Eunice concinna, Zanol & Hutchings & Fauchald, 2020

Zanol, Joana, Hutchings, Pat A. & Fauchald, Kristian, 2020, Eunice sensu latu (Annelida: Eunicidae) from Australia: description of seven new species and comments on previously reported species of the genera Eunice, Leodice and Nicidion, Zootaxa 4748 (1), pp. 1-43 : 6-9

publication ID	https://doi.org/ 10.11646/zootaxa.4748.1.1
publication LSID	lsid:zoobank.org:pub:B9EC373A-DF9B-47E2-916C-CF211D8F0727
DOI	https://doi.org/10.5281/zenodo.3704687
persistent identifier	https://treatment.plazi.org/id/8C0D3355-C013-D12B-33BC-FB99FD709E62
treatment provided by	Plazi
scientific name	Eunice concinna
status	sp. nov.

Treatment

Eunice concinna View in CoL , new species

( Figs 1 View FIGURE 1 , 2 View FIGURE 2 )

Material examined. Queensland. Port Denison , 20°03’S, 148°15’E, AM W.197117 (HOLOTYPE), parapodia 4, 19, 94 removed and mounted for SEM ( AM W.197117.001) GoogleMaps . PARATYPES, Port Molle reef, 20º16’S, 148°50’E, AMW GoogleMaps . 197116 (1). One Tree Island , 23°30’S, 152º05’E, 3–6 m depth, coral outcrop in the lagoon facing station, at a rotenone station, coll, P. Hutchings, 29 Sep 1971, AM GoogleMaps W.17203 (l). Northern Territory. Fannie Bay Rocks , Darwin, 12°26’S, 130°49’E, coll. E. Pope, 12 Oct 1965, AM GoogleMaps W.6171 (1).

Description. Holotype incomplete with 116 chaetigers; total length 60 mm; length through chaetiger 10,7 mm; maximum width 3 mm at chaetiger 10. Body slightly dorsoventrally flattened, truncated anteriorly. Color (in alcohol) cream with strong iridescence.

Prostomium nearly as wide and less than half as deep as peristomium ( Figs 1E, F View FIGURE 1 ; 2A View FIGURE 2 ), anteriorly rounded; dorsally inflated; bearing a wide and relatively shallow sulcus. Prostomial appendages in semicircle; median antenna separated from lateral antennae by a distinct gap; lateral antennae located immediately posterior and slightly medial to the palps. Palpophores long, cylindrical; palpostyles short, digitiform with three or four irregular cylindrical articulations. Ceratophores short, ring-shaped; lateral antennae not much longer than palps; ceratostyles tapering with three or four irregular cylindrical articulations ( Fig. 2A View FIGURE 2 ). Median antenna distinctly longer than lateral antennae; ceratostyle slender, digitiform with irregular articulations. Eyes present posterior to palps. Peristomium cylindrical with deep nuchal fold covering bases of antennae completely. Ventrolateral lips visible, but not obviously inflated ( Fig. 2A View FIGURE 2 ). First peristomial ring about 3/4 of total peristomial length; separation between rings distinct on all sides. Peristomial cirri tapering to digitiform; reaching anterior half of first peristomial ring, surface of cirri wrinkled, articulations absent. Maxillary formula 1+1, 5+6, 9+9, 9+6, 1+1. MxVI absent. Maxillae symmetrical, with well developed MxIII on both sides in holotype. Maxillae asymmetrical in all other observed specimens, in paratype (AM W.197116) 1+1, 5+5, 9+0, 8+12, 1+1 ( Fig. 2B View FIGURE 2 ). Mandibles missing calcareous cutting plate.

Branchiae present from chaetiger 13 to end of incomplete holotype. First branchia single filament; all others pectinate ( Fig. 1A View FIGURE 1 ); where best developed branchiae with seven slender, tapering filaments; branchial stem slender. Branchiae extending beyond notopodial cirri in all chaetigers present; branchial filaments longer than notopodial cirri as well.

Anteriormost chaetal lobes symmetrically rounded with transverse prechaetal lobes; postchaetal lobe symmetrically rounded, displaced towards dorsal side in relation to chaetal lobe, longer than chaetal lobe ( Figs 1G, J View FIGURE 1 ; 2F View FIGURE 2 ). Median chaetal lobes asymmetrically sharply pointed with high end dorsally; both pre- and postchaetal lobes low, transverse folds ( Figs 1A View FIGURE 1 ; 2H View FIGURE 2 ). Posterior chaetal lobes sharply pointed with high end median; both pre- and postchaetal lobes low, transverse folds ( Fig. 2G View FIGURE 2 ). Anterior notopodial cirri slightly inflated basally; median ones tapering evenly to slender tip ( Fig. 1A, G View FIGURE 1 ) and smooth throughout, lacking articulations. Anterior ventral cirri thick, digitiform, becoming basally inflated by chaetiger 6; inflated base small, ovate; free tip slightly tapering from median chaetigers to the posterior end.

