Sarcocystis scandentiborneensis sp. nov. was discovered in histological sections of striated musculature of treeshrews (Tupaia minor, T. tana) from Northern Borneo. Sarcocysts were cigar-shaped, 102 μm–545 μm long, and on average 53 μm in diameter. The striated cyst wall varied in thickness (2–10 μm), depending on whether the finger-like, villous protrusions (VP) were bent. Ultrastructurally, sarcocysts were similar to wall type 12 but basal microtubules extended into VPs that tapered off with a unique U-shaped, electron-dense apical structure. In phylogenetic trees of the nuclear 18S rRNA gene, S. scandentiborneensis formed a distinct branch within a monophyletic subclade of Sarcocystis spp. with (colubrid) snake-rodent life cycle. We mapped all intraspecific (two haplotypes) and interspecific nucleotide substitutions to the secondary structure of the 18S rRNA gene: in both cases, the highest variability occurred within helices V2 and V4 but intraspecific variability mostly related to transitions, while transition/transversion ratios between S. scandentiborneensis, S. zuoi, and S. clethrionomyelaphis were skewed towards transversions. Lack of relevant sequences restricted phylogenetic analysis of the mitochondrial Cytochrome C oxidase subunit I (COI) gene to include only one species of Sarcocystis recovered from a snake host (S. pantherophisi) with which the new species formed a sister relationship. We confirm the presence of the functionally important elements of the COI barcode amino acid sequence of S. scandentiborneensis, whereby the frequency of functionally important amino acids (Alanine, Serine) was markedly different to other taxa of the Sarcocystidae. We regard S. scandentiborneensis a new species, highlighting that structurally or functionally important aspects of the 18S rRNA and COI could expand their utility for delineation of species. We also address the question why treeshrews, believed to be close to primates, carry a parasite that is genetically close to a Sarcocystis lineage preferably developing in the Rodentia as intermediate hosts.

肉胞藻scandentiborneensis sp。十一月 在婆罗洲北部的树（Tupaia minor，T . tana）的横纹肌组织组织切片中发现了这种细菌。结节囊呈雪茄状，长102 μm–545μm，平均直径53μm。条纹状的囊肿壁的厚度（2-10μm）不同，这取决于手指状的绒毛状突起（VP）是否弯曲。在超微结构上，肌囊类似于12型壁，但基底微管延伸成VP，并以独特的U形，电子致密的顶端结构逐渐缩小。在核18S rRNA基因的系统发育树中，S。scandentiborneensis在一个单系亚科中形成了一个明显的分支肉囊藻属 （蛇蝎）啮齿动物的生命周期。我们将所有种内（两个单倍型）和种间核苷酸取代定位到18S rRNA基因的二级结构：在两种情况下，最高的变异发生在螺旋V2和V4内，但种内变异主要与过渡有关，而S之间的过渡/转化比率。scandentiborneensis，ş。zuoi和小号。腕线虫偏向颠覆。缺乏相关序列限制了线粒体细胞色素C氧化酶亚基I（COI）基因的系统发育分析，仅包括一种肉囊藻从蛇宿主（S. pantherophisi）中恢复过来，与新物种形成了姐妹关系。我们确认S的COI条码氨基酸序列中功能上重要的元素的存在。scandentiborneensis，其中功能上重要的氨基酸（丙氨酸，丝氨酸）的频率与肉胞科的其他分类单元明显不同。我们认为小号。scandentiborneensis是一个新物种，强调了18S rRNA和COI在结构或功能上的重要方面可以扩展其在描述物种方面的效用。我们还解决了一个问题，为什么据信与灵长类动物接近的树h所携带的寄生虫在遗传上与肉胞藻接近 谱系优选在啮齿动物中发展为中间宿主。