Although Russia is the largest country in the world spread over two continents with a long tradition of education and research, pseudoscorpion species received little attention until the turn of the 20th century. Taking into account the current borders of the Russian Federation, among the earliest publications belongs that of Tullgren (1907) with the first record of Dactylochelifer amurensis. A major part of the pseudoscorpion data from Russia consists of scattered findings mainly from the east of the country. Beier (1979) recorded three new species, Mundochthonius ussuricus, Centrochthonius ussuriensis, and Bisetocreagris silvicola, from Primorsky Krai. Ćurčić (1985) added the new Orientocreagris syrinx from the same area. Later Schawaller (1985, 1986, 1989) published most of the known records of the Far East and Schawaller (1994) also summarized all known data, which comprised 15 species in five families. Comprehensive research has been carried out only in a few areas. Main attention has been paid to the Caucasus Mountains and surroundings. Beier (1937) recorded Neobisium granulatum and N. labinskyi from the Northwest Caucasus for the first time. Schawaller and Krumpál (1983) published other neobisiid species, N. golovatchi and N. vilcekii, from the area. Later Krumpál (1986) added N. speleophilum from a cave located in the Caucasus. Finally, Schawaller and Dashdamirov (1988) and Dashdamirov and Schawaller (1992) summarized all known records from the Caucasus, which comprised 20 species from seven families for the Russian part of the mountains. Recently Kozminykh (2017) compiled data from the Ural Mountains based on preserved specimens and new material collected in 2016 and 2017. Ten species from four families, including one new record, are presently known from the Urals (Kozminykh, 2017). Due to its enormous size and different zoogeographical zones, Russia is guaranteed to have high species biodiversity. However, according to Harvey (2013) and Kozminykh (2017), the Russian pseudoscorpion fauna to date includes 40 species from eight families, which is a relatively small number. This could be due to the fact that the species composition and distribution has not been studied in detail. The majority of the records represent specimens from litter and soil and little is known about species living in tree microhabitats, such as tree hollows, microhabitats under tree bark, or deadwood. Similarly, very little is known about species inhabiting bird or mammal nests (Schawaller, 1985, 1989). The country still offers many opportunities and is very attractive for zoological research. Thus, the aim of the present paper is to provide new data about pseudoscorpions from Russia based on samples collected during the parasitological research of bird nests. The samples were taken at eleven localities during 1997-2016 (Table 1; Figure 1). All of the pseudoscorpion material was collected by the second author. All nests were collected immediately after the fledging of chicks and were
