Neanthes goodayi Drennan & Wiklund & Rabone & Georgieva & Dahlgren & Glover 2021, sp. nov.

Neanthes goodayi sp. nov.

urn:lsid:zoobank.org:act: C5CDA152-0C73-46BB-955F-9BD5F02BE0F6

Figs 2–6, 8

Diagnosis

Anterior eye pair very large, distinct, posterior eyes minute. Posterio-dorsal tentacular cirri reaching chaetigers 8–12. Two pigmented spots on dorsum of apodous segment. Palpostyles and palpophores rounded, spherical to ovoid. Paragnaths in pharangeal areas: I = 1–2, II = 9–12, III = 6, IV = 12–16, V = 0, VI = 1–4, VII-VIII = 12–19; area VI–I–VI pattern λ-shaped on oral ring. Chaetigers 1–2 uniramous, remaining chaetigers biramous. Parapodial lobes conical, becoming narrower in posterior chaetigers. Neuracicular postchaetal lobe longer than or equal to neuraciular ligule on anterior chaetigers, shorter on medial chaetigers, papilliform or absent on posterior chaetigers. Dorsal cirri exceed length of ligules on anterior chaetigers, as long as or slightly shorter than ligules on medial chaetigers, becoming longer and exceeding ligules towards posterior end; on largest specimens, dorsal cirri exceed ligules on all chaetigers. Notochatae with homogomph spinigers throughout, supraciular nerurochaetae with homogomph spinigers and heterogomph falcigers throughout, subacicular neurochaetae with homogomph spinigers, homogomph falcigers and heterogomph falcigers throughout.

Etymology

Named in honor of Andy Gooday, member of the science party of both ABYSSLINE cruises. This etymology is part of the ABYSSLINE naming convention where all new taxon names are based on a randomised list of both crew and scientists of the two research cruises in order to recognise the team effort involved in this extensive sampling program (Wiklund et al. 2019).

Material examined

Holotype PACIFIC OCEAN • Eastern Central Pacific, Clarion Clipperton Fracture Zone; 12.53717° N, 116.60417° W; depth 4425 m; 20 Feb. 2015; A.G. Glover, H. Wiklund, T. Dahlgren and M. Brasier leg.; Brenke epibenthic sled, collected from epi-net; specimen guid:21b3d59f-5ec4-40da-9d65-4177e7674f63, field ID: NHM_739, DNA voucher barcode: 0109493268, GenBank COI gene: MZ407918; NHMUK ANEA 2020.260.

Paratypes PACIFIC OCEAN – Eastern Central Pacific, Clarion Clipperton Fracture Zone • 1 spec.; 13.75833° N, 116.69852° W; depth 4080 m; 11 Oct. 2013; A.G. Glover, H. Wiklund, T.G. Dahlgren and M.N. Georgieva leg.; Brenke epibenthic sled, collected from epi-net; specimen guid: 2d448c5f-bf70-4ed1-a541-9b505ec46434, field ID: NHM_127, DNA voucher barcode: 0109492959, GenBank 16S gene: MZ408645; NHMUK ANEA 2020.33 • 1 spec.; 13.93482° N, 116.55018° W; depth 4082 m; 14 Oct. 2013; same collectors and collection method as for preceding; specimen guid: f5f08fc7-49b4-446f-9f04-fbbca84f7886, field ID: NHM_171, DNA voucher barcode: 0109492952, GenBank 18S gene: MZ408643, 16S gene: MZ408646, COI gene: MZ407911; NHMUK ANEA 2020.34 • 1 spec.; 13.81167° N, 116.71° W; depth 4076 m; 16 Oct. 2013; same collectors as for preceding; USNEL box corer, collected from 0–2 cm fraction; specimen guid: fb66da6c-f627-487f-a386-3454541ad33a, field ID: NHM_238, DNA voucher barcode: 0109493276, GenBank 16S gene: MZ408648, COI gene: MZ407913; NHMUK ANEA 2020.36 • 1 spec.; 12.41628° N, 116.71485° W; depth 4127 m; 16 Feb. 2015; A.G. Glover, H. Wiklund, T.G. Dahlgren and M. Brasier leg.; USNEL box corer, collected from nodule; specimen guid: e1461d7d-c6c8-46fc-b951-f5ee88550a5b, field ID: NHM_512, DNA voucher barcode: 0109493273, GenBank 16S gene: MZ408651; NHMUK ANEA 2020.1 • 1 spec.; 12.53717° N, 116.60417° W; depth 4425 m; 20 Feb. 2015; same collectors as for preceding; Brenke epibenthic sled, collected from epi net; specimen guid: 0d2be1b6-4348-46a2-a1a7-b214562c7b18; field ID: NHM_790, DNA voucher barcode: 0109493261, GenBank 16S gene: MZ408660; NHMUK ANEA 2020.7 • 1 spec.; 12.25733° N, 117.30216° W; depth 4302 m; 1 Mar. 2015; same collectors and collection method as for preceding; specimen guid: bb93253e-2d66-4592-b569-cfa5976fed33, field ID: NHM_1254, DNA voucher barcode: 0109493252, GenBank 16S gene: MZ408667; NHMUK ANEA 2020.17 • 1 spec.; 12.59688° N, 116.49357° W; depth 4258 m; 9 Mar. 2015; same collectors as for preceding; USNEL box corer, collected from nodule; specimen guid: 333370c7-eb36-429c-96ed-fce5658f2ad2, field ID: NHM_1624, DNA voucher barcode: 0109493249, GenBank 16S gene: MZ408670; NHMUK ANEA 2020.20 • 1 spec.; 12.17383° N, 117.19283° W; depth 4045 m; 11 Mar. 2015; same collectors as for preceding; Brenke epibenthic sled, collected from epi-net; specimen guid: 6d7f58fc-a657-47f4-9261-7517228de6a1, field ID: NHM_1783, DNA voucher barcode: 0109493246, GenBank 16S gene: MZ408673, COI gene: MZ407927; NHMUK ANEA 2020.23 • 1 spec.; 12.02738° N, 117.3252° W; depth 4139 m; 17 Mar. 2015; same collectors as for preceding; USNEL box corer, collected from nodule; specimen guid: 8abc43ad-193d-4e35-b548-6d2d0b7777f8, field ID: NHM_2069, DNA voucher barcode: 0109493237, GenBank 16S gene: MZ408681; NHMUK ANEA 2020.31.

