A new gregarine species (Eugregarinida: Gregarinidae) was previously reported from daikon leaf beetle, Phaedon brassicae at Daegwallyeong in Korea. Here, we found another novel gregarine species from the striped flea beetle, Phyllotreta striolata (Coleoptera: Chrysomelidae). This paper describes the morphological and molecular-biological characteristics of Gregarine species associated to P. brassicae and P. striolata. The size and body shape at mature trophozoite stage were the main diagnostic characteristics of those species. Gregarines from P. brassicae were bigger size (100um) with square shaped body while Gregarines from P. striolata were slightly smaller size (80um) with egg shaped body. Based on the partial 18S rDNA sequence, gregarine species from P. striolata was grouped in eugregarine and also this new gregarine showed 85% homology that of the reported Gregarina sp. from P. brassicae. However, gut dissection result showed that each species had own gregarine parasite species association. These results were identical in local populations from three surveyed locations. There was positive relationship between infection rates and elevation for gregarine related to P. striolata. Therefore, we suggested that the gregarines and their coleopteran hosts have species-specific interaction via co-evolution.