Eupolymnia meissnerae, Lavesque & Daffe & Londoño-Mesa & Hutchings, 2021

Lavesque, Nicolas, Daffe, Guillemine, Londoño-Mesa, Mario H. & Hutchings, Pat, 2021, Revision of the French Terebellidae sensu stricto (Annelida, Terebelliformia), with descriptions of nine new species, Zootaxa 5038 (1), pp. 1-63 : 25-28

Eupolymnia meissnerae n. sp.

Figures 2C ; 10–11

Material examined. Holotype. MNHN-IA-TYPE 2024, posteriorly incomplete specimen, gravid, Northeastern Atlantic Ocean, Brittany, Bay of Brest , station ZC, 48°18’55”N 4°21’53”W, depth 5 m, May 2018, posterior part used for molecular analysis . Paratypes. AM W.53327, posteriorly incomplete specimen, Northeastern Atlantic Ocean, Brittany, Bay of Brest, Rozegat , 48°18’19”N 4°22’16”W, depth 1 m, March 2009. MNHN-IA-TYPE 2025, posteriorly incomplete specimen, Northeastern Atlantic Ocean , Brittany, Bay of Brest , Rozegat , 48°18’19”N 4°22’16”W, depth 1 m, March 2009, mounted for SEM.

Description. In life, body uniformly light orange, except branchiae, buccal tentacles and upper lip, which are dark orange, and prostomial eyespots brown ( Fig. 10A ).

Small species, holotype incomplete (22 segments), 11.7 mm long (11.5–13.6 mm) and 1.8 mm wide (1.2–2.8 mm).

Transverse prostomium attached to dorsal surface of upper lip; basal part with continuous row of black to reddish eyespots, without short mid-dorsal gap, with eyespots more or less separated from each other ( Fig. 10A, C ); distal part forming a shelf-like tentacular membrane from which the few remaining filiform and grooved buccal tentacles originate ( Fig. 10D ). Peristomium forming lips; hood-like upper lip, circular, wider than long; lower lip thin, wider than long, pharyngeal organ everted ( Fig. 10B ).

Arborescent branchiae present on SG II–IV, longitudinally aligned, dorsal to line of notopodia; with long branches and few short branchial filaments branching dichotomously; with a short basal stem on the first pair only; second and third pairs without stem; first pair longer, following ones progressively shorter ( Figs 10A–D ; 11A–B ).

Segment I conspicuous all around, ventrally developed, forming ventral lobe below lower lip ( Fig. 10B–D ); SG II with one pair of auricular-shaped ventro-lateral lobes, connected ventrally by a low crest, anterior margins undulating; SG III with almost spherical short dorso-lateral lobes; SG IV with a pair of short rounded dorso-lateral lobes; dorsal margins of lateral lobes on SG II–IV aligned with dorsal margins of neuropodia ( Figs 10C–D ; 11A–B ).

SG II–XV with glandular, rectangular, smooth to slightly corrugated anteriorly mid-ventral shields ( Fig. 10D ); mid-ventral groove extending posteriorly from SG XVI.

Rectangular notopodia beginning from SG IV, extending for 17 segments, until SGXX, laterally aligned ( Figs 10B–C ; 11A–B ). Narrowly-winged notochaetae in two rows ( Fig. 10E ), first row shorter.

Neuropodia present from SG V, as low ridges until end of notopodia ( Figs 10B–C ; 11A–B ), as rectangular pinnules thereafter. Neurochaetae throughout as short-handled avicular uncini, arranged in completely intercalated double rows on SG XI–XX, in a face-to-face arrangement. Uncini with short triangular heel and pointed prow, dorsal button inserted at about halfway distance between base of main fang and tip of prow, elongate convex base, and main fang surmounted by crest with two rows of secondary teeth, first row with two large teeth, second row with two large teeth and several small ones ( Figs 2C ; 10F–G ; 11C–D ).

Nephridial papillae on SG III–V, posteriorly to bases of branchiae and dorsally to notopodia ( Fig. 10C ); genital papillae on SG VI–VIII, globular, inserted posteriorly to neuropodia.

Pygidium unknown.

Etymology. This species is dedicated to Karin Meiβner, for her great contribution to polychaete taxonomy and her friendship with NL and PH.

Habitat. Shallow waters (depth 1–5 m), in maërl (rhodolith) beds.

Type locality. Bay of Brest , Bay of Biscay, Northeastern Atlantic Ocean, France, 48°18’55”N, 4°21’53”W .

Distribution. Only known from the type locality.

Remarks. Among the European species, Eupolymnia meissnerae n. sp. differs from E. gili n. sp. by the absence of long branchial stems which are long for E. gili n. sp., by having eyespots with a mid-dorsal gap instead of a continuous band of eyespots for E. gili n. sp. and by having uncini with two large teeth on both first and second rows above main fang instead of uncini with two and one large tooth on the first and second rows above the main fang, respectively for E. gili n. sp. Eupolymnia meissnerae n. sp. differs also from E. gili n. sp. by the presence of a ventral crest on SG II, by the absence of thick and translucent lateral lobes on SG II–IV and the absence of abdominal neuropodia with pointed dorsal projections which are present for E. gili n. sp. Finally, E. meissnerae n. sp. differs from E. gili n. sp. by the colour pattern of live specimens, with specimens having orange pattern for E. meissnerae n. sp. and red body covered by white spots for E. gili n. sp.

