In the past century the desmid flora of Serbia has been investigated during several well-defined periods. Investigations have been dedicated mostly to desmid assemblages of peat bogs, fens, marshes, swamps and lakes, as typical desmid habitats. Considering that high-mountain peat bogs in Serbia are the southernmost refuge habitats of many boreal and arctic-alpine desmid taxa, there has been a considerable interest in obtaining data on the composition of the desmid flora in these habitats. In all, 626 desmid taxa belonging to 23 genera have been reported from the Republic of Serbia. On the basis of these records, an annotated checklist has been compiled. In the present paper, the main taxonomic and ecological characteristics of elongate baculiform desmid taxa of the families Mesotaeniaceae, Peniaceae, Closteriaceae and Desmidiaceae (Actinotaenium, Haplotaenium, Pleurotaenium and Tetmemorus), comprising 133 taxa (92 species and 41 varieties), are discussed. Among them 40 taxa have been reported from only one locality in Serbia, and therefore they are designated here as exceptionally rare.