Ophryotrocha nunezi, Ravara, Ascensão, Wiklund, Helena & Cunha, Marina R., 2021

Ravara, Ascensão, Wiklund, Helena & Cunha, Marina R., 2021, Four new species and further records of Dorvilleidae (Annelida, Polychaeta) from deep-sea organic substrata, NE Atlantic, European Journal of Taxonomy 736, pp. 44-81 : 64-67

publication ID

https://doi.org/10.5852/ejt.2021.736.1251

publication LSID

lsid:zoobank.org:pub:68249639-5FAD-4860-A2EA-0D34690C10FC

DOI

https://doi.org/10.5281/zenodo.4570319

persistent identifier

https://treatment.plazi.org/id/5526CBA2-A3C3-4E2E-9195-99E4BD6B04D2

taxon LSID

lsid:zoobank.org:act:5526CBA2-A3C3-4E2E-9195-99E4BD6B04D2

treatment provided by

Plazi

scientific name

Ophryotrocha nunezi
status

sp. nov.

Ophryotrocha nunezi sp. nov.

urn:lsid:zoobank.org:act:5526CBA2-A3C3-4E2E-9195-99E4BD6B04D2

Fig. 10 View Fig

Etymology

The species is named after Dr Jorge Nuñez, who described several of the currently known Ophryotrocha species and first examined the specimens from the Cantabrian Sea. Dr Nuñez has always been very helpful in our requests for assistance on these taxa.

Material examined

Holotype MOROCCO • complete spec. (formalin), 0.97 mm long, 0.14 mm wide, 16 chaetigers; GoC, Mercator MV; 35°17.916′ N, 06°38.709′ W; 354 m depth; 2 Mar. 2008; Stn 64PE284_12750W; wood substratum; NHMUK 2020.1514 View Materials . GoogleMaps

Paratypes MOROCCO • 2 specs (formalin); same collection data as for holotype; NHMUK 2020.1515 View Materials GoogleMaps 2 specs (slide preparation), 1 spec. (ethanol);same collection data as for holotype; DBUA0002294.02 View Materials (paragenophores) GoogleMaps .

Other material

MOROCCO • 3 specs (formalin); same locality as for holotype; 19 May 2009; Stn B09-14b_01W; wood substrata; DBUA0002295.01 View Materials GoogleMaps .

Additional material

SPAIN • 4 specs; Bay of Biscay , Cantabrian Sea ; 43°22.18′ – 43°23.14′ N, 02°15.00′ – 02°15.21′ W; 93–101 m depth; 22 Jun. 1991; cruise Fauna II; Stn 150A; MNCN 16.9/13680 GoogleMaps .

Description

Relatively small specimens compared to most Ophryotrocha species, with proportionally long chaetae. Larger specimens measure from approximately 0.70 to 0.99 mm long and 0.12 mm wide, for 12 to 17 chaetigers ( Fig. 3 View Fig ). Prostomium broadly rounded ( Fig. 10A View Fig ), without eyes. Antennae small, spherical, inserted dorsally in mid prostomium; palps bi-articulated with spherical palpophores and ovoid palpostyles, inserted laterally on the posterior part of prostomium ( Fig. 10A View Fig ). Peristomium achaetous, with two rings of similar length to the following segments; anterior ring apparently fused to prostomium. Jaw apparatus light brown, almost inconspicuous ( Fig. 10A View Fig ). Mandibles rod-like, weakly sclerotinized, with curved, serrated cutting edge (with 14 teeth) and large, wing-like apophyses confined to the anterior part of the mandibulae, giving a butterfly-like appearance ( Fig. 10C View Fig ). Maxillae with falcate forceps with a large subdistal tooth below the main fang and transversal ridges posteriorly, giving a wrinkled appearance ( Fig. 10 View Fig D–E), basely fused to the maxillary carrier; approximately seven free denticles (D1–7) very weakly sclerotized and difficult to examine ( Fig. 10D View Fig ); D1 elongated and lightly serrated, parallel to forceps, D2–7 apparently small and compacted above the forceps ( Fig. 10E View Fig ); the small size of the specimen and the poor sclerotization makes it impossible to count the exact number of free denticles and to observe their morphology more thoroughly. Parapodia long, uniramous, with conical acicular lobes, inconspicuous pre-chaetal lamellae, long sub-acicular lobes and conical dorsal cirri inserted subdistally on the parapodia ( Fig. 10H View Fig ). Anterior parapodia (chaetigers 1–3 or 1–4) with a single compound chaeta (similar to the sub-acicular chaetae) protruding from the sub-acicular lobe ( Fig. 10H View Fig ); following parapodia with simple chaetae protruding from the sub-acicular lobe ( Fig. 10I View Fig ). Supra-acicular chaetae simple, slightly curved sub-distally, coarsely serrated, 2–3 per fascicle ( Fig. 10G View Fig ). Sub-acicular chaetae compound with lightly serrated blades, all of subequal length; shafts distally serrated ( Fig. 10F View Fig ), 3 per fascicle. Pygidium with terminal anus and two clavate anal cirri ( Fig. 10 View Fig A–B).

