Laonice insolita, 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 : 6-9

Laonice insolita sp. nov.

Figures 5–7

Material examined. Holotype: Indian Ocean, Shark Bay region, L6, Stn SS07/2005 81, 25º57.583ʹ S, 112º15.417´E, 28 Jan 2005, 393 m, MV F 110764. Paratypes: Indian Ocean, Shark Bay region, L6, Stn SS07/2005 80, 25º57.567ʹ S, 112º15.233ʹ E, 28 Jan 2005, 404 m, 1 specimen, MV F 110725; Indian Ocean, Shark Bay region, L6, Stn SS07/2005 81, 25º57.583ʹ S, 112º15.417ʹ E, 28 Jan 2005, 393 m, 1 specimen, MV F 110763; Indian Ocean, Shark Bay region, L6, Stn SS07/2005 81, 25º57.583ʹ S, 112º15.417ʹ E, 28 Jan 2005, 393 m, 2 af plus 1 mf specimens, ZMH-P25871 (ex MV F 110727); Indian Ocean, Shark Bay region, L6, Stn SS07/2005 81, 25º57.583ʹ S, 112º15.417ʹ E, 28 Jan 2005, 393 m, 2 af plus 1 mf specimens, ZSRO-P2062 (ex MV F 110727); Indian Ocean, Kalbarri region, L8 400, Stn SS07/2005 88, 27º55.833ʹ S, 113º4.683ʹ E, 29 Jan 2005, 416 m, 1 specimen, MV F107028; Indian Ocean, Abrolhos region, T3 400, Stn SS07/2005 98, 28º59.433ʹ S, 113º45.967´E, 30 Jan 2005, 388 m, 1 specimen, MV F 110741.

Additional material examined. Australia: Indian Ocean, Point Cloates region, L3, Stn SS07/2005 68, 22º51.533ʹ S, 113º19.683ʹ E, 27 Jan 2005, 448 m, 7 specimens, MV F167393; Indian Ocean, Shark Bay region, L6, Stn SS07/2005 80, 25º57.567ʹ S, 112º15.233ʹ E, 28 Jan 2005, 404 m, 2 specimens, MV F 150639; Northwestern Australia, Leveque L27 transect, Stn SS05/2007 137, 14º58.233ʹ S, 121º38.933ʹ E, 230 m, 1 specimen, MV F 110739; Northwestern Australia, Karratha L21 transect, Stn SS05/2007 0 42, 18º46.45ʹ S, 116º55.033ʹ E, 400 m, 1 specimen, MV F 110735; Indian Ocean, Point Cloates region, L3, Stn SS07/2005 69, 22º51.533ʹ S, 113º19.617ʹ E, 27 Jan 2005, 451 m, 3 specimens, MV F 110733; Indian Ocean, Zyutdorp region, L7 400, Stn SS07/2005 85, 27º10.05ʹ S, 112º46.683ʹ E, 29 Jan 2005, 375 m, 2 specimens, MV F 110753; Indian Ocean, Kalbarri region, L8 400, Stn SS07/2005 89, 27º56.1ʹ S, 113º4.867ʹ E, 29 Jan 2005, 417 m, 4 specimens, MV F158694; Indian Ocean, Jurian region, L10 400, Stn SS07/2005 127, 29º51.083ʹ S, 114º22.433ʹ E, 2 Jan 2005, 361 m, 1 specimen, MV F167411; Indian Ocean, Zyutdorp region, L7 400, Stn SS07/2005 85, 27º10.05ʹ S, 112º46.683ʹ E, 29 Jan 2005, 375 m, 8 specimens, MV F158685; Indian Ocean, Abrolhos region, T3 400, Stn SS07/2005 98, 28º59.433ʹ S, 113º45.967´E, 30 Jan 2005, 388 m, 2 specimens, MV F167416; Indian Ocean, Two Rocks region, T4 400, Stn SS07/2005 136, 31º39.7ʹ S, 114º58.867ʹ E, 4 Jan 2005, 403 m, 2 specimens, MV F167433; Indian Ocean, Carnarvon region, L5, Stn SS07/2005 76, 24º35.183ʹ S, 112º15.233ʹ E, 27 Jan 2005, 405 m, 2 specimens, MV F167436; Indian Ocean, Kalbarri region, L8 400, Stn SS07/2005 88, 27º55.833ʹ S, 113º4.683ʹ E, 29 Jan 2005, 416 m, 7 specimens, MV F 110606; Indian Ocean, Carnarvon region, L5, Stn SS07/2005 75, 24º35.25ʹ S, 112º15.183ʹ E, 27 Jan 2005, 405 m, 2 specimens, MV F 110609; Indian Ocean, Point Cloates region, L3, Stn SS07/2005 69, 22º51.533ʹ S, 113º19.617ʹ E, 27 Jan 2005, 451 m, 1 specimen, MV F 110618; off Pelsart Island, near Geraldton, Stn SS07 2005 122, 29º0.167ʹ S, 113º46.433ʹ E, 409 m, 6 specimens, MV F 110626; Indian Ocean, Zuytdorp region, L7 400, Stn SS07/2005 84, 27º9.65ʹ S, 112º46.267ʹ E, 29 Jan 2005, 392 m, 1 specimen, MV F 110628; Indian Ocean, Ningaloo region, T1 200 S, Stn SS 07/2005 8, 22º4.783ʹ S, 113º47.817ʹ E, 22 Jan 2005, 205 m, 1 specimen, MV F167385; Indian Ocean, Mentelle region, L14 400, Stn SS07/2005 157, 34º1.35ʹ S, 114º27ʹ E, 7 Jan 2005, 398 m, 1 specimen, MV F158745; Indian Ocean, Shark Bay region, L6, Stn SS07/2005 81, 25º57.583ʹ S, 112º15.417ʹ E, 28 Jan 2005, 393 m, 2 specimens, MV F 160686; Indian Ocean, Perth Canyon region, Focus Area, Stn SS07/2005 221, 31º51.2ʹ S, 115º1.317ʹ E, 15 Jan 2005, 413 m, 2 specimens, MV F158751; Indian Ocean, Bunbury region, L13 400, Stn SS07/2005 153, 33º0.017ʹ S, 114º34.733ʹ E, 6 Jan 2005, 399 m, 1 specimen, MV F158744.

Description. Six complete specimens, remainder anterior fragments only, entire specimens 2.2–16 mm long, 0.1–0.7 mm wide (holotype 16 mm long, 0.5 mm wide).

Prostomium blunt, broadly rounded, entire. Posterior margin of prostomium not discernable as completely fused with dorsum, lateral margin of prostomium defined by low dorsolateral ridges that continue until posterior margin of chaetiger 1 ( Fig. 6 A). Occipital antenna absent. Four small eyes present, generally pale and deep-set. Peristomium separated from prostomium, not well developed. Palps simple, with double undulating ridge; about 12 chaetigers long. No nuchal organ observed ( Figs. 5 A–B; 6A).

Dorsal branchiae present from chaetiger 2 to about chaetiger 14–17 (chaetiger 7–8 in small specimens); branchiae free, separate from notopodial lamellae throughout; all branchiae similar in width and size to notopodial lobe, except chaetiger 2, which is about half the length, last few pairs also slightly shorter ( Figure 5 E–F, 6A–F).

Both notopodial and neuropodial postchaetal lobes relatively small, short and tapering. Anteriorly, notopodial lobes thin and tapering, neuropodial lobes similar but slightly more triangular. Posteriorly, both notopodial and neuropodial lobes somewhat triangular ( Figs. 5 E–F, 6E–F). Dorsal crests absent ( Figs. 5 A–B, 6A–F). Interparapodial pouches present on chaetigers 6–18; beginning between chaetigers 6 and 7 regardless of specimen size, terminating chaetiger 10–12 on smaller specimens, chaetiger 15–18 on larger specimens; some anterior pouches with additional dorsal flap from above, connected to anterior end of pouch ( Fig. 6 E); termination of pouches somewhat correlated with last branchiae.

