Leitoscoloplos bifurcatus (Hartman, 1957)

Zhadan, Anna, 2020, Review of Orbiniidae (Annelida, Sedentaria) from Australia, Zootaxa 4860 (4), pp. 451-502 : 466

Leitoscoloplos bifurcatus (Hartman, 1957)

Figure 8

Haploscoloplos bifurcatus Hartman, 1957: 277–279 .

Leitoscoloplos bifurcatus: Day 1977: 223–224 ; Hutchings & Rainer 1979: 760–761; Mackie 1987: 13–14, fig. 14a–f; Zhadan et al., 2015: 786 , figs 5, 6.

Material examined. Northern Territory: Darwin Harbour, Mandorah , 12°26’54”S, 130°45’56”E, 06.07.1993, muddy sand, coll. P.A. Hutchings, AM W.25435, 1 specimen . Queensland: Lizard Island, August 2013: 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.46089, 1 specimen ; 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.44299, 2 specimens ; Casuarina Beach , 14°40’46”S, 145°26’49”E, intertidal, sand, coll. P.A. Hutchings, P. Rodgers, J. Zanol Silva, N. Budaeva, AM W.44761, 4 specimens ; Mangrove Beach , 14°40’47”S, 145°27’44”E, intertidal, sand, coll. N. Budaeva, T. Alvestad, AM W.44938, 1 specimen . New South Wales: Towlers Bay, Pittwater , 33°37’30”S, 151°17’E, April 1992, depth 12 m, coll. C.L. Rose, fine mud, AM W.24101, 5 specimens ; Port Hacking, Artificial Reef , 08.01.1975, 34°04′S, 151°08′E, AM W.43442, 1 specimen ; east of Marley , 34°08’05” S, 151°09’39” E, 31.07.1989, sand, depth 60 m, coll. Fisheries Research Institute ( NSW), AM W.24302, 1 specimen ; Bass Point , 34°36’S, 150°54’E, 01.02.1990, Smith-McIntyre Grab, depth 50 m, coll. The Ecology Lab for RMI/ Pioneer Project, AM W.22967, 1 specimen .

Type locality. Encounter Bay , South Australia .

Description. Body cylindrical, thorax wider than abdomen, slightly flattened in posterior part; abdomen cylindrical. Thoracic width 2–4.4 mm ( Fig. 8A, B ). Prostomium sharply conical. Peristomium bearing pair of dorsolateral nuchal organs. Thoracic chaetigers numbering 18–22 ( Fig. 8A, B, D ). Branchiae from chaetiger 8 as minute papillae, becoming prominent from chaetiger 16; in abdomen digitate-triangular, shorter or equal to notopodial lobes in anterior abdomen, becoming 1.5–2 times longer than notopodia in posterior abdomen ( Fig. 8B, E, F, G ). Thoracic postchaetal lobes developed from first chaetiger, gradually increasing in size, narrow triangle, equal size or neuropodia longer in anterior thorax, notopodia lobes longer in middle and posterior thorax ( Fig. 8 A–D). Neuropodial lobes becoming bilobed from chaetiger 10–12 ( Fig. 8A, C, D ). No subpodal or stomach papillae. Abdominal notopodial lobes digitate, triangular; neuropodia bilobed with inner lobe longer than outer, with two dark aciculae ( Fig. 8 D–G). Subpodal notch and flange present. No flange papillae. Chaetae crenulate capillaries in all parapodia, abdominal notopodia also bearing forked chaetae ( Fig. 8H ). Pygidium with two anal cirri.

Distribution. Australia, Northern Territory, Queensland, New South Wales, Victoria, South Australia.

Habitat. Intertidal and upper subtidal, sand, mud, seagrass.

Remarks. Leitoscoloplos bifurcatus was described from South Australia and later reported from Victoria, New South Wales, Queensland, and the Northern Territory ( Hutchings & Rainer 1979). Recently, this species was redescribed and illustrated based on specimens from Lizard Island, Queensland ( Zhadan et al. 2015). The specimens investigated in the present study generally are consistent with previous descriptions; forked chaetae in abdominal notopodia are noted for the first time here. Leitoscoloplos bifurcatus is similar to S. dayi regarding general appearance, shape of thoracic neuropodia, and the first segment with branchiae. The differences between these two species are listed with the account for S. dayi (above).

Figures

FIGURE 8. Leitoscoloplos bifurcatus, A–F: AM W.22967, G, H: AM W.24101. A–E: stereomicroscope, methylene blue staining; F–H: compound microscope.A.Anterior part, lateral view; B.Anterior part, dorsal view; C. Thorax, parapodia of chaetigers 8–13, lateral view; D. Thorax-abdomen transition, lateral view; E. Abdomen, dorsal view; F. Parapodium of chaetiger 37; G. Posterior parapodia; H. Notochaetae (capillary and forked chaetae) of posterior parapodia.Arrows indicate the appearing of the first branchia. a, acicula; br, branchia; cc, crenulated capillaries; fc, forked chaeta; ne, neuropodium; no, notopodium.