Unrecognized diversity of Trocheta species (Hirudinea: Erpobdellidae): resolving a century-old taxonomic problem in Crimean leeches

Abstract

Erpobdellid leeches of the genus Trocheta are among the biggest and most charismatic members of their class. The studies of the group have a long and complicated history due to the lack of reliable distinguishing features, which impedes the taxonomy of the genus. A number of Trocheta species have been misclassified for years if not centuries. Our present research demonstrates that the genus Trocheta is characterized by high cryptic diversity since some populations that have been viewed as the same species should be, in fact, assigned to different species. Trocheta leeches from the Dniester basin and the Crimean Peninsula have been both confused with each other and erroneously assigned to species that do not occur in southern Ukraine. Here, a new species from the Crimean Peninsula, Trocheta blanchardi sp. nov., is described based on a phylogenetic analysis of cox1 gene sequences and a reassessment of morphological characters such as colouration, annulation, size and arrangement of papillae, and genital anatomy. The analysis suggests close relationships of T. blanchardi sp. nov. to Anatolian species. Given its fragile habitats and restricted range, the species needs serious protection and further surveys. Obviously, more species await description as is evident from the significant genetic differences between leech populations.

http://zoobank.org/urn:lsid:zoobank.org:pub:8610460D-862B-4F28-8520-5C8D11AEB015

Key words:

• Annelida
• cytochrome c oxidase subunit I
• DNA-barcoding
• leeches
• phylogeny
• species delimitation
• taxonomy
• Trocheta blanchardi sp. nov.
• Ukraine

Acknowledgements

Our sincere thanks go to our colleagues for their invaluable help and assistance during field trips throughout southern Ukraine. Grigoriy Prokopov shared important information on the ecology and habitats of macroinvertebrates of the Crimean Peninsula. Oleksandr Zinenko and Mikhail Son made pictures of T. blanchardi and T. danastrica respectively in their natural habitats. Vasiliy Dyadichko, Mikhail Son and Mariia Shrestkha-Kolesnykova helped us to sample in the Danube, Dniester and Dnieper deltas. Taxonomically important specimens were collected during joint field trips in collaboration with Boris Sket, Maja Zagmajster and Cene Fišer supported by two grants of the Slovenian-Ukrainian Intergovernmental Programme.

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2020.1739776.

Associate Editor: Polly Hayes

Additional information

Funding

This research was supported in part by the grant No. 0117U004836 of the Ministry of Education and Science of Ukraine and a grant of the Systematic Research Fund for the project Taxonomic revision of the Caucasian leeches (Annelida, Hirudinida) as well as through the Slovenian Research Agency Core Funding P1-0184.