Anguillosyllis villarae, Neal & Drennan & Wiklund & Stewart & Rabone & Dahlgren & Glover, 2025

Neal, Lenka, Drennan, Regan, Wiklund, Helena, Stewart, Eva C. D., Rabone, Muriel, Dahlgren, Thomas G. & Glover, Adrian G., 2025, New species of Anguillosyllis Day, 1963 (Annelida, Syllidae) from polymetallic nodule exploration areas, eastern Clarion-Clipperton Zone, central Pacific Ocean, European Journal of Taxonomy 1026, pp. 30-64 : 52-57

Anguillosyllis villarae sp. nov.

urn:lsid:zoobank.org:act:

Figs 6C, 13–16

Diagnosis

Body with 10 chaetigers. Prostomium in two parts, with three short antennae. Palps elongated, free to the base. Parapodia with large conical dorsal lobes (flaps). Heterogomph chaetae unidentate with some tips hooked or with tips bidentate; some chaetae with wide strap-like blades.

Etymology

The species name is dedicated to Lucía Villar Muñoz a member of the science party on expeditions C5a, C5d, C7a, and C7b to the NORI-D area, particularly for her work slicing and sieving boxcore samples.

Material examined

Holotype

PACIFIC OCEAN – Eastern Central Pacific , Clarion Clipperton Fracture Zone • 10.354901 ° N, 117.220794° W; 4273.8 m depth; 23 Nov. 2020; H. Wiklund, R. Drennan, C. Boolukos and G. Bribiesca Contreras leg.; USNEL Box Core; specimen GUID: aa8735af-ee3a-456f-bc57-888dd874e7fc; field ID; NHM_08811; GenBank COI gene: PV577536; 16S gene: PV579024; 18S gene: PV579032; NHMUK ANEA 2024.2704 .

Paratypes

PACIFIC OCEAN – Eastern Central Pacific , Clarion Clipperton Fracture Zone • 1 spec.; 10.32909125 ° N, 117.1971482° W; 4281 m depth; 9 Nov. 2020; H. Wiklund, R. Drennan, C. Boolukos and G. Bribiesca Contreras leg.; USNEL Box Core; specimen GUID: c382ab84-7641-40bb-91db-

107aa41c8eee; field ID NHM_05657; GenBank COI gene: PV577533; NHMUK ANEA 2024.2701 • 1 spec.; 10.34811115 ° N, 117.1706608° W; 4282.6 m depth; 17 May. 2021; H. Wiklund, R. Drennan, C. Boolukos and G. Bribiesca Contreras leg.; USNEL Box Core; specimen GUID: 2280eace-04fb- 430a-aa3f-d2163f629c86; field ID NHM_07689B; GenBank COI gene: PV577537; NHMUK ANEA 2024.2706 .

