Eunice confusus, 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 : 9-12

Eunice confusus new species

( Figs 3 , 4 )

Material examined. New South Wales. Off headland between Store and Quarantine Bays, Sydney Harbour , 33°51’S, 151°16’E, rotenone station, coll. Museum Party, 06 May 1967, AM W.22240 (HOLOTYPE), parapodia 5, 22, 137, 215, removed for SEM ( AM W.22240.001 ) .

Description. Holotype complete with 220 chaetigers; total length 280 mm; length through chaetiger 10, 23 mm; maximum width 8 mm at chaetiger 10, in 3 pieces.

Prostomium with dorsal buccal lips as paired median dorsal ridges projecting anteriorly slightly beyond the obliquely truncate ventral part of prostomium, bearing narrow deep median sulcus, reaching nearly to base of median antenna ( Figs 3A, B ; 4A, B ). Prostomial appendages in semicircle. Lateral antennae reaching chaetiger 1; median antenna incomplete. Palps located anterior to lateral antennae. Palpophores and ceratophores short, ringshaped. Ceratostyles and palpostyles irregularly articulated; slender, digitiform. Dark eyes present lateral to lateral antennae. Peristomium cylindrical; separation between rings only dorsally and ventrally. First ring 5/6 of total length of peristomium. Ventrolateral lips muscular and inflated. Peristomial cirri reaching anterior half of first ring; slightly tapering; articulations absent.

Maxillary formula 1+1, 7+7, 6+0, 4+8, 1+1, 1+1 ( Fig. 4C ). MxVI ridge-shaped. Base of MxII wide with distinct thickened outer ridge. MxIII short; part of distal arc with left MxIV and V. Mandibles calcareous cutting plates wing shaped ( Fig. 4D ).

Branchiae present from chaetiger 6 to end of body, first with two or three filaments, best developed at about chaetiger 20 with slender, tapering stems and about 12 slender filaments ( Fig. 3E, F ). Notopodial cirri about as long as branchiae in anterior and median branchiated chaetigers. In posterior chaetigers, notopodial cirri distinctly longer than branchiae. Last 20 chaetigers with very short branchial filaments, decreasing rapidly in complexity to a single filament in last few chaetigers.

Anterior chaetal lobes truncate; posteriorly chaetal lobes increasingly oblique ( Figs 3E, F, L ; 4F, I, J ); acicula emerging near dorsal edge in all parapodia. Pre- and postchaetal lobes low, transverse folds. Anteriormost ventral cirri tapering, becoming basally inflated from about chaetiger 6; inflated bases ovate; free tip tapering in all chaetigers. Notopodial cirri without articulations, slender and tapering from inflated bases in all chaetigers.

Slender, tapering limbate chaetae present in all chaetigers. Pectinate chaetae with flattened shafts; tapering more abruptly subdistally in posterior chaetigers ( Figs 3D, G, J ; 4E, L ). Numbers of teeth varying from 10 to 15; each tooth flattened, distally abruptly tapering to slender, hair-like tip; all with similar length. Distal end of shafts of anterior and median compound falciger chaetae as wide as proximal end, becoming slightly wider in posterior chaetigers ( Figs 3C, H, K ; 4G, H, K ). Appendages tapering with distal tooth thick, nearly erect; proximal tooth directed laterally. Aciculae and subacicular hooks with distinct dark cores and clear sheaths. Acicula single in most parapodia; tapering to blunt tips. Subacicular hooks bidentate present from chaetiger 38; one in each parapodium. Distal tooth erect, tapering, directed laterally in most posterior chaetigers; proximal tooth about as large as distal tooth; directed laterally ( Figs 3I ; 4K ). Subacicular hooks unusually small compared to compound falciger chaetae ( Fig 4I, J ).

Dorsal pygidial cirri digitiform, about as long as five last chaetigers. Ventral pygidial cirri absent.

Type locality. Off headland between Store and Quarantine Bays, Sydney Harbour, 33°51’S, 151°16’E, New South Wales .

Etymology. The species name, confusus , is thoroughly deserved. We became aware that this species was mixed among specimens of Leodice laticeps ( Ehlers, 1868) , a very common species from Australia, very late in the study.

Remarks. Eunice confusus n. sp., is similar to species E. aphroditois , E. dijiboutiensis Gravier, 1900 , E. kinbergi Ehlers, 1868 and E. roussaei Quatrefages, 1866 , which have dorsal buccal lips as paired median dorsal ridges in the prostomium, peristomial cirri reaching anterior half of first peristomial ring, branchiae pectinate starting anterior to chaetiger 10 and distributed along more than 65% of the body and single dark bidentate subacicular hooks. The new species differentiates from all these species in the shape of pectinate chaetae and the start of subacicular hook, but the latter may be due to size differences of the animals. From all others with exception of E. dijiboutiensis , it also differs in the shape of the inflated base of ventral cirri. Eunice roussaei is the only one that shares branchiae shorter than notopodial cirri with E. confusus n. sp.

Figures

FIGURE 3. Eunice confusus n. sp. AM W.22240. A, anterior end, lateral view; B, anterior end, dorsal view; C, compound falciger chaeta, parapodium 50; D, pectinate chaeta, parapodium 50; E, parapodium 50, anterior view; F, parapodium 23, anterior view; G, pectinate chaeta, parapodium 23; H, compound falciger chaeta, parapodium 23; I, subacicular hook, parapodium 50; J, pectinate chaeta, parapodium 4; K, compound falciger chaeta, parapodium 4; L, parapodium 4, anterior view.

FIGURE 4. Eunice confusus n. sp. AM W.22240. A, anterior end, ventrolateral view; B, anterior end, dorsal view; C, maxillae, dorsal view; D, mandible ventral view; E, pectinate chaetae, parapodium 137; F, parapodium 5, anterior view; G, compound falciger chaetae, parapodium 215; H, compound falciger chaetae, parapodium 5; I, parapodium 137, anterior view; J, parapodium 215, anterior view; K, subacicular hook and compound falciger chaetae, parapodium 215; L, compound falciger and pectinate chaetae, parapodium 215.