Other material

PACIFIC OCEAN – Eastern Central Pacific, Clarion Clipperton Fracture Zone • 1 spec.; 13.93482° N, 116.55018° W; depth 4082 m; 14 Oct. 2013; A.G. Glover, H. Wiklund, T.G. Dahlgren and M.N. Georgieva leg.; Brenke epibenthic sled, collected from epi-net; specimen guid: 022c1d2a-8b2a-479f-8ed2-20ff4e9610dd, field ID: NHM_173, DNA voucher barcode: 0109493277, GenBank 18S gene: MZ408644, 16S gene: MZ408647, COI gene: MZ407912; NHMUK ANEA 2020.35 • 1 spec.; 13.81167° N, 116.71° W; depth 4076 m; 16 Oct. 2013; same collectors as for preceding; USNEL box corer, collected from 0–2 cm fraction; specimen guid: 57002bc8-fa3a-4a55-b823-0af978cd2fcd, field ID: NHM_239, DNA voucher barcode: 0109493275, GenBank 16S gene: MZ408649, COI gene: MZ407914; NHMUK ANEA 2020.37 • 1 spec.; same collection data as for preceding; specimen guid: 4a8718c5-d675-4044-9d2b-613f1d8d5fda, field ID: NHM_240, DNA voucher barcode: 0109493274, GenBank 16S gene: MZ408650, COI gene: MZ407915; NHMUK ANEA 2020.38 • 1 spec.; 12.38624° N, 116.54867° W; depth 4202 m; 17 Feb. 2015; A.G. Glover, H. Wiklund, T.G. Dahlgren and M. Brasier leg.; Brenke epibenthic sled, collected from epi-net; specimen guid: f61f9136-a39a-4696-8fdc-68aee0af5101, field ID: NHM_614, DNA voucher barcode: 0109493272, GenBank 16S gene: MZ408652, COI gene: MZ407916; NHMUK ANEA 2020.2 • 1 spec.; same collection data as for preceding; specimen guid: 1033aa6b-4093-41fc-af75-9ad090dd4c56, field ID: NHM_644, DNA voucher barcode: 0109493271, GenBank 16S gene: MZ408653, COI gene: MZ407917; NHMUK ANEA 2020.257 • 1 spec.; 12.53717° N, 116.60417° W; depth 4425 m; 20 Feb. 2015; same collectors and collection method as for preceding; specimen guid: 9a97230a-4b78-4823-88a5-d02d9c874db9; field ID: NHM_678, DNA voucher barcode: 0109493270, GenBank 16S gene: MZ408654; NHMUK ANEA 2020.258 • 1 spec.; same collection data as for preceding; specimen guid: 954c9c61-3e45-45a4-8522-7aadd1c86c60; field ID: NHM_692, DNA voucher barcode: 0109493269, GenBank 16S gene: MZ408655; NHMUK ANEA 2020.259 • 1 spec.; same collection data as for preceding; specimen guid: 76f62614-0cae-4177-8312-e231f5107f8c; field ID: NHM_743, DNA voucher barcode: 0109492976, GenBank 16S gene: MZ408656; NHMUK ANEA 2020.261 • 1 spec.; same collection data as for preceding; specimen guid: 3951d751-f1ba-44ae-8368-261047c07b12; field ID: NHM_755, DNA voucher barcode: 0109493257, GenBank COI gene: MZ407919; NHMUK ANEA 2020.3 • 1 spec.; same collection data as for preceding; specimen guid: 67a9133b-c57b-49c6-b6e4-124eb1315eac; field ID: NHM_757, DNA voucher barcode: 0109493258, GenBank 16S gene: MZ408657; NHMUK ANEA 2020.4 • 1 spec.; same collection data as for preceding; specimen guid: b13dc262-c631-44dc-927e-6a04c3608bda; field ID: NHM_766, DNA voucher barcode: 0109493259, GenBank 16S gene: MZ408658; NHMUK ANEA 2020.5 • 1 spec.; same collection data as for preceding; specimen guid: d9e557c5-3ffd-4a39-9eed-5ecead5e735f; field ID: NHM_783A, DNA voucher barcode: 0109493260, GenBank 16S gene: MZ408659; NHMUK ANEA 2020.6 • 1 spec.; same collection data as for preceding; specimen guid: 792a4c9a-9653-4ce1-8683-ca2556c1999a8; field ID: NHM_793, DNA voucher barcode: 0109493262, GenBank COI gene: MZ407920; NHMUK ANEA 2020.8 • 1 spec.; 12.57903° N, 116.68697° W; depth 4237 m; 22 Feb. 2015; same collectors as for preceding; USNEL box corer, collected from 0–2 cm fraction; specimen guid: a933dd63-64d1-4e45-95ad-7d68282dd892; field ID: NHM_865, DNA voucher barcode: 0109493263, GenBank COI gene: MZ407921; NHMUK ANEA 2020.9 • 1 spec.; 12.57133° N, 116.6105° W; depth 4198 m; 23 Feb. 2015; same collectors as for preceding; Brenke epibenthic sled, collected from epi-net; specimen guid: 3e7262c7-fd75-4a53-9d6c-9d01955d1bef; field ID: NHM_950, DNA voucher barcode: 0109493264, GenBank 16S gene: MZ408661, COI gene: MZ407922; NHMUK ANEA 2020.10 • 1 spec.; same collection data as for preceding; specimen guid: 06c15319-2b89-4899-b2e5-1fcd8e4a9413; field ID: NHM_971, DNA voucher barcode: 0109493265, GenBank COI gene: MZ407923; NHMUK ANEA 2020.11 • 1 spec.; 12.13367° N, 117.292° W; depth 4122 m; 24 Feb. 2015; same collectors and collection method as for preceding; specimen guid: 165a459f-8b81-4e97-8e82-cdcd013e1ed1; field ID: NHM_1011, DNA voucher barcode: 0109493266, GenBank 