Research Article |
Corresponding author: Adrian G. Glover ( a.glover@nhm.ac.uk ) Academic editor: Andrew Davinack
© 2022 Lenka Neal, Helena Wiklund, Laetitia M. Gunton, Muriel Rabone, Guadalupe Bribiesca-Contreras, Thomas G. Dahlgren, Adrian G. Glover.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Neal L, Wiklund H, Gunton LM, Rabone M, Bribiesca-Contreras G, Dahlgren TG, Glover AG (2022) Abyssal fauna of polymetallic nodule exploration areas, eastern Clarion-Clipperton Zone, central Pacific Ocean: Amphinomidae and Euphrosinidae (Annelida, Amphinomida). ZooKeys 1137: 33-74. https://doi.org/10.3897/zookeys.1137.86150
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This is a contribution in a series of taxonomic publications on benthic fauna of polymetallic nodule fields in the eastern abyssal Clarion-Clipperton Zone (CCZ). The material was collected during environmental surveys targeting exploration contract areas ‘UK-1’, ‘OMS’ and ‘NORI-D’, as well as an Area of Particular Environmental Interest, ‘APEI-6’. The annelid families Amphinomidae and Euphrosinidae are investigated here. Taxonomic data are presented for six species from 41 CCZ-collected specimens as identified by a combination of morphological and genetic approaches; of the six species, three are here described as new, one species is likely to be new but in too poor condition to be formalised and the two others likely belong to known species. Description of three new species Euphrosinella georgievae sp. nov., Euphrosinopsis ahearni sp. nov., and Euphrosinopsis halli sp. nov. increases the number of formally described new annelid species from the targeted areas to 21 and CCZ-wide to 52. Molecular data suggest that four of the species reported here are known from CCZ only, but within CCZ they have a wide distribution. In contrast, the species identified as Bathychloeia cf. sibogae Horst, 1910 was found to have a wide distribution within the Pacific based on both morphological and molecular data, using comparative material from the abyssal South Pacific. Bathychloeia cf. balloniformis Böggemann, 2009 was found to be restricted to APEI-6 based on DNA data available from CCZ specimens only, but morphological data from other locations suggest potentially a wide abyssal distribution. The genus Euphrosinopsis was previously known only from Antarctic waters, and Euphrosinella georgievae sp. nov. was recovered as a sister taxon to the Antarctic specimens of Euphrosinella cf. cirratoformis in our molecular phylogenetic analysis, strengthening the hypothesised link between the deep-sea and Antarctic benthic fauna.
Amphinomida, CCZ, COI, deep-sea mining, molecular phylogeny, species distribution, taxonomic novelty, 18S, 16S
The Clarion-Clipperton Zone (CCZ) polymetallic nodule region, a vast area (ca. 6 million km2) of the central abyssal Pacific, has been explored in recent decades for its deep-sea mineral resources and their potential for commercial mining (e.g.,
The knowledge of the biodiversity and distribution of benthic taxa found within areas of potential mining operations is paramount to informed environmental impact assessments and conservation efforts (
Our main objective has been to provide taxonomic hypotheses on macrofaunal annelids collected from the targeted areas within the CCZ based on morphology and molecular data. These data build up on previous taxonomic work on annelids from the target areas (
Annelids of order Amphinomida are commonly known as fire worms due to the skin burning sensation upon contact with their chaetae caused by a complex mixture of defensive toxins (
In terms of their systematics, Amphinomida were regarded as part of the Errantia (e.g.,
The first UKSR ABYSSLINE cruise (AB01) took place in October 2013 onboard the RV ‘Melville’ and targeted the UK-1 exploration contract area (Fig.
For a comprehensive description of the methodological pipeline, see
In the laboratory, preserved specimens were re-examined using stereo and compound microscopes. They were identified to morphospecies, and the best-preserved examples (voucher specimens) were then used to provide informal descriptions with key morphological features photographed with digital camera. Shirlastain A was used during the morphological examination on some specimens, in order to better observe certain characters. Scanning electron microscopy (SEM) using a SEM FEI Quanta 650 was conducted on selected specimens, following graded ethanol dehydration, critical point drying, and gold coating. Figures were assembled using Adobe Photoshop CS6 software. In some instances, a fine line was used to outline and highlight particular morphological features where such features were unclear from images alone. Line drawings were made using camera lucida system.
