This paper presents the results obtained from a short survey performed in Bulgaria, southeast Europe, where the trichomycetes (sensu lato), an ecological group of arthropod gut endosymbionts, were previously completely unknown. The present study initiates the comprehension of these cryptic organisms, members of the Kickxellomycotina ( Harpellales , Orphellales ) and the Mesomycetozoea ( Amoebidiales ), in this Balkan country. Eighteen new geographic records for Bulgaria are reported, including 10 species of Harpellales , three species of Orphellales and five species of Amoebidiales . Within the Harpellales , the species Glotzia balkanensis sp. nov. is described. This new species is most related to the rare species G. centroptili Gauthier ex Manier & Lichtw. and G. stenospora White & Lichtw., but is differentiated by spore and thallial characteristics. Photographs are provided and biogeographic implications of these records are discussed.