16S gene: MZ408662, COI gene: MZ407924; NHMUK ANEA 2020.12 • 1 spec.; 12.1155° N, 117.1645° W; depth 4100 m; 26 Feb. 2015; same collectors and collection method as for preceding; specimen guid: a343e242-410a-4817-98c6-7125db7d03e7; field ID: NHM_1079, DNA voucher barcode: 0109493267, GenBank 16S gene: MZ408663; NHMUK ANEA 2020.13 • 1 spec.; same collection data as for preceding; specimen guid: 7ead0546-d0bd-4381-83af-89f58d8f8f4c; field ID: NHM_1167A, DNA voucher barcode: 0109492975, GenBank 16S gene: MZ408664; NHMUK ANEA 2020.14 • 1 spec.; same collection data as for preceding; specimen guid: 6b51d602-83f1-4bb4-b71a-e85cdbcbe8dc; field ID: NHM_1171, DNA voucher barcode: 0109493254, GenBank 16S gene: MZ408665, COI gene: MZ407925; NHMUK ANEA 2020.15 • 1 spec.; 12.00945° N, 117.17812° W; depth 4144 m; 27 Feb. 2015; same collectors as for preceding; USNEL box corer, collected from nodule; specimen guid: 9e903864-55e8-4a1a-b532-c47af39b95f4; field ID: NHM_1194, DNA voucher barcode: 0109493253, GenBank 16S gene: MZ408666; NHMUK ANEA 2020.16 • 1 spec.; 12.45433° N, 116.61283° W; depth 4137 m; 3 Mar. 2015; same collectors as for preceding; Brenke epibenthic sled, collected from epi-net; specimen guid: e5797775-7141-4eb5-bb5e-dbcb29f7b42e; field ID: NHM_1480E, DNA voucher barcode: 0109493251, GenBank 16S gene: MZ408668; NHMUK ANEA 2020.18 • 1 spec.; 12.51317° N, 116.49133° W; depth 4252 m; 5 Mar. 2015; same collectors and collection method as for preceding; specimen guid: 35bae0ad-f00e-442b-a8f5-b1b318bf1015; field ID: NHM_1515, DNA voucher barcode: 0109493250, GenBank 16S gene: MZ408669, COI gene: MZ407926; NHMUK ANEA 2020.19 • 1 spec.; 12.59688° N, 116.49357° W; depth 4258 m; 9 Mar. 2015; same collectors as for preceding; USNEL box corer, collected from nodule; specimen guid: 29f1c1bf-5bca-4ed1-a893-edcd45493e04; field ID: NHM_1631A, DNA voucher barcode: 0109493248, GenBank 16S gene: MZ408671; NHMUK ANEA 2020.21 • 1 spec.; 12.17383° N, 117.19283° W; depth 4045 m; 11 Mar. 2015; same collectors as for preceding; Brenke epibenthic sled, collected from epi-net; specimen guid: 83507a57-c168-4b6f-b984-1c69ccbebc27; field ID: NHM_1764, DNA voucher barcode: 0109493247, GenBank 16S gene: MZ408672; NHMUK ANEA 2020.22 • 1 spec.; 12.0999° N, 117.1966° W; depth 4051 m; 12 Mar. 2015; same collectors as for preceding; USNEL box corer, collected from 0–2 cm fraction; specimen guid: f79fb7b6-ed29-4cc3-9f7f-8d4ace75c585; field ID: NHM_1836A, DNA voucher barcode: 0109493245, GenBank 16S gene: MZ408674; NHMUK ANEA 2020.24 • 1 spec.; 12.0415° N, 117.21717° W; depth 4094 m; 13 Mar. 2015; same collectors as for preceding; Brenke epibenthic sled, collected from epi-net; specimen guid: 0508d326-ef73-4f52-bdc6-757b2ab745fe; field ID: NHM_1866, DNA voucher barcode: 0109492983, GenBank 16S gene: MZ408675, COI gene: MZ407928; NHMUK ANEA 2020.25 • 1 spec.; same collection data as for preceding; specimen guid: 922ad1d7-bd75-4588-ba2e-be32cfe432c5; field ID: NHM_1891, DNA voucher barcode: 0109492960, GenBank 16S gene: MZ408676; NHMUK ANEA 2020.26 • 1 spec.; same collection data as for preceding; specimen guid: e991eafe-0593-4e08-8967-d77e017eabac; field ID: NHM_1929A, DNA voucher barcode: 0109493233, GenBank 16S gene: MZ408677, COI gene: MZ407929; NHMUK ANEA 2020.27 • 1 spec.; same collection data as for preceding; specimen guid: 62b28de1-a797-4ec0-99cf-e38625b0e01c; field ID: NHM_1929B, DNA voucher barcode: 0109493234, GenBank 16S gene: MZ408678; NHMUK ANEA 2020.28 • 1 spec.; same collection data as for preceding; specimen guid: 25953aef-8a48-48d1-9fc2-b0a86ec7d052; field ID: NHM_1947D, DNA voucher barcode: 0109493235, GenBank 16S gene: MZ408679; NHMUK ANEA 2020.29 • 1 spec.; 12.0505° N, 117.40467° W; depth 4235 m; 16 Mar. 2015; same collectors and collection method as for preceding; specimen guid: d8edb41d-51d6-4fbd-a547-92fa290209d4; field ID: NHM_2014, DNA voucher barcode: 0109493236, GenBank 16S gene: MZ408680, COI gene: MZ407930; NHMUK ANEA 2020.30 • 1 spec.; 12.57133° N, 116.6105° W; depth 4198 m; 23 Feb. 2015; same collectors as for preceding; Brenke epibenthic sled, collected from supra-net; specimen guid: 1c30624d-19a0-43f0-92dc-9a315a3e43fc; field ID: NHM_3074, DNA voucher barcode: 0109493238, GenBank 16S gene: MZ408682; NHMUK ANEA 2020.32.