Additionally, Amphinomidae specimens recently collected from the abyssal South Pacific (ca. 4000 m) as part of the RV ‘Investigator’ voyage ‘Sampling the Abyss’ were made available for examination (see also
Extraction of DNA was done with DNeasy Blood and Tissue Kit (Qiagen) using a Hamilton Microlab STAR Robotic Workstation. Approximately 1800 bp of 18S were amplified using the primers 18SA 5’-AYCTGGTTGATCCTGCCAGT-3’(
Molecular data were used to place species covered in this study within the Amphinomida phylogenetic relationships. The phylogenetic analyses were done in two parts, producing one tree for Euphrosinidae with a taxon from Amphinomidae as root, and one for Amphinomidae with a taxon from Euphrosinidae as root. Sequences added from GenBank are listed in Supplementary data with taxon names and sequence accession numbers. The program jModelTest (
Here we use a phylogenetic species concept sensu
List of taxa presented in this paper – family, DNA taxonomy ID (a species-level identification based on combined DNA and morphological evidence), cruise record number, GUID (Global Unique Identifier link to data record at http://data.nhm.ac.uk),
DNA taxonomy ID | NHM no. | GUID | Reg no. |
MCf no. | COI AK no. | 16S AK no. | 18S AK no. |
---|---|---|---|---|---|---|---|
Family Amphinomidae | |||||||
Bathychloeia cf. balloniformis | NHM_2107 | c79b4600-e8e9-4484-b06a-e18330a1421d | ANEA 2022.630 | 0118302190 |
ON903198 |
ON900088 | ON905671 |
Bathychloeia cf. balloniformis | NHM_2109 | ac3dd714-64ac-44ea-9168-22437dc3cfba | ANEA 2022.631 | 0118302189 | ON900113 | ||
Bathychloeia cf. sibogae juvenile | NHM_6880_HW01 | 06f82805-e608-4715-af62-ab1d44df2a79 | ANEA 2022.632 | 0118302159 | ON903200 | ON900089 | |
Bathychloeia cf. sibogae | NHM_0821 | 73a7200a-ae19-4c0c-8381-8d4509a318cf | ANEA 2022.633 | 0118302202 | ON903197 | ON900100 | ON905670 |
Bathychloeia cf. sibogae | NHM_2906 | d3848fcf-4cb2-49fd-b49c-e09422419a70 | ANEA 2022.634 | 0118302177 | ON900116 | ||
Bathychloeia cf. sibogae juvenile | NHM_2115 | 2cbc0d92-247c-4197-bd7a-4715adb5e8f4 | ANEA 2022.635 | 0118302188 | ON900114 | ||
Bathychloeia cf. sibogae | NHM_3539 | 083df63d-60e7-48ae-95c4-6a11a61b01e8 | ANEA 2022.636 | 0118302158 | ON903199 | ON900118 | |
Bathychloeia cf. sibogae | NHM_8922 | 805f34aa-ec4f-4318-b18b-46447350aa1e | ANEA 2022.637 | 0118302156 | ON903201 | ||
Paramphinome sp. NHM_6022E | NHM_1167D | fd4902df-aef2-44cf-991f-31905434c2a1 | ANEA 2022.638 | ||||
Paramphinome sp. NHM_6022E | NHM_4044 | 56235559-3f2c-426e-b4cd-37462593a4ba | ANEA 2022.639 | 0118302160 | |||
Paramphinome sp. NHM_6022E | NHM_6022E | bd4b405d-3e56-4671-909e-fdf9c3e7fbcf | ANEA 2022.640 | 0118302162 | ON900125 | ON905673 | |
Family Euphrosinidae | |||||||
Euphrosinopsis halli sp. nov. | NHM_0779 | 1a683870-d904-4c2c-bf1a-a34ead0a42fc | ANEA 2022.641 | 0118302182 | ON900099 | ||
Euphrosinopsis halli sp. nov. | NHM_4339 (holotype) | 670dfd34-338d-4edc-8856-b0a9a728efc9 | ANEA 2022.642 | 0118302157 | ON900119 | ON905672 | |
