Nereis edentata, Hadiyanto, 2023

Hadiyanto, Hadiyanto, 2023, Nereididae (Annelida: Phyllodocida) from intertidal macroalgae in Western Australia, Zootaxa 5239 (2), pp. 151-203 : 168-170

Nereis edentata n. sp.

Fig. 9A–I

Material examined. Holotype. Western Australia: Port Denison , 29°16′33.59″S 114°54′45.68″E, 29 December 2020, 1 specimen ( WAM V11651 ) . Paratypes: Kalbarri , 27°43′17.09″S 114°09′11.39″E, 15 November 2020, 2 specimens ( WAM V11652 ) . Horrock , 28°23′23.32″S 114°25′48.98″E, 18 November 2020, 2 specimens ( WAM V11653 ) . Glenfield Beach , 28°41′01.32″S 114°36′21.65″E, 17 November 2020, 2 specimens ( WAM V11654 ) . Dynamite Bay , Green Head, 30°04′15.62″S 114°57′44.93″E, 28 December 2020, 2 specimens ( WAM V11655 ) . Yanchep Beach , 31°33′02.36″S 115°37′24.86″E, 14 January 2021, 3 specimens ( WAM V11656 ) . Beaumaris Beach , 31°44′23.57″S 115°43′17.82″E, 18 January 2021, 1 specimen ( WAM V11657 ) . Cape Peron , 32°15′59.14″S 115°41′06.74″E, 12 January 2021, 1 specimen ( WAM V11658 ) . Hunters Beach , Green Head, 30° 4′27.54″S 114°58′11.46″E, 29 July 2016, 1 specimen ( WAM V11659 ) .

Description. Holotype a complete specimen with 54 chaetigers, body 19.1 mm long and 1.3 mm wide; cream yellow in alcohol.

Prostomium wider than long. Eyes black, two pairs, equal sizes, in trapezoidal arrangement. Palps one pair, palpophores globose, palpostyles conical. Antennae one pair, extending to level of palps. Tentacular cirri four pairs with basal articulation, longest one extending to chaetiger 5. Pharyngeal jaws translucent reddish black, curved at tips, with nine teeth on each jaw. Paragnaths reddish black, conical, present on maxillary and oral rings, arranged as follows: Area I= small, 1; Area II= small, 7 on left and 8 on right, in a triangle in each side; Area III= small, 2 in one straight transverse row; Area IV= small, 10 on left and 11 on right, in a curved cluster in each side; Area V= 0; Area VI= small, 6 on left in 2 rows and 5 on right in a circle; Areas VII–VIII= 12 in one row (8 large paragnaths widely spaced and 4 small paragnaths in ventromedial row) ( Fig. 9A–B ).

Apodous segment slightly longer than first chaetiger. First two chaetigers uniramous. Notopodia present with digitiform dorsal and ventral ligules ( Fig. 9C–E ), basal dorsal ligules enlarged in middle ( Fig. 9D ) and posterior chaetigers ( Fig. 9E ). Dorsal cirri cirriform, attached on middle of dorsal parapodia, twice longer than dorsal ligules, similar length throughout chaetigers. Neuropodia with digitiform ventral ligules, acicular ligules, and triangular postchaetal lobes extending below acicular ligule tips ( Fig. 9C–E ). Ventral cirri cirriform, attached basally on ventral parapodia, slightly shorter than ventral ligules in all chaetigers.

Notochaetae present with homogomph spinigers in anterior chaetigers, homogomph falcigers ( Fig. 9F ) from chaetiger 20, two falcigers in each notopodium. Notopodial falcigerous blades short, smooth, slightly curved at tips. Neurochaetae present with heterogomph falcigers ( Fig. 9G ) and homogomph spinigers ( Fig. 9H ) in dorsal fascicles, heterogomph spinigers ( Fig. 9I ) and falcigers in ventral fascicles. Neuropodial falcigerous blades medium size, with fine serrations. All spinigerous blades long, with fine serrations. Acicula black. Pygidium with anus on dorsal side, anal cirri cirriform, as long as last four chaetigers.

Variations in paratypes. Complete specimens with 39–69 chaetigers, body 6.2–37.3 mm long and 0.4–1.5 mm wide; cream yellow in alcohol. Incomplete specimens with 29–44 chaetigers, posterior end missing, remaining body 5.7–32.9 mm long and 0.7–1.5 mm wide; cream yellow in alcohol.

Longest tentacular cirri extend to chaetiger 2–5. Paragnaths small but larger in Areas VII–VIII, arranged as follows: Area I= 0–1, Area II= 3–8 in a triangle, Area III= 0–5 in one straight transverse row, Area IV= 5–12 in a curved cluster, Area V= 0, Area VI= 2–7 in an oval, Areas VII–VIII= 6–10 in one row, including 1–3 smaller paragnaths in ventromedial row in some specimens. Notopodial homogomph falcigers present from chaetiger 18– 24, two falcigers (occasionally 3) in each notopodium or 1–2 falcigers in small specimens (<15 mm long). Anal cirri as long as last three to four chaetigers.

