Libellule di Liguria (Odonata)

Abstract

This paper updates the knowledge about dragonflies observed within the administrative boundaries of Liguria (North-west of Italy) to nearly seventy years since the last paper at regional scale (Capra 1945). The study was carried out through the collection of new data and through a revision of bibliography and museological collections. A geographic database was compiled with approximately 3,000 records, representing a relevant sampling effort with about one record every two square kilometers. Of these, 500 are published and 2,500 are unpublished data, the latter mainly collected in the last seven years (88%). A total of 57 species, 23 Zygoptera and 34 Anisoptera, are recorded for the study area, representing the 61% of the Italian odonatofauna. Four species are recorded as new for Liguria: Coenagrion pulchellum, Ophiogomphus cecilia, Libellula fulva and Trithemis annulata. Conversely, five historically-recorded species were not found during the last years: Coenagrion mercuriale, Erythromma najas, Sympetrum vulgatum, Somatochlora flavomaculata e Somatochlora meridionalis. The Ligurian odonatofauna is mainly composed by palearctic species (84%), followed by holoartic (7%), afro-european (5%) and afro-tropical (4%) species. Specimens were observed in flight from the sea level up to 1700 m a.s.l., with a higher number of species present at elevation of up to 1000 m, and only six species reaching the highest altitude. The flight season is mainly concentrated in the summer with the following number of species observed for each month: January (0), February (1), March (0), April (7), May (25), June (43), July (47), August (45), September (27), October (10), November (4), December (0). The most important areas, for biogeographical reasons or for highest number of species, are located in the “Genoese Apennine” (Aveto valley, Roccagrande and Orba valley), in the Po valley encompassing the provinces of Genoa and Savona (Stura valley and Erro valley), in the Bormida valley and in the western area (River Centa basin, high Tanaro valley and Roja valley).