Euphrosinopsis halli sp. nov. | NHM_6018 (paratype) | ab26e2ea-ab87-4013-8106-e817c0485cc9 | ANEA 2022.643 | 0118302167 | ON900124 | ||
Euphrosinopsis ahearni sp. nov. | NHM_0095 | a351cb41-736c-4390-8ad8-02c0358b73e0 | ANEA 2022.644 | 0118302201 | ON900092 | ON905668 | |
Euphrosinopsis ahearni sp. nov. | NHM_0888 | 4d76b4e2-569d-4a17-9276-3ce721cbdf72 | ANEA 2022.645 | 0118302187 | ON900101 | ||
Euphrosinopsis ahearni sp. nov | NHM_0551 (paratype, SEM) | 241b828d-a574-47f2-995d-0bdef239c427 | ANEA 2022.646 | 0118302186 | ON900094 | ||
Euphrosinopsis ahearni sp. nov | NHM_5042 | 1662fd8b-54a5-4f97-9083-02dbb2df7e39 | ANEA 2022.647 | 0118302178 | ON900121 | ||
Euphrosinopsis ahearni sp. nov. | NHM_1737A | 4f372c07-c466-4b6c-91a9-229cd7c7a17d | ANEA 2022.648 | 0118302171 | ON900107 | ||
Euphrosinopsis ahearni sp. nov. | NHM_1876 | 6ad5c2b3-ece8-4195-a19f-3913de511e71 | ANEA 2022.649 | 0118302175 | ON900112 | ||
Euphrosinopsis ahearni sp. nov. | NHM_0550 | 92791783-35c2-4fbf-80b0-2b074ef70828 | ANEA 2022.650 | 0118302203 | ON900093 | ||
Euphrosinopsis ahearni sp. nov. | NHM_1302 | 7aabe644-2ec6-4671-8c1a-f826eeeb0b46 | ANEA 2022.651 | 0118302168 | ON900105 | ||
Euphrosinopsis ahearni sp. nov. | NHM_1302A (holotype) | 479933d3-9943-4d87-a1b8-ea120bd8f4ee | ANEA 2022.652 | 0118302169 | ON900104 | ||
Euphrosinopsis ahearni sp. nov. | NHM_1737 | 2ca3e584-a68d-4ea5-98d2-75ce10515386 | ANEA 2022.653 | 0118302173 | ON900110 | ||
Euphrosinopsis ahearni sp. nov. | NHM_1737C (paratype) | efe95a8c-fc88-4849-ad26-1df3d292ef20 | ANEA 2022.654 | 0118302172 | ON900109 | ||
Euphrosinopsis ahearni sp. nov. | NHM_ 0616 | 4758bf19-c6d0-42e0-b5ba-e83e203d2e18 | ANEA 2022.655 | 0118302185 | ON900096 | ||
Euphrosinopsis ahearni sp. nov. | NHM_0759 | b0f9162f-a861-4eb2-89a1-ce25c2bd09c4 | ANEA 2022.656 | 0118302184 | ON900097 | ||
Euphrosinopsis ahearni sp. nov. | NHM_1839 | 02a5ace7-841e-4f50-bf03-57ba21f02f7c | ANEA 2022.657 | 0118302174 | ON900111 | ||
Euphrosinella georgievae sp. nov. | NHM_0587 | b7a0bf33-0dc4-4f61-90de-35865647a99f | ANEA 2022.658 | 0118302191 | ON900095 | ON905669 | |
Euphrosinella georgievae sp. nov. | NHM_0777 | a8f0e776-d7b6-4ec6-a549-78f40f17d89b | ANEA 2022.659 | 0118302183 | ON900098 | ||
Euphrosinella georgievae sp. nov. | NHM_1737B | 2784df45-eec0-4151-b12d-11d955985faa | ANEA 2022.660 | ON900108 | |||
Euphrosinella georgievae sp. nov. | NHM_0910 | 05dfb32c-fc3a-4028-bf09-3eb840175661 | ANEA 2022.661 | 0118302181 | ON900102 | ||
Euphrosinella georgievae sp. nov. | NHM_1134 (paratype) | 00590d2b-f952-4c69-8bc2-ac2a408da17a | ANEA 2022.662 | 0118302180 | ON900103 | ||
Euphrosinella georgievae sp. nov. | NHM_1514 | 96cb7b69-c0ea-4559-9b57-3abe6af4a4c7 | ANEA 2022.663 | 0118302170 | ON900106 | ||
Euphrosinella georgievae sp. nov. | NHM_2391 (holotype) | 1ce8325f-74de-47de-a776-2dc50b8d69ae | ANEA 2022.664 | 0118302176 | ON900115 | ||
Euphrosinella georgievae sp. nov. | NHM_4975 | 677b7d67-d9cc-4ebd-8d79-cf5da5dc40da | ANEA 2022.665 | 0118302165 | ON900120 | ||
