Terebellides resomari, Lavesque & Hutchings & Daffe & Nygren & Londoño-Mesa, 2019

Lavesque, Nicolas, Hutchings, Pat, Daffe, Gullemine, Nygren, Arne & Londoño-Mesa, Mario H., 2019, A revision of the French Trichobranchidae (Polychaeta), with descriptions of nine new species, Zootaxa 4664 (2), pp. 151-190 : 176-181

Terebellides resomari n. sp.

Figures 17–18 , Table 2

Type material: Holotype: MNHN-IA-TYPE 1889, complete specimen, North Sea , Dunkerque harbour, 51°02’52”N, 2°21’14”E, 10 m depth, May 2016 ; Paratypes: MNHN-IA-TYPE 1890, one specimen, complete, North Sea , Dunkerque harbour, 51°02’52”N, 2°21’14”E, 10 m depth, May 2016 ; MNHN-IA-TYPE 1891, one specimen, complete, North Sea , Dunkerque harbour, 51°02’52”N, 2°21’14”E, 10 m depth, May 2016 ; MNHN-IA-TYPE 1892, one specimen, complete, North Sea , Dunkerque harbour, 51°02’52”N, 2°21’14”E, 10 m depth, May 2016 , mounted for SEM; MNHN-IA-TYPE 1893, one specimen, complete, North Sea , Dunkerque harbour, 51°02’52”N, 2°21’14”E, 10 m depth, May 2016 , mounted for SEM; AM W.51397, one specimen, complete, gravid, North Sea , Dunkerque harbor, 51°02’52”N, 2°21’14”E, 10 m depth, May 2016 ; AM W.51398, one specimen, complete, North Sea , Dunkerque harbour, 51°02’52”N, 2°21’14”E, 10 m depth, May 2016 ; AM W.51399, one specimen, complete, North Sea , Dunkerque harbour, 51°02’52”N, 2°21’14”E, 10 m depth, May 2016 .

Additional material examined: SMA _BR_51, complete, Northeast Atlantic Ocean, Brittany, Bay of Brest , BK, 48°21’28”N, 4°26’38”W, 7 m depth , 2011.

Description. Large species, holotype 36.7 mm long (30.1–35.5 mm) and 3.4 mm (2.6–3.9 mm). Body tapering posteriorly with segments becoming increasingly shorter and more compacted towards pygidium.

Prostomium compact; eyespots absent; large upper lip surrounding mouth with many buccal tentacles, with dorsal lobe very elongated and with convoluted margins ( Figs 17 A–B & 18A, C). Buccal tentacles of two types, uniformly cylindrical and with expanded tips, spatulate. Lower lip forming an expanded structure below upper lip ( Figs 17 A–B, D & 18C). S1 and S2 short, only visible ventrally; following segments with lobes as ventral collars ( Fig. 17 A–B, D). Lateral lappets on SG 3–7 ( TC 1–5), continuing ventrally in TC 1–5, largest on TC 1 and declining in size posteriorly ( Fig. 17 A–B, D). No conspicuous dorsal rounded projection on anterior chaetigers. Glandular lateral region on TC 3 elongated, with lateral deep ridges ( Fig. 17B, D ).

Branchiae arising as a single structure from TC 1, reaching TC 4 ( TC 5), consisting of a single elongate and annulated long stalk placed mid-dorsally ( Figs 17 A–D & 18A), two pairs of lobes, fused for less of half of length, lower pair thinner. Upper lobes with 50 to 60 not well-packed lamella, not uniform in height, slightly expanded at one end ( Figs 17 B–C & 18A–B.) Both sides of branchial lamellae provided with more than eight well-marked parallel rows of cilia, no tufts of cilia on outer edge ( Fig. 18 A–B). Margins of most of individual lamellae slightly convoluted with digitiform papillae, visible under stereomicroscope ( Figs 17 B–C & 18A–B). Distal region of upper with short terminal pointed projections and of lower lobes with long projections ( Fig. 17 A–D). Anterior branchial projection (5 th lobe) present and very long ( Fig. 17D ).

