The genome sequences of 16 Nostocales cyanobacteria have been determined. Most of them are complete or near-complete genome sequences derived by long-read metagenome sequencing of recent harmful algal blooms (HABs) in freshwater lakes without the potential bias of culture isolation. The genomes are all members of the recently recognized ADA clade (Driscoll et al., Harmful Algae, 77:93, 2018), which we argue represents a genus. We identify 10 putative species-level branches within the clade, on the basis of 91-gene phylogenomic and average nucleotide identity analyses. The assembled genomes each correspond to a single morphotype in the original sample, but distinct genomes from different HABs in some cases correspond to similar morphotypes. We present data indicating that the ADA clade is a highly significant component of current cyanobacterial HABs, including members assigned to the prevalent Dolichospermum and Aphanizomenon genera, as well as Cuspidothrix and Anabaena. In general, currently used genus and species names within the ADA clade are not monophyletic. We infer that the morphological characters routinely used in taxonomic assignments are not reliable for discriminating species within the ADA clade. Taxonomic revisions will be needed to create a genus with a single name (we recommend Anabaena) and to adopt species names that do not depend on morphological traits that lack sufficient discrimination and specificity, while recognizing the utility of some easily observable and distinct morphologies.

已经确定了16个诺氏藻蓝细菌的基因组序列。它们中的大多数是完整的或接近完整的基因组序列，这些序列是通过对淡水湖中最近有害藻华（HAB）进行长时间阅读的元基因组测序而得出的，而没有潜在的培养物分离偏见。基因组是最近被认可的ADA进化枝的所有成员（Driscoll等人，Harmful Algae，77:93，2018），我们认为这代表了一个属。我们根据91基因的植物遗传学和平均核苷酸同一性分析，在进化枝中鉴定出10个假定的物种水平分支。组装后的基因组每个都对应于原始样本中的单个形态型，但是在某些情况下，来自不同HAB的不同基因组则对应于相似的形态型。Dolichospermum和束丝属，以及Cuspidothrix和鱼腥。通常，ADA进化枝中当前使用的属和种名不是单系的。我们推断，在分类任务中常规使用的形态特征对于区分ADA进化枝中的物种并不可靠。需要进行分类学修订，以创建一个具有单个名称的属（我们建议鱼腥藻），并采用不依赖于缺乏足够辨别力和特异性的形态特征的物种名称，同时要认识到一些易于观察和区分的形态的效用。