fig. 4 A–B). Neuropodial sabre chaetae first present on chaetiger 10–11, 1–2 per fascicle.

Pygidium unknown.

Colour. White (unpigmented) in ethanol.

Distribution. Southwestern Australia, shelf, 102–196m ( Figs. 1–2 ).

Remarks. The prominent dorsal crests distinguish this species from other known Laonice species. Of the descriptions that mention dorsal crests, the majority describe them as low or incomplete, not reaching the dorsal midline, except L. japonicus ( Moore, 1907) and L. magnacristata Maciolek, 2000 , which both have large dorsal crests. The crests of L. japonicus start around chaetiger 38, much later than those of L. lemniscata sp. nov.. Laonice magnacristata has crests starting on chaetiger 11, similar to L. lemniscata sp. nov., but has a very limited number of branchiae (6 pairs compared to over 50 pairs in L. lemniscata sp. nov.).

Etymology. Latin for ‘adorned with ribbons’ lemniscata refers to the appearance of the long, thin branchiae of this species.

Figures

FIGURE 1. Locations in Australia where Laonice specimens were collected. Cross: L. insolita. White circle: L. cf. quadridentata. Grey circle: L. quadridentata. White square: L. lemniscata. Grey square: L. pectinata. Black square: L. hermaphroditica (data from unpublished Museum Victoria data). Grey diamond: Laonice cf. weddellia. Black diamond: L. bassensis (data from Blake & Kudenov 1978).

FIGURE 2. Bathymetric distribution of Australian Laonice species. L. hermaphroditica data based on the depth of Morton Bay, L. bassensis data from Blake & Kudenov 1978, L. weddellia data from OBIS (http: // www. obis. org. au /)

FIGURE 3. Laonice lemniscata sp. nov. holotype. A. Anterior end, dorsal view. B. Parapodium 10 (left), branchia lost. C. Parapodium 18 (left). D. Parapodium 25 (left). E. Chaetigers 15 – 19, anterolateral view. Scales: A – E 0.5 mm.

FIGURE 4. Laonice lemniscata sp. nov., holotype. A. Chaetiger 33 neuropodial hook, hood removed. B. Chaetiger 22 neuropodial hook, hood removed. Scales: A – B 1 µm.