Data on the distribution of Osmoderma barnabita Motschulsky, 1845 (Coleoptera: Cetoniidae) in Bulgaria from 1904 to 2022

The hermit beetle, Osmoderma eremita s.l. (Scopoli 1763), is a species complex of scarab saproxylic beetles listed in the IUCN Red List of Threatened Species and protected in Bulgaria by Bern Convention, the Habitats Directive, and the Bulgarian Biodiversity Act. The taxonomic status of the species complex in Bulgaria is not fully known. It is believed that Osmoderma barnabita Motschulsky, 1845 is the main species present in the country, but it is also possible that Osmoderma lassalei Baraud and Tauzin, 1991 exists in the southernmost parts, where is the northern limit of its distribution. Data collected over the years on the presence of O. barnabita are very scarce due to its hidden lifestyle and lack of interest from the scientists. The present study aims to summarise all available data on O. barnabita in Bulgaria (literature, National Natural History Museum - Bulgarian Academy of Sciences collection, field work, and citizen science) for the period from 1904 to 2022. A map of the current species distribution was generated. The altitudinal distribution ranged from 0 to 1700 m, mainly in mountainous areas with well-preserved forests. Eighty-three percent of the records with exact coordinates were from forests aged above 50 years, and 35% were from forests aged above 100 years. There were also individual records from cities, showing the need to protect urban green spaces and the old trees within them. Based on the results obtained, O. barnabita is newly registered for six Natura 2000 sites, confirmed in 18 sites; and for the remaining 18, where it is included in the standard data forms based on modelling its habitat, additional studies are needed to confirm or exclude it.