The first study reporting the morphological characterization of Sarcocystis sybillensis was performed in 1983; however, without any molecular analysis. Sarcocystis nipponi has been recently described as a species synonymic to S. sybillensis. We reconfirmed the presence of S. sybillensis in Japanese sika deer (Cervus nippon) captured in its native territory; and performed its molecular and phylogenetic characterization. The morphological characteristics of the sarcocysts were consistent with those of S. nipponi and S. sybillensis described in the first report. However, the nucleotide sequence of 18S rRNA gene of S. sybillensis showed only 91.9% identity to that of S. nipponi, suggesting low homology among the concerned Sarcocystis spp. Accordingly, S. sybillensis was found to occupy a clade distinct from that of S. nipponi in a phylogenetic tree of Sarcocystis. Therefore, the present study provides essential information on 18S rRNA-based molecular characterization of S. sybillensis and disproves the existing notion of morphology-based species synonymity of S. sibillensis and S. nipponi. These results also suggest that S. sybillensis belongs to type 2 Sarcocystis.

1983年进行了第一项报道了Sycocystis sybillensi s形态特征的研究。但是，没有任何分子分析。日本肉孢囊藻（Sarcocystis nipponi）最近被描述为sybillensis的同义词。我们再次确认了在其本土捕获的日本梅花鹿（Servus nippon）中是否存在sybillensis。并进行了分子和系统发育鉴定。卵囊的形态特征与第一份报告中描述的日本葡萄球菌和sybillensis的形态特征一致。但是，sybillensis 18S rRNA基因的核苷酸序列与Sippo nipponi的同源性只有91.9％，提示所涉及的Sarcocystis spp同源性低。因此，S. sybillensis发现占据从不同的进化枝S. nipponi中的系统树肉孢子虫。因此，本研究为sybillensis的基于18S rRNA的分子表征提供了必要的信息，并且反驳了现有的基于形态学的西伯利亚链球菌和日本链球菌物种同义的概念。这些结果还表明，sybillensis属于2型肉囊藻。