We report results of a faunal survey of Aradidae flat bugs sampled by sifting litter in 14 wet and discrete Tanzanian primary forests (= Tanzanian Forest Archipelago, TFA) of different geological origins and ages. Images, locality data and, when available, DNA barcoding sequences of 300 Aradidae adults and nymphs forming the core of the herein analyzed data are publicly available online at dx.doi.org/10.5883/DS-ARADTZ. Three Aradidae subfamilies and seven genera were recorded: Aneurinae (Paraneurus), Carventinae (Dundocoris) and Mezirinae (Afropictinus, Embuana, Linnavuoriessa, Neochelonoderus, Usumbaraia); the two latter subfamilies were also represented by specimens not assignable to nominal genera. Barring the six nominal species of Neochelonoderus and Afropictinus described earlier by us from these samples and representing 11 of the herein defined Operational Taxonomic Units (OTU), only one of the remaining 52 OTUs could be assigned to a named species; the remaining 51 OTUs (81%) represent unnamed species. Average diversity of Aradidae is 4.64 species per locality; diversity on the three geologically young volcanoes (Mts Hanang, Meru, Kilimanjaro) is significantly lower (1.33) than on the nine Eastern Arc Mountains (5.67) and in two lowland forests (5). Observed phylogeographic structure of Aradidae in TFA can be attributed to vicariance, while the depauperate fauna of Aradidae on geologically young Tanzanian volcanoes was likely formed anew by colonisation from nearby and geologically older forests., Vasily V. Grebennikov, Ernst Heiss., and Obsahuje bibliografii