Protistology 16 (1) 30–41 (2022)

The trypanosomatid flagellates of the genus Phytomonas were found in the salivary glands and gut of the invasive western conifer seed bug Leptoglossus occidentalis (Hemiptera, Coreidae) in Crimea. The parasites were isolated into axenic culture and identified by phylogenetic analysis based on the 18S rRNA and gGAPDH genes as P. serpens. Previously, all isolates of this species have been obtained in Brazil, from either tomato fruits or their pest bugs Phthia picta (Hemiptera, Coreidae). We investigated the morphology of trypanosomatids from the new isolate in the host bug, laboratory culture, and experimentally infected tomato fruits using light and transmission electron microscopy. We propose hypothetical scenarios of L. occidentalis involvement in the life cycle of P. serpens in the territory, which is new for both species.