Integrative taxonomic consideration of the Holarctic Euconulus fulvus group of land snails (Gastropoda, Stylommatophora)

Abstract

While among the most common Holarctic land snails, species of the Euconulus fulvus group have been subject to considerable recent taxonomic controversy. Based on 76 Euconulus populations collected across Eurasia and North America, we empirically evaluated these competing taxonomic hypotheses through an integration of nDNA and mtDNA phylogenetics, shell morphometrics and various qualitative traits. Our results support the existence of five taxa: Euconulus alderi (Atlantic Europe to western North America), E. fresti sp. nov. (North America), E. fulvus fulvus (Europe), E. fulvus egenus (central Asia to Atlantic North America), and E. polygyratus (north-eastern North America). Each species-level entity possessed a unique suite of observable shell features allowing for accurate identification without need of DNA sequence information. Our data did not support the recent erection of E. callopisticus, E. praticola, and E. trochiformis to species-level status. This work also helps illustrate the importance of using consensus across DNA and shell/soft body features in assessing species-level taxonomy and in determining those features which allow for accurate identification. It furthermore documents the importance of basing taxonomic work on samples drawn from across the entire geographic and ecological range of the study group.

http://zoobank.org/urn:lsid:zoobank.org:pub:97985479-EDF8-4B94-A825-AC42BF31F597

Key words:

• Euconulus
• morphometrics
• phylogenetics
• species delimitation
• taxonomy
• terrestrial gastropod

Acknowledgements

We would like to express our thanks to B. Coles for a thorough revision of his material of E. fresti sp. nov., P. Tattersfield and B. Coles for providing fresh material of E. alderi from England, P. G. Oliver, H. Morgenroth and E. Tardy for sharing material from museum collections, P. G. Oliver also for providing photographs and measurements of E. trochiformis syntypes, D. Ortiz for his generous advice regarding the phylogenetic analysis and V. Polášková for her help with the laboratory work. We also thank F. Welter-Schultes and B. Coles valuable comments and advice on the manuscript, O. Gargominy for providing Euconulus COI sequences, and T. von Proschwitz for providing Euconulus spp. material to check variation of Scandinavian populations. Two reviewers and B. Páll-Gergely made many useful suggestions on how to improve the first draft of this study. The research was partially funded by the Czech Science Foundation (P504-20-18827S).

Disclosure Statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here: https://dx.doi.org/10.1080/14772000.2020.1725172.

Associate Editor: Barna Pall-Gergely

Additional information

Funding

This work was supported by the Czech Science Foundation under Grant P504-20-18827S.