Scoloplos acutissimus Hartmann-Schröder 1991

Zhadan, Anna, 2020, Review of Orbiniidae (Annelida, Sedentaria) from Australia, Zootaxa 4860 (4), pp. 451-502 : 454-455

Scoloplos acutissimus Hartmann-Schröder 1991

Scoloplos acutissimus Hartmann-Schröder, 1991: 48–49 , figs 73–80.

Scoloplos acutissimus: Zhadan et al. 2015: 779–781 , figs 1, 2, 12A.

Leodamas acutissimus: Blake 2017: 49 , 50, 55.

Material examined. Queensland: Gladstone, mangrove tidal creek; fine sand with silt and many plant fragments, Holotype, ZMH P–20562; Lizard Island, August 2013: Vicki’s Reef , 14°41’17”S, 145°26’35”E, SCUBA diving, depth 5–7 m, muddy sand, coll. N. Budaeva, A. Zhadan, AM W.44248, 1 specimen; Off Casuarina Beach, 14°40’46”S, 145°26’49”E, snorkeling, depth 0.5 m, sand, seagrass, coll. K. Meissner, N. Budaeva, A. Murray, AM W.46090, 3 specimens; off Casuarina Beach, 14°40’46”S, 145°26’49”E, intertidal, fine sand, coll. M. Capa, J. Parapar, Q. Parapar, M. T. Aguado, AM W.46091, 6 specimens; AM W.46092, off Casuarina Beach, in front of Lizard Island Research Station , 14°40’46”S, 145°26’49”E, intertidal, sand, coll. J. Parapar, Q. Parapar, P.A. Hutchings, P. Rodgers, 12 specimens; Casuarina Beach, 14°40’46”S, 145°26’49”E, intertidal, sand and seagrass, coll. T. Alvestad, N. Budaeva, AM W.46096, 20 specimens; off Casuarina Beach, near Big Vicki’s reef, 14°40’53”S, 145°26’31”E, depth 10 m, van Veen grab, coll. N. Budaeva, T. Alvestad, A. Zhadan, AM W.46097, 3 specimens; Casuarina Beach, 14°40’46”S, 145°26’49”E, intertidal, sand and seagrass, coll. V. I. Radashevsky, A. Zhadan, AM W.44940, 6 specimens; Mangrove Beach, 14°40’47”S, 145°27’44”E, intertidal, sand, coll. N. Budaeva, T. Alvestad, AM W.44942, 3 specimens.

Type locality. Gladstone , Queensland .

Description (after Zhadan et al. 2015). Body long, slender; thorax slightly flattened, abdomen cylindrical. Colour in life pale yellowish-brown with red blood vessels and yellow gut content. Thoracic width up to 0.9 mm. Prostomium sharply conical with drawn out tapering tip. Peristomium with pair of dorso-lateral nuchal organs. Thoracic chaetigers numbering 14–20 (usually 17–19). Branchiae starting from penultimate thoracic chaetiger, usually chaetiger 16–18 (13 in smallest specimen). First branchiae small and digitiform; becoming larger and triangular in anterior abdomen; then long, strap-like, markedly wider and longer than notopodia, in middle and posterior abdomen. Thoracic postchaetal lobes well developed from chaetiger 1 (neuropodia) or 2 (notopodia). Notopodial lobes short and papilliform in anterior thorax; gradually increasing in length, becoming digitiform, as long as branchiae in posterior thorax. Lateral organs below notopodia of all segments well developed. Thoracic neuropodial postchaetal lobes round papilliform, in posterior thorax becoming elongated and arising from low ridge, more developed below papilla (mammiform shape). No subpodal or stomach papillae. Abdominal notopodial lobes narrow, lanceolate, shorter than branchiae. Abdominal neuropodia supported by one thin acicula and bilobed with subequal lobes; inner lobe rounded, slightly longer and thicker than outer one. Parapodial flange well developed, with deep notch and round upper margin without flange papilla. Ciliated dorsal organs with two short ciliated strips present mid-dorsally. Thoracic notopodia bearing only crenulate capillary chaetae; neuropodia with 3–4 anterior rows of uncini and one posterior row of capillaries, neuropodial lobe located on same level as capillary chaetae in middle of row; uncini in anterior chaetigers slightly curved, serrated with 4 denticles; in posterior thoracic chaetigers uncini almost straight, smooth, hooded, very short in anterior row; in one or two last thoracic chaetigers uncini replaced by capillary chaetae. In abdomen both rami bearing thin capillaries, besides forked chaetae present in notopodia and flail chaetae in neuropodia. Pygidium with two long anal cirri.

Distribution. Australia, Queensland.

Habitat. Intertidal and upper subtidal, sand, possibly with silt and plant parts.

Remarks. Scoloplos acutissimus was described from Gladstone, Queensland, and recently redescribed and illustrated based on type material and specimens from Lizard Island, Queensland ( Zhadan et al. 2015). Blake (2017) transferred S. acutissimus to the genus Leodamas , group B.