Other material

PACIFIC OCEAN – Eastern Central Pacific , Clarion Clipperton Fracture Zone • 1 spec.; 10.33498329 ° N, 117.1741855° W; 4286 m depth; 6 Nov. 2020; H. Wiklund, R. Drennan , C. Boolukos and G. Bribiesca Contreras leg.; USNEL Box Core; specimen GUID: 8a50f3cb-93de-4aa6-8792- cac45d2b2137; field ID NHM_05399; GenBank 16S gene: PV579028; NHMUK ANEA 2024.2712 • 1 spec.; 10.3861134 ° N, 117.1309018° W; 4308 m depth; 12 Nov. 2020; H. Wiklund, R. Drennan , C. Boolukos and G. Bribiesca Contreras leg.; USNEL Box Core; specimen GUID: bc633595-9ba5- 4320-a0c8-e0022060eac7; field ID NHM_05908; GenBank 16S gene: PV579025; NHMUK ANEA 2024.2705 • 1 spec.; 10.33426964 ° N, 117.1901234° W; 4287.72 m depth; 12 May. 2021; H. Wiklund, C. Boolukos, M. Rabone and G. Bribiesca-Contreras leg.; USNEL Box Core; specimen GUID: 50527b56- 3f4d-430f-929b-fa4d91b1d858; field ID NHM_06940; GenBank 16S gene: PV579027; NHMUK ANEA 2024.2711 • 1 spec.; 10.37726533 ° N, 117.1558078° W; 4302.03 m depth; 14 May. 2021; H. Wiklund, C. Boolukos, M. Rabone and G. Bribiesca Contreras leg.; USNEL Box Core; specimen GUID: 45112357-3af9-4c7f-8c93-d014c68f64ca; field ID NHM_07227A; GenBank 16S gene: PV579026; NHMUK ANEA 2024.2710 • 1 spec.; 10.33079203 ° N, 117.1940202° W; 4290.89 m depth; 1 Jun. 2021; H. Wiklund, R. Drennan , C. Boolukos and G. Bribiesca Contreras leg.; USNEL Box Core; specimen GUID: 71da1d0f-f4b9-4390-a8de-4c55e8351ad0; field ID NHM_08730; GenBank COI gene: PV577534; NHMUK ANEA 2024.2702 • 1 spec.; 10.33079203 ° N, 117.1940202° W; 4290.89 m depth; 1 Jun. 2021; H. Wiklund, R. Drennan , C. Boolukos and G. Bribiesca Contreras leg.; USNEL Box Core; specimen GUID: 290627ed-657b-4965-a9bd-920e8ca878ce; field ID NHM_08730B; GenBank COI gene: PV577535; 18S gene: PV579031; NHMUK ANEA 2024.2703 • 1 spec.; 10.332533 ° N, 117.187352° W; 4281 m depth; 24 Aug. 2022; H. Wiklund, C. Boolukos and E. Stewart leg.; USNEL Box Core; specimen GUID: d38da487-db2d-4274-bc96-ba7af0112e02; field ID NHM_09396_HW18; GenBank COI gene: PV577538; NHMUK ANEA 2024.2707 • 1 spec.; 10.334243 ° N, 117.185992° W; 4279 m depth; 12 Mar. 2022; H. Wiklund, C. Boolukos, E. Stewart and A. Bessell leg.; USNEL Box Core; specimen GUID: 82b4921b-0ff9-4337-9bc4-034367e808c5; field ID NHM_10276; GenBank COI gene: PV577539; NHMUK ANEA 2024.2708 • 1 spec.; 10.334296 ° N, 117.17708° W; 4282 m depth; 21 Nov. 2022; H. Wiklund, C. Boolukos, E. Stewart and A. Bessell leg.; USNEL Box Core; specimen GUID: fe6b7444-31bf-400f-9ed1-66530bb53a8c; field ID NHM_10374_ CB12 ; GenBank COI gene: PV577540; NHMUK ANEA 2024.2709 .

Description

MEASUREMENTS AND APPEARANCE. Moderately sized species, up to 2 mm in length for 10 chaetigers ( Fig. 13A–C). Holotype NHMUK ANEA 2024.2704, posteriorly complete, 1.6 mm long and 0.25 mm at widest point for 10 chaetigers; only left lateral antenna remains attached, pygidium with cirri missing ( Fig. 13A–B). Paratype NHMUK ANEA 2024.2701, live specimen translucent with 10 chaetigers ( Fig. 13C), now as SEM specimen on stub, posteriorly incomplete, ~ 0.8 mm long and 0. 25 mm wide at widest point for 5 chaetigers, left lateral antenna missing ( Fig. 14A). Paratype NHMUK ANEA 2024.2706, specimen with 10 chaetigers, with pygidium removed for tissue sampling for DNA analysis, rest of the body well preserved, ~ 1.3 mm long 0.25 mm wide. Other specimens in variable condition, usually posteriorly incomplete due to preservation or tissue sampling for DNA. Body somewhat dorsoventrally flattened. Fixed specimen opaque, creamy white in ethanol ( Fig. 13 A–B).