Remarks

Ophryotrocha nunezi sp. nov. can be distinguished from all other species by the combination of four characteristics: bi-articulated palps, winged mandibulae, falcate maxillary forceps with internal tooth, and clavate anal cirri. According to the phylogenetic analysis ( Fig. 2 View Fig ), six described species of Ophryotrocha and one of Exallopus are placed in the same clade as O. nunezi sp. nov.: O. longidentata Josefson, 1975 , O. nauarchus Wiklund et al., 2012 , O. magnadentata Wiklund et al., 2012 , O. longicollaris Wiklund et al., 2012 , O. globopalpata Blake & Hilbig, 1990 , O. flabella Wiklund et al., 2012 and E. jumarsi Blake, 1985 ( Josefson 1975; Blake 1985; Blake & Hilbig 1990; Wiklund et al. 2012). All these species of Ophryotrocha have bi-articulated palps, but, unlike the others, O. longicollaris does not have winged mandibulae. Furthermore, of all of them, only O. flabella has toothed K-type forceps and only O. magnadentata has clavate anal cirri. The latter species also has sub-acicular lobes sustained by a compound falciger similarly to O. nunezi sp. nov. However, all the other characteristics of both species are different. There are two more species of Ophryotrocha with bi-articulated palps and winged mandibulae (not included in the phylogenetic analysis), O. paragerlachi Brito & Nuñez, 2003 and O. platykephale Blake, 1985 , but both these species have long cirriform anal cirri and different parapodial and chaetal morphology ( Blake 1985; Brito & Nuñez 2003). Two other species, O. mammillata Ravara, Marçal, Wilund & Hilário, 2015 and O. wubaolingi Miura, 1997 , have bi-articulated palps but different mandibulae and anal cirri as well as other morphological features ( Miura 1997; Ravara et al. 2015). Ophryotrocha labidion Hilbig & Blake, 1991 , from the US Atlantic coast, have bi-articulated palps, winged mandibulae and clavate anal cirri, but strongly differs in the maxillary, parapodial and chaetal morphology ( Hilbig & Blake 1991). Another species from the West Atlantic coast, O. atlantica Hilbig & Blake, 1991 , with winged mandibulae, falcate forceps with teeth and clavate anal cirri, have simple palps and different maxillary and chaetal morphology ( Hilbig & Blake 1991). Paxton & Morineaux (2009) gave a brief description of an undetermined species ( Ophryotrocha sp.) reported from the Mid-Atlantic Ridge (Menez Gwen vent field, 865 m depth), that although larger in size, had a similar appearance to this species but with simple palps and mandibulae with a smooth cutting edge. The genus Exallopus also includes species with bi-articulated palps, although this is not the case for the species E. jumarsi , which further differs from O. nunezi sp. nov. by having the antennae weakly annulated, the P-type maxillae and by the presence of strongly modified chaetae in the first chaetigerous segment. This latter characteristic is the main morphological difference between the genera Exallopus and Ophryotrocha . Nevertheless, based on the molecular analyses done to date, the two genera cannot be separated at the molecular level ( Fig. 2 View Fig ; Wiklund et al. 2012). The lack of molecular data for the type species of the genus Exallopus ( Exallopus cropion Jumars, 1974 ) has prevented concluding the synonymy of the two genera. Four other non-described species ( Ophryotrocha ‘Seep 3, 4 and 5’ and Exallopus ‘seep’, Fig. 2 View Fig ) are placed in the same clade as O. nunezi sp. nov., but no morphological descriptions are available for comparison.

When examining the material of O. cantabrica deposited in the MNCN, Madrid, a vial with additional material was found under the collection number MNCN 16.9/13680 (see Nuñez et al 2014), containing four specimens of the new species described here. It was not possible to perform molecular analyses with this material. Nevertheless, all the morphological characteristics are the same as the specimens from the GoC.

Ecology and distribution

NE Atlantic: from the Cantabrian Sea (Bay of Biscay) to the Gulf of Cadiz (Moroccan Margin). Found in sandy sediments with shells and experimentally deployed wood substrata, at 93–354 m depth.

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Order

Eunicida

Family

Dorvilleidae

Genus

Ophryotrocha