Votýpka J, Hypsa V, Jirků M, Flegr J, Vávra J, Lukes J
Institute of Parasitology, Czech Academy of Sciences, Czech Republic.
J Eukaryot Microbiol. 1998 Jan-Feb;45(1):137-41. doi: 10.1111/j.1550-7408.1998.tb05081.x.
The coccidians Frenkelia microti and F. glareoli (Apicomplexa: Sarcocystidae) form tissue cysts in the brain of small rodents (intermediate hosts) while oocysts are formed in the intestine of final hosts, buzzards of the genus Buteo. The inclusion of the small subunit ribosomal RNA gene sequences (SSU rRNA) of both Frenkelia species into the SSU rRNA trees of other, tissue cyst-forming coccidia strongly supports paraphyly of the genus Sarcocystis. Frenkelia spp. exhibit close relatedness to Sarcocystis falcatula Stiles 1893, a bird-opossum parasite, recognized under its junior synonym S. neurona Dubey et al. 1991, as the causative agent of equine protozoan myeloencephalitis on the American continent. As the definition of the genus Frenkelia is based on a plesiomorphic character (affinity to the neural tissue) of supposedly low phylogenetic value, the synonymization of the genus Frenkelia with Sarcocystis is proposed. This renders the genus Sarcocystis monophyletic.
球虫类的微小弗氏球虫（Frenkelia microti）和格氏弗氏球虫（F. glareoli）（顶复门：肉孢子虫科）在小型啮齿动物（中间宿主）的大脑中形成组织囊肿，而卵囊则在终末宿主——𫛭属（Buteo）的秃鹰的肠道中形成。将这两种弗氏球虫的小亚基核糖体RNA基因序列（SSU rRNA）纳入其他形成组织囊肿的球虫类的SSU rRNA树中，有力地支持了肉孢子虫属（Sarcocystis）的并系性。弗氏球虫属与1893年发现的肉孢子虫（Sarcocystis falcatula）关系密切，后者是一种鸟类-负鼠寄生虫，其次异名是1991年杜贝等人命名的神经元肉孢子虫（S. neurona），被认为是美洲大陆马原生动物脑脊髓炎的病原体。由于弗氏球虫属的定义基于一个可能具有较低系统发育价值的近裔共性特征（与神经组织的亲和性），因此建议将弗氏球虫属与肉孢子虫属同义化。这使得肉孢子虫属成为单系的。
