Catalogue of Bracychthoniidae (Sarcoptiformes, Oribatida) specimens deposited in the State Museum of Natural History NASU, Lviv, Ukraine

Brachychthoniids are tiny mites, typically measuring less than 250 µm in length (Krant et al. 2009). Brachychthoniids can be distinguished from other oribatids by the fact that their notogaster is divided into 3 plates by 2 transverse furrows (Weigmann, 2006). The anteriormost plate has 6 pairs of setae (c and d rows) (Krant et al., 2009). Without extra cupules immediately lateral to mid-dorsal setae (Krant et al., 2009). The genital plates and the combined anal/peranal plates are of similar size (Krant et al., 2009). There is 1 pair of aggenital setae, 2 pairs of setae on the anal plates, and the peranal plates are present with 1 pair of setae (Krant et al., 2009). In terms of geography and ecology, brachychthoniids may be the most extensively spread family among oribatid mites (Krant et al., 2009). Besides being varied and plentiful in damp forest soil and litter, they are frequently found in disclimax communities and newly established habitats (Norton and Palmer, 1991). The world fauna of Brachythoniidae is represented by 163 species belonging to 12 genera (Subias, 2004). In Ukraine, 40 species of mites of this family, belonging to 9 genera. Thus, the species diversity in Ukraine is 25% of the world's fauna. The collection of oribatid mites of the State Museum of Natural History of the NAS of Ukraine contains 9 species of brachychthoniids, as follows: Liochthonius alpestris (Forsslund, 1958), L. hystricinus (Forsslund, 1942), L. muscorum Forsslund, 1964, L. brevis (Michael, 1888), L. sellnicki (Thor, 1930), Sellnickochthonius suecicus (Forsslund, 1942), S. zеlawaiensis (Sellnick, 1928), Eobrachychthonius oudemansi van der Hammen 1952 and Synchthonius crenulatus (Jacot, 1938). They have been collected in the western regions of Ukraine and are represented by 96 individuals, which make up 16 records. In particular, the collection contains samples collected from Zakarpatska, Lvivska and Ivano-Frankivska provinces. Some materials were collected in nature conservation areas: Nature Reserve Roztochchia, National Natural Park Synevyr and Carpathian Biosphere Reserve. This article was written with the support of the National Research Foundation of Ukraine, call 2022.01 «Science for the Recovery of Ukraine in the War and Post-War Periods» the project 2022.01/0013 «Digitization of natural history collections damaged as a result of hostilities and related factors: development of protocols and implementation on the basis of the State Museum of Natural History of the National Academy of Sciences of Ukraine». The contents of this article do not necessarily reflect the views of the National Research Foundation of Ukraine and are the sole responsibility of the State Museum of Natural History, NAS of Ukraine.