Abstract—

This article discusses the system of green microalgae of the clade Parachlorella, based on morphological, ecological, and molecular genetic data. The diagnostic characteristics of the selected genera and species and the systematic position of some taxa are discussed. Phylogenetic analysis of the Parachlorella-clade has shown that, despite the relative simplicity of morphology, it is characterized by high cryptic diversity. The polyphyletic nature of the genus Dictyosphaerium and some species (D. libertatis, D. ehrenbergianum, Compactochlorella kochii, Mucidosphaerium pulchellum, M. palustre, and Closteriopsis acicularis) was shown. Theuse of the intron as a universal criterion for closely related species was effective for representatives of groups II, IV, VII, and VIII, as well as for strains of the species Compactochlorella kochii and D. libertatis. The application of the classical CBC approach, based on the search for CBC in conservative ITS2 regions, was successful only for the representatives of group II. The results of analysis of genetic distances and the GMYC, PTP, and ABGD species delimitation algorithms are not universal tools for determining species boundaries and need to be confirmed by other characteristics (cell shape, ability to form colonies, the way the cells attach to hyaline interconnecting strands, the type of chloroplast, the number of pyrenoids, the presence of mucilage, the presence/absence of introns, the level of genetic differences, the presence of CBC in ITS1 and ITS2, the habitat). Due to the combined use of morphological, ecological and genetic features, it was possible to characterize 11 groups and 2 phylogenetic lines within the clade Parachlorella and to make assumptions about the division of genera and species within the selected groups.

中文翻译：

---

副小球藻-克拉德微藻（绿藻）的物种定界和隐性多样性分析

摘要——

本文基于形态学、生态学和分子遗传数据讨论了副小球藻进化枝的绿色微藻系统。讨论了所选属和种的诊断特征以及某些分类群的系统位置。副小球藻进化枝的系统发育分析表明，尽管形态学相对简单，但它的特点是高度隐秘的多样性。Dictyosphaerium属和一些物种（D. libertatis、D. ehrenbergianum、Compoctorella kochii、Mucidosphaerium pulchellum、M. palustre和Closteriopsis acicularis）的多系性质) 显示。使用内含子作为密切相关物种的通用标准对于 II、IV、VII 和 VIII 组的代表以及Compactochlorella kochii和D. libertatis物种的菌株是有效的. 基于在保守的 ITS2 区域中搜索 CBC 的经典 CBC 方法的应用仅对组 II 的代表成功。遗传距离分析结果和 GMYC、PTP 和 ABGD 物种定界算法不是确定物种边界的通用工具，需要通过其他特征（细胞形状、形成集落的能力、细胞附着透明质的方式）来确认相互连接的链、叶绿体的类型、蛋白核糖体的数量、粘液的存在、内含子的存在/不存在、遗传差异的水平、在 ITS1 和 ITS2 中 CBC 的存在、栖息地）。由于形态学、生态学和遗传学特征的结合使用，可以表征进化枝内的 11 个群体和 2 个系统发育谱系。副小球藻，并对选定组内的属和种划分做出假设。