Coexistence of Placobdella costata (Fr. Muller, 1846) (Hirudinida: Glossiphoniidae) and mud turtle Emys orbicularis

Emys orbicularis is receding from Europe, mainly due to anthropogenic habitat changes. Its parasite, Placobdella costata, is widely distributed within both the former and the present distribution range of the host. Though closely associated with the mud turtle, it may have other hosts (birds, amphibians, reptiles). Its reproductive period coincides with that of its host's migration to the breeding grounds, thus facilitating dispersal of the parasite. Based on literature data we have analyzed the geographic spread of P. costata and mud turtle to observe the possible overlap of their habitats. Observations on the population of mud turtle and the associated leech species (P. costata) were carried out in eastern Poland - Podlasie Lowland. The studies were conducted in spring and summer in 1986-1993. The leeches were collected from the turtles caught in the water and on land. Observations showed that most leeches were found on turtles inhabiting the lake or moving to a breeding area. The greatest intensity of invasion was observed in June and July and that most leeches were observed in female E. orbicularis characterized by greater length of the carapace and weight, compared with males and juvenile individuals.