Comparative material examined

Holotype of Neanthes heteroculata (Hartmann-Schröder, 1981)

ATLANTIC OCEAN • Northeastern Atlantic, Bay of Biscay; 46º35.0′ N, 7º45.5′ W; depth 4700 m; 24 Oct. 1967; ZMH P-16464.

Paratypes of Neanthes heteroculata (Hartmann-Schröder, 1981)

ATLANTIC OCEAN • 2 specs; same collection data as for preceding; ZMH P-16465.

Description

Holotype (NHM_739) complete, TL = 12 mm, L15 = 4.7 mm, W15 = 0.9 mm, for 47 chaetigers. Body somewhat ‘baseball bat-shaped’, wide, swollen anteriorly but tapering gradually posteriorly (Fig. 2A–B). Live specimen pale, iridescent and semi-translucent, with yellow gut and red blood vessels visible through body wall (Fig. 2A, C); specimen in ethanol opaque, pale beige, with some red vasculature still visible (Fig. 2B, D). Two pigmented spots on either side of dorsum of apodous segment visible in both live specimens and in ethanol, with some pigmentation also visible on dorsum of anterodorsal tentacular cirrophores (Fig. 2C–D).

Prostomium short, rounded trapezoid with shallow dorsal depression extending anteriorly from midpoint to distal margin (Fig. 2C–D); antennae cirriform, medium-sized, barely extending beyond palps. Palps nearly as long as prostomium, with both palpophores and palpostyles short, spherical, with palpostyles half as long as palpophores. Tentacular cirri with short, cylindrical cirrophores; posterior-dorsal pair of tentacular cirri longest, extending to chaetiger 12 (Fig. 2A–B). Two pairs of dark red eyes; anterior pair very large, rounded teardrop-shaped, with large, rounded lenses inserted anterolaterally and with an irislike structure visible in preserved specimen (Fig. 2C); posterior pair of eyes minute, rounded, with small anterolateral lenses. Apodous anterior segment collar-like, slightly longer and narrower than chaetiger 1.

