Unexpected cryptic species among streptophyte algae most distant to land plants

Streptophytes are one of the major groups of the green lineage (Chloroplastida or Viridiplantae). During one-billion-years of evolution, streptophytes have radiated into an astounding diversity of uni- and multicellular green algae as well as land plants. Most divergent from land plants is a clade formed by Mesostigmatophyceae, Spirotaenia spp., and Chlorokybophyceae. All three lineages are species-poor and the Chlorokybophyceae consist of a single described species, Chlorokybus atmophyticus. In this study, we used phylogenomic analyses to shed light into the diversity within Chlorokybus using a sampling of isolates across its known distribution. We uncovered a consistent deep genetic structure within the Chlorokybus isolates, which prompted us to formally extend the Chlorokybophyceae by describing four new species. Gene expression differences among Chlorokybus species suggest certain constitutive variability that might influence their response to environmental factors. Failure to accou...

链型植物（Streptophytes）是绿色演化支（叶绿体植物门Chloroplastida 或 Viridiplantae）的主要类群之一。历经十亿年的演化历程，链型植物辐射演化出种类繁多的单细胞与多细胞绿藻以及陆生植物。其中与陆生植物差异最为显著的演化支由中杆藻纲（Mesostigmatophyceae）、转板藻属（Spirotaenia）物种以及被孢藻纲（Chlorokybophyceae）构成。这三个类群均物种贫乏，其中被孢藻纲仅包含1个已描述物种——陆生被孢藻（Chlorokybus atmophyticus）。本研究通过系统发育基因组学分析（phylogenomic analyses），对陆生被孢藻已知分布范围内的分离株进行采样，以阐明该类群内的多样性。我们在陆生被孢藻分离株中发现了稳定的深层遗传结构，这一结果促使我们正式修订扩充被孢藻纲，描述4个新物种。陆生被孢藻各物种间的基因表达差异表明存在特定的组成型变异，这类变异或可影响其对环境因子的响应。若未能充分考量……