Aphelids (Aphelida) are intracellular parasitoids of algae and represent one of the early diverging or sister lineages of the kingdom Fungi. Although Aphelida is a small group, molecular phylogenetic analyses revealed that many environmental sequences belong to Aphelida, suggesting that aphelids are distributed worldwide; however, the extent of their diversity is unclear. Here, we investigated a novel aphelid culture APH2 that parasitizes the green alga Coccomyxa sp. APH2 produced posteriorly uniflagellate zoospores, a defining character of the genus Aphelidium. The residual body of APH2 was spherical in the mature plasmodium, but became amorphous during zoospore formation and collapsed after zoospore discharge, which has not been described for other Aphelidium species. Zoospores of APH2 possessed a striated rhizoplast that extended anteriorly from the kinetosome to the posterior end of the nucleus, and a microtubular root arising from the side of the kinetosome and lying almost parallel to the rhizoplast, both of which are unique among aphelid taxa. A molecular phylogenetic analysis based on the 18S rDNA sequences placed APH2 as sister lineage to all other known aphelid sequences. Based on these results, we describe this aphelid as a new species, Aphelidium collabens.

苯丙胺（Aphelida）是藻类的细胞内寄生物，代表真菌界的早期发散或姊妹谱系之一。尽管Aphelida是一小群，但分子系统发育分析表明，许多环境序列都属于Aphelida，这表明甲壳类动物分布在全世界。但是，它们的多样性程度尚不清楚。在这里，我们研究了一种新型的将绿色藻类Coccomyxa sp寄生化的苯丙氨酸文化APH2 。APH2产生后单鞭毛游动孢子，这是无头孢属的定义特征。APH2的残留体在成熟的疟原虫中呈球形，但在游动孢子形成过程中变为无定形，在游动孢子放电后塌陷，这在其他A虫中均未见报道。种类。APH2的游动孢子具有横纹状的根状体，从动子体向前延伸到细胞核的后端，还有一个微动的根部，从动子体的侧面伸出，几乎平行于根际，这两者在阿弗利德类群中都是独特的。基于18S rDNA序列的分子系统发育分析将APH2作为所有其他已知的苯丙氨酸序列的姐妹谱系。根据这些结果，我们将这种甲壳虫描述为一个新物种，即Aphelidium collabens。