Terebellides lilasae, 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 : 170-173

Terebellides lilasae n. sp.

Figures 13–14 , Table 2

Type material: Holotype: MNHN-IA-TYPE 1879, complete, Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-8, 45°38’55”N, 01°45’47”W, 62 m depth, 29 October 2016 . Paratypes: MNHN-IA- TYPE 1880, complete, Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-8, 45°38’55”N, 01°45’47”W, 62 m depth, 29 October 2016 ; MNHN-IA-TYPE 1881, anterior part, Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-8, 45°38’55”N, 01°45′47”W, 62 m depth, 29 October 2016 , mounted for SEM; MNHN-IA-TYPE 1882, complete, Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-4, 45°36’50”N, 01°49’37”W, 69 m depth, 16 August 2017 ; MNHN-IA-TYPE 1883, complete (posterior part used for molecular analysis), Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-4, 45°36’50” N, 01°49’37” W, 69 m depth, 29 April 2018 ; AM W.51394, one specimen, complete, Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-3, 45°40’57”N, 1°41’30”W, 54 m depth, 27 October 2016 , mounted for SEM; AM W.51450, one specimen, complete, Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-4, 45°38’55”N, 1°45’47”W, 69 m depth, 28 October 2016 .

Additional material examined: SMA _ VOG8C2 -A, complete (posterior part used for molecular analysis), Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-8, 45°38’55”N, 01°45’47”W, 61 m depth, 20 August 2017 ; SMA _ VOG8C2 -B, complete (posterior part used for molecular analysis), Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-8, 45°38’55”N, 01°45’47”W, 61 m depth, 20 August 2017 ; SMA _ VOG8C2 -C, complete (posterior part used for molecular analysis), Northeast Atlantic Ocean , Bay of Biscay, West Gironde Mud Patch, JERICO-8, 45°38’55”N, 01°45’47”W, 61 m depth, 20 August 2017 ; SMA _BR_ 42, complete (posterior part used for molecular analysis), Northeast Atlantic Ocean , Northern Bay of Biscay, APP 5220, 47°28’51”N, 03°45’23”W, 85 m depth, May 2018 ; SMA _BAN_13, one specimen, gravid, complete, Mediterranean Sea , Gulf of Lion, Appeal I2, 42 °45’18”N, 3°17’40”E, 83 m depth, September 2019 ; SMA _BAN_ 07, juvenile, Mediterranean Sea , Gulf of Lion, A90, 42°32’39”N, 3°16’03”E, 90 m depth, April 2018 , entirely used for molecular analysis.

Description. Large species, holotype 35.2 mm long (34.6–55.9 mm) and 3.2 mm (2.3–3.8 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 ( Fig. 13 A–B, D). Buccal tentacles of 2 types, uniformly cylindrical, with expanded spatulate tips ( Fig. 13B ). Lower lip expanded, below upper lip ( Fig. 13 A–B, D). SG 1 and 2 short, visible ventrally; following segments with lobes forming ventral collars. Lateral lappets on SG 3–6, thoracic chaetigers TC 1–4 continuing ventrally, larger on TC 1–2 and decreasing in size posteriorly ( Fig. 13 A–B, D). No conspicuous dorsal rounded projection on anterior chaetigers. Oval-shaped glandular lateral region on TC 3 ( Fig. 13D ).

Branchiae arising as a single structure between TC 1– TC 2, reaching TC 5 ( TC 6), consisting of a single elongate and annulated stalk placed mid-dorsally ( Figs 13 A–B, D & 14A), two pairs of lobes, fused for about 3/4 of length, lower pair thinner ( Figs 13C & 14A ). Upper lobes with 60 to 80 tightly packed lamellae ( Figs 13 A–B, D & 14A). Both sides of branchial lamellae provided with several parallel rows of cilia, no tufts of cilia on outer edge ( Fig. 14B ). Margins of most of individual branchial lamellae with numerous rounded projecting papillae, visible under stereomicroscope ( Figs 13B, D & 14 A–B). Distal region of both upper and lower lobes with short terminal pointed projections for upper lobes and long terminal projections for lower lobes ( Figs 13 A–D & 14A). Anterior branchial projection (5 th lobe) present ( Figs 13 A–B, D & 14A).

