Cerastium fontanum vs. Cerastium holosteoides
Due to a taxon change, the very common subspecies Cerastium fontanum subsp. vulgare was elevated to species status and given the name Cerastium holosteoides.
Previously, many observations of this subspecies were only made on species status (Cerastium fontanum). This was also correct until then.
With the taxon change, the observations identified up to the subspecies Cerastium fontanum vulgare were automatically given the name Cerastium holