Spiophanes prestigium, MEISSNER & Hutchings, 2003

MEISSNER, Karin & Hutchings, Pat A., 2003, Spiophanes Species (Polychaeta: Spionidae) From Eastern Australia-With Descriptions of New Species, New Records and an Emended Generic Diagnosis, Records of the Australian Museum 55, pp. 117-140 : 131-133

Spiophanes prestigium n.sp.

Fig. 11

Spiophanes sp. 3 .–Wilson & McDiarmid, 2003.

Type material. HOLOTYPE: Australia, Tasmania , Central Bass Strait , 40°31.1'S 145°04'E, in 29 m, 3–XI 1980 ( MV F92141 ). P ARATYPES: Australia, Tasmania , Central Bass Strait , 40°31.1'S 145°04'E, in 29 m, 3–XI 1980, 3 specimens ( MV F90006 ); Tasmania, 41°09.68'S 146°27.38'E, in 3 m, May 1939, 1 specimen ( MV F 90027 ) .

Other species examined. Spiophanes tcherniai Fauvel, 1950 , SOUTHERN OCEAN: 45°59.8'S 49°58.3'E, in 210–217 m, 14 Apr 1976, 2 specimens (South African Museum A20308 ); South Shetlands, King George Island, Ardley Bay, 62°12'S 58°58'E, in 15 m, 9 Feb 1987, 1 specimen (ZSRO P1257) and Fildes Strait, 62°14'S 58°58'E, in 50 m, 18 Jan 1986, 1 specimen (ZSRO P1256); Wedell Sea, 20 Mar 1998, several specimens (ZMH P23931); Ross Island, McMurdo Sound, 77°13.08'S 166°26.4'E, in 54 m, 4 Jan 1971, several specimens (AM W22463).

Description. Holotype incomplete, with 27 chaetigers, 6.0 mm long and about 0.8 mm wide. Paratypes between 0.7– 0.9 mm wide. Body slender, subcylindrical. Prostomium broad anteriorly, subtriangular, with elongate, digitiform anterolateral horns (Fig. 11A). Occipital antenna absent. Up to 2 pairs of eyes present. Nuchal organs as short ciliated bands, extending from posterior prostomium margin to beginning of chaetiger 3 (Fig. 11A). Peristomium poorly developed. Parapodia of chaetiger 1 oriented dorsally; postchaetal lamellae cirriform, notopodial lamellae slightly longer than neuropodial lamellae (Fig. 11A). Postchaetal notopodial lamellae of parapodia of chaetigers 2–4 cirriform, lamellae of chaetiger 3 usually longest (Fig. 11A,C,D). Neuropodial postchaetal lamellae of parapodia of chaetiger 2 subulate, tapered; in chaetiger 3 subulate with rounded tip; in chaetiger 4 short and rounded. In subsequent chaetigers, notopodial postchaetal lamellae subtriangular, with tapered tips becoming gradually thinner in middle and posterior body region; neuropodial lamellae reduced (Fig. 11E,F). Chaetal spreader not observed; glandular organ of chaetigers 9–15 opens as lateral vertical slit (Fig. 11B). Ventrolateral intersegmental genital pouches absent. Inconspicuous dorsal ciliated crests mostly present from chaetiger 4. Chaetiger 1 usually with 1 stout, crook-like chaeta in neuropodium; remainder of chaetae capillaries; notochaetae arranged in tuft; neurochaetae arranged in 2 rows. Chaetigers 2–4 with capillaries with narrow sheath (Fig. 11L,M); notochaetae in tuft, neurochaetae in 2 rows. Notopodial capillaries of first 4 chaetigers not much longer than those in subsequent chaetigers. Notochaetae of chaetigers 5–13 capillaries with narrow sheath, arranged in 3 rows. From chaetigers 14–19, special spatulate chaetae with fine tips (mucro) present in addition to small number of capillaries with narrow sheath (Fig. 11G,I); spatulate chaetae number 12–25, most numerous on chaetigers 16 and 17. From chaetiger 20, notochaetae capillaries with narrow sheath, arranged in tuft. Neurochaetae of chaetigers 5–15 stout, bilimbate, distally pointed (Fig. 11J), arranged in 1–2 rows. From chaetiger 16 neuropodia with quadridentate, hooded hooks (Fig. 11K); initially with 5–7 hooks in 1 row, less numerous in more posterior chaetigers. Bacillary chaetae not emergent. Ventral sabre chaetae from chaetiger 4, very long, appearing granulated (Fig. 11H). Pygidium unknown.

Pigmentation. Conspicuous dark brownish pigmentation in chaetigers 9–15 encompasses the neuropodium as well as interramal region (Fig. 11B), absent in some alcoholpreserved material.

Methyl green staining pattern. Pigmented areas of parapodia 9–15 take up stain most intensely; if pigmentation is lost, respective area becomes visible by staining. In addition, small round stained patches detectable between noto- and neuropodia of chaetigers 5–8, in region where chaetal spreader usually occurs.

Biology. Species found in shallow water, between 3–29 m; in sandy substrates.

Remarks. Spiophanes prestigium is similar to S. tcherniai Fauvel, 1950 with regard to the structure of the nuchal organs, the shape of the prostomium, in having spatulate notochaetae in median segments, and the first appearance of hooks in chaetiger 16. However, S. tcherniai differs from S. prestigium in exhibiting spatulate notochaetae on chaetigers 15–18 instead of chaetigers 14–19; the number of spatulate chaetae in a tuft is considerably lower: 12 in S. tcherniai compared to up to 25 in S. prestigium; hooks in S. tcherniai are accompanied by thin simple capillaries which are absent in S. prestigium. In addition, the anterior row of chaetae in the neuropodia of chaetiger 3 consists of special geniculate chaetae in S. tcherniai but are simple capillaries in S. prestigium. Spiophanes tcherniai is known from Antarctic and Subantarctic waters only.

The diagnosis should be enhanced if material for SEM studies becomes available.

Etymology. prestigium —Latin for illusion, deception; referring to the close resemblance to S. tcherniai.

Geographical distribution. Australia: Bass Strait (Tasmania/Victoria).