We currently have a name-mapping from NCBI that looks like:
| NCBI |
GTDB |
| Aphanizomenon flos-aquae (×15) |
Dolichospermum flosaquae |
| Aphanizomenon flos-aquae (×3) |
Dolichospermum heterosporum |
| Dolichospermum flos-aquae (×1) |
Dolichospermum planctonicum |
| Dolichospermum flos-aquae (×1) |
Dolichospermum lemmermannii (representative) |
| Dolichospermum flos-aquae (×1) |
Dolichospermum heterosporum |
At the core of the problem is this:
- Ap. flos-aquae and D. flos-aquae (= Anabaena flos-aquae) are two different morphospecies (See Rajaniemi05)
- Ap. flos-aquae falls in the Dolichospermum clade (Also see Rajaniemi05)
This problem isn’t unknown: the article creating Dolichospermum (Wacklin09) acknowledges that the new genus is not monophyletic, but argues that taking “unique and distinct” subgroups like Aphanizomenon out into small genera is okay on p63.
(Yes, the GTDB tree display for s__Dolichospermum flosaquae does link to the LPSN page describing the Wacklin name.)
What can be done? Well…
- It’s preferable if most NCBI D. flos-aquae are called GTDB D. flosaquae. GTDB can do that by renaming one of the clusters… but which? Three are equally plausible if we only look at genomes…
- If GTDB D. flosaquae becomes something else, NCBI Aphanizomenon flos-aquae has to take on another specific epithet in GTDB. There are like 4 later synonyms of Ap. flos-aquae to choose from (the 1888 one is invalid).
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Hello,
Thanks for your request.
Cyanobacterial taxonomy is a special case due to its historical affiliation with algae and we are aware that many genera and species are still separated based on ‘morphological markers’. In addition, we are still missing majority of type strains from ex-holotypes, therefore, we cannot be 100% sure if currently applied names are indeed applied to the correct taxon. We do our best with information we have from NCBI and other public resources. Please note that our taxonomy is based on phylogeny and current classification supports union of Aphanizomenon and Dolichospermum into one genus.
“* It’s preferable if most NCBI D. flos-aquae are called GTDB D. flosaquae. GTDB can do that by renaming one of the clusters… but which? Three are equally plausible if we only look at genomes…”
There is only one species cluster in GTDB with this name. If anything needs to be renamed in NCBI, we should let them know and provide published evidence. I agree that they should delete the ‘-’ in this name…
“* If GTDB D. flosaquae becomes something else, NCBI Aphanizomenon flos-aquae has to take on another specific epithet in GTDB. There are like 4 later synonyms of Ap. flos-aquae to choose from (the 1888 one is invalid).”
If it becomes “something else,” we hope that it will be published and we will follow the proposed nomenclature. The epithet would only change if the species is merged with another species that has an earlier specific epithet…
Hope this helps!
Best wishes,
Masha
Hello,
The issue mentioned here is well known in then field. It has been addressed most recently in Dreher et al. Harmful Algae 103 (2021) 102005 using phylogenomics and not morphological characters.
This paper establishes that Aphanizomenon flos-aquae falls within the same genus as Dolichospermum, and that almost any of the establish specific epithets are not monophyletic, including D. lemmermannii.
Many nomenclature changes will be needed. A group of us is in midst of sequencing 100+ genomes selected to fill gaps in the ADA clade/genus.
It’s best to await such a comprehensive result so that subsequent taxonomic adjustments won’t be necessary. For the time being, it’s best for GTDB to avoid using any established species names, and just use the strain number of a reference genome.
Theo Dreher
theo.dreher@oregonstate.edu
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Hi Theo,
Thanks for your comments!
It is great to hear that you are going to add new genomes to resolve the taxonomy of that clade.
At the moment, we are doing our best with information we have to apply cyanobacterial names.
Looking forward to your paper and improved cyano’s taxonomy/nomenclature!
Best wishes,
Masha