As a large majority of modern green algae are freshwater rather than marine, it can be hypothesized that algae were an important component of early terrestrial environments. However, this component remains overlooked as algal affinities are difficult to decipher, due to the lack of distinctive characters observable in standard light microscopy. Herein, we use a new approach to studying microfossils from the Devonian (407 Ma) Rhynie cherts, renowned as one of the earliest exceptionally preserved terrestrial ecosystem. Using data from confocal laser scanning microscopy, the microfossils were reconstructed in 3D allowing us to gather information on morphological and physiological traits. We document Triskelia scotlandica gen. et sp. nov., which is the resting stage of a new species of microalgae. Numerous individuals were discovered preserved inside the remains of a flooded plant aerial axis. They are shown to be spheroidal to ellipsoidal walled cells, with a pseudo‐reticulate surface ornamentation and occasional large openings probably resulting from the germination process. We draw comparison with fossil and modern microorganisms demonstrating morphological convergences in wall ornament and physiological traits, especially with zygospores of modern Chlorophyta. Our description of Triskelia leads us to critically evaluate the Rhynie chert fossils Cymatiosphaera and Pterospermella. We conclude that it is unlikely that the Rhynie cherts contained prasinophycean algae of these types. We suggest that our microfossils are Chlorophyta (green algae) incertae sedis that were highly adapted to the special ecological conditions encountered in a geothermal wetland.

中文翻译：

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早期陆地环境中被忽视的水生绿色藻类成分：Triskelia scotlandica gen。等 十一月 来自Rhynie cherts

由于绝大多数现代绿藻是淡水而不是海洋，因此可以假设藻类是早期陆地环境的重要组成部分。然而，由于缺乏在标准光学显微镜下可观察到的独特特征，藻类的亲和力难以解读，因此该组分仍然被忽略。在这里，我们使用一种新的方法来研究泥盆纪（407 Ma）Rhynie cherts的微化石，该物种被誉为最早的保存完好的陆地生态系统之一。利用共聚焦激光扫描显微镜获得的数据，以3D方式重建了微化石，使我们能够收集有关形态和生理特征的信息。我们记录Triskelia scotlandicagen。等 十一月，这是一个新的微藻物种的休息阶段。发现许多人被保存在被淹没的植物空中轴的遗骸内。它们显示为球形到椭圆形壁细胞，具有伪网状表面装饰，发芽过程中偶尔可能会出现大的开口。我们与化石和现代微生物进行比较，这些微生物在壁饰和生理特性上表现出形态学上的趋同，特别是与现代绿藻的合子孢子。我们对Triskelia的描述使我们严格评估Rhynie chert化石Cymatiosphaera和Pterospermella。我们得出的结论是，Rhynie cher石不可能包含这些类型的藻类藻类藻类。我们建议，我们的微化石是绿藻（intestae sedis），非常适应地热湿地中遇到的特殊生态条件。