Phylogenetic analyses elucidate the identity and distribution of two early-described species of Arctic Cirratulidae (Annelida, Sedentaria)
Abstract
Recent expeditions to the North-East Atlantic and the Arctic Ocean yielded an abundance of specimens resembling two species of polychaetes of the family Cirratulidae Ryckholt, 1851 originally described in 1879 and tentatively placed within the genus Cirratulus Lamarck, 1818. In this study, we set out to confirm their identity, assess the potential presence of cryptic species, determine their correct generic placement, and gain insights into their distributions. Our approach involved comprehensive analyses using four molecular markers (COI, 16S, 28S, and 18S) through Bayesian inference, maximum likelihood analyses, and haplotype networks. Additionally, we conducted detailed morphological examinations of the specimens using both light and electron microscopy techniques. Notably, this study provides the first DNA sequences for a species within the genus Chaetocirratulus Blake, 2018. By integrating molecular phylogenetic analyses with morphological assessments, we establish the revised taxonomic placements of these two species as Chaetocirratulus abranchiatus (Hansen, 1879) comb. nov. and Aphelochaeta abyssorum (Hansen, 1879) comb. nov. Phylogenetic analyses also recover a close relationship between Chaetocirratulus, Cirratulus and Cirriformia. Furthermore, our research reveals the wide distribution of these species in the North-East Atlantic and Arctic waters, marking the first report of Chaetocirratulus in this region. We present re-descriptions of these species according to contemporary taxonomic standards, complemented by extensive illustrations. A lectotype is selected for Chaetocirratulus abranchiatus and a neotype is selected for Aphelochaeta abyssorum.
References
Barraclough T.G. 2019. The Evolutionary Biology of Species. Oxford University Press, Oxford, UK. https://doi.org/10.1093/oso/9780198749745.001.0001
Blake J.A. 1991. Revision of some genera and species of Cirratulidae (Polychaeta) from the Western North Atlantic. Ophelia Supplement 5: 17–30. https://doi.org/10.1163/9789004629745_005
Blake J.A. 2018. Bitentaculate Cirratulidae (Annelida, Polychaeta) collected chiefly during cruises of the R/V Anton Bruun, USNS Eltanin, USCG Glacier, R/V Hero, RVIB Nathaniel B. Palmer, and R/V Polarstern from the Southern Ocean, Antarctica, and off Western South America. Zootaxa 4537 (1): 1–130. https://doi.org/10.11646/zootaxa.4537.1.1
Blake J.A. 2019. New species of Cirratulidae (Annelida, Polychaeta) from abyssal depths of the Clarion-Clipperton Fracture Zone, North Equatorial Pacific Ocean. Zootaxa 4629 (2): 151–187. https://doi.org/10.11646/zootaxa.4629.2.1
Blake J.A. 2022. New species and records of Caulleriella, Chaetocirratulus and Chaetozone (Annelida, Cirratulidae) from continental shelf and slope depths of the Western North Atlantic Ocean. Zootaxa 5113 (1): 1–89. https://doi.org/10.11646/zootaxa.5113.1.1
Blake J.A. 2023. New species of Cirratulidae (Annelida) from continental slope and abyssal depths off eastern Australia. In: Kupriyanova E.K. & Gunton L.M. (eds) RV Investigator—Abyssal Annelida. Records of the Australian Museum 75 (3): 249–270. https://doi.org/10.3853/j.2201-4349.75.2023.1799
Blake J.A. & Dean H.K. 2019. New species of Cirratulidae (Annelida, Polychaeta) from the Caribbean Sea. Zootaxa 4671(3): 301–338. https://doi.org/10.11646/zootaxa.4671.3.1
Bouckaert R., Vaughan T.G., Barido-Sottani J., Duchêne S., Fourment M., Gavryushkina A., Heled J., Jones G., Kühnert D., De Maio N., Matschiner M., Mendes F.K., Müller N.F., Ogilvie H.A., du Plessis L., Popinga A., Rambaut A., Rasmussen D., Siveroni I., … & Drummond F.J. 2019. BEAST 2.5: An advanced software platform for Bayesian evolutionary analysis. PLoS Computational Biology 15 (4): e1006650. https://doi.org/10.1371/journal.pcbi.1006650
Brix S., Meissner K., Stransky B., Halanych K., Jennings R.M. & Svavarsson J. 2014. The IceAGE project — a follow up of BIOICE. Polish Polar Research 35 (2): 141–150.