Euphrosinella georgievae sp. nov. | NHM_6087 | eebfaecd-5ee2-49d6-be73-51eb91678487 | ANEA 2022.666 | 0118302166 | ON900126 | ||
Euphrosinella georgievae sp. nov. | NHM_5802 | c0e408e3-91e7-408f-aaef-3be86507105a | ANEA 2022.667 | 0118302164 | ON900123 | ||
Euphrosinella georgievae sp. nov. | NHM_5057 | d92b1574-eccb-443c-a15d-b79357360b59 | ANEA 2022.668 | 0118302179 | ON900122 | ||
Euphrosinella georgievae sp. nov. | NHM_7235 | 55637dc0-f9b9-4586-9bfb-7a821c785279 | ANEA 2022.669 | 0118302163 | ON900127 | ||
Euphrosinella georgievae sp. nov. | NHM_2908 | fba3fab7-ae4b-4415-a73c-a2ba6cd44601 | ANEA 2022.670 | 0118302161 | ON900117 |
The field and laboratory work led to a series of databases and sample sets that were integrated into a ‘data-management pipeline’. This included the transfer and management of data and samples between a central collections database, a molecular collections database and external repositories (GenBank, WoRMS, OBIS, GBIF, GGBN, ZooBank) through DarwinCore archives (Suppl. material
Amphinomidae Lamarck, 1818
Bathychloeia sibogae Horst, 1910.
(modified from
As the name Bathychloeia suggests, this genus was established for deep-water representatives similar to forms in predominantly shallow water genus Chloeia Lamarck, 1818. Chloeia was established by
NHM_2107,
Amphinomidae spp.; AM. W.52607; 3 specimens; IN2017; sta. V03_110; 4005 m; South Pacific, Australia, off Fraser Island (-25.220, 154.160); col. 11/06/2017; EBS.
This very small species is represented by two specimens, up to 2.9 mm long and 0.75 mm wide for ten chaetigers. Body compact, spindle-shaped, of bloated appearance (Figs
Bathychloeia cf. balloniformis (specimen,
Bathychloeia cf. balloniformis (specimen
Prostomium rounded, longer than wide; anterior lobe broadly rounded, bearing a pair of cirriform lateral antennae (Figs
Parapodia biramous. Parapodial appendages often broken off, where attached dorsal, lateral and ventral cirri observed, including on chaetiger 1 (Fig.
Specimen,
Majority-rule consensus trees from the Bayesian analyses with posterior probability values on nodes. Taxon names highlighted in blue are news species or new sequences for already known species. A Amphinomidae phylogenetic tree using a combined datasets for COI, 16S, and 18S with 26 terminal taxa of which Euphrosine foliosa (Euphrosinidae) was used as a root B Euphrosinidae phylogenetic tree using a combined datasets for 16S and 18S with nine terminal taxa of which Paramphinome jeffreysii (Amphinomidae) was used as a root.
The CCZ-collected specimens correspond morphologically to another abyssal species Bathychloeia balloniformis Böggemann, 2009 described from Cape and Guinea Basins in SE Atlantic, 5048–5144 m depth. The specimens agree in small, spindle-shaped body, having ca. 10 chaetigers, the form of greatly folded and crenulated caruncle and the form and distribution of branchiae (see comparative Fig.
Central Pacific Ocean, Eastern CCZ, in the Area of Particular Environmental Interest, ‘APEI-6’ only (Fig.