Remarks. Nereis edentata n. sp. most closely resembles Nereis species having one row of paragnaths on Areas VII–VIII and smooth notopodial homogomph falcigers including: Nereis coutieri Gravier, 1899 , Nereis eugeniae ( Kinberg, 1865) and Nereis posidoniae Hutchings & Rainer, 1979 .

Nereis edentata n. sp. and N. coutieri have enlarged dorsal notopodial ligules in posterior chaetigers, but they differ in the ornamentation of the dorsal chaetiger 2 and the arrangement of paragnaths on Areas III and VII–VIII. Nereis coutieri has a brown band dorsally on chaetiger 2 ( Gravier 1899a; Gravier 1902; Fauvel 1911; Yousefi et al. 2011), while Nereis edentata n. sp. lacks a band. Nereis coutieri has more paragnaths on Area III (5–7) ( Gravier 1899a; Gravier 1902; Yousefi et al. 2011) and those paragnaths are arranged in a curved row with a deep concavity ahead in specimens from the Red Sea (type locality) ( Gravier 1899a; Gravier 1902) or an irregular group in specimens from South Africa and Mozambique ( Day 1967), instead of in a straight transverse row as for Nereis edentata n. sp. Paragnaths on Areas VII–VIII are present in a similar size for N. coutieri ( Gravier 1899a; Gravier 1902; Day 1967; Bonyadi-Naeini et al. 2017) but in two sizes for some specimens of Nereis edentata n. sp. In addition, N. coutieri has only one uniramous chaetiger in the first parapodium ( Fauvel 1911) although this is not mentioned in the original description ( Gravier 1899a) and previous studies ( Gravier 1902; Day 1967; Yousefi et al. 2011), while Nereis edentata n. sp. has two uniramous chaetigers in first two parapodia. Nereis edentata n. sp. also differs from materials from Lizard Island, Queensland that were identified by Glasby (2015) as Nereis cf. coutieri . Dorsal notopodial ligules of the latter species are shorter than ventral notopodial ligules ( Glasby 2015). Hartmann-Schröder (1982, 1983) found N. coutieri from south-west Australia (Yallingup and Margaret River). These specimens need to be assessed further as there was no description of the ornamentation of the dorsal chaetiger 2 and the arrangement of paragnaths on Area III.

Nereis edentata n. sp., N. eugeniae , and N. posidoniae do not have a pigmented band on the dorsal chaetiger 2, but they differ in the size of the eyes, the length of the tentacular cirri, the presence of paragnaths on Area VI, and the enlargement of dorsal notopodial ligules in posterior chaetigers. The eyes of N. eugeniae are small and occasionally absent ( Hartman 1964; Day 1967; Darbyshire 2014). The tentacular cirri of N. eugeniae and N. posidoniae are shorter than those of Nereis edentata n. sp., with the longest one extending to only the apodous segment ( Kinberg 1865; Hartman 1964; Day 1967; Hutchings & Rainer 1979; Darbyshire 2014). Paragnaths on Area VI are absent for N. posidoniae ( Hutchings & Rainer 1979) but present for Nereis edentata n. sp. and N. eugeniae (3–6) ( Hartman 1964; Day 1967; Darbyshire 2014). Dorsal notopodial ligules in posterior chaetigers are not expanded in N. eugeniae ( Hartman 1964; Day 1967; Darbyshire 2014) and not described in N. posidoniae ( Hutchings & Rainer 1979) but enlarged in Nereis edentata n. sp.

Etymology. The new species is named after the Latin adjective, edentates, meaning toothless, referring to the smooth-bladed homogomph falcigers.

Distribution. South-west Australia. Distribution records indicate that the new species appears to be transitional between the tropical and temperate Australia realms ( Table 2 ).

Habitat. Intertidal, rocky shores ( Table 2 ).

Figures

FIGURE 9. Nereis edentata n. sp. (WAM V11651); A, head, dorsal view; B, head, ventral view; C, parapodium, chaetiger 6, posterior view; D, parapodium, chaetiger 23, posterior view; E, parapodium, chaetiger 40, posterior view; F, notochaetae, homogomph falciger, chaetiger 30; G, neurochaetae, dorsal fascicle, heterogomph falciger, chaetiger 40; H, neurochaetae, dorsal fascicle, homogomph spiniger, chaetiger 40; I, neurochaetae, ventral fascicle, heterogomph spiniger, chaetiger 40. Scale: A–B, 1 mm; C–E, 0.1 mm; F–I, 0.02 mm.