Carr C.M., Hardy S.M., Brown T.M., Macdonald T.A. & Hebert P.D.N. 2011. A tri-oceanic perspective: DNA barcoding reveals geographic structure and cryptic diversity in Canadian polychaetes. PloS ONE 6: e22232. https://doi.org/10.1371/journal.pone.0022232
Clement M., Snell Q., Walke P., Posada D. & Crandall K. 2002. TCS: estimating gene genealogies. Proceedings 16th International Parallel and Distributed Processing Symposium 2: 184. https://doi.org/10.1109/IPDPS.2002.1016585
Costello M.J., Tsai P., Wong P.S., Cheung A.K.L., Basher Z. & Chaudhary C. 2017. Marine biogeographic realms and species endemicity. Nature Communications 8: 1057. https://doi.org/10.1038/s41467-017-01121-2
Dean H.K. & Blake J.A. 2016. Aphelochaeta (Polychaeta: Cirratulidae) from the Pacific coast of Costa Rica, with a description of five new species. Zootaxa 4103 (2): 101–116. https://doi.org/10.11646/zootaxa.4103.2.1
Douglas J., Jiménez-Silva C.L. & Bouckaert R. 2022. StarBeast3: Adaptive parallelized Bayesian inference under the multispecies coalescent. Systematic Biology 71 (4): 901–916. https://doi.org/10.1093/sysbio/syac010
Edgard R.C. 2004. MUSCLE: Multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Research 32 (5): 1792–1799. https://doi.org/10.1093/nar/gkh340
Elías R. & Rivero M.R. 2009 Two new species of Cirratulidae (Annelida: Polychaeta) from Mar del Plata, Argentina (SW Atlantic). Zoosymposia 2: 139–148. https://doi.org/10.11646/zoosymposia.2.1.12
Folmer O., Black M., Hoeh W., Lutz R. & Vrijenhoek R. 1994. DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Molecular Marine Biology and Biotechnology 3: 294–299.
Geller J., Meyer C., Parker M. & Hawk H. 2013. Redesign of PCR primers for mitochondrial cytochrome c oxydase subunit I for marine invertebrates and application in all-taxa biotic surveys. Molecular Ecology Ressources 13: 851–861. https://doi.org/10.1111/1755-0998.12138
Grosse M., Bakken T., Nygren A., Kongsrud J.A. & Capa M. 2020. Species delimitation analyses of NE Atlantic Chaetozone (Annelida, Cirratulidae) reveals hidden diversity among a common and abundant marine annelid. Molecular Phylogenetics and Evolution 149: 106852. https://doi.org/10.1016/j.ympev.2020.106852
Guggolz T., Meissner K., Dahlgren T., Wiklund H., Bonifacio P. & Brandt A. 2020. High diversity and pan-oceanic distribution of deep-sea polychaetes: Prionospio and Aurospio (Annelida: Spionidae) in the Atlantic and Pacific Ocean. Organisms Diversity and Evolution 20: 171–187. https://doi.org/10.1007/s13127-020-00430-7
Hansen G.A. 1879. Annelider fra den norske Nordhavsexpedition i 1876. Nyt Magazin for Naturvidenskaberne 24 (1): 1–17. Available from https://www.biodiversitylibrary.org/page/9491620 [accessed 25 Mar. 2025].
Hansen G.A. 1882. Annelida. In: The Norwegian North Atlantic Expedition 1876–1878 Part 7: 1–53. Grøndahl & Søn, Christiania. https://doi.org/10.5962/bhl.title.2168
Hartman O. 1959. Catalogue of the polychaetous annelids of the world. Allan Hancock Foundation Occasional Paper 23: 1–628.
