This paper presents the first complete and updated list of all 3597 species of beetles (Insecta: Coleoptera) belonging to 92 familiesfound and published in Lithuania until 2011, with comments also provided on the main systematic and nomenclatural changes since the last monographic treatment in two volumes (Pileckis and Monsevičius 1995, 1997). The introductory section provides a general overview of the main features of the territory of Lithuania, the origins and formation of the beetle fauna and their conservation, the faunistic investigations in Lithuania to date revealing the most important stages of the faunistic research process with reference to the most prominent scientists, an overview of their work, and their contribution to Lithuanian coleopteran faunal research.
Species recorded in Lithuania by some authors without reliable evidence and requiring further confirmation with new data are presented in a separate list, consisting of 183 species. For the first time, analysis of errors in works of Lithuanian authors concerning data on coleopteran fauna has been conducted and these errors have been corrected. All available published and Internet sources on beetles found in Lithuania have been considered in the current study. Over 630 literature sources on species composition of beetles, their distribution in Lithuania and neighbouring countries, and taxonomic revisions and changes are reviewed and cited. An alphabetical list of these literature sources is presented. After revision of public beetle collections in Lithuania, the authors propose to remove 43 species from the beetle species list of the country on the grounds, that they have been wrongly identified or published by mistake. For reasons of clarity, 19 previously noted but later excluded species are included in the current checklist with comments. Based on faunal data from neighbouring countries, species expected to occur in Lithuania are matnioned. In total 1390 species are attributed to this category and data on their distribution in neighbouring countries is presented. Completion of this study provides evidence that the Lithuanian coleopteran fauna has yet to be completely investigated and it is estimated that approximately 28 % of beetle species remain undiscovered in Lithuania. More than 85% of beetle species expected for Lithuania have been found in the following families: Cerylonidae, Geotrupidae, Haliplidae, Kateridae, Lycidae, Lucanidae, Mycetophagidae, Scarabaeidae and Silphidae. In families with few species such as Alexiidae, Boridae, Byturidae, Dascilidae, Drilidae, Eucinetidae, Lampyridae, Lymexilidae, Megalopodidae, Nemonychidae, Nosodendridae, Noteridae, Orsodacnidae, Pyrochroidae, Pythidae, Psephenidae, Rhysodidae, Sphaeritidae, Sphaeriusidae, Sphindidae, Stenotrahelidae and Trogidae, all possible species have already been discovered. However in some beetle families such as Aderidae, Bothrideridae, Eucnemidae, Laemoploeidae, Mordellidae, Ptiliidae, Scraptidae and Throscidae less than 50% of all possible species are known. At present the beetle species recorded in Lithuania belong to 92 families, with species from 9 other families such as Agyrtidae, Biphylidae, Deradontidae, Mycteridae, Ochodaeidae, Phleophilidae, Phloeostichidae, Prostomidae, Trachypachidae are expected to be found.
A bibliography and a index of subfamily and genus levels are provided. The information published in the monograph will serve to further faunistic and distribution research of beetles and will help to avoid confusion in the identificatation of coleopteran fauna of Lithuania.