Eighteen pairs of thoracic notopodia ( SG 3–20). Notopodia on TC 1 and TC 2 inserted slightly more dorsally than subsequent notopodia; notopodia from TC 1 smaller in size than following ones, and transversally aligned; notochaetae from TC 1 slightly longer (all of same length) than following notochaetae ( Fig. 13B ). 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 six (5) sharply bent acute tipped, geniculate chaetae.All subsequent thoracic neuropodia with around 12–20 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 five to eight short teeth and an upper crest of several minute denticles ( Fig. 14C ). About 25 abdominal neuropodia as erect pinnules paddle-shaped with entire margin provided with about 36 uncini; uncini with three or five pointed teeth above main fang, surmounted by a row of five pointed short teeth and an upper crest of minute teeth ( Fig. 14D ).

Two pairs of globular nephridial openings, located dorsal to each notopodium from TC 4 to TC 5. Pygidium blunt, slightly crenulated, as a funnel-like depression.

Methyl green staining pattern: First six TC stain solid; from TC 7 to about TC 11, stain with distinct stripes, fading towards posterior thoracic region, width of stained stripes decreases posteriorly ( Fig. 13D ); glandular region on TC 3 white (except dorso-anterior region stained in blue) ( Fig. 13D ).

Etymology. The species is named after Lilas Lavesque, NL and GD’ beloved daughter.

Habitat. in coastal mud and sandy mud, at 50–105 m depth.

Type locality. West Gironde Mud Patch , Bay of Biscay, France, NE Atlantic .

Distribution. Northeast Atlantic Ocean (Bay of Biscay, from south of Brittany to off Gironde estuary), Western Mediterranean Sea (Gulf of Lion), France ( Fig. 1 ).

Remarks. Among the European previously known species, Terebellides lilasae n. sp. differs by the presence of papillar projections pointing over the edge of the branchial lamellae. By this character, T. lilasae n. sp. is similar to T. bonifi n. sp., T. europaea n. sp., T. gentili n. sp. and T. resomari n. sp. Among these last species, only T. bonifi n. sp., shares the presence of oval glandular region on TC 3. However, T. lilasae n. sp. differs from T. bonifi n. sp. by the staining of the glandular region (mostly white for T. lilasae n. sp., dark blue for T. bonifi n. sp.), by the presence of papillar projections on most of the branchial lamellae (instead of anterior lamellae only for T. bonifi n. sp.) and the absence of conspicuous dorsal projections on TC 1–3 (presence on T. bonifi n. sp.).

Based on the literature, T. lilasae n. sp. is similar to T. stroemii from Adriatic Sea ( Parapar et al. 2013), in having a size greater than 30 mm, the same type of papillar projections pointing over the margins of the branchial lamellae and the same shape of glandular region on TC 3. However, T. lilasae n. sp. differs by a few characters such as the number of lamellae on upper lobes (about 30 for Adriatic specimens vs about 60–80 for T. lilasae n. sp.), the length of branchiae (reaching TC 3 vs TC 6, respectively) and the number of abdominal uncinus (about 23 for Adriatic specimens vs about 36 for T. lilasae n. sp.). As suggested previously by Parapar & Hutchings (2014), specimens from the Adriatic Sea cannot belong to T. stroemii . They are more similar to T. lilasae n. sp. although they differ by a few characters. Further molecular analysis should permit to test if these variations are intra specific or if specimens from Adriatic belong to an undescribed species.

Finally, molecular results confirm that T. lilasae n. sp. is present from off Gironde estuary to North of the Bay of Biscay and the Mediterranean Sea. Molecular results, based on material available for this study, show that this species appears to be absent from Northern waters ( Fig. 23 ).

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 13. Terebellides lilasae n. sp. holotype MNHN-IA-TYPE 1879 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 14. Terebellides lilasae n. sp. SEM paratype AM W.51394 A. Anterior part, dorsal view; B. Ciliation and papillar projection of branchial lamellae; C. Uncini, thoracic chaetiger; D. Uncini, abdominal chaetiger.

FIGURE 23. Maximum likelihood trees of valid European Terebellides species and available sequences of Terebellides species obtained in this study, based on A. 16S sequences; B. COI sequences. Values on nodes represent posterior probabilities> 0.5 (first values), or Maximum likelihood bootstrap support> 50 (second values). Sequence accession numbers refer to Table 1 and Nygren et al. (2018), text in red to specimens sequenced during this study.