A checklist and areography of the longhorn beetles (Coleoptera, Cerambycidae) of Pirin Mountains, Bulgaria

Abstract Background The longhorn beetles fauna of Pirin Mountains, Bulgaria, was studied, based on literature data and original material. As a result, 100 taxa from five subfamilies are listed for the area, as follows: Prioninae (7 taxa), Lepturinae (31 taxa), Spondylidinae (9 taxa), Cerambycinae (28 taxa) and Lamiinae (25 taxa). New information This study presents two new records for Pirin Mts. (Oxymiruscursor and Tetropiumfuscumfuscum) and new localities or additional information for 13 cerambycid taxa (species and subspecies). The 100 longhorn beetle taxa belong to 17 zoogeographical categories and eight complexes. The European complex occupies a dominant position (34%), followed by those from Palaearctic (17%), Eurosiberian (15%), Mediterranean (15%), European-Iranoturanian (9%), Balkan endemic (5%) and Holarctic (4%) complexes.


Introduction
Pirin is the second highest mountain in Bulgaria. The highest peak of the mountain, Vihren (2914 m), occupies the third position on the Balkan Peninsula after Musala (2925 m) in Rila (Bulgaria) and Mytikas (2918 m) in Olympus (Greece). The average altitude of Pirin Mts. is 1033 m a.s.l. and the total area is 2585 km .
The vegetation of Pirin Mts. is vertically divided into three altitude belts: forest, subalpine and alpine. The lower part of the forest belt is predominantly made up of broad-leaved species stands (Carpinus betulus, Quercus petraea, Fagus sylvatica, Populus tremula etc.) and the upper part is mainly occupied by conifers (Pinus nigra, P. sylvestris, P. peuce, P. heldreichii, P. mugo, Abies alba and Picea abies) (Stoyanov 1966).
The aim of this study is to summarise the published data about longhorn beetles in the Pirin Mts., report new records and provide a chorological analysis of the cerambycid fauna of this mountain range.

Materials and methods
The longhorn beetles of Pirin Mts. were studied using literature data, our original records and unpublished materials from the entomological collection of the National Museum of Natural History, Sofia. The original material was collected on flowers, host plants and using an interception trap in a tree crown of Pinus heldreichii.
This paper provides a map with all known localities of the longhorn beetles recorded from Pirin Mts. It includes new localities from the current study and those already published. The records without a specific location, such as "Pirin Mt.", were not marked on the map.
Thecerambycid specimens collected in this study were deposited in the private entomological collection of Georgi Georgiev (mentioned with the abbreviation [GG]

Analysis
According to the present study, 15 species are reported for Pirin Mountains. Of these, two species Oxymirus cursor and Tetropium fuscum fuscum are new records and new localities or new specimens are given for 13 species. Summarising our data with the published one, 100 cerambycid taxa from 32 localities are recorded in Pirin Mts. (Fig. 1).

Discussion
The number of cerambycid taxa found in Pirin Mts. (100 species and subspecies) is closest to the West Balkan Range (107 taxa) (Georgiev 2011, Gradinarov and (Georgiev et al. 2021). It is also comparable to the number of cerambycids in other Bulgarian mountains studied: Strandzha (154 taxa) (Georgiev et al. 2018) and Western Rhodopes (161 taxa) .
In this study, taxa of the European complex occupy a dominant position (34%). They are connected with deciduous forests, which cover the largest parts of the lower territories of Pirin Mts. The second place is taken by the species and subspecies belonging to the Palaearctic complex (17%). These more eurybiont taxa are normally better represented in the high mountains, because of the harsh climatic conditions. Eurosiberian and Mediterranean complexes with equal value (15%) occupy the third place. This pattern differentiates Pirin from the rest of the studied high mountains -Vitosha (Topalov 2018) and Rila (Georgiev et al. 2021), where the third place is taken by Eurosiberian taxa. The difference is due not only to the more southerly location of the Pirin Mts., but also to the presence of the large valleys of Struma and Mesta Rivers, which allows the penetration of Mediterranean taxa.
The high territories mostly covered by coniferous trees and shrubs are favourable for distribution of the Eurosiberian taxa (fourth place). The refugial character of the region is underlined by the presence of five (5.0%) Balkan endemic cerambycids.
In future investigations, the cerambycid fauna of Pirin Mt. will undoubtedly be enriched with species trophically associated with coniferous trees in the the mountains of Bulgaria, such as: Only three cerambycids were recorded in trophic associations with tree and shrub species in the Pirin Mts.: Arhopalus rusticus rusticus and Pogonocherus fasciculatus fasciculatus were reared from stems and branches of Pinus nigra ( Doychev et al. 2017) and Phymatodes glabratus from a stem of Cupressus sempervirens .
In conclusion, finding of 100 taxa (approximately 35% of longhorn beetles in Bulgaria) indicates that this taxonomic group is not yet well-studied and about 70-80 taxa are expected to be recorded in future investigations in the Pirin Mts.