A short row of 6–9 pits (sometimes accompanied by a row of smaller pits) present on dorsum from chaetiger 6, near base of branchiae and intersegmental boundary ( Fig. 6 C–D).

Anterior capillaries in two rows; only a single row and fewer capillaries per fascicle posteriorly; capillaries of similar width throughout. Notopodial hooded hooks beginning from chaetiger 20–40, tridentate, main fang surmounted by pair of apical teeth somewhat perpendicular to main fang ( Fig. 6 G). Neuropodial hooded hooks first present from chaetiger 16–22, tridentate, similar to notopodial hooks. Neuropodial sabre chaetae absent.

Pygidium with four large leaf-shaped cirri, small specimens with two large leaf-shaped cirri and two thin, elongated cirri ( Fig. 5 C–D).

Colour. White (unpigmented) in ethanol.

Distribution. Western coast of Australia, 205–451 m ( Figs. 1–2 ).

Remarks. This species has many characters that are not typical of Laonice species; however, placement in this genus is justified as most of these characters are present in at least one other described species in the genus. The defining specific characters include the absence of an occipital antenna, the presence of notopodial hooded hooks (with apical teeth that are more perpendicular to the main fang than in other Laonice species), the lack of sabre chaetae, a reduced number of branchiae (generally 12–15 pairs), and interparapodial pouches always starting between chaetigers 6 and 7 and ending between chaetiger 10 and 18. The early termination of both branchiae and interparapodial pouches results in an obvious division between the anterior and posterior regions, giving this species a distinctive appearance.

Laonice brevicristata Pillai, 1961 , L. shamrockensis Sikorski, 2003 , and L. dayianum Sikorski, 1997 have all been described as lacking an occipital antenna. Maciolek (2000) noted that both L. brevicristata and L. dayianum need to be reevaluated, especially the latter, which was illustrated as having at the least the scar of an occipital antenna. Regardless, all three species have sabre chaetae and interparapodial pouches that begin much later than the species described here. The SEM photo ( Fig. 6 A) shows a small ridge across the prostomium. This structure is not visible on other specimens using the light microscope, and it is not in a position typical of the occipital antenna (the ridge seen is anterior to the position of the eyes) and so is not thought to be homologous with this structure.

Laonice sarsi Söderström, 1920 is the only other species in the genus reported to have notopodial hooded hooks ( Maciolek 2000). However, it has interparapodial pouches that start later, at chaetigers 14–28, rather than at setiger 6 as in L. insolita sp. nov.

Due to the large number of specimens available, it was possible to study size dependency of characters in this species. The difficulty of measuring size (in the form of width) in such small specimens means that some resolution has most likely been lost, however the general trend can be observed ( Fig. 7 ).

Etymology: Latin for ‘unusual, uncommon, strange’, insolita refers to the many characters of this species that are uncommon in other Laonice 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 5. Laonice insolita sp. nov. (MV F 110725 except where noted). A. Anterior end, dorsal view. B. Chaetigers 21 – 24, dorsal view. C. Pygidium (MV F 110606), dorsal view. D. Juvenile pygidium (MV F 110741), dorsal view. E. Parapodium 5 (right). F. Parapodium 34 (right), branchia lost. Scales: A – B 0.5 mm; C – D 0.1 mm; E – F 0.05 mm.

FIGURE 6. Laonice insolita sp. nov. (ZMH-P 25871). A. Anterior end, dorsal view. B. Anterior end, lateral view. C. Chaetiger 6 – 10 from dorsal, arrow indicating row of tiny holes present near the notopodial base. D. Left side of chaetiger 6 and 7 from dorsal. E. Interparapodial pouch between chaetigers 8 – 9, arrow indicating additional flap from above. F. Chaetigers 16 – 18 with interparapodial pouches. G. Neuropodial hook from chaetiger 37, hood removed. Scales: A – C, E, F 100 µm; D 20 µm; G 1 µm.

FIGURE 7. Laonice insolita sp. nov. Morphometric data. A. first chaetiger with neuropodial hooks. B. last chaetiger with branchiae. C. last chaetiger with interparapodial pouches. All in relation to body width.