To date, 13 species of Ponto-Caspian amphipods have been reported from the inland waters of Turkey. Two, probably overlooked species, Echinogammarus trichiatus and Dikerogammarus villosus, are here recorded for the first time from this country. Due to the atypical morphology, the identity of E. Trichiatus was also verified with molecular methods, based on the mtDNA COI barcode. Both species, along with five other co-occurring Ponto-Caspian amphipods, were collected from Lake Durusu in September 2007. Our finding reveals high diversity of amphipods in this water body. It also presents the southernmost known localities of both species, and expands the checklist of Ponto-Caspian amphipod fauna of Turkey to 15 species. Taking into account the geographical range of both species, we may conclude that they are native to Lake Durusu and their presence there was previously overlooked.