Eupolymnia meissnerae n. sp. differs from E. lacazei n. sp. by the presence of a short branchial stem for the first pair of branchiae and the absence of stem for the second and third pairs, instead of the presence of long stems for E. lacazei n. sp. Eupolymnia meissnerae n. sp. also differs from E. lacazei n. sp. by the presence of eyespots that are separated by a mid-dorsal gap instead of a continuous band of eyespots for E. lacazei n. sp. and by uncini with two large teeth on both first and second rows above main fang instead of uncini with two and one large tooth on the first and second rows above the main fang, respectively for E. lacazei n. sp. Eupolymnia meissnerae n. sp. has auricular-shaped lateral lobes on SG II and E. lacazei n. sp. semi-circular lateral lobes. Finally, E. meissnerae n. sp. differs from E. lacazei n. sp. by the colour pattern of live specimens; live specimens of E. lacazei n. sp. have an orange body whereas E. meissnerae n. sp. have a red body covered by white spots.

Eupolymnia meissnerae n. sp. differs from E. nebulosa by by the presence of 14 ventral shields instead of 10 in E. nebulosa , by the shape of the lateral lobes of SG III, which are spherical in E. meissnerae n. sp. and bilobed in E. nebulosa . The two species also differ by the denticulation of the uncini. The main fang is surmounted by a crest with two rows of secondary teeth, first row with two large teeth, second row with two large teeth and several small ones for E. meissnerae n. sp., and with first row with two large teeth, second row with one large tooth and several small ones in E. nebulosa .

Terebella abbreviata Quatrefages, 1866 , a non valid species synonymysed with E. nesidensis , was described from the same area (La Rochelle or St Vaast). We have observed the syntype (MNHN-IA-TYPE0390) but this specimen is in very poor condition and we were not able to identify it to genus, as branchiae are missing and lateral lobes are absent (or damaged?). This species should be considered as species inquirenda.

Genus Lanice Malmgren, 1866

Type-species: Nereis conchilega Pallas, 1766 , by monotypy.

Diagnosis. (after Hutchings et al. 2021b). Transverse prostomium attached to dorsal surface of upper lip; basal part as a thick crest, eyespots sometimes present; distal part shelf-like. Buccal tentacles all uniformly cylindrical. Peristomium restricted to lips; lips expanded, relatively short upper lip, hood-like, about as wide as long; short, button-like, mid-ventral lower lip. Segment I conspicuous all around, dorsally narrow, with pair of dorso-lateral to lateral lobes extending anteriorly to level of upper lip or beyond, and ventrally connected to each other by lower membrane across ventrum, partially exposing lower lip; SG III with large lateral lobes. Anterior segments highly glandular ventrally, with discrete, smooth to markedly corrugated, rectangular to trapezoidal shields. Three pairs of progressively shorter arborescent branchiae, on SG II–IV, with short main stems. Cylindrical to rectangular notopodia beginning on SG IV; notochaetae all narrowly-winged. Neuropodia beginning on SG V, as low, sessile ridges in conjunction with notopodia and as short pinnules posteriorly; neurochaetae as short-handled uncini, in partially intercalated to completely separated double rows, in back to back arrangement, from SG XI until end of notopodia, on SG XX. Nephridial and genital papillae usually poorly developed, almost inconspicuous, of variable position and distribution. Pygidium smooth to papillate.

Remarks. Recently, Jirkov & Leontovitch (2017) proposed the synonymy between the genera Lanice and Axionice , based on the great variability that the arrangement of the uncini in double rows in the posterior thoracic segments can exhibit. So, these authors suggested that the uncinal alignment in the the double rows character, in a back-to-back or a face-to-face arrangement, is not a sufficiently stable character in order to define genera, and that, together with other characters, such as the development of lateral lobes, the arrangement of the uncini is not a consistent character. In contrast, Londoño-Mesa et al. (in prep.) sustain that the different arrangement of uncini in double rows in the posterior thoracic segments is a useful taxonomic character in the family that would have evolved only once and very early, according to both morphological and molecular data.

Figures

FIGURE 2. Schematic illustrations of different uncini morphologies, in lateral views (following Nogueira et al. 2010). A. Terebella cf lapidaria, MNHN-IA-PNT 131, SG X; B. Lomia ramzega, paratype MNHN-IA-TYPE 1791, SG XII; C. Eupolymnia meissnerae n. sp., holotype MNHN-IA-TYPE 2024, SG X. D. Pista sauriaui n. sp., paratype MNHN-IA-TYPE 2036, SG V. Abbreviations: Af, anterior filament; Ba, base; Cext, comma-shape extension; Cr, crest; DB, dorsal button; He, heel; LH, long handle; MF, main fang; Pr, prow. Scale bars: 25 µm.

FIGURE 10. Eupolymnia meissnerae n. sp. holotype MNHN-IA-TYPE 2024 (A–D, G), paratype AM W.53327 (E–F). A. Anterior end, dorsal view, live specimen; B. Anterior end, lateral view, MG staining; C. Anterior end, dorso-lateral view, MG staining; D.Anterior end, ventral view; E. Notochaetae, SG VII; F. Uncini, SG VIII; G. Uncinus, SG X.Abbreviations: Ll, lower lip; NP, nephridial papillae; Po, pharyngeal organ; Ul, upper lip. Numbers referring to segments.

FIGURE 11. Eupolymnia meissnerae n. sp. SEM paratype MNHN-IA-TYPE 2025. A–B. Anterior end, lateral view; C–D. Uncini, SG VIII. Numbers referring to segments.