Morphological and Molecular Characterization, and Demonstration of a Definitive Host, for from an Alpaca () in China.

Only rDNA sequences of spp. in South American camelids (SACs) are deposited in GenBank as references, and the definitive host of in SACs is still unclear. Here, sarcocysts detected in an alpaca () in China were investigated with the aid of light (LM) and transmission electron (TEM) microscopy, and characterized using four genetic markers, i.e., rDNA, rDNA and , and the mitochondrial 1. Additionally, the life cycle of the parasite was completed via experimental animal infection. Under LM, sarcocysts exhibited numerous 1.3-2.1 μm conical protrusions. Under TEM, the sarcocyst wall contained conical, cylindrical, or irregular-shaped villar protrusions, similar to type 9j. Two dogs () fed sarcocysts shed sporocysts with a prepatent period of 8-9 days. The newly obtained rDNA sequences showed 98.4-100% identity with those of in SACs previously deposited in GenBank. Interestingly, the newly obtained sequences of rDNA and mitochondrial 1 shared 99.6-100% and 98.2-98.5% identity, respectively, with those of . in dromedary camels (). Phylogenetic analysis based on sequences of rDNA, rDNA, or mitochondrial 1 revealed that has a close relationship with spp. in ruminants. The relationship between and . deserves to be further clarified in the future.