Pharynx not everted. Jaws dark red-brown with 6 lateral teeth; All paragnaths brown, conical, arranged as follows (Fig. 2E): area I: 2, one large cone, one smaller cone distally; area II: 12 in cluster; area III: approx. 6 (area damaged), four cones in row with two smaller cones laterally; area IV: 13 in teardropshaped cluster, with curved line of cones extending from jaws posteriorly, ending in cluster of 7 cones; area V: no paragnaths; area VIa: 1; area VIb: 4, one large and three smaller cones in trapezoid arrangement; areas VII–VIII: 19, eight large cones in a single well-spaced row with 11 smaller cones scattered laterally. Areas VI–V–VI with λ-shaped ridge pattern.

Chaetigers 1 and 2 uniramous, with all subsequent chaetigers biramous.

Dorsal cirri inserted at base of median and dorsal ligule in uniramous and biramous chaetigers, respectively, slightly inflated on uniramous chaetigers (Fig. 3A), more slender from chaetiger 3 onwards (Fig. 3B–H); dorsal cirri extending beyond median ligule on anteriormost chaetigers (Fig. 3A–B), as long as or slightly shorter than median ligules from chaetiger 6 onwards (Fig. 3C–D) and extending beyond median ligules from around chaetiger 29 (Fig. 3E), up to twice as long as median ligules on posterior chaetigers from chaetiger 40 (Fig. 3G–H).

Dorsal ligule conical throughout, slightly shorter than median ligules on anterior chaetigers (Fig. 3B–C), approximately two-thirds the length of median ligules from chaetiger 10 onwards. Dorsal and median ligules reduced in size on posterior chaetigers from chaetiger 40, with dorsal ligule vanishing in posteriormost chaetigers (Fig. 3H). Median ligule slightly inflated on uniramous chaetigers (Fig. 3A), conical on biramous chaetigers, narrower from chaetiger 29 (Fig. 3E), bluntly conical on posteriormost chaetigers (Fig. 3H). Notopodial prechaetal lobe indistinct.

Neuracicular ligule shorter than ventral neuropodial ligule on anterior chaetigers (Fig. 3A–C), becoming equal in length or slightly shorter from chaetiger 10, equal or slightly longer from chaetiger 29 (Fig. 3E). Superior neuropodial lobe indistinct, truncate throughout; inferior lobe short, rounded on anterior and medial chaetigers, gradually shortening, giving neuracicular ligule pointed appearance on posterior chaetigers (Fig. 3G–H). Neuracicular prechaetal lobe indistinct. Neuracicular postchaetal lobe conical, longer than neuracicular lobe on anteriormost chaetigers (Fig. 3A–B), equal in length at chaetiger 6 (Fig. 3C), gradually shortening and becoming more digitiform on subsequent chaetigers to papilliform nub around chaetiger 29 (Fig. 3F), absent in posterior chaetigers from around chaetiger 40.

Ventral neuropodial ligule conical throughout, gradually narrowing on medial (Fig. 3E) and posterior chaetigers (Fig. 3G–H). Ligule sub-equal in length to median ligule in anterior and early medial chaetigers (Fig. 3A–D), becoming shorter in remaining chaetigers from chaetiger 29 (Fig. 3E), to two-thirds as long as ligule from chaetiger 40 (Fig. 3G) and half as long on posteriormost chaetigers (Fig. 3H).

Ventral cirri cirriform (Fig. 3C–F), inserted basally to ventral neuropodial ligule throughout, slightly shorter than ligule on anterior and medial chaetigers, subequal in length on posteriormost chaetigers (Fig. 3F).

Pygidium somewhat pyriform, truncate distally, with two filamentous anal cirri attached ventro-laterally, extending 8 chaetigers in length (Fig. 2A–B).

Caecal glands present, small, white, slightly thickened.

Multiple aciculae per parapodial lobe observed on some chaetigers in holotype: double neuraciculae in chaetigers 2, 3, 6 and 20 (Fig. 3B–D), and triple notoaciculae on chaetiger 6 (Fig. 3C). This feature was not observed in parapodial dissections from paratypes.

Notochaetae all homogomph spinigers with long blades, of similar width towards toothed edge but drastically slendering to an aristate distal end (Fig. 3I); 4 present in anterior chaetigers, 5 in medial chaetigers, 3 in posterior chaetigers and absent from chaetiger 46.

Supracicular neurochaetae with homogomph spinigers and heterogomph falcigers, both types present in all falcigers except final two chaetigers, where supracicular falcigers are absent. Homogomph spinigers similar in appearance to those of notopodia (Fig. 3J), though with blades reducing in length moving ventrally (shortest blades two-thirds as long as longest blade), numbering 4 on first two chaetigers, 3–5 on anterior and medial chaetigers and 2 on posterior chaetigers where fascicles remain. Heterogomph falcigers with knob-like tips (Fig. 3K) and blades roughly half the length of shortest spinigers, numbering 1 on anterior chaetigers, 2 on medial chaetigers and 1 on posterior chaetigers where fascicles remain.

