Resumen
A description of the male and female imago and pupal exuviae of Thienemannia spiesi sp. nov. is provided based on material collected in the Schapbach Quelle (spring), Bavaria, Germany. This description increases the total number of species known worldwide in the genus to eleven. The new species, T. spiesi, can be distinguished from other related species (except T. libanica Laville and Moubayed, 1985) by the following combination of characters: chaetotaxy of the wing membrane, inferior volsella nose-shaped and not sinuous, gonostylus bearing a crista dorsalis, spines present on tergite VII of the pupal exuviae. Comments on its ecology and taxonomic position are provided.