Eighteen pairs of thoracic notopodia ( SG 3–20). First notopodium same size as subsequent notopodia; size of notopodia increasing posteriorly and notopodia becoming more erect; notochaetae from TC 1 slightly smaller in length than following notochaetae, and transversally aligned ( Fig. 17B ). All notochaetae simple capillaries, arranged in two rows. Neuropodia present as sessile pinnules from TC 6 ( SG 8) to pygidium; uncini arranged in single rows from TC 7. First thoracic neuropodium ( TC 6) provided with 6–7 (5) sharply bent acute tipped, geniculate chaetae. All subsequent thoracic neuropodia with about 20–25 uncini per torus arranged in one irregular row. Uncini as shafted denticulate hooks provided with long, thin and pointed main fang, straight terminally. Three or four teeth above the main fang, surmounted by a row of three to five short teeth and an upper crest of several minute denticles ( Fig. 18D ). About 35 abdominal neuropodia arising from raised glandular ridges on either side of mid-ventral groove, far pos- terior neuropodia very elongated, with entire margin provided with about 45 uncini; uncini with three pointed teeth above main fang, surmounted by a row of three short pointed teeth and an upper crest of minute teeth ( Fig. 18E ).

Two pairs of raised globular nephridial papillae, located dorso-posteriorly to each notopodium from TC 4 to TC 5. Pygidium blunt, as a funnel-like depression.

Methyl green staining pattern. Stained with solid from TC 1– TC 5 ( TC 1 and TC 2, poorly stained), striped from TC 6 to about TC 12, bands becoming slightly narrower and more widely spaced; glandular region on TC 3 white ( Fig. 17D ).

Etymology. The species is named after the RESOMAR, French marine stations and observatories network (Réseau des Stations et Observatoires MARins) which organized the venue for the workshops of Mario Londoño-Mesa and Pat Hutchings in France and whose participants sent us all the material examined in this paper.

Habitat. Muddy sediments of harbour, from 10 to 15 m depth and maerl (rhodolith) beds (2–3 m depth).

Type locality. Dunkerque harbour, North Sea, France .

Distribution. North Sea (Dunkerque), Bay of Biscay (Bay of Brest), France, NE Atlantic ( Fig. 1 ).

Remarks. Except T. stroemii from Adriatic Sea ( Parapar et al. 2013) (see T. lilasae n. sp. Remarks), T erebellides resomari n. sp. differs from other European previously known species by the presence of papillar projections pointing over the edge of the branchial lamellae. By this characteristic, T. resomari n. sp. is similar to T. bonifi n. sp., T. europaea n. sp., T. gentili n. sp. and T. lilasae n. sp. Among these last species, T. resomari n. sp. differs by the presence of an elongated upper lip, of individually well separated branchial lamellae and of conical branchial papillae ( Table 2 ).

Figures

FIGURE 1. Schematic distribution of the different Trichobranchidae species along the French coasts. Text in italic represents type locality of new species. Abbreviation: WGMP, West Gironde Mud Patch.

FIGURE 17. Terebellides resomari n. sp. holotype MNHN-IA-TYPE 1889 (A–C) and paratype MNHN-IA-TYPE 1890 (D) A. Entire worm, lateral view; B. Anterior part, lateral view; C. Anterior part, dorsal view; D. Anterior part, lateral view, methyl green staining. Abbreviation: glr, glandular lateral region. Scales: A=2 mm, B–D=1 mm.

FIGURE 18. Terebellides resomari n. sp. SEM Additional material SMA_DUN_09 (A–B), SEM paratype MNHN-IA-TYPE 1893 (C) and SEM paratype MNHN-IA-TYPE 1892 (D–E) A. Anterior part, dorsal view; B. Papillar projections on edge of branchial lamellae, lateral view; C. Anterior part, frontal view; D. Uncini, thoracic chaetiger; E. Uncini, abdominal chaetiger. Scales: A–C=600 µm, B=200 µm, D=25 µm, E=15 µm.