The curious and intricate case of the European Hediste diversicolor (Annelida, Nereididae) species complex, with description of two new species

Abstract

Past molecular studies using mtDNA sequences and alloenzymes signalled the existence of at least two cryptic species within the Hediste diversicolor morphotype, in European coasts. However, to this day, no new species descriptions have been made. In this study, we identified five completely sorted lineages using a multi-locus approach, including the mitochondrial DNA cytochrome oxidase I gene (COI-5P) and the nuclear markers ITS2 rRNA and 28S rRNA. The molecular data were complemented with morphometric measurements examined through multivariate statistical analysis and the incorporation of statistical dissimilarities. Apart from the Baltic Sea, where three of the lineages occur in sympatry, Hediste diversicolor comprises four deeply divergent allopatric lineages in the rest of Europe. They group populations from the NE Atlantic and part of the Western Mediterranean Sea; from the Tyrrhenian Sea; from the Adriatic and Ionian Sea; and, lastly, from the Caspian, Black and the northern Aegean Seas. The lineage from the Ionian Sea revealed low genetic distances compared with the one from the Adriatic Sea and lacked enough specimens for the morphometric analysis, preventing further conclusions about its independent status. Three independent morphometric clusters were identified mainly based on worm size, the distance between the anterior and posterior eyes, parapodia proportions and the length of several prostomial appendages. Two sympatric lineages present in the Baltic Sea, showed evidence of possible hybridization and lacked significant PCA morphometric variation between them. The two remaining lineages were formally described as new species, namely Hediste pontii sp. nov. (Adriatic Sea) and Hediste astae sp. nov. (northern Aegean, Caspian and Black Seas). These new species can now be formally recognized and used in biomonitoring or other relevant ecological studies. Finally, a neotype is defined for H. diversicolor, whose usage is restricted to the NE Atlantic lineage.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:948C73FC-B07F-40A3-B8FA-03B60DE2089D

Key words:

• Annelida
• cryptic species
• Hediste
• mitochondrial DNA
• morphometry
• nuclear DNA

Acknowledgements

The authors would like to thank Massimo Ponti for the Hediste specimens from the Adriatic Sea; Eivind Oug for Norwegian specimens; Sarah Faulwetter for the large number of samples provided from several Greek locations in the northern Aegean Sea; Katerina Vasileidou for the northern Greek Hediste specimens; Julio Parapar for the Spanish samples; Juan Pardo for the northern French specimens; and lastly to Jorge Lobo and Claudia Hollatz for the help in collecting several Hediste samples in the Portuguese capital (Lisbon). Moreover, we would like to thank the reviewer and the Associate Editor Christoph Bleidorn for taking the time reviewing our manuscript.

SEM work was performed at the EMSO-PT Laboratory of Biodiversity and Connectivity & COBI, Universidade de Aveiro. EMSO-PT is funded by Portugal 2020, in the framework of COMPETE2020 (Programa Operacional Competitividade e Internacionalização-POCI), and FEDER (Fundo Europeu de Desenvolvimento Regional, ref. 01/SAICT/2016) and by national funds (OE), through FCT/MCTES (ref. PINFRA/22157/2016 EMSO-PT).

Conflict of interests

The authors declare no conflicts of interest.

Availability of data and materials

New sequence data and specimen metadata were uploaded in the project ‘Hediste species complex’ (DS-MTHD) within BOLD (http://v4.boldsystems.org/) and in the following link: dx.doi.org/10.5883/DS-MTHD. The alignments (FASTA and NEXUS formats) for each marker (COI, ITS2 and 28S) and the concatenated one (COI + ITS2 + 28S) are all publicly available online at Figshare (DOI: dx.doi.org/10.6084/m9.figshare.19224600). GenBank accession numbers for the original data: OP038674-OP038788, OP038790-OP038834, OP038836-OP038897 (COI); OP028540-OP028635 (ITS2), and OP028725-OP028820 (28S). The new biological material is deposited at the Biological Research Collection (Marine Invertebrates) of the Department of Biology of the University of Aveiro (COBI at DBUA), Portugal, while specimens from Norway at the Norwegian University of Science and Technology, NTNU University Museum, all available upon request, with the exception of the ones exhausted in the DNA analysis mentioned in the Methods.

Supplemental material

Supplemental material for this article can be accessed here: https://doi.org/10.1080/14772000.2022.2116124.

Associate Editor: Dr Christoph Bleidorn

Additional information

Funding

This work was funded by the project ‘River2Ocean – Socio-ecological and biotechnological solutions for the conservation and valorization of aquatic biodiversity in the Minho Region’ (NORTE-01-0145-FEDER-000068), co-financed by the European Regional Development Fund (ERDF), through Programa Operacional Regional do Norte (NORTE 2020). Thanks are due, for the financial support to the Centre for Environmental and Marine Studies (CESAM, UIDB/50017/2020 + UIDP/50017/2020), to Portuguese Foundation for Science and Technology and Ministry of Education and Science (FCT/MEC) through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020. The research leading to these results also received partial funding, from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730984, ASSEMBLE Plus project (application no. 8229, 4th CALL, ‘Crypticism in the marine realm: DNA barcode-based outlook into selected invertebrate taxa of the Eastern Mediterranean’). Marcos A.L. Teixeira was supported by a PhD grant from FCT (SFRH/BD/131527/2017), co-financed by the European Science Foundation (ESF). Pedro Vieira’s work was supported by national funds through the Portuguese Foundation for Science and Technology (FCT, I.P.) in the scope of the project NIS-DNA (Early detection and monitoring of non-indigenous species in coastal ecosystems based on high-throughput sequencing tools, PTDC/BIA-BMA/29754/2017). Ascensão Ravara was funded by national funds, through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. Financial support to Arne Nygren from the Norwegian Taxonomy Initiative [http://www.biodiversity.no/Pages/135523] (Cryptic polychaete species in Norwegian waters, knr 49-13, pnr 70184228), the Swedish Taxonomy Initiative [https://www.artdatabanken.se/en/the-swedish-taxonomy-initiative/] (Polychaete species complexes in Swedish waters, dnr 140/07 1.4 and 166/08 1.4), and Kungliga Fysiografiska sällskapet Nilsson-Ehle donationerna [https://www.fysiografen.se/sv/]. Financial support to Torkild Bakken from the Norwegian Taxonomy Initiative project Polychaetes in Norwegian Ports project no. 70184238.