Subacicular neurochaetae with homogomph spinigers and both homogomph and heterogomph falcigers. Homogomph spinigers also similar in appearance to those of notopodia (Fig. 3L) but with blades twothirds as long and numbering 1–2 on all chaetigers. Homogomph falcigers with knob-like tips (Fig. 3L), blades three-quarters the length of spinigers (Fig. 3L), numbering 1–3 on all chaetigers. Heterogomph falcigers similar in appearance to those of supracicular fascicles (Fig. 3M), numbering 3 on first two chaetigers, 4–6 on anterior, 2–4 on medial and 2–3 on posterior chaetigers.

Variations

Largest specimen (paratype NHM_2069) damaged, in two parts, TL = 17 mm, L15 = 6.7 mm, W15 = 1 mm for 55 chaetigers. Smallest specimen (paratype NHM_127) with TL = 1 mm for 10 chaetigers (see Juveniles section below). Pigment spots on dorsum as in holotype, consistent across most specimens both live and preserved (Fig. 4A–D), pigmentation on tentacular cirrophores more variable. Palpophores spherical to ovoid in shape (e.g., Fig. 4B). Posterior-dorsal pair of tentacular cirri extending to chaetiger 8–12 in most specimens (max. chaetiger 6 in juveniles). Eyes dark red to purple, anterior pair ranging from circular/ovoid (Fig. 4B–D) to teardrop-shaped concave discs or deeper cups (Figs 4A, 5A), becoming more crescent-shaped with decreasing size (Fig. 5B–D); posterior pair mostly circular (Fig. 4A–B), but occasionally oblong (Fig. 4A) or seeming to fuse with anterior pair (Fig. 6A–B), or with one missing (Fig. 4D). Posterior eye pair often less distinct in smaller specimens (Fig. 5A–B), becoming tiny spots (Fig. 5A) or patchy and irregularly shaped (Fig. 5B), completely absent in smallest specimens (Fig. 5C–D), with trace of lens not obvious. Apodous anterior segment longer and narrower than chaetiger 1, as in holotype, to similar in length and width as chaetiger 1 (Fig. 4A–D).

Jaws with 6–7 lateral teeth; paragnaths in pharangeal areas in non-holotype specimens: I = 1–2, II = 9–12, III = 6, IV = 12–16, V = 0, VI = 2–3, VII–VIII = 12–17 (8 large cones in a row as in holotype, varying number of smaller cones scattered laterally). Only one specimen (epitoke male, paratype NHM_1783) with pharynx everted (Fig. 6B).

In largest specimen, dorsal cirrus exceeds median ligule on all chaetigers, neuracicular ligule remains slightly longer than ventral ligule on median and posterior chaetigers, prechaetal lobe remains as

visible papilliform process on posterior chaetigers, ventral ligule subequal to ventral ligule from medial chaetigers onwards and ventral cirri longer than ventral ligule on posteriormost chaetigers.

Numbers of chaetae greater for most fascicles in largest specimen: notochaetae 6 homogomph spinigers on anterior and medial chaetigers, 4 in posterior chaetigers, 1 in posteriormost chaetigers; supracicular neurochaetae with 5–7 homogomph spinigers on first two chaetigers, 2–4 on anterior and medial chaetigers, 1 on posterior chaetigers, heterogomph falcigers 3 on first two chaetigers, 4–6 on anterior chaetigers, 0–3 on medial chaetigers and 1 on posterior chaetigers; subacicular neurochaetae with 2–4 homogomph spinigers most chaetigers, 1 on posteriormost chaetigers, homogmph falcigers 3–5 on anterior chaetigers, 1–2 on medial chaetigers, 1 on posterior chaetigers, heterogomph falcigers 6–9 on anterior chaetigers, 1–3 on medial and posterior chaetigers.

Description of epitoke paratype

One epitokous specimen observed (paratype NHM_1783) (Fig. 6A). Specimen moderately damaged, posteriorly incomplete, TL= 10 mm, L15 = 4 mm, for 37 chaetigers (chaetiger 15 damaged, width at chaetiger 14 excluding parapodia 0.8 mm). Body divided into two regions: pre-natatory with 14 chaetigers and natatory with at least 23 chaetigers; post-natatory region unknown. Eyes not notably modified (Fig. 6A–B); anterior pair with iris-like structure as in holotype, posterior pair somewhat fused to anterior pair.

Pre-natatory chaetigers with modified dorsal and ventral cirri on chaeigers 1–7; notably thickened, but with distalmost tip remaining fine and cirriform (Fig. 6C). Chaetal types in pre-natatory chaetigers as in holotype.

