A phylogenetic analysis of the Saxifraga-associated species of Dichotrachelus was carried out based on morphological and, for some species, molecular data. The various methods implemented gave congruent results and yielded a significantly supported phylogenetic inference of the relationships among the species. Saxifraga-associated species form a monophyletic unit, and some species-groups were evidenced, distributed in the eastern, central and western Alps, respectively. Based on the phylogenetic inference, and taking into account palaeogeological and palaeogeographical information, a biogeographic scenario of the events that may have led to the present-day distribution is proposed.

A new procedure for mark-recapture of Coleoptera Dytiscidae was developed. It consists of marking one elytron directly in the field using a battery driven mini-drill for making a small scratch, followed by attachment of a small label with an alpha-numeric code printed on hydro-resistant paper. The results of a four-year long study on some Dytiscidae species living in a montane peat-bog are summarized and discussed. The application of the method to other taxa is also outlined

A phylogenetic analysis of the genus Dichotrachelus (Curculionidae: Cyclominae) was carried out, based on a morphological matrix and, for some species, on mitochondrial cytochrome oxidase I sequences. Bayesian Inference, Maximum Likelihood and Maximum Parsimony were implemented and the results were compared. The genus is found to be isolated in the subfamily, not related to the only other Palaearctic tribe (Hipporhinini) and possibly nearer to the south-American genera of Cyclominae of the tribe Listroderini. Among these, Macrostyphlus is also equally associated to mosses as the host plant. In Dichotrachelus, two main clades were recognized, one distributed in the western part of the Mediterranean region (Iberian Peninsula, northern Africa and southern France) and the second distributed in the Alps and Apennines. Within each clade, some differentiated monophyletic subgroups could be identified. An evaluation of the most important characters that led to the phylogenetic reconstruction indicated the male genital sclerite as the most useful structure to characterize the different clades.