Current distribution of the Rosalia longicorn Rosalia alpina (LINNAEUS, 1758) (Coleoptera: Cerambycidae) in Poland

AbstractThe former range of the Rosalia longicorn Rosalia alpina in Poland probably overlapped with the range of the European beech Fagus sylvatica. In the 20thcentury, the species was recorded in the following parts of Poland: the Carpathians (almost the entire range), the Świętokrzyskie Mountains, the Roztocze Upland, Lower Silesia, and the northern and northwestern parts of the country. Although the Rosalia longicorn appears to have regressed in the countries of central Europe, the current population trend of this species in Poland is not known. This study presents data on the distribution of the Rosalia longicorn in Poland in 2000-2013 and defines its current distribution and range. A total of 210 sites of the Rosalia longicorn were identified, situated in 42 UTM squares (10x10 km). The total area of the species’ occurrence (maximum convex polygon) was 3334 km2and the effectively used area was 1877 km2. The Rosalia longicorn has withdrawn from most of its former sites in Poland and at present occurs only in parts of the Carpathians. Its continuous distribution range comprises the Bieszczady Zachodnie and Beskid Niski Mountains. Scattered and less abundant sites occur in the Beskid Sądecki, Pieniny Mountains and Sanok-Turka Mountains. At present, therefore, the species’ range of occurrence in Poland is significantly smaller than that recorded in the 20thcentury. The median nearest neighbour distance between sites was 1023 m (mean = 1640 m ±1702 SD, range 502-10870 m). Those situated on the peripheries of the range are thinly scattered, and the distance between them is probably too large to allow free movement of the species. This can disrupt the current range and lead to the formation of isolated sites (islands) along its peripheries, from which the Rosalia longicorn may gradually disappear. Such a development could cause its total extinction. The current distribution of the Rosalia longicorn in the Carpathians suggests that certain detrimental processes are taking place in the population, demonstrating that the species’ extinction in Poland is ongoing.