Neanthes cricognatha ( Ehlers, 1904 )

Hadiyanto, Hadiyanto, 2023, Nereididae (Annelida: Phyllodocida) from intertidal macroalgae in Western Australia, Zootaxa 5239 (2), pp. 151-203 : 159-161

Neanthes cricognatha ( Ehlers, 1904)

Figs 4A–F , 19A–B

Nereis cricognatha Ehlers, 1904: 29–30 , pl. IV, figs 3–7; Augener 1913: 163–164.

Nereis (Neanthes) cricognatha .— Kott 1951: 106.

Neanthes cricognatha .— Knox 1951: 217–218, pl. XLV, figs 6–8; Hutchings & Rainer 1979: 754; Hutchings & Turvey 1982: 110–111; Wilson 1984: 213–214; Glasby 2015: 218–219 .

Type locality. New Zealand .

Material examined. Western Australia: Dynamite Bay, Green Head , 30°4′15.62″S 114°57′44.93″E, 28 December 2020, 2 ( WAM V11625 ) . Cape Peron , 32°15′59.14″S 115°41′6.74″E, 12 January 2021, 2 specimens ( WAM V11626 ) .

Comparative material. Neanthes cricognatha , det. C. Glasby, Bandy Creek Jetty, Esperance , Western Australia, 33°51′S 121°55′E, 1 ( NTM W18357 ), coll. Mulligan, 17 March 2002 .

Description. Incomplete specimens with 20–28 chaetigers, posterior end missing, remaining body 3.4–5.7 mm long and 0.6–1.0 mm wide; cream yellow in alcohol.

Prostomium as long as 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 6–7 ( Fig. 4A ). Pharyngeal jaws reddish black, curved at tips, with eight teeth on each jaw. Paragnaths reddish to black, conical, present on both maxillary and oral rings, arranged as follows: Area I= 5–6, Area II= 32–33 in a triangle, Area III= 30 in an ellipse, Area IV= 33–36 in a triangle, Areas V–VIII= a continuous band of paragnaths about 2–5 deep dorsally, 4–5 deep ventrally ( Fig. 4B–C ).

Apodous segment as long as first chaetiger. All chaetigers biramous. Notopodia present with triangular dorsal ligules, digitiform intermediate and inferior ligules. Dorsal cirri cirriform, attached on lower-middle of dorsal parapodia, as long as dorsal ligules, similar length throughout chaetigers. Neuropodia with digitiform ventral ligules, acicular ligules, and subconical postchaetal lobes extending well beyond acicular ligule tips. Ventral cirri cirriform, attached basally on ventral parapodia, shorter than ventral ligules, similar length throughout chaetigers ( Fig. 4D ).

Notochaetae present with homogomph spinigers ( Fig. 4E ). Neurochaetae present with homogomph spinigers and heterogomph falcigers ( Fig. 4F ) in both dorsal and ventral fascicles. Spinigerous blades long, with fine serrations. Falcigerous blades long, with fine serrations, and a small, hooked tooth. Acicula translucent.

Remarks. Pettibone (1963) and Imajima (1972) synonymized N. cricognatha with N. caudata ( delle Chiaje, 1828) and N. arenaceodentata ( Moore, 1903) ; the two latter species were assigned to N. acuminata ( Ehlers, 1868) by Day (1973). However, we are following the more recent studies that have used the name N. cricognatha for Australian specimens ( Hutchings & Turvey 1982; Wilson 1984; Glasby 2015). The dorsal cirri of our specimens are longer and attached more basally than that of materials identified as Nereis (Neanthes) arenaceodonta from Massachusetts, Rhode Island, New Jersey, and Maryland, USA ( Pettibone 1963). In addition, the falcigers of our specimens have a hooked distal tooth ( Fig. 4F ), while those of N. caudata from Japan have a blunt tip ( Imajima 1972). A recent molecular study has found that N. caudata , N. arenaceodentata , and N. acuminata show multiple evolutionary significant units although they are identical in terms of paragnath distribution and parapodial characteristics ( Reish et al. 2014). In our study specimens, Area I has fewer paragnaths than that reported by Augener (1913), Hutchings & Rainer (1979), Hutchings & Turvey (1982), and Wilson (1984) and seen in the comparative material from Esperance, Western Australia, which has 12 paragnaths ( Fig. 19A ); the comparative specimen also has many more paragnaths in Areas VII–VIII ( Fig. 19B ). In addition, all chaetigers are biramous, instead of uniramous for first two chaetigers ( Ehlers 1904). Possibly, it represents an undescribed species, but more specimens are required to establish the extent of size-dependent variation in paragnath number.

Distribution. Indo-West Pacific: India, Philippine, Australia, New Zealand ( Table 2 ).

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

Figures

FIGURE 4. Neanthes cricognatha (Ehlers, 1904) (WAM V11626);A, head, dorsal view; B, proboscis, dorsal view; C, proboscis, ventral view; D, parapodium, chaetiger 14, anterior view; E, notochaetae, homogomph spiniger, chaetiger 14; F, neurochaetae, ventral fascicle, heterogomph falciger, chaetiger 14. Scale: A–C, 0.5 mm; D, 0.05 mm; E–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.