Natatory chaetigers with distinctly enlarged, elongate modified parapodia (Fig. 6D). Noto- and neuropodia elongated basally, with ligules and lobes not significantly larger than on non-modified parapodia. Neuracicular ligule with lamellar structure distally. Both dorsal and ventral cirri notably elongate, with a pair of conical lobes emerging from the upper and lower base of each cirrus, not present on anterior chaetigers; dorsal cirri slightly papillated (Fig. 6D–E). Both notopodial and neuropodial fascicles dense, up to 40 chaetae per fascicle, and with only a single chaetal type: long, simple sesquigomph spinigers with ensiform (knife-shaped) blades (Fig. 6F). No gametes observed, though the presence of slightly papillated dorsal cirri on natatory chaetigers suggests that this specimen is a male (Read 2007).

Juveniles

Several small, possibly juvenile specimens were observed; paratypes NHM_127, NHM_171, NHM_1254, TL = 1.0– 2.5 mm, L15 = max. 2.2 mm, W15 = max. 0.2 mm, 10–18 chaetigers (Fig. 5A–D). Posterio-dorsal tentacular cirri extending to chaetiger 6. Eyes poorly developed in these specimens, with anterior eye pair observed only as faintly pigmented crescents (Fig. 5B–D), lenses not obvious; posterior eye pair not visible in smallest specimens (Fig. 5C–D). The identity of these specimens was confirmed with genetic data. Due to their size and the delicate nature of specimens, pharyngeal and parapodial dissections were not conducted to preserve specimen integrity.

Genetic data

All 43 individuals were sequenced for 16S and COI. The gene 16S was successfully sequenced in all but six specimens. COI sequencing was less successful; however, each specimen had coverage of at least one of the two genes. All specimens formed a single clade with low intraspecific divergence. Several specimens were also sequenced for 18S in order to assess deeper taxonomic relationships. This species was genetically distinct from all other species included in our phylogenetic analyses, and forms the basal branch of a clade including Neanthes fucata (Savigny, 1822) and five species of Perinereis Kinberg, 1865 (Fig. 7).

Remarks

This species is most consistent with the genus Neanthes Kinberg, 1865, most recently defined by Ibrahim et al. (2019). Previous analyses based on morphological parsimony suggested that neither of the three most species-rich nereidid genera, Neanthes, Nereis and Perinereis, can be considered monophyletic, with many generic characters displaying high homoplasy (Bakken & Wilson 2005). Molecular phylogenetic analyses carried out in this study supported the polyphyly of Neanthes, as sequences of species currently regarded as Neanthes, both from the ABYSSLINE material and from GenBank, rarely grouped together and were evenly distributed throughout a tree that included 11 other nereidid genera.

Neanthes goodayi sp. nov. can be differentiated from the majority of its congeners by the notably large anterior pair of eyes. Only N. heteroculata (Hartmann-Schröder, 1981), described from abyssal (4700 m) waters off the Bay of Biscay in the northeastern Atlantic, appears to possess comparably large anterior and minute posterior pairs of eyes. Neanthes heteroculata and N. goodayi sp. nov. also display similarities with regard to several other characters, such as the appearance of the prostomium, antennae and tentacular cirri, in addition to the types of chaetae present and their appearance and arrangement. Based on an examination of the type material of N. heteroculata, N. goodayi sp. nov. differs in having distinctly rounded, spherical to ovoid palpophores (e.g., Fig. 4B), with palpophores in N. heteroculata found to be narrower, bluntly conical in shape. Furthermore, the dorsal cirri are relatively short in N. heteroculata, not exceeding the length of the notopodial ligules, whereas they exceed the length of the notopodial ligules in at least anterior and posterior chaetigers in N. goodayi sp. nov.

Notably, N. heteroculata is one of a handful of species of Neanthes reported from the deep sea. Of the 84 currently valid species of Neanthes (Read & Fauchald 2020b) only 13 have been reported from depths greater than 200 m (Khlebovich 1996; Shimabukuro et al. 2017; Hsueh 2019). Of these, N. goodayi sp. nov. also resembles N. papillosa (Day, 1963), described from deep (2745 m) waters off Cape Town, South Africa. Neanthes papillosa similarly possesses an enlarged anterior pair of eyes relative to the posterior pair, in addition to long tentacular cirri, relatively elongate, conical parapodial ligules, and dorsal cirri that exceed the length of the notopodial ligules, becoming longer on posterior chaetigers. The holotype of N. papillosa is noted to have pale, poorly chitinised paragnaths, thus making them difficult to observe (Day 1963). However, despite having fewer paragnaths in number across all areas, they appear to be organised in similar arrangements as in N. goodayi sp. nov., such as a single row of paragnaths on areas VII–VIII (single row of large cones in N. goodayi sp. nov. with varying numbers of smaller cones laterally). However, N. papillosa can primarily be differentiated from N. goodayi sp. nov. in that the anterior pair of eyes does not appear to be as strikingly large as in N. goodayi sp. nov. or N. heteroculata; thus, there is less disparity between the anterior and posterior eye pairs in size. Additionally, N. papillosa can be further distinguished in that it does not bear homogomph falcigers and that parapodial lobes of midbody and posterior chaetigers bear numerous club-shaped papillae; however, it is worth considering that some characters of N. papillosa may be reproductive modifications, as the holotype is described from a single epikotous female specimen.