Hebert P.D.N., Cywinska A., Ball S.L. & deWaard J.R. 2003a. Biological identifications through DNA barcodes. Proceedings of the Royal Society, London B 270: 313–321. https://doi.org/10.1098/rspb.2002.2218
Hebert P.D.N., Ratnasingham S. & deWaard J.R. 2003b. Barcoding animal life: Cytochrome c oxydase subunit 1 divergences among closely related species. Proceedings of the Royal Society, London B 270: S96–S99. https://doi.org/10.1098/rsbl.2003.0025
Hoang D.T., Chernomor O., von Haeseler A., Minh B.Q. & Vinh L.S. 2018. UFBoot2: Improving the Ultrafast Bootstrap approximation. Molecular Biology and Evolution 35 (2): 518–522. https://doi.org/10.1093/molbev/msx281
Kalyaanamoorthy S., Minh B.Q., Wong T.K.F., von Haeseler A. & Jermiin L.S. 2017. ModelFinder: Fast model selection for accurate phylogenetic estimates. Nature Methods 14: 587–589. https://doi.org/10.1038/nmeth.4285
Katoh K., Rozewicki J. & Yamada K.D. 2017. MAFFT online service: multiple sequence alignment, interactive sequence choice and visualization. Briefings in Bioinformatics 20 (4): 1160–1166. https://doi.org/10.1093/bib/bbx108
Larsson A. 2014. AliView: A fast and lightweight alignment viewer and editor for large datasets. Bioinformatics 30 (22): 3276–3278. https://doi.org/10.1093/bioinformatics/btu531
Le H.L.V., Lecointre G. & Perasso R. 1993. A 28S rRNA-based phylogeny of the gnathostomes: First steps in the analysis of conflict and congruences with morphologically based cladograms. Molecular Phylogenetics and Evolution 2 (1): 31–51. https://doi.org/10.1006/mpev.1993.1005
Leigh J.W. & Bryant D. 2015. PopART: Full-feature software for haplotype network construction. Methods in Ecology and Evolution 6 (9): 1110–1116. https://doi.org/10.1111/2041-210x.12410
Leutunic I. & Bork P. 2021. Interactive Tree Of Life (iTOL) v5: An online tool for phylogenetic tree display and annotation. Nucleic Acids Research 49 (1): 293–296. https://doi.org/10.1093/nar/gkab301
Macke A. & Flores H. 2018. The Expeditions PS106/1 and 2 of the Research Vessel POLARSTERN to the Arctic Ocean in 2017. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany. https://doi.org/10.2312/BzPM_0719_2018
Magalhães W.F., Linse K. & Wiklund H. 2017. A new species of Raricirrus (Annelida: Cirratuliformia) from deep-water sunken wood off California. Zootaxa 4353 (1): 51–68. https://doi.org/10.11646/zootaxa.4353.1.3
Medlin L., Elwood H.J., Stickel S. & Sogin M.L. 1998. The characterization of enzymatically amplified eukaryotic 16S-like rRNA-coding regions. Gene 71 (2): 491–499. https://doi.org/10.1016/0378-1119(88)90066-2
Meissner K., Schwenter M., Götting M., Knebelsberger T. & Fiege D. 2023. Polychaetes distributed across oceans — examples of widely recorded species from abyssal depths of the Atlantic and Pacific Oceans. Zoological Journal of the Linnean Society 199 (4): 906–944. https://doi.org/10.1093/zoolinnean/zlad069.
