Sarcocystis in Norwegian roe deer (Capreolus capreolus): molecular and morphological identification of Sarcocystis oviformis n. sp. and Sarcocystis gracilis and their phylogenetic relationship with other Sarcocystis species.

Fresh muscle tissue from six roe deer from Southeastern Norway was examined for sarcocysts. Cysts were excised and morphologically classified by light microscopy, and some cysts were further examined by scanning electron microscopy or DNA amplification and sequencing of the small subunit (ssu) rRNA gene. Two Sarcocystis species, Sarcocystis gracilis and Sarcocystis oviformis n. sp., were found and described by morphological and molecular methods. S. gracilis was found in all animals, whereas S. oviformis was found in only one roe deer. Polymerase chain reaction identification was necessary for definitive species identification, since cysts of S. gracilis varied in surface structure and since cysts of both S. gracilis and S. oviformis were morphologically indistinguishable from sarcocysts in other cervidae. Phylogenetic analyses based on complete ssu rRNA gene sequences revealed a close relationship between S. gracilis and other canine-transmitted Sarcocystis species, whereas S. oviformis formed a well-supported group with Sarcocystis hardangeri of reindeer and Sarcocystis ovalis of moose.