Leodice unifrons Verrill 1900
Creators: name: Souza, Thaís Kananda Da Silva
name: Zapff, Luana
name: Christoffersen, Martin Lindsey
name: Zanol, Joana
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Eunicida
Eunicidae
Leodice
Leodice unifrons

description: Leodice unifrons Verrill, 1900
(Fig. 9)
Leodice unifrons Verrill, 1900: 644
Eunice vittata –sensu Hartman, 1942: 9, not Delle Chiaje, 1929
Eunice unifrons — Fauchald, 1992: 330.
Material examined. NON-TYPE material Paraíba State: Nine specimens analyzed. One complete specimen, station 1 (POLY-UFPB –2008); one incomplete specimen, station 4 (POLY-UFPB –2009); one complete specimen, station 35 (POLY-UFPB –2015); one incomplete specimen, station 37 (POLY-UFPB –466); one incomplete specimen, station 39 (POLY-UFPB –2014); one incomplete specimen, station 60 (POLY-UFPB –2010); one complete specimen, station 62 (POLY-UFPB –2011); two incomplete specimens, station 66 (POLY-UFPB –2012; POLY-UFPB –2013).
Description. Six incomplete specimens with 41–64 chaetigers and three complete specimens with 80–98 chaetigers. Total length of complete specimens 12–24 mm; L10 1,5–2,5 mm; W10 without parapodia 2.0– 2.5 mm.
Prostomium bilobed, with a shallow median groove, distinct anteriorly and ventrally, but not dorsally; truncate, anteriorly steep with conspicuous ventral buccal lips, distinctly shorter and narrower than peristomium, (Fig. 9A, B, C). Prostomial appendages evenly spaced in semicircle, palps anterior and slightly lateral to lateral antennae. Palpophores and ceratophores short and ring–shaped, without articulations. Ceratostyles digitiform, tapering, with cylindrical articulations, palpostyles short and digitiform, with cylindrical articulations (Fig. 9A, B, C). Median antenna slightly longer than lateral antennae; lateral antennae about twice as long as palps; palps reaching posterior end of first peristomial ring with 4–7 articulations. Lateral antennae reaching third chaetiger to fifth chaetiger with 7–10 articulations. Median antenna reaching fourth chaetiger to eighth chaetiger with 8–13 articulations. Pair of eyes present, posterior to palps and lateral to lateral antennae.
Peristomium cylindrical, laterally longer than medially; dorsal anterior margin covering posterior margin of median antenna ceratophore; with slightly conspicuous ventro-lateral lips. First peristomial ring about ⅔ of total length, separation between rings conspicuously visible on all sides (Fig. 9A). Peristomial cirri tapering, reaching anterior part of first peristomial ring to almost middle of prostomium, with 3–4 articulations (Fig. 9B).
Maxillary formula: 1+1; (7–8)+(9–10); (9–10)+0; (8–10)+10, 1+1. MxI with not extended falcal arch, outer edge arched, rectangular, basal inner edge with curvature where most posterior region of MxII fits; MxIII almost same length as MxI, located partially ventral to MxII, anterior end part of distal arch with left MxIV. Left MxIV with decreasingly sized teeth on right portion. MxV wide, with a small tooth. MxVI absent. MxIV left attachment lamellae semi-circular in shape, tapering on right innermost portion; right attachment lamella semi-circular in shape, tapering on left innermost portion (Fig. 9D).
Branchiae pectinate present from chaetiger 3 to 30–38, in less than 55% of total number of chaetigers. First branchia with one branchial filament shorter than notopodial cirri, maximum number of branchial filaments 2–4, between chaetigers 20 and 32. Branchiae longer than notopodial cirri. Branchial filaments tapering, longer than notopodial cirri and longer than central axis of branchia.
Anterior chaetal lobe conical with short projection resembling a nipple near middle of lobe and posterior to aciculae; median and posterior chaetal lobe conical, with aciculae emerging from dorsal half. All prechaetal lobes low transverse folds. Anterior postchaetal lobes rounded, longer than chaetal lobe; median and posterior low transverse folds.
Ventral cirri longer than chaetal lobes in all parapodia, ventral cirri robust and digitiform until chaetigers 3– 6, cirri basally inflated from chaetigers 4–7, inflated base oval with elongated digitiform tips decreasing in size around chaetiger 30–33, after which ventral cirri taper to digitiform tips, longer than in anterior parapodia. Anterior notopodial cirri tapering to digitiform tips, with four articulations becoming shorter in median and posterior parapodia; median and posterior with 2–3 articulations.
Limbate chaetae marginally serrated. Pectinate chaetae flat with 7–9 fine teeth and one much longer marginal tooth (Fig. 9E). Compound falcigers bidentate, marginally serrated; anterior with long, narrow article, proximal tooth triangular tapering laterally, of similar length to distal tooth, tapering laterally (Fig. 9I); median with article longer and wider than in anterior parapodia, proximal tooth triangular, tapering laterally, larger than distal tooth, tapering laterally (Fig. 9F, H); posterior article longer and wider than in median parapodia, article with proximal tooth triangular tapering laterally, larger than distal tooth tapering laterally.Aciculae paired, yellow, anterior straight, tapering to blunt tips, one mucronate (Fig. 9F, G); median gently curved tapering to blunt tips, one mucronate; posterior tapering to fine tips, one mucronate acicula; last one acicula larger and longer than other in same parapodia. Subacicular hooks yellow, tridentate, first present on chaetiger 20–27. Subacicular hooks always single; leaf-shaped guards covering first and second basal teeth (Fig. 9F).
Pygidium with two pairs of anal cirri, without articulations. Dorsal pygidial cirri about four times longer than ventral pygidial cirri.
Distribution. Leodice unifrons Verrill, 1900 was originally described from Bermuda (Read & Fauchald 2023). It has been reported in various locations in Brazil, including Salvador, Bahia and Rio de Janeiro States, at 79–1126 m depth (Amaral et al. 2022).
Remarks. The analyzed specimens share with L. unifrons redescribed by Fauchald (1992) most characteristics, except for: 1. the presence of eyes located posterior to palps and lateral to lateral antennae, not observed in type and topotype specimens; 2. antennae and palps in semi-circular distribution, while they are horseshoe–shaped in type and topotype specimens; 3. last branchiae is in chaetigers 30–33, while it is in chaetigers 45–54 in the type and topotype specimens with more than 70 chaetigers; and 4. maximum number of branchial filaments is 2–4, while it is 5 in the type and topotype specimens.
We propose the placement of Eunice unifrons (Verrill, 1900) back to the genus Leodice, as it was first described, based on the presence of yellow tridentate subacicular hooks.
description: Published as part of Souza, Thaís Kananda Da Silva, Zapff, Luana, Christoffersen, Martin Lindsey & Zanol, Joana, 2024, Taxonomy of Leodice Lamarck, 1818 (Annelida, Eunicidae) from Northeast Brazil (Tropical Southwest Atlantic Ocean) with description of a new species, pp. 151-175 in Zootaxa 5492 (2) on pages 171-173, DOI: 10.11646/zootaxa.5492.2.1, http://zenodo.org/record/13219174