Neanthes unifasciata ( Willey, 1905 )

Hadiyanto, Hadiyanto, 2023, Nereididae (Annelida: Phyllodocida) from intertidal macroalgae in Western Australia, Zootaxa 5239 (2), pp. 151-203 : 161-162

Neanthes unifasciata ( Willey, 1905)

Figs 5A–H , 19C–D

Nereis unifasciata Willey, 1905: 271–272 , pl. 4, figs 85–88; Ehlers 1918: 237–238; Fauvel 1932: 93; Fauvel 1953: 182–183, fig. 92.a–h.

Nereis (Neanthes) unifasciata .— Day 1967: 318, fig. 14.7.u–y.

Neanthes unifasciata .— Mohammad 1973: 29; Pamungkas & Glasby 2015: 9–11 , fig. 4A–B.

Type locality. Gulf of Mannar , Sri Lanka .

Material examined. Western Australia: Cowrie Creek, Bidyadanga , 18°32′23.82″S 121°46′09.91″E, 4 November 2020, 1 specimen ( WAM V11627 ) . Cape Keraudren , 19°57′46.76″S 119°46′58.51″E, 5 November 2020, 1 specimen ( WAM V11628 ) . Cemetery Beach, Port Hedland , 20°18′21.44″S 118°36′40.39″E, 2 November 2020, 2 specimens ( WAM V11629 ) .

Comparative material. Neanthes unifasciata , det. C. Glasby, Field Island, Kakadu National Park , Northern Territory, 12°3.431′S 132°24.557′E, 1 ( NTM W19021 ), coll. C.J. Glasby & S.K. Horner, 19 August 2004 .

Description. A complete specimen with 78 chaetigers, body 20.1 mm long and 0.7 mm wide; cream yellow in alcohol. Incomplete specimens with 28–61 chaetigers, posterior end missing, remaining body 7.2–15.3 mm long and 0.8–1.4 mm wide; light green or cream yellow in alcohol. Dark green or brown bands present on posterior half of chaetiger 2, gradually disappearing towards chaetiger 11–12.

Prostomium longer than wide. Eyes black, two pairs, equal sizes, in trapezoidal arrangement. Palps one pair, palpophores globose, palpostyles conical. Antennae one pair, shorter than palps. Tentacular cirri four pairs with basal articulation, longest one extending to chaetiger 6 ( Fig. 5A ). Pharyngeal jaws reddish brown, curved at tips, with 11 teeth on each jaw. Paragnaths reddish black, conical, present on both maxillary and oral rings, arranged as follows: Area I= 0–1, Area II= 10–16 in two curved rows, Area III= 8 in two rows, Area IV= 20–22 in curved rows, Area V= 0, Area VI= 6–8, small, in two rows, Areas VII–VIII= 9–10 in one row ( Fig. 5B ).

Apodous segment as long as first chaetiger. First chaetiger uniramous. Notopodia present with digitiform dorsal and ventral ligules throughout chaetigers. Dorsal cirri cirriform, attached on middle of dorsal parapodia, about twice longer than dorsal ligules, similar length throughout chaetigers. Neuropodia with digitiform ventral ligules, acicular ligules, and conical postchaetal lobes extending well beyond acicular ligule tips. Ventral cirri cirriform, attached basally on ventral parapodia, shorter than ventral ligules, similar length throughout all chaetigers ( Fig. 5C ).

Notochaetae present with homogomph spinigers. Neurochaetae present with heterogomph falcigers and homogomph spinigers ( Fig. 5D ) in dorsal fascicles and heterogomph falcigers ( Fig. 5E, 5G ) and spinigers ( Fig. 5F ) in ventral fascicles. Spinigerous blades short, with fine serrations. Falcigerous blades medium size, slightly curved, with a small hook at tip and subdistal tendon (only visible in Fig. 5G ). Acicula translucent. Pygidium with anus on dorsal side, anal cirri cirriform, as long as last three chaetigers.

Remarks. In our specimens, Area III has fewer paragnaths than that of epitokous specimens from Indonesia (22–25 cones) ( Pamungkas & Glasby 2015) and those paragnaths are arranged in two rows, instead of three in specimens from southern India ( Fauvel 1932, 1953). Paragnaths on Areas VII–VIII can also be arranged in two rows in specimens from Kuwait ( Mohammad 1973). In the original description, neurochaetae in the ventral fascicles consist of heterogomph falcigers and hemigomph (incomplete heterogomph) spinigers ( Willey 1905) but those spinigers were described as heterogomph by Ehlers (1918). Other studies did not describe the composition of neurochaetae ( Fauvel 1932, 1953; Day 1967; Mohammad 1973; Pamungkas & Glasby 2015).

The comparative material from Northern Territory matched closely the Western Australian material, except that the antennae extended beyond the palps in the Northern Territory material ( Fig. 19C–D ). The chaetae of the comparative material, imaged under a 60 x plan apochromatic objective lens, revealed fine serrations on the heterogomph falcigers ( Fig. 5H ), which are difficult to see under lower magnifications.

Distribution. Tropical Indo-West Pacific; in Australia confirmed that the species occurs from Cape Keraudren, Western Australia to Kakadu, Northern Territory ( Table 2 ).

Habitat. Intertidal, subtidal, rocky shores ( Table 2 ).

Figures

FIGURE 5. Neanthes unifasciata (Willey, 1905) (WAM V11629); A, anterior body, dorsal view; B, proboscis, ventral dissection; C, parapodium, chaetiger 59, anterior view; D, neurochaetae, dorsal fascicle, homogomph spiniger, chaetiger 59; E, neurochaetae, ventral fascicle, heterogomph falciger, chaetiger 59; F, neurochaetae, ventral fascicle, heterogomph spiniger, chaetiger 4; G–H, neurochaetae, ventral fascicle, heterogomph falciger, chaetiger 10, NTM W19021. I–VIII, area of paragnaths. Scale: A–B, 0.5 mm; C, 0.05 mm; D–F, 0.01 mm.

FIGURE 19. Comparativematerial fromWesternAustralia and the Northern Territory sourced from the Museum &Art Gallery of the Northern Territory. Neanthes cricognatha (Ehlers, 1904) (NTM W18357; 1.8 mm wide at chaetiger 1): A, anterior segments, dorsal view; B, anterior segments, ventral view. Neanthes unifasciata (Willey, 1905) (NTM W19021; 1.5 mm wide at chaetiger 1): C, anterior segments, dorsal view; D, proboscis, ventral dissection. Nereis cockburnensis Augener, 1913 (NTM W18361; 2.0 mm wide at chaetiger 1): E, anterior segments, dorsal view; F, proboscis, ventral dissection. Nereis denhamensis Augener, 1913 (NTM W19015; 1.5 mm wide at chaetiger 1): G, anterior segments, dorsal view; H, anterior segments, ventral view.