Predation of anurans in southern England by Batracobdella algira, a leech previously unknown in the UK

Leech predation of amphibians is known to occur in Europe. Observation of severe leech infestation affecting a common toad Bufo bufo in southern England in summer 2020, with leeches covering the toad’s eyes, throat and axillae, initiated a collaborative investigation to learn more about the occurrence of such leech predation of anurans in the UK. Soliciting reports from the general public identified leech predation of common toads and common frogs Rana temporaria in Devon, Greater London, Hampshire, the Isle of Wight and Somerset in southern England. Through morphological and/or molecular investigation of samples, Batracobdella algira, a leech species not previously reported in the UK, was identified in the majority of cases. The known native Placobdella costata was also identified, with the observed feeding behaviour on anuran hosts being indistinguishable from that of B. algira. Whether the latter is a previously unrecorded or an introduced species has not yet been established. However, sequence data from multiple gene loci were identical to B. algira found in Tunisia, suggesting it more likely to be a non-native species to the UK. Further work is required to elucidate the potential origin and distribution of B. algira in the UK and whether it has any impact on amphibian populations. Keywords: amphibians, Bufo bufo, Glossiphoniidae, Hirudinea, Rana temporaria