Odonate diversity of a highly urbanised region: An annotated checklist of the damselflies and dragonflies (Insecta, Odonata) of Lario and Brianza (Lombardy, N Italy)

Background Given their sensitivity to environmental alterations, odonates act as reliable bioindicators to assess the effects of changes in freshwater ecosystems and associated terrestrial habitats. The region comprised between Lario and Brianza (Provinces of Como, Lecco and Monza and Brianza - Lombardy, N Italy) is one of the most urbanised of the Italian peninsula and large parts of its territory have been heavily altered, especially at low elevation. Despite this pervasive anthropogenisation, the area is still characterised by a considerable variety of freshwater habitats, possibly harbouring rich odonate communities, which, however, have been never thoroughly investigated. This study aimed to produce the first commented checklist of the Odonata of this region, accompanied by distribution maps. New information The work is based on 12,093 records spanning from 1981 and 2022, derived from literature (289), revision of collections (42), citizen-science projects (1249) and unpublished data from the authors and their collaborators (10,513). Overall, fifty-five species occur - or occurred in the past - in the study area (20 Zygoptera and 35 Anisoptera). One species, Erythromma najas, was confirmed exclusively before 1978, while seven species (Lestes barbarus, Coenagrion scitulum, Aeshna affinis, Anax ephippiger, Somatochlora arctica, Sympetrum meridionale and Trithemis annulata) have been recorded only after 2000. Records referring to Chalcolestes parvidens and Sympetrum flaveolum were considered questionable and excluded from the checklist. A list of species for each protected site is additionally provided. This work highlighted the importance for odonates of Lario and Brianza Regions from a national perspective, in particular for species of conservation priority/interest, such as Sympecma paedisca, Oxygastra curtisii and Sympetrum depressiusculum.