NHM_6880HW,
Bathychloeia cf. sibogae;
Body size variable, up to 18 mm long and 6 mm wide for larger specimens with 15 or 16 chaetigers (Figs
Bathychloeia cf. sibogae (specimen
Bathychloeia cf. sibogae (specimen
Bathychloeia cf. sibogae CCZ-collected specimens A large live specimen (
Prostomium indistinctly divided into an anterior and a posterior lobe; tightly surrounded by reduced first chaetigerous segment. Anterior lobe rounded, bearing a pair of lateral cirriform antennae plus a pair of slightly shorter ventrolateral palps. Posterior lobe bell-shaped, ca. as long as wide. One pair of tiny red eyes present (Fig.
Parapodia biramous with distinctly separated rami, bearing cirri that are easily detached. Dorsal and lateral cirri slender, filiform, and long, present in notopodia; dorsal cirrus inserted dorsolaterally to notochaetae, lateral cirrus, inserted medially behind notopodial chaetae. Ventral cirri also filiform and elongated (particularly in chaetiger 1, Fig.
Notopodia with chaetae much larger and usually thicker than those of neuropodia, almost forming a “cage” over dorsum, obscuring the branchiae in some specimens, but very fragile and easily lost in most specimens, best preserved in juvenile specimens (Fig.
Bathychloeia cf. sibogae (specimen
Molecular analysis suggests that smaller and larger specimens that differ predominantly in the form of caruncle and form of branchiae as described above, represent the same species. Therefore, the size difference likely represents different developmental changes.
Only one CCZ specimen of B. cf. sibogae, specimen
The enlarged branchiae of chaetiger 5 suggest close affiliation of CCZ specimens to Bathychloeia sibogae Horst, 1910 described from the Banda Sea, depth of 1100 m. Since its original description and subsequent re-description (
Although the original definition of B. sibogae given by
Comparative figure of form of enlarged branchiae from chaetiger 5 showing variation in development of long branchial filaments, Ms – Main stalk, Lb – lateral branches, Lf – long filaments A Bathychloeia cf. sibogae CCZ specimen,
Central Pacific Ocean, Eastern CCZ, in the exploration areas UK-1, OMS, NORI-D (Fig.
It is of interest that a closely related form to the CCZ species known as Cholenopsis atlantica (McIntosh, 1885) has been described in association with a sponge growing on a dead coral coated with manganese of peroxide (
Paramphinome pulchella M. Sars in G. Sars, 1872.
Small but long long-bodied forms. Prostomium posteriorly with Y-shaped or elongated caruncle. Branchiae comb-shaped, limited to the anterior chaetigers. First chaetiger with curved hooks in notopodia.
NHM_1167D,
(after
Paramphinome sp. NHM_6022E (specimen,
Parapodia biramous. Dorsal cirri small and ovoid (Fig.
Only one specimen,
Three very small posteriorly incomplete specimens were collected in CCZ samples. They differ from known species by its very small size and low number of branchial pairs (only two pairs) and undeveloped prostomial appendages, which are tiny and globular. While body size, number of segments and number of branchial pairs were previously linked to developmental stages (e.g.,
Of the known deep-sea Paramphinome species, none were described from the abyssal depths. Paramphinome pacifica Fauchald & Hancock, 1981 has been described from NE Pacific Ocean: off central Oregon (USA), 1800–2900 m; (type locality: Cascadia Abyssal Plain, 2860 m). Paramphinome australis Monro, 1930 has type locality off Signy Island, South Orkney Islands, Southern Ocean in depths between 244–344 m, although it has been widely reported from the Southern Ocean (
It is likely that the CCZ-collected specimens represent a new species; however, their tiny size and poor morphological preservation prevent its formal description, therefore the specimens are assigned to morphospecies only.
Central Pacific Ocean, Eastern CCZ, the exploration contract areas UK-1, OMS, and NORI-D (Fig.
Euphrosine cirratoformis Averincev, 1972.
(modified from
Genus Euphrosinella was established by
NHM_0587,
Holotype
(
Euphrosinella georgievae sp. nov. (holotype,
Euphrosinella georgievae sp. nov. (paratype
Parapodia biramous, two rami well separated. Parapodia of chaetiger 1 well developed, not reduced, with dorsal, lateral, and ventral cirri (Fig.
