ABSTRACT

Until recently, there was no agreement on species delimitation within the morphologically similar chrysophycean genera Uroglena, Uroglenopsis and Urostipulosphaera. In this study, we aimed at a modern taxonomic revision based on the combination of morphological characters (ultrastructure of cysts, cell and colony features) and a multigene phylogeny (SSU, ITS rDNA and rbcL sequences), with ecology taken into account. Of more than 650 explored localities, only approximately one in 10 hosted a viable and detectable population of these colonial chrysophytes at the time of sampling. We established and examined 189 short-term cultures along with single colony isolates, derived mostly from blooming or encysting populations. We obtained the cyst morphology for four species and two lineages of Uroglena, two species of Uroglenopsis, and four species of Urostipulosphaera. A total of 12 resolved lineages could be attributed to previously described species or new species (Uroglena imitata sp. nov., Urostipulosphaera granulata sp. nov.). Based on our molecular analyses and morphological observations, we assign all the previously described Uroglena-like taxa to newly recognized genera and propose a key to identification. Consequently, Uroglena now includes 16 species and two varieties, Uroglenopsis contains four species and Urostipulosphaera encompasses nine species. Within Uroglena and Urostipulosphaera, species are defined by the ultrastructure of their cysts. On the contrary, as Uroglenopsis has simple cysts, species are defined by cell and colony characteristics.

摘要

直到最近，在形态相似的金藻属Uroglena、Uroglenopsis和Urostipulosphaera内的物种划分还没有达成一致意见。在这项研究中，我们旨在基于形态特征（囊肿的超微结构、细胞和集落特征）和多基因系统发育（SSU、ITS rDNA 和rbcL 序列），考虑到生态学。在 650 多个已探索的地点中，只有大约十分之一在采样时拥有这些殖民地金植物的可行且可检测的种群。我们建立并检查了 189 种短期培养物以及单菌落分离物，这些分离物主要来自开花或包囊种群。我们获得了Uroglena 4种和2个谱系、Uroglenopsis 2种和Urostipulosphaera 4种的孢囊形态。共有 12 个已确定的谱系可归因于先前描述的物种或新物种（Uroglena imitata sp. nov., Urostipulosphaera granulatasp。十一月）。基于我们的分子分析和形态学观察，我们将所有先前描述的Uroglena样分类群分配给新识别的属，并提出鉴定的关键。因此，Uroglena现在包括 16 个物种和两个变种，Uroglenopsis包含 4 个物种，Urostipulosphaera包含 9 个物种。在Uroglena和Urostipulosphaera中，物种由其包囊的超微结构定义。相反，由于Uroglenopsis具有简单的囊肿，因此物种由细胞和菌落特征定义。