Thick-walled rosette-like snow algae were long thought to be a life stage of various other species of snow algae. Rosette-like cells have not been cultured, but by manually isolating cells from 38 field samples in southern British Columbia, we assigned a variety of rosette morphologies to DNA sequence. Phylogenetic analysis of Rubisco large-subunit (rbcL) gene, ribosomal internal transcribed spacer 2 (ITS2) rRNA region, and 18S rRNA gene revealed that the rosette-like cells form a new clade within the phylogroup Chloromonadinia. Based on these data, we designate a new genus, Rosetta, which comprises five novel species: R. castellata, R. floranivea, R. stellaria, R. rubriterra, and R. papavera. In a survey of 762 snow samples from British Columbia, we observed R. floranivea exclusively on snow overlying high-elevation glaciers, whereas R. castellata was observed at lower elevations, near the tree line. The other three species were rarely observed. Spherical red cells enveloped in a thin translucent sac were conspecific with Rosetta, possibly a developmental stage. These results highlight the unexplored diversity among snow algae and emphasize the utility of single-cell isolation to advance the centuries-old problem of disentangling life stages and cryptic species.

中文翻译：

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罗塞塔一代十一月（绿藻）：解析红雪藻莲座丛的身份

厚壁莲座状雪藻长期以来被认为是各种其他雪藻种类的生命阶段。玫瑰花状细胞尚未培养，但通过从不列颠哥伦比亚省南部的 38 个现场样本中手动分离细胞，我们将各种玫瑰花结形态分配给 DNA 序列。 Rubisco 大亚基 ( rbc L) 基因、核糖体内转录间隔区 2 (ITS2) rRNA 区域和 18S rRNA 基因的系统发育分析表明，玫瑰花状细胞在系统群 Chloromonadinia 内形成了一个新的进化枝。根据这些数据，我们指定了一个新属，Rosetta，它包含五个新种：R.castellata、R.floranivea、R.stellaria、R.rubriterra和R.paavera。在对不列颠哥伦比亚省 762 个雪样本的调查中，我们仅在高海拔冰川上的雪上观察到了R. floranivea ，而在较低海拔、靠近林线的地方观察到了R.castellata 。其他三个物种很少被观察到。包裹在薄薄的半透明囊中的球形红细胞与罗塞塔同种，可能是一个发育阶段。这些结果强调了雪藻之间未经探索的多样性，并强调了单细胞分离的实用性，以推进解开生命阶段和神秘物种的数百年历史的问题。