Diagrammatic representation of prostomial (A–C) and parapodial appendages from mid-body chaetigers (D, E) of CCZ-collected Euphrosinidae species (relative lengths preserved, but not drawn to scale) A Euphrosinella georgievae sp. nov. B Euphrosinopsis ahearni sp. nov. C Euphrosinopsis halli sp. nov. D Euphrosinella georgievae sp. nov. E Euphrosinopsis ahearni sp. nov. F Euphrosinopsis halli sp. nov. Abbreviations: P – palps, La – lateral antennae, Ma – median antenna, Car – caruncle, E – eyes, DC – dorsal cirrus, LC – lateral cirrus, VC – ventral cirrus, Br – branchiae.
All chaetae well developed, but prone to breakage, all bifurcate (Fig.
Euphrosinella georgievae sp. nov. (specimen
One specimen,
Euphrosinella georgievae sp. nov. is consistent with the genus Euphrosinella in having five prostomial appendages, caruncle mostly free from body wall and absence of ringent chaetae. Only two valid species in Euphrosinella are currently known as mentioned earlier. A known Pacific species Euphrosinella paucibranchiata can be distinguished by having some branchiae branched, as well as much shallower depth distribution of 1737 m in Santa Cruz Basin. Euphrosinella georgievae sp. nov. is more similar to the Antarctic species E. cirratoformis in having simple unbranched branchiae. The species also share a similar form and length of caruncle and median antenna. However, the two species differ in the following characters: 1. The presence of two pairs of eyes in the Antarctic species, while CCZ specimens are eyeless; 2. Notochaetae arranged in 3 tiers in new species, rather than 2 tiers in the known species and 3. Branchiae are not developed on first chaetiger in E. georgievae sp. nov., whilst they are present in E. cirratoformis. As further evidence, the molecular data suggest that Antarctic specimens identified in a previous study as Euphrosinella cf. cirratoformis (see
Central Pacific Ocean, Eastern CCZ, the exploration areas UK-1, OMS, and NORI-D (Fig.
This species is named for Dr. Magdalena Georgieva, who took part in ABYSSLINE expeditions to CCZ. She also collected Bathychloeia cf. sibogae specimens from CCZ used in this study as well as samples from the South Pacific during the RV Investigator cruise used here as a comparative material.
Euphrosinopsis antipoda Kudenov, 1993.
(after
The genus Euphrosinopsis is currently endemic to Antarctica and has been established to accommodate three known Antarctic species (
NHM_0095,
NHM_1737C (paratype),
Holotype
(
Euphrosinopsis ahearni sp. nov. (holotype
Parapodia biramous, two rami well separated. Parapodia of chaetiger 1 well developed, not reduced, parapodial cirri, branchiae or ringent chaetae not observed. In subsequent parapodia, parapodial appendages in the following dorsoventral order: dorsal cirrus, 1st branchia, lateral cirrus, 2nd branchia, ventral cirrus (Fig.
Euphrosinopsis ahearni sp. nov. (paratype
Chaetae fragile, prone to breakage, of two main types: 1. Numerous, bifurcate chaetae arranged in three rows in notopodia; their shafts of various length and thickness (Fig.
Euphrosinopsis ahearni sp. nov. (paratype
Specimen (
The CCZ species agrees well with the genus Euphrosinopsis in having five prostomial appendages, caruncle partially free from the body wall and the presence of large, deeply embedded eyes lateral to median antenna and caruncle. However, this species shows differences from all known species in this genus, suggesting it belongs to a new species. Euphrosinopsis crassiseta (type locality: Weddell Sea, 3697 m) can be easily distinguished by having only small, cirriform branchia per segment rather than two pairs of branched branchiae, by the absence of ringent chaetae and presence of coarsely serrated neurochaetae. Euphrosinopsis horsti (type locality: Pacific Antarctic Ridge, 3219–3255 m) also has only one very small, cirriform branchia per segment. Ringent chaetae are present in the known species, but they possess a distal tooth in the gap, which is absent in the new species. Finally, the most similar species, Euphrosinopsis antarctica can be distinguished by having up to three branchiae per segment, the first branched, but the others cirriform and style of median antenna of similar length to caruncle, rather than much longer as in the new species.
