Distribuzione di Zerynthia polyxena ([Denis & Schiffermüller],1775) (Lepidoptera, Papilionidae) e della sua pianta nutriceAristolochia pallida Willd. in Valle d’Aosta.

The present study updates the distribution of Zerynthia polyxena and its host plant Aristolochia pallida in the alpine region of Aosta Valley, NW Italy. Unpublished data and confirmations of historically known sites are provided and updated to the years 2022-2023. We searched for the two species within 212 cells of one square kilometer, and we confirmed both species to be more widespread in the region than known, with reproductive confirmations for Z. polyxena within 73 cells in an extent of occurrence of 221 km 2 and A. pallida within in 82 cells in an extent of occurrence of 239 km 2. Regarding the altitudinal distribution, rather high observations are reported for both species, with confirmation of reproduction for Z. polyxena up to 1.570 m, the highest altitude ever reported in Italy and Europe, and the presence of A. pallida up to 1.630 m. Z. polyxena was observed on wing between 25th of March and 11th of June, while the earliest data of observations for A. pallida was recorded on the 25th of February. For both species, we report the semi-quantitative results carried out in a sample area that returned density values of considerable interest: 24 adults of Z. polyxena along a transect of 400 m and 50 preimagine instar within a 25 m2 sample area. Finally, some management and conservation aspects concerning Z. polyxena, a protected species by “Habitat” Directive 92/43/EEC, are considered, confirming its presence in Aosta Valley exclusively outside of protected areas of the Natura 2000 network.