Spiophanes dubitalis, 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 : 135

Spiophanes dubitalis n.sp.

Fig. 13

Spiophanes sp. 5 .–Wilson & McDiarmid, 2003.

Type material. HOLOTYPE: Australia, Victoria , Central Bass Strait , 66 km S of Rodondo Island, 39°49.5'S 146°18.5'E, in 82 m, 13 Nov 1981, ( MV F 90005 ).

Other species examined. Spiophanes bombyx : NORTH ATLANTIC OCEAN: North Sea, German Bight, 54°20.01'N 7°20.01'E, in 43 m, 26 May 1987, several specimens (SM 4950); 55°54'N 3°27.6'E, in 65 m, 10 Aug 1990, 2 specimens (SM 6476); 55°46.93'N 3°52.38'E–55°53.09' N 3°28.8'E, in 48.4 m, 10 Aug 1990, 3 specimens (SM 6480); 53°41.46'N 6°59.58'E, in 3.5 m, 13 Mar 1989, 8 specimens (SM 6527). MEDITERRANEAN: Spain, between Cape San Antonio and Valencia harbour, 29 Apr 1996, two specimens (MNCN 16.01/2648, 2661). INDIAN OCEAN: 34°16.8'S 18°42.8'E, in 60 m, 25 Feb 1959, several specimens (South African Museum A20779 ). PACIFIC OCEAN: Alaska, Bering Sea, 58°46.36'N 164°14'W, in 35 m, 23 May 1976, 2 specimen (CAS 23887); Alaska, Chukchi Sea, 67°44.29'N 164°33.45'W, in 5.7 m, 17 Aug 1976, 1 specimen (CAS 1675); California, 37°49.27'N 122°25.55'W, in 58–67 m, 24 Sep 1973, several specimen (CAS 1915); 37°46'N 122°41.5'W, in 31 m, 14 Aug 1973, several specimen (CAS 123655).

Spiophanes tcherniai : 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 15 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; about 3 mm long, 0.15 mm wide. Body slender, subcylindrical. Prostomium broad anteriorly, bell-shaped to subtriangular, with distinct anterolateral projections (Fig. 13A,B). Occipital antenna absent. Eyes not observed. Nuchal organs as indistinct pair of dorsal loops or kind of short ciliated band, extending from posterior prostomium margin to beginning of chaetiger 3 (Fig. 13A,B). Peristomium poorly developed. Parapodia of chaetiger 1 oriented dorsally; postchaetal lamellae subulate, more or less equal in length in both rami (Fig. 13A). Parapodia of chaetigers 2–4 positioned laterally; notopodial postchaetal lamellae subulate, those of chaetiger 2 longest; neuropodial postchaetal lamellae subulate to rounded (Fig. 13A,C). Chaetigers 5–8 with ovoid notopodial postchaetal lamellae; neuropodial lamellae reduced (Fig. 13D). From chaetiger 9, notopodial lamellae short, digitiform to subulate; neuropodial lamellae reduced (Fig. 13E,F). Chaetal spreader of “0+1 type” with semicircular glandular opening on chaetigers 5–7 (Fig. 13A); glandular opening absent in chaetiger 8; glandular organ of chaetigers 9–14 opens as lateral, vertical slit. Ventrolateral intersegmental genital pouches absent. Dorsal ciliated crests indistinct. Chaetiger 1 with 1–2 stout, crook-like chaetae in the neuropodia; remainder of chaetae capillaries; notochaetae arranged in tuft; neurochaetae arranged in 2 rows. Chaetigers 2–4 notopodia with capillaries with narrow sheaths (Fig. 13K,M), arranged in tuft; neurochaetae capillaries with narrow and broad sheaths (Fig. 13L,N), arranged in 2 rows. Notopodial capillaries of chaetigers 1–4 only slightly longer than those of subsequent chaetigers. Chaetigers 5–14 with stout, bilimbate neurochaetae, distally pointed (Fig. 13H,I), arranged in 1 irregular row; notochaetae with narrow sheath (Fig. 13P), arranged in 3 rows. From chaetiger 15, notopodial capillaries with narrow sheaths (Fig. 13 O), arranged in tuft; neuropodia with quadridentate hooded hooks (Fig. 13G), initially with 5 hooks in 1 row, smaller number of hooks in more posterior chaetigers. Bacillary chaetae not present in the holotype. Sabre chaetae from chaetiger 4, long, granulated, without sheath (Fig. 13J). Pygidium unknown.

Pigmentation. Orange-brown pigment on chaetigers 10– 13; encompasses neuropodia and lateral side of the body.

Methyl green staining pattern. Posterior tip of the prostomium and postchaetal lamellae stain dark blue (Fig. 13B).

Biology. Substrate at the sampling locality was described as “sand-silt-mud”.

Remarks. This species resembles S. prestigium n.sp., S. tcherniai and S. bombyx with regard to the appearance of nuchal organs, being a short ciliated band or kind of ciliated loop on the dorsum, extending to the beginning of chaetiger 3, the presence of hooded hooks, and the absence of an occipital antenna. However, S. prestigium and S. tcherniai clearly differ from S. dubitalis in having spatulate notochaetae in the middle body region, which are absent in S. dubitalis , and bearing neuropodial hooded hooks from chaetiger 16 rather than 15. Spiophanes bombyx is readily distinguished from S. dubitalis by its long anterolateral horns compared to only short anterolateral horns in S. dubitalis , the presence of sabre chaetae only accompanying the neuropodial hooks rather than being present from chaetiger 4, and its chaetal spreaders of the “0+1 type” with a wavy glandular opening in chaetigers 5–8 rather than chaetal spreaders of the “0+1 type” with a semicircular glandular opening on chaetigers 5–7. Spiophanes tcherniai has not been reported from Australian waters; previous records of S. bombyx were found to be incorrect (this paper) and the occurrence of this species could not be substantiated from investigating all Spiophanes material available from Australian collections.

Etymology. dubitalis —Latin for dubious, to be doubted; referring to the unfortunate situation of having only one specimen for establishing a new species which shares several of its characters with other species in the genus but still has a clearly different character combination.

Geographical distribution. Species only known from the type locality.