Fifty spider species new to the Bulgarian fauna, with a review of some dubious species (Arachnida: Araneae).

This study is a part of an ongoing comprehensive inventory of Bulgarian spiders. A total of fifty spider species belonging to thirteen families are reported for the first time from Bulgaria. Four species are rejected from the Bulgarian spider checklist due to misidentification: Callilepis concolor Simon, 1914, Centromerus capucinus (Simon, 1884), Hoplopholcus labyrinthi (Kulczynski, 1903) and Mansuphantes prope fragilis (Thorell, 1875). Another four species (Drassodes villosus (Thorell, 1856), Entelecara flavipes (Blackwall, 1834), Lepthyphantes notabilis Kulczynski, 1887 and Singa semiatra L. Koch, 1867) are rejected after a new interpretation of the locations. Six species were omitted from the list of Bulgarian spiders as obviously doubtful records (Dysdera nicaeensis Thorell, 1873, Haplodrassus rufipes (Lucas, 1846), Harpactea hispana (Simon, 1882), Macaroeris cata (Blackwall, 1867), Nomisia celerrima (Simon, 1914) and Tenuiphantes monachus (Simon, 1884)). A new synonymy is proposed for Cyclosa strandjae Drensky, 1915 (= Cyclosa sierrae Simon, 1870 syn. nov.). In addition, new images with essential taxonomic value are provided for twenty-five species to facilitate their identification or to illustrate their intraspecific variability. To ensure correct identification, DNA barcoding was additionally used in some species.