Scoloplos normalis ( Day, 1977 )

Zhadan, Anna, 2020, Review of Orbiniidae (Annelida, Sedentaria) from Australia, Zootaxa 4860 (4), pp. 451-502 : 457-460

Scoloplos normalis ( Day, 1977)

Figures 2 , 3

Leitoscoloplos normalis Day, 1977: 224–225 , fig. la–d; Hutchings & Rainer 1979:761.

Scoloplos normalis: Mackie 1987: 22–23 , fig. 22.

Material examined. New South Wales: Hunter River, Fullerton Cove, 32°50’S, 151°47’ E, 16.04.1971, coll. Australian Littoral Society, Holotype, AM W.7345 (previously examined by Mackie (1987) and Hutchings & Rainer (1979)); western shore of Shaw’s Bay, Ballina, 28°52’06”S, 153°34’54”E, intertidal, sandy mud, 02.03.1992, coll. G.D.F. Wilson, R. T. Springthorpe, L. Albertson, AM W.25968, 1 specimen. South Australia: South east of Lake Hamilton via Cummins, Hamilton Spring, 34°34’04”S, 135°16’E, 11.07.2004, coll. B. V. Timms, salt lake floodout pond, AM W.42941, 4 specimens.

Type locality. Fullerton Cove, Hunter River , New South Wales .

Description. Holotype with thoracic width about 2.5 mm, posteriorly incomplete ( Fig. 2A ). Other specimens 1.5– 2 mm width with about 80 chaetigers. Prostomium sharply conical. Proboscis everted and lobed in holotype ( Fig. 2A ). 15 thoracic chaetigers in holotype, 13–14 in other specimens ( Figs 2 A–C, 3A, C, D). Thorax often swollen. Thoracic postchaetal lobes absent in chaetiger 1, arising as small lobes in chaetiger 2, gradually increasing in size along thorax. Notopodial lobes triangular, neuropodial lobes as low ridges with median papilla, both lobes gradually increasing in length along thorax ( Figs 2B, C , 3E ). No subpodal or stomach papillae. Branchiae from chaetiger 14–17 (first or second abdominal chaetiger ( Fig. 3D ), small, digitate, rapidly increasing in size; becoming long, slender and triangular; shorter or equal length with notopodial lamellae ( Fig. 3B, I ). In abdomen, notopodial postchaetal lobes abruptly increase in size, becoming more foliaceous; inner margins ciliated ( Figs 2C, D , 3B, I ). Anterior abdominal neuropodia weakly bilobed; outer lobe small and rapidly lost, posterior abdominal neuropodia uniramous ( Figs 2B, C, D , 3F, I ). Subdistal notch present at insertion of narrow subpodal flange. Subpodal papillae and interramal cirri absent. Thoracic chaetae mostly crenulate capillaries, some anterior neuropodia also with few uncini (in specimen AM W.25968 five uncini in neuropodia of chaetiger 2) ( Fig. 3H ). Uncini short, thin, almost straight, finely serrated. Abdominal chaetae all thin crenulated capillaries, notopodial forked chaetae not found. Pygidium with two short dorso-lateral cirri, anus terminal ( Fig. 3G ).

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

Habitat. Intertidal and upper subtidal, sandy mud.

Remarks. Scoloplos normalis was originally described as part of the genus Leitoscoloplos , as the uncini in the thoracic neuropodia were overlooked ( Day 1977, Hutchings & Rainer 1979). Mackie (1987) re-examined the type material, and found thoracic uncini were present and transferred S. normalis to the genus Scoloplos . Specimens examined in the present study are in agreement with previous descriptions, with small variations. These variations are: the first chaetiger with branchiae varies from 14 to 17, instead of 15–16, and the number of thoracic chaetigers is 13–15 instead of 14–15. The pygidium and anal cirri are illustrated for the first time ( Fig. 3G ).

Figures

FIGURE 2. Scoloplos normalis, A–D: AM W.7345, holotype, methylene blue staining. A. General lateral view; B. Transition between thorax and abdomen, lateral view; C. Same, dorso-lateral view; D. Abdominal parapodia, dorso-lateral view.

FIGURE 3. Scoloplos normalis, A–G: AM W.42941, methylene blue staining. A. General view, ventro-lateral; B. Abdominal parapodia, lateral view; C. Thorax and beginning of the abdomen, lateral view; D. Anterior end, dorsal view; E. Anterior end, lateral view; F. Transition between thorax and abdomen, lateral view; G. Pygidium, posterior view; H, I: AM W.25968, glycerol mounts of parapodia. H. Parapodium of chaetiger 2, five uncini are seen in neuropodium in anterior row (indicated by arrows); I. Abdominal parapodium. br, branchia; ne, neuropodium; no, notopodium. cc, crenulated capillaries.