Abstract
New species of carrot wasp—Gasteruption slovacum sp. nov.—is described based on a male collected near the village Čenkov in south of Slovakia. This species is similar and phylogenetically related to G. erythrostomum, from which it differs especially by the rough sculpture of mesoscutum, larger occipital carina, longer third and fourth antennal segments and larger total length. This species is also morphologically and in total length similar to G. insidiosum, from which it differs especially by the very small proportion of ivory colouration on legs. Phylogenetically, it forms a group with G. erythrostomum, which is nearest related to the group of G. nigrescens and G. foveiceps.