Ecology and Biology of the Rare Endemic Land Leech Xerobdella anulata (Xerobdellidae)

The genus Xerobdella contains three species of land leeches confined to the Palearctic region, one of which is X. anulata (Autrum, 1958), an exceptionally rare endemic of the Dinaric Alps. In the current study, we provide new data and a literature overview on this rarely encountered species, presenting its currently known distribution, providing additional data on its morphology and, for the first time, presenting comprehensive data on its habitat preferences and seasonal dynamics. Additionally, we provide novel DNA barcodes for the Dinaric land leech and compare the obtained sequences with the related X. lecomtei. Altogether, 22 specimens of X. anulata were collected using pitfall traps in three habitat types: managed forests with adjacent meadows and a primeval forest in the Dinaric Alps of Croatia. We report the first finding of X. anulata in open habitats, which harbored most of the specimens. Our findings show that X. anulata exhibits surface activity, highlighting the effectiveness of pitfall traps in sampling such elusive taxa, with perspectives for future morphological, phenological and even molecular research.