Miller M.A., Pfeiffer W. & Schwartz T. 2010. Creating the CIPRES Science Gateway for inference of large phylogenetic trees. Proceedings of the Gateway Computing Environments Workshop (GCE), 14 Nov. 2010, New Orleans, LA: 1–8. https://doi.org/10.1109/GCE.2010.5676129
Minh B.Q., Schmidt H.K., Chernomor O., Schrempf D., Woodhams M.D., von Haeseler A. & Lanfear R. 2020. IQ-TREE 2: New models and efficient methods for phylogenetic inference in the genomic era. Molecular Biology and Evolution 37 (5): 1530–1534, https://doi.org/10.1093/molbev/msaa015
Nygren A. 2014. Cryptic polychaete diversity: A review. Zoologica Scripta 43: 172–183. https://doi.org/10.1111/zsc.12044
Nygren A. & Sundberg P. 2003. Phylogeny and evolution of reproductive modes in Autolytinae (Syllidae, Annelida). Molecular Phylogenetics and Evolution 29 (2): 235–249. https://doi.org/10.1016/S1055-7903(03)00095-2
Nygren A., Parapar J., Pons J., Meißner K., Bakken T., Kongsrud J.A., Oug E., Gaeva D., Sikorski A., Johansen R.A., Hutchings P.A., Lavesque N. & Capa M. 2018. A mega-cryptic species complex hidden among one of the most common annelids in the North East Atlantic. PLoS ONE 13 (6): e0198356. https://doi.org/10.1371/journal.pone.0198356
Oug E., Bakken T. & Kongsrud J.A. 2014. Original specimens and type localities of early described polychaete species (Annelida) from Norway, with particular attention to species described by O.F. Müller and M. Sars. Memoirs of Museum Victoria 71: 217–236. https://doi.org/10.24199/j.mmv.2014.71.17
Oug E., Bakken T., Kongsrud J.A. & Alvestad T. 2017. Polychaetous annelids in the deep Nordic Seas: Strong bathymetric gradients, low diversity and underdeveloped taxonomy. Deep Sea Research Part II: Topical Studies in Oceanography 137: 102–112. https://doi.org/10.1016/j.dsr2.2016.06.016
Palumbi S.R. 1996. Nucleic acid II: The polymerase chain reaction. In: Hillis D.M. & Mable B.K. (eds) Molecular Systematics: 205–247. Sinauer Associates, Sunderland, MA.
Passamaneck Y.J., Schander C. & Halanych K.M. 2004. Investigation of molluscan phylogeny using large-subunit and small-subunit nuclear rRNA sequences. Molecular Phylogenetics and Evolution 32 (1): 25–38. https://doi.org/10.1016/j.ympev.2003.12.016
Rambaut A., Drummond A.J., Xie D., Baele G. & Suchard M.A. 2018. Posterior summarisation in Bayesian phylogenetics using Tracer 1.7. Systematic Biology 67 (5): 901–904. https://doi.org/10.1093/sysbio/syy032
Ratnasingham S. & Hebert P.D.N. 2007. BOLD: The Barcode of Life Data System. Molecular Ecology Notes 7: 355–364. https://doi.org/10.1111/j.1471-8286.2007.01678.x
Soltwedel T., Bauerfeind E., Bergmann M., Budaeva N., Hoste E., Jaeckisch N., von Juterzenka K., Matthiessen J., Mokievsky V., Nöthig E.-M., Quëric N.-V., Sablotony B., Sauter E., Schewe I., Urban-Malinga B., Wegner J., Wlodarska-Kowalczuk M. & Klages M. 2005. HAUSGARTEN:. Multidisciplinary investigations at a deep-sea, long term observatory in the Arctic Ocean. Oceanography 18 (3): 46–61. https://doi.org/10.5670/oceanog.2005.24
Struck T.H., Purschke G. & Halanych K.M. 2006. Phylogeny of Eunicida (Annelida) and exploring data congruence using a Partition Addition Bootstrap Alteration (PABA) approach. Systematic Biology 55 (1): 1–20. https://doi.org/10.1080/10635150500354910
Teixeira M.A.L., Vieira P.E., Fenwick D., Langeneck J., Pleijel F., Sampieri B.R., Hernández J.C., Ravara A., Costa F.O. & Nygren A. 2023. Revealing the diversity of the green Eulalia (Annelida, Phyllodocidae) species complex along the European coast, with description of three new species. Organisms Diversity and Evolution 23: 477–503. https://doi.org/10.1007/s13127-022-00597-1
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