Pseudopolydora cf. paucibranchiata ( Okuda, 1937 )

Radashevsky, Vasily I., 2015, Spionidae (Annelida) from Lizard Island, Great Barrier Reef, Australia: the genera Aonides, Dipolydora, Polydorella, Prionospio, Pseudopolydora, Rhynchospio, and Tripolydora, Zootaxa 4019 (1), pp. 635-694 : 681-682

Pseudopolydora cf. paucibranchiata ( Okuda, 1937)

( Fig. 30 )

Polydora (Carazzia) paucibranchiata Okuda, 1937: 231 –233, figs. 11, 12.

Pseudopolydora paucibranchiata .— Hartman 1959: 387; Blake & Kudenov 1978: 268; Hutchings & Murray 1984: 61 –62; Hutchings & Turvey 1984: 17, fig. 7.

Material examined. Queensland: AM W.45380, MI QLD 2440 (1).

Adult morphology. Single 12-chaetiger anterior fragment 1.5 mm long, 0.25 mm wide. Pigmentation on body absent. Anterior margin of prostomium and occipital antenna slightly damaged and unclear (apparently prostomium rounded and occipital antenna present). Caruncle extending to end of chaetiger 3. Nuchal organs ciliary bands on lateral sides of caruncle. Two pairs of small black eyes arranged trapezoidally. Palps in life with eight branching yellow chromatophores; chromatophores invisible after fixation.

Chaetiger 1 fused to peristomium ventrally and weakly separated from it dorsally, with few very short capillaries in neuropodia, small notopodial postchaetal lamellae and well-developed neuropodial lamellae; notochaetae absent. Notochaetae of chaetigers 2–4 and 6 slender capillaries with narrow wing ( Fig. 30 E). Anteriorrow notopodial capillaries from chaetiger 7 to end of fragment with triangular pennon-like wing ( Fig. 30 F), 3–5 in a series; superior and posterior-row notochaetae in these chaetigers slender capillaries with narrow wing; superior capillaries longer than posterior-row capillaries, with longer wing ( Fig. 30 G, H).

Chaetiger 5 same size as chaetigers 4 and 6, with four dorsal superior winged capillaries, two kinds of notopodial spines arranged in a double J-shaped series, and eight ventral winged capillaries; notopodial postchaetal lamellae lacking but neuropodial lamellae well developed. Dorsal superior capillaries slightly shorter and fewer than those capillaries on chaetigers 4 and 6. Ventral capillaries same as those on chaetiger 4 or 6. Anterior-row notochaetae enlarged pennon spines with curved tip and weak constriction between tip and shaft ( Fig. 30 A, B, C), eight in a series; posterior-row notochaetae simple falcate spines, with fine scales on distal end, seven in a series ( Fig. 30 A, B, D).

Hooks in neuropodia from chaetiger 8, up to seven in a series, accompanied by 1–3 hair-like alternating capillaries until chaetigers 10–11 ( Fig. 30 I); alternating capillaries situated between upper hooks in a row, very short, mostly embedded into body wall and slightly protruding above surface. Hooks bidentate, with upper tooth closely applied to main fang; upper part of shaft with constriction, lower part of shaft bent at right angle ( Fig. 30 J). Branchiae from chaetiger 7 to end of fragment, free from notopodial postchaetal lamellae.

Remarks. Pseudopolydora paucibranchiata was originally described from the Inland Sea, Japan by Okuda (1937). The species is common in tidal flats and estuaries in the temperate northern Pacific along the Asian and American coasts ( Radashevsky 1993; Blake 1996). It was likely introduced to eastern Mediterranean ( Dagli & Çinar 2008) and Brazil ( Junqueira et al. 2009). In Australia, P. paucibranchiata was reported from New South Wales, Victoria and South Australia ( Blake & Kudenov 1978; Poore & Kudenov 1978a, b; Hutchings & Rainer 1979; Hutchings & Murray 1984; Hutchings & Turvey 1984).

The only anterior fragment from Lizard Island and other worms collected by the author from Victoria and Northern Territory and examined alive appear morphologically identical to worms from the northern Pacific. However, preliminary molecular analysis of 28S rDNA showed more than 3% difference between specimens from Australia and the Sea of Japan and 2.4% difference between specimens from Victoria and Northern Territory (Radashevsky unpublished). It is possible that two or more sibling species are actually present. Further molecular analysis is needed to clarify their taxonomy.

Habitat. In this study, a single individual of P. cf. paucibranchiata was found in fine coral sand at 14 m depth.

Distribution. Native in northern Pacific; introduced to the Mediterranean and Brazil.? Australia.

Figures

FIGURE 30. Pseudopolydora cf. paucibranchiata. A – J—AM W. 45380. A, B. Right parapodia of chaetiger 5, ventral view. C, D. Notopodial spines of chaetiger 5; C. Anterior-row enlarged pennon spine with curved tip and weak constriction between tip and shaft; D. Posterior-row simple falcate spine with fine scales on distal end; E. Anterior-row notopodial capillary chaeta of chaetiger 6; F – H. Notopodial capillary chaetae of chaetiger 7; F. Anterior-row capillary chaeta with triangular pennon-like wing; G. Posterior-row slender capillary chaeta; H. Dorsal superior slender capillary chaeta; I, J. Neurochaetae of chaetiger 8; I. Hair-like alternating capillary chaeta; J. Bidentate hooded hook. Abbreviations: an—anterior-row notopodial spines, poposterior-row notopodial spines, ve—ventral capillary chaetae. Scale bars: A, B— 10 µm.