PROSTOMIUM. Oval, wider than long ( Fig. 13A) under light microscope; SEM shows differentiation with distinct median lobe approximating the diamond shape in postero-dorsal view ( Figs 6C, 14B). Eyes absent. Prostomium bearing three short digitiform to club-shaped antennae and two palps ( Fig. 14A–B). Antennae about the length of prostomium; median antenna club shaped, slightly longer than lateral antennae, and inserted on the prostomial median lobe ( Fig. 14A–B); lateral antennae digitiform, inserted more anteriorly on the inferior prostomial lobe ( Fig. 14A–B). Palps slightly longer than the prostomium, thick, digitiform and distally rounded, free to the base ( Fig. 14A–B).

TENTACULAR SEGMENT. Achaetous, bearing two short oval tentacular cirri, ~ ½ the length of median antenna, inserted laterally ( Fig. 14A–B). Pharyngeal tube extending to chaetiger 3; proventricle spanning from chaetigers 3–5 lightbulb shaped; number of muscle cell rows mostly obscured by body wall.

PARAPODIA. Long, rectangular, and uniramous. Parapodia with well-developed conical dorsal lobe and two smaller lobes, best observed in paratype NHMUK 2024.2706 ( Fig. 16A–B). Internal glands in the distal part of parapodia retain Shirlastain A. Dorsal cirri always missing, SEM shows presence of cirrophores on chaetiger 1, unclear in other chaetigers. Ventral cirri short and conical, approximately half the length of the antennae, inserted medially on parapodia ( Fig. 14C). Only one aciculum per parapodium confirmed, with non-emergent tip ( Fig. 16C). Each parapodium with sparse bundles of ~15–20 chaetae. All chaetae compound heterogomph, falcigerous to spiniger-like ( Fig. 16D–E). Shafts of falcigerous chaetae in chaetigers 1–4 denticulated with denticles arranged in irregular horizontal rows ( Fig. 15B), other shafts smooth. Blades variable ranging from sturdy and thin with sparse serration to wide, strap-like, ‘floppy’ and densely serrated chaetae, best observed in mid body parapodia ( Fig. 15A, D). Tips of chaetae blunt, unidentate gently curved ( Fig. 15E–F) or distinctly hooked ( Fig. 15G), some tips distinctly bidentate ( Fig. 15C).

PYGIDIUM. Damaged; pygidial appendages missing.

Genetic data

Specimens (n = 12) assigned to A. villarae sp. nov. form a monophyletic clade (Supp. file 3: Fig. S1, Supp. file 4: Fig. S2), with low intraspecific divergence across all sequences (maximum intraspecific p-distance/K2P 0.8/0.8% for 16S and 0.5/0.5% for COI). No close matches on GenBank were returned following blastn analysis. In the combined phylogenetic analysis ( Fig. 6), this species forms a polytomy with sequences identified as Anguillosyllis sp. MTA_2011 (discussed in A. finnelli genetics section) in addition to being close to Anguillosyllis finnelli sp. nov. In separate gene analyses (Supp. file 3: Fig. S1, Supp. file 4: Fig. S2), minimum interspecific p-distances/K2P of 13.4/14.8% 16S, and 17.1/19.5% COI were observed between A. villarae and A. finnelli , and 12.3/13.2% 16S and 19.3/26.6% COI between A. villarae and Anguillosyllis sp. MTA_2011. Anguillosyllis villarae differed from A. finnelli and Anguillosyllis sp. MTA_2011 by two and six mutations respectively in an alignment of nuclear 18S (1630 bp).

Remarks

The new species described here is easily distinguished from most known species, by the presence of hooked and bidentate chaetae. Currently only three known species, Anguillosyllis palpata , A. hampsoni and A. truebloodi (CCZ species), possess hooked chaetae. However, only in the new species described here, we have observed distinctly bidentate tips ( Fig. 15C). Another character shared with A. palpata is the presence of well-developed dorsal lobes in parapodia. However, all known species that possess the enlarged dorsal lobe have a body with 11 chaetigers, while the new species has only 10. The prostomium of the new species cannot be meaningfully compared as no SEM investigations have been published previously, but it possesses a distinct median lobe approximating the diamond shape ( Fig. 14B) at least when observed postero-dorsally.

Distribution

Eastern CCZ: NORI-D exploration area, depth ~ 4300 m.