Synthèse des connaissances sur les fourmis (Hymenoptera, Formicidae) du Parc national des Écrins (SE France)

The synthesis of 1686 occurrence data of ants (family Formicidae, Hymenoptera) identified to the species level, distributed across the entire Écrins National Park (core zone and adhesion zone) revealed 83 species, i.e. more than one third of the myrmecofauna of metropolitan France. The species accumulation curve shows, however, that the completeness of the inventory is moderate. Although the first data date back to 1984, more than 90% of the data have been obtained since 2018. To remedy to the knowledge deficit, the park adopted a strategy in 2018 which consisted in: first mobilizing park agents for opportunistic collections throughout the territory and an association of ant specialists for identification, and second occasionally involving ant specialists in field surveys. This sampling effort allowed exploring the distribution of diversity and species according to the type of environment and to elevation, and to reveal the presence of species that could represent an issue for the park. In particular, Formica paralugubris Seifert, 1996, a species of redwood ant endemic to the western Alps and the Jura, very little known in France, was detected in several sites. This species being difficult to distinguish from Formica lugubris Zetterstedt, 1838 – a very common boreomontane species – the identification was based on a double diagnosis: morphological and molecular. The inventory revealed other remarkable species such as Leptothorax gredleri Mayr, 1855, a species from central and northern Europe whose only known station in France is the one in the park, and Leptothorax pacis (Kutter, 1945), a very rare species occurring mainly in the Alps and the Pyrenees. A conservation value analysis relying on a method specific to the park revealed Formica paralugubris as a species with a particularly high conservation value within the territory of the park.