Monocystis perplexa n. sp., a parasite of an important invasive Japanese earthworm in North America, Amynthas agrestis, is described from a site in Vermont. An improved standard for Monocystis species descriptions is proposed including a standard nomenclature to reduce synonymies, a standard set of biometrics and shape descriptions for living cells, and a DNA genomic sequence for the 18S rRNA (∼1,700 base pairs). Comparing morphologies of Monocystis parasites in sympatric earthworm species indicates that M. perplexa is specific to A. agrestis in the study region. Also, polymerase chain reaction primers specific to M. perplexa amplified samples of A. agrestis earthworms taken from several sites in Japan. This suggests the parasite entered North America from Japan, the origin of the invasive Amynthas earthworm, and thus M. perplexa would be the first Monocystis described from the diverse Japanese Amynthas earthworms and the first from East Asia. Monocystis perplexa was found in every population of A. agrestis surveyed in Vermont, always reaching 100% prevalence by late summer (the host has an annual life cycle in Vermont). The 18S gene sequence differed from that of Monocystis agilis from the sympatric earthworm Lumbricus terrestris (the only other sequence available for Monocystis), and a genetic similarity tree places them closest among other gregarines. Many of the 95 described species of Monocystis are very similar in morphology (based on species descriptions), so the 18S gene can act as a barcode for Monocystis species and thus will help to eliminate both synonymies and reveal cryptic species.

Monocystis perplexa ñ。从佛蒙特州的一个站点描述了一种在北美重要的日本入侵worm Amynthas agrestis的寄生虫。提出了一种改进的单囊藻物种描述标准，包括减少同义词的标准命名法，活细胞的生物特征和形状描述的标准集以及18S rRNA的DNA基因组序列（约1,700个碱基对）。比较同胞earth物种中单胞藻寄生虫的形态，表明在研究区域，多年生支原体对A. agrestis具有特异性。此外，聚合酶链式反应的引物特异于M. perplexa从日本几个地点采集的Agrestis worm的扩增样品。这表明寄生虫来自日本，侵入性的起源进入北美Amynthas蚯蚓，因而M. perplexa将是第一个Monocystis从不同的日本描述Amynthas蚯蚓和来自东亚第一。在佛蒙特州进行调查的每个A. agrestis种群中都发现了单囊藻，到夏末时该病的患病率始终达到100％（寄主在佛蒙特州的生命周期为一年）。的18S从不同的基因序列Monocystis AGILIS从同域蚯蚓蚯蚓（可用于唯一的其他序列Monocystis）和遗传相似度树形地方他们的其他gregarines中最接近的一次。在描述的95种单胞藻物种中，有许多在形态上非常相似（基于物种描述），因此18S基因可以作为单孢藻物种的条形码，从而有助于消除同义性并揭示隐性物种。