Simple SummaryNational conservation management is informed by knowledge on the species diversity of the taxon group in focus, specifically on the occurrence of endemics. Turkey, at the intersection of the Caucasus, Irano-Anatolian, and Mediterranean biodiversity hotspots, harbors a rich anuran diversity including two species considered endemic. The species status of one of them, the Beyşehir water frogPelophylax caralitanus, has been in question since its proposal in 2001. We provide evidence that mating vocalizations of this taxon do not differ sufficiently from those of the widespreadP. bedriagaeto function as a premating barrier between the two, preventing significant gene flux. The low degree of bioacoustic differentiation agrees with earlier genetic, karyological, and morphological findings. We conclude that the Beyşehir frogs do not deserve species status and thatP. caralitanusare in factP. bedriagae. Therefore, the number of endemic anuran species in Turkey decreases to one.AbstractInformed conservation management requires exact knowledge on the species diversity of the taxon group in focus within a geographic area, specifically on the occurrence of endemics. In Turkey, there are three water frog taxa of the genusPelophylax; one is the widespreadP. bedriagae, the other two are geographically restricted to either Thrace (P. ridibundus) or to the Anatolian Lake district (P. caralitanus). The species status of the Beyşehir frogP. caralitanushas been questioned since its proposal in 2001. We recorded and analyzed advertisement and release vocalizations at representative populations ofPelophylaxtaxa to assess the degree of inter-taxon differentiation and the potential for premating isolation. We found thatP. bedriagaeandP. caralitanushave much more similar vocalizations than both have compared toP. ridibundus. A functional bioacoustic premating barrier betweenbedriagaeandcaralitanusin syntopy does not exist according to our study. The low degree of bioacoustic differentiation mirrors earlier genetic, karyological, and morphological findings. We conclude that the Beyşehir frogs do not deserve species status and thatP. caralitanusshould be considered a junior synonym ofP. bedriagae. Therefore, the number of endemic anuran species in Turkey decreases to one.