Slender limbate chaetae present in all chaetigers. All pectinate chaetae scoop-shaped with transverse distal edges; total number of teeth about 12–19; one marginal tooth distinctly longer than other teeth ( Figs 1B, H View FIGURE 1 ; 2C, D View FIGURE 2 ). Shafts of compound falciger chaetae subdistally marginally serrated and distinctly inflated in median and posterior chaetigers ( Figs 1C, I View FIGURE 1 ; 2E View FIGURE 2 ). Appendages small, slender; distal tooth curved, slender, tapering. Proximal tooth triangular in anterior chaetigers becoming slender in median chaetigers; tip curved distally in all chaetigers. Distinct core and shaft-construction present with dark brown cores and clear shafts in aciculae and subacicular hooks. Anterior and posterior parapodia with single acicula; median parapodia with two aciculae; all aciculae tapering to slender, straight tips. Bidentate subacicular hooks present from chaetiger 35 ( Fig. 1D View FIGURE 1 ); present in all subsequent parapodia as a single hook. Hooks tapering distally to small head; proximal tooth larger than distal tooth, directed laterally and slightly bent up distally; distal tooth straight, tapering.

Variation. Preserved material varies from grey to pale cream, all strongly iridescent, level of chinitisation of maxillae varies between individuals. The number of articulations on the ceratostyles varies between paratypes. Right MxIII is present only in the holotype. Paratypes, AM W.197116 posteriorly incomplete with 70 chaetigers, branchiae from chaetiger 18, subacicular hooks from chaetiger 28; AM W.6171 missing few posterior chaetigers with 64 chaetigers, branchiae from chaetiger 17, subacicular hooks from chaetiger 25; AM W.17203 complete with 72 chaetigers, branchiae from chaetiger 15; subacicular hooks from chaetiger 29.

Type locality. Port Denison , Queensland, 20°03’S, 148°15’E GoogleMaps .

Etymology. The species name concinna, Latin , meaning neat, beautiful, was used in classical Latin also to indicate the presence of symmetry; here referring to the symmetrical presence of MxIII in the holotype.

Remarks. Eunice concinna n. sp., belongs to one of the larger species groups in Eunice , group B-4 sensu Fauchald (1992) in that it has branchiae starting posterior to chaetiger 10 and dark bidentate subacicular hooks. Several species in this group have articulated prostomial appendages and the new species is here compared to these. Six species have tapering subacicular hooks with both teeth directed distally, including E. afra Peters, 1854 , E. collaris Grube, 1869 , E. fauveli Gravier, 1900 , E. modesta Grube, 1866 , E. pacifica Kinberg, 1865 and E. prognatha McIntosh, 1885 . In E. concinna n. sp., the proximal tooth of the subacicular hook is directed laterally. Eunice excariboea Fauchald, 1992 has subacicular hooks first present in chaetigers 78–87; in E. concinna n. s p., they are present from chaetiger 35. In E. denticulata Webster, 1884 , subacicular hooks start at a chaetiger anterior to the start of branchiae, while the hooks first start well posterior to the beginning of branchiae in the current species. In E. guanica ( Treadwell, 1921) only two branchial filaments are present where the branchiae are best developed; in the remaining three species of group B-4, including E. concinna n. sp., the branchiae have six or seven long, slender filaments in a distinctly pectinate arrangement. Finally, in the two last species of group B-4 (sensu stricto), E. jagori Grube, 1878 and E. petersi Fauchald, 1992 , the notopodial cirri are articulated, either throughout the body or at least in anterior chaetigers; in E. concinna n. sp. the notopodial cirri lack articulations throughout.

Two additional species have dark aciculae and subacicular hooks combined with a very late start of the branchiae. However, E. cirrobranchiata McIntosh, 1885 has in part tridentate subacicular hooks with the teeth in tandem and hammer-headed aciculae and E. sonorae Fauchald, 1970 has tapering, distally bluntly falcate subacicular hooks and up to four aciculae in anterior chaetigers.

Apparently, among this group of species, the presence of very narrow slender appendage in the compound falciger chaetae is unique to E. concinna n. sp.