Thus, Euphrosinopsis ahearni sp. nov. can be distinguished mainly by having two pairs of branched branchiae in midbody chaetigers, both with very long thin branches. That is also the main distinguishing character from its congener from the CCZ, E. halli sp. nov. also described in this study, which possess only single cirriform branchia in each parapodium. Both new species possess ringent notochaetae, that can be distinguished as follow: 1. They are numerous (ca. 20 per notopodium) and easily observed in E. ahearni sp. nov., whilst only few (ca. 5 per notopodium) can be found in E. halli sp. nov.; 2. The serration of inner margin is more pronounced in E. ahearni sp. nov. and 3. The distal tip is shorter and stubbier in E. ahearni sp. nov. Further, the caruncle is more developed in E. ahearni sp. nov. reaching to chaetiger four, not two as in E. halli sp. nov., and style of median antenna is much longer than caruncle in the former species, whilst they are ca. the same length in the latter.
Central Pacific Ocean, Eastern CCZ, the exploration areas UK-1, OMS, and NORI-D (Fig.
This species is named for Patrick A’Hearn, technician from the University of Washington onboard the RV Thomas G Thompson.
NHM_0779,
Holotype
(
Euphrosinopsis halli sp. nov. A preserved holotype
Parapodia biramous, two rami well separated. With parapodial appendages observed dorso-ventrally as follow (Figs
Chaetae fragile, prone to breakage, of two main types: 1. Numerous, bifurcate chaetae arranged in approximately three rows in notopodia; their shafts of various length and thickness (Fig.
Euphrosinopsis halli sp. nov. (holotype
Specimen
CCZ species agrees well with the genus Euphrosinopsis in having five prostomial appendages, caruncle partially free from the body wall and the presence of large, deeply embedded eyes lateral to median antenna and caruncle. However, this species shows differences from all known species in this genus, suggesting it belongs to a new species. The presence of single, small, unbranched cirriform branchia per parapodium suggest affiliation with E. crassiseta and E. horsti, which share the same character. However, the new species differs from E. crassiseta in possessing the ringent chaetae and lacking the coarse serration on neurochaetae. The most similar species, E. horsti can be easily separated by having anal cirri fused instead of typical cylindrical tube feet as in the new species. For comparison with another new Euphrosinopsis species also described in this study see the remarks section for E. ahearni sp. nov.
Central Pacific Ocean, Eastern CCZ, the exploration areas UK-1 and NORI-D (Fig.
This species is named for Preben Hall, the captain onboard the ship Maersk Launcher that was used in NORI-D expeditions in 2020 and 2021.
This study has added six annelid species, three of those formally described and one likely new, and 41 records to the knowledge of the benthic annelid macrofauna of the CCZ, bringing a published record from the targeted areas (Fig.
Unlike other annelid taxa, each Amphinomida species is represented by several specimens (no singletons), most with wide CCZ-distribution. More importantly molecular data confirmed a wide abyssal distribution for one species identified as Bathychloeia cf. sibogae. This species has been found in CCZ (Central Pacific) and off Australia (South Pacific) with the sampling sites separated by the distance of ca. 7500 km. However, both sampling areas were at similar depths of ca. 4000 m, providing further evidence that genetic connectivity over large geographic areas is more likely to be maintained at similar depths (
Molecular phylogeny of the family Euphrosinidae has not been undertaken hitherto, as the number of taxa available on GenBank is very low. The difficulties of getting COI from members of Euphrosinidae further complicates the analyses, and more data (both in terms of number of genetic markers and taxa,) is needed to resolve the relationships within this family. Our phylogenetic results (Fig.
The phylogenetic analyses of the family Amphinomidae resulted in a tree similar to that of
To summarise, the number of DNA sequences for benthic faunal groups from the CCZ available on GenBank are growing, representing echinoderms (e.g.
We thank the masters, crew, and technical staff on the RV ‘Melville’, RV ‘Thomas G Thompson’, M/V #Pacific Constructor’, and Maersk Launcher for their outstanding support. We acknowledge the expert leadership of the research cruises and ABYSSLINE project by Prof Craig R Smith, University of Hawaii. We received help sorting and sieving samples at sea from science teams in successful deep-sea coring operations on all cruises. Joke Bleeker communicated information about type material held at Naturalis Biodiversity Centre, Leiden. We would also like thank Eva Stewart for providing the map in Fig.
DarwinCore database of CCZ Amphinomida
Data type: excel file
Explanation note: DarwinCore database.