Neanthes goodayi sp. nov. also bears similarities to N. vitiazi Khlebovich, 1996 from abyssal waters (3342–4160 m) of southern Japan, primarily in terms of broadly similar paragnath distributions, bearing homogomph falcigers and in having a large anterior pair of eyes, which are illustrated as rings without strong pigment. Neanthes vitiazi differs in that it has long, digitate median ligules positioned at right angles to the notoacicula on midbody and posterior chaetigers. Neanthes vitiazi is also described as having brown pigmentation on parapodial appendages and dense spot-like pigmentation on the apodous anterior segment; N. goodayi sp. nov. similarly bears two pigmented spots on the dorso-lateral anterior margin of this segment; however, these are relatively small, whereas the spots in Neanthes vitiazi span much of the length of the segment and are placed dorsally, behind the eyes.

The geographically most proximal deep-water species, N. mexicana Fauchald, 1972, described from abyssal waters off Baja California, and N. sandiegensis Fauchald, 1977 from the San Diego Trough (728–855 m), can also be differentiated from N. goodayi sp. nov. Neanthes mexicana was originally described from a single damaged specimen, re-examined and revised by de León-González & Solís- Weiss (2000) with the addition of several nereidids collected from abyssal waters off California USA agreeing with the type specimen. Neanthes mexicana is described as bearing a single pair of very large red eyes, with diffuse pigment spots posterior to the eyes noted to perhaps represent the posterior eye pair (Fauchald 1972). In ABYSSLINE specimens, the appearance of the posterior eye pair was variable, ranging from discrete dark spots to more faint, irregular shapes, occasionally with one or both eyes absent all together, particularly in smaller specimens. The eye morphology of N. mexicana therefore falls within the variation observed in the ABYSSLINE samples. Neanthes mexicana and N. goodayi sp. nov. also share similarities in terms of parapodial morphology, with all parapodial ligules broadly conical to somewhat triangular in shape (see de León-González & Solís-Weiss 2000: fig. 3). However, N. mexicana differs from N. goodayi sp. nov. in terms of palp morphology (long, digitate palpostyles), the arrangement and number of paragnaths (4 cones in areas II and IV versus 12 cones in both areas in N. goodayi sp. nov.,) and in lacking homogomph falcigers.

Neanthes sandiegensis is only known from a single damaged specimen. However, it differs from N. goodayi sp. nov. primarily in terms of parapodial morphology, bearing large, foliose dorsal notopodial ligules with medially inserted, long, flattened digitate dorsal cirri, long digitate prechaetal notopodial lobes and notably elongate ventral neuropodial ligules. Neanthes sandiegensis also differs in terms of the distribution and number of paragnaths on most pharyngeal areas (I = 0, II =2, VI= 6–8, VII–VIII = 35 in N. sandiegensis, I = 2, II = 12, VI = 1–4, VIII–VIII = 19 in the holotype of N. goodayi sp. nov.).

While none of the morphologically most similar or geographically proximal congeners had genetic data available for comparison, morphological differences existed in each case. Neanthes goodayi sp. nov. can be differentiated from other deep-water Neanthes spp. primarily in terms of eye morphology: N. articulata Knox, 1960, N. donggungensis Hsueh, 2019, N. kerguelensis (McIntosh, 1885) and N. suluensis Kirkegaard, 1995 bear two relatively small, subequal eye pairs, whereas N. bioculata (Hartmann-Schröder, 1975) bears a single pair of small eyes; N. abyssorum Hartman 1967, N. kermadeca (Kirkegaard, 1995), N. shinkai Shimabukuro et al., 2017 and N. typhla (Monro, 1930) are recorded as lacking eyes altogether and can be further differentiated from N. goodayi sp. nov. in terms of paragnath distribution, among other characters (see Shimabukuro et al. 2017 for comparative morphological table of most deep water Neanthes spp.).

Ecology

Neanthes goodayi sp. nov. was found at depths ranging from 4000 to 4400 m living in crevices of polymetallic nodules (Fig. 8A–B), burrowing in xenophyophore foraminifera growing on nodules (Fig. 8C–E) or in mud balls on nodule surfaces (Fig. 8F–H). As in other nereidids, the strong eversible jaws, together with large eyes, indicate an active and predatory behaviour. While we were able to observe live, moving specimens kept at cold temperatures even after recovery from 4000 m water depth, behaviours such as predation were not observed. Polymetallic nodules are thought to contain a diverse meiofaunal community of nematodes, copepods and other small crustaceans; thus, it is possible that N. goodayi sp. nov. is a ‘sit and wait’ predator that is able to remain inside the nodules and detect prey passing overhead through extremely small variations in light (from local bioluminescence, detected by the large eyes) or other physio-chemical cues.

Distribution

Eastern Clarion Clipperton Fracture Zone, Central Eastern Pacific.