Chrysomela populi (Coleoptera: Chrysomelidae) is the most abundant and most important pest species that causes damage to poplar trees. Members of the family Chrysomelidae are frequently infected by protist pathogens but no neogregarine has been reported to date at the species level. In the present study we identify a new neogregarine pathogen from the chrysomelid C. populi. The infection was observed in the Malpighian tubules of adult beetles. A reddening of the Malpighian tubules was the most distinctive symptom of the infection. Single fusiform oocysts (9.8 x 4.7 mu m) were formed within a gamontocyst. The polar plugs were very thin, varying from 380 to 525 nm in thickness. The oocyst wall was smooth and also quite thin (90-120 nm). Morphological and ultrastructural characteristics of the pathogen indicate that the described neogregarine in C. populi is clearly different from known Ophryocystis species which infect coleopterans. Therefore, the neogregarine pathogen was determined to be a newly discovered species and named Ophryocystis anatoliensis sp. nov. (C) 2017 Elsevier GmbH. All rights reserved.