We collected Tandonia at many sites in Dalmatia and Montenegro and examined the material in view of open taxonomic questions or limited knowledge of the morphology. New anatomical data strongly support the hypothesis that Amalia montenegrina Simroth, 1900 is a junior synonym of Tandonia reuleauxi (Clessin, 1887). The type locality of Tandonia cavicola (Simroth, 1916) has been recently located and, consequently, the literature data have been revised and compared with anatomical data provided by the newly collected specimens from historic localities cited for the species, but not from the type locality itself. The results show that the specimens so far referred to as T. cavicola could be assigned also to other nominal species, e.g. T. dalmatina (Simroth, 1900) or, less likely, to T. lagostana (Wagner, 1940). New dissections of Tandonia fejervaryi (Wagner, 1929) and Tandonia rara Wiktor, 1996 revealed new undescribed anatomical features, e.g. the internal structure of the distal female genitalia for the T. fejervaryi and the spermatophore for T. rara.