Nothria edwardsi ( Roule, 1898 )

Arias, Andrés & Paxton, Hannelore, 2016, Hyalinecia (sic) Edwardsi Roule, 1898 — the enigmatic ghost from abyssal depths — redescribed as Nothria edwardsi (Annelida: Onuphidae), Zootaxa 4147 (1), pp. 97-100 : 97-100

Nothria edwardsi ( Roule, 1898) combinatio nova

Figures 1 and 2

Hyalinecia Edwardsi Roule, 1898: 193 –194.

Hyalinoecia edwardsi Roule, 1898 .— Roule 1906: 45 –51, pl. I fig. 7, pl. VI figs 40–46, pl. VIII figs 74–80; Campoy 1982: 550; Gil 2011: 538.

Onuphis sp. Fauvel 1914: 129 –130, pl. IX, fig. 21–26 (Azores, 4020 m deep). Not Audouin & Milne Edwards, 1833.

Material examined. Two Syntypes (MNHN POLY TYPE 1305), Talisman station 136 located between the Azores archipelago and the Iberian Peninsula, 4255 m deep, Atlantic Ocean, coll. Mission Expedition du Talisman Navire 26 August 1883.

Comparative material. Nothria abyssia Kucheruk, 1978 (AM W.42762), 2 specimens, RV Franklin station 69, epibenthic sled, 38º29.33’S, 149º19.98’E, 1840 m deep, SE Australia.

Diagnosis. First pair of parapodia extending beyond frontal margin of prostomium, with simple uni- and bidentate hooks. Second pair of parapodia with bidentate pseudocompound hooks, limbate and pectinate chaetae. Third pair of parapodia without hooks, only limbate and pectinate chaetae present. Pectinate chaetae varying from almost flat to slightly rolled, with 17–20 teeth. Simple branchiae from chaetiger 12–15. Subacicular hooks from chaetiger 9–13. Prostomial eyes absent.

Description. Both syntypes incomplete, consisting of anterior ends; largest specimen ( Fig. 1 A) measuring 12 mm in length for 17 (?18) chaetigers, width about 2 mm; smallest specimen measuring 7 mm for 12 chaetigers, width about 1 mm (at chaetiger 10, excluding parapodia). Alcohol stored specimens overall cream-coloured, no pigment pattern ( Fig. 1 A).

Prostomium anteriorly rounded; paired ovoid frontal lips almost twice as long as wide ( Figs 1 A, 2A). Palps reaching chaetiger 1, lateral antennae reaching chaetiger 3–4, median antenna reaching chaetiger 6; ceratophores of antennae with 3–4 rings ( Figs 1 A, 2A). Prostomial eyes absent. Nuchal grooves straight with narrow mid-dorsal separation ( Fig. 2 A). Peristomium half as long as first chaetiger, peristomial cirri as long as peristomium (only right peristomial cirrus of larger syntype well preserved, left one missing; both cirri of smaller syntype missing) ( Figs 1 A, 2A).

Anterior two pairs of parapodia modified; first pair greatly enlarged, extending beyond anterior margin of prostomium ( Figs 1 A, 2A), with large auricular prechaetal lobes, subulate postchaetal lobes, digitiform dorsal cirri and subulate ventral cirri ( Fig. 2 B). Second pair of parapodia smaller with much smaller prechaetal lobes ( Fig. 2 C). Third pair of parapodia only slightly larger than subsequent parapodia with further reduced prechaetal lobes; ventral cirri conelike. From chaetigers 4 onwards parapodial structures more uniform; dorsal cirri gradually becoming thinner and shorter, prechaetal lobes becoming short and rounded, postchaetal lobes gradually decreasing, ventral cirri replaced by round glandular pads from chaetiger 4. Simple branchiae present as a short filament from chaetiger 12–15.

First pair of parapodia with two thick simple unidentate hooded hooks ( Figs 2 D, E) and one thinner simple bidentate hook ( Fig. 2 F). Second pair of parapodia with three pseudocompound bidentate hooded hooks ( Fig. 2 G). Third pair of parapodia with two to four limbate chaetae and two to ten pectinate chaetae varying from having almost flat ( Fig. 2 H) to slightly rolled lateral margins ( Fig. 2 I), with 17–20 teeth. Hooks absent from chaetiger 3, limbate and pectinate chaetae present. Subacicular hooks present from chaetiger 9–13.

