The Eurasian Pelophylax esculentus hybridogenetic complex, including Pelophylax ridibundus (R), P. lessonae (L), and their hybrid P. kl. esculentus (E), is considered to be one of the most complicated animal hemiclonal systems. It has been attracting the attention of evolutionary and molecular biologists as well as ecologists for decades. Despite the considerable number of studies describing population structure, reproductive modes, and distribution of the species complex, data on the rarely observed REL scenario, i.e., the presence of all three species at one site, are lacking. This study compared the morphological (morphometry, external morphology) and ecological (diet) profiles of all three species from a REL complex population located in the northwestern part of Croatia (Bjelovarsko-Bilogorska County). In terms of external morphology, the species varied interspecifically, but some features, for example, the yellow or green femoral colouration found in P. ridibundus, had not been expected. All three species exhibited a strong predilection for terrestrial prey, but interspecific differences were noticed. This paper aims to provide a better and more comprehensible insight into the ecological relationships of the REL complex, allowing comparisons with other study areas across Europe
