Contributo allo studio della distribuzione degli Odonati nel Piacentino

[Autom. eng. transl.] The territory of Piacenza, the extreme western edge of the Emilia bounded on the north by the course of the Po and to the south by the northern Apennine ridge, includes the catchment basins of some right Po tributaries (Tidone, Trebbia, Nure, Chiavenna, Arda). Among the wetlands the areas sheltered by the Po stand out with the mouths of the aforementioned tributaries and, in the agricultural district of Po, the network of irrigation canals. In the hills and mountains there are also artificial basins (lake of Trebecco, lake of Mignano) and, at higher altitudes, other smaller lakes. Against this hydrographic variety, of undoubted relevance for the purposes of research on amphibious entomofauna, it can be stated that the current knowledge on the distribution of Odonates in the province of Piacenza is relatively scarce if compared with those available for example for some other provinces in the region or of neighboring regions. Considering the importance of Odonates as bioindicators and to obtain a more in-depth knowledge of their distribution in the territory and of any changes in the same over time, we have identified the unpublished material of the Piacentino preserved in the collections of the Institute of Entomology of the Catholic University. The collection time frame of the approximately 200 specimens examined covers the last thirty years; the localities are about sixty, located above all in the plain and hilly areas of the province. The original geonemic data concern the following 38 species: Calopteryx haemorrhoidalis (VdLind.), C. splendens (Harris), C. virgo (L.), Sympecma fusca (VdLind.), Lestes dryas Kirby, L. sponsa (Hansem.) , L. viridis (VdLind.), Platycnemis pennipes (Pall.), Pyrrhosoma nymphula (Sulz.), Ischnura elegans (VdLind.), I. pumilio (Charp.), Enallagma cyathigerum (Charp.), Coenagrion puella (L. ), Ceriagrion tenellum (Vill.), Aeshna affinis VdLind., A. cyanea (Müll.), A. isosceles (Müll.), A. mixta Latr., Anax imperator Leach, Hemianax ephippiger (Burm.), Gomphus flavipes ( Charp.), G. vulgatissimus (L.), Onychogomphus forcipatus (L.), Somatochlora metallica (VdLind.), Libellula depressa L., L. fulva Müll., L. quadrimaculata L., Orthetrum albistylum (Selys), O brunneum (Fonsc.), O. cancellatum (L.), O. coerulescens (F.), Crocothemis erythraea (Brullé), Sympetrum depressiusculum (Selys), S. fonscolombii (Selys), Southern S. (Selys), S . pedemontanum (Müll. in Allioni), S. sanguineum (Müll. ), S. striolatum (Charp.). Some of these species had been reported several times for the territory under examination, while for others the citations in the literature are very scarce or absent. For the Piacentino there are further bibliographic data for less than a dozen other species. It is probable that above all the Apennine mountain environments, less investigated, can provide other findings of a certain faunistic interest.