Mandibles with high calcareous cutting plates with three indentations ( Roule 1906: pl. VI, fig. 41); maxillae not examined. Tubes ( Figs 1 B, C) flattened with thin inner parchment-like layer covered with small foreign particles (up to 2 mm in diameter), i.e. agglutinated foraminifera and sand grains.

Remarks. The species has been redefined on the basis of its syntypes, the original description and the emendation of Roule (1906). Accordingly, we have reassigned the species to the genus Nothria . Originally, Roule (1898) placed the species into the genus Hyalinoecia on the basis of its alleged absence of peristomial cirri. Nevertheless, our examination of the types has demonstrated that the species has peristomial cirri, which are missing in the smaller specimen and this may account for Roule’s statement in this regard.

Despite the fact that the syntypes had originally been preserved in their tubes ( Roule 1906) and had started “macération” ( Roule 1898), they are still in a relatively good state of preservation. Some of the antennae and peristomial cirri are broken or lost and several anterior parapodia of the larger specimen are missing as a result of previous examination ( Fig. 1 A). However, we consider the types as good representatives for displaying the diagnostic features.

Descriptions of only two presently recognised Nothria species precede the original description of N. edwardsi comb. nov.: N. conchylega ( M. Sars, 1835) and N. hyperborea ( Hansen, 1878) . These two species can be distinguished from N. edwardsi comb. nov. in that the former has hooks only on the first two pairs of parapodia whilst in the latter two species hooks are present on the first three pairs of parapodia.

Nothria edwardsi comb. nov. resembles N. abyssia in many aspects. Both are deep-water species that have hooks on the first two pairs of parapodia and limbate and pectinate chaetae starting from chaetiger 3. They also share the presence of almost flat pectinate chaetae rather than the characteristic scoop-shaped pectinate chaetae of most species in the genus. However, the two species can be easily differentiated in that N. edwardsi comb. nov. has both uni - and bidentate simple hooks in the first pair of parapodia, single branchiae from chaetiger 12–15 and lacks prostomial eyespots; in contrast, N. abyssia only presents bidentate hooks in the first pair of parapodia, lacks branchiae and can bear prostomial eyespots ( Budaeva & Paxton 2013).

Specimens reported as Onuphis sp. from the Azores (at 4020 m deep), collected by the Hirondelle and the Princesse Alice cruises (1885–1910), by Fauvel (1914) most likely correspond to N. edwardsi comb. nov.

Habitat and distribution. Nothria edwardsi comb. nov. is known from abyssal depths (4020 to 4255 m) of the central and eastern North Atlantic, including the Azores archipelago and the area comprised between Azores and the Iberian Peninsula ( Roule 1898; 1906; Fauvel 1914).

Thanks to Tarik Meziane ( MNHN) for the loan of the syntypes, Jorge Núñez and an anonymous reviewer for their careful reading of the manuscript. This is a contribution from the Fauna Ibérica Project, subprojects “ Polychaeta IV: Palpata-Canalipalpata I ” (ref. CGL2014-53332-C5-3-P), and the Marine Observatory of Asturias ( OMA).

Figures

FIGURE 1. Nothria edwardsi comb. nov. (MNHN POLY TYPE 1305, larger syntype A, C; smaller syntype B). Photomicrographs. A, anterior end, dorsal view; B, C, tubes.

FIGURE 2. Nothria edwardsi comb. nov. (MNHN POLY TYPE 1305, larger syntype). Line drawings. A, anterior end, dorsal view; B, parapodium 1, posterior view; C, parapodium 2, posterior view; D, E, unidentate simple hooks from parapodium 1; F, bidentate simple hook from same; G, bidentate pseudocompound hook from parapodium 2; H, almost flat pectinate chaeta from parapodium 2; I, slightly rolled pectinate chaeta from the same.