The only Palearctic representative of the leech genus Placobdella Blanchard, 1893 is P. costata, an ectoparasite of freshwater turtles. To date, no conclusive evidence about the possible presence of coevolutionary patterns between this leech and its turtle hosts is available due to the paucity of DNA sequence data available for P. costata; moreover, comparative host data is also mostly lacking, making any inferences more difficult. The discovery of new populations of the species in northern Italy and Sicily allowed us to generate novel mitochondrial DNA sequences and to compare the topology of the resulting phylogenetic trees with the phylogeny of the turtle hosts occurring in the study area, i.e., Emys orbicularis and E. trinacris. The branching pattern of the phylogenetic tree for P. costata is not congruent with that of its turtle hosts, thus suggesting the lack of coevolutionary or cospeciation phenomena between these taxa. The lack of a coevolutionary pattern might be ascribed to the different dispersal ability of Placobdella costata and Emys spp. and to the host generality of the leech, as confirmed by the occurrence of P. costata on aquatic turtles belonging to the genus Mauremys in areas where Emys spp. are rare or absent.A single leech cytochrome c oxidase subunit 1 haplotype was found in each study region, and the overall nucleotide diversity was very low throughout the investigated distribution. This apparent lack of a clear phylogeographical pattern was unexpected in the P. costata populations occurring in the circum-Mediterranean areas, where the occurrence of high haplotype and nucleotide diversity is customary for most terrestrial and freshwater species. Based on the available data, we suggest a recent, post-glacial origin of the studied P. costata populations.

First record of the alien leech Myzobdella lugubris Leidy, 1851 (Hirudinea, Piscicolidae) in the PalearcticIn this study, we report the occurrence of the Nearctic leech Myzobdella lugubris in a brackish water body of the Riserva Naturale dello Stato "Le Cesine" (Apulia, Italy). Two specimens of the species were collected in October 2016 from the neck and the forelimbs of a European pond turtle, Emys orbicularis hellenica, and identified both based on morphology and molecular sequence data. In its native range, M. lugubris is known to be a host and vector of bacteria and viruses, among which some serious fish pathogens. In light of the possible noxious ecological effects exerted through pathogen spillover on autochthonous vertebrates, the distribution of the species and its possible role as a vector of pathogens in the invaded area should be urgently monitored.

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Behavioural and spatial distribution analyses were quantified during a phase of activity and lethargy in a wild population of the European pond turtle inhabiting a protected internal wetland area of the Venice lagoon. The marked individuals (13 males and 16 females) provided informative radiotracking data to study differential patterns of activity, dispersion and habitat use between the two study periods (“October-November both 2019 and 2020” and “June-July 2020”). The differences in the movements behaviours and habitat selection were affected by period. Movements were higher in the period of activity than lethargy, but they were not influenced by sex and size. The presence of the European pond turtle in the transitional woodland/shrubs and brackish water valley habitats was significantly higher in the period of activity than lethargy. During the latter one, pond turtles were observed to brumate gregariously in a small area for brumation, usually in shallow water. In contrast, all individuals have changed water bodies during the activity period. Part of those movements has occurred towards aquatic habitat with higher salinities 1-17 (mean: 10.64). These findings provide a set of information to better understand the behavioural ecology of Emys orbicularis in the lagoon area. This is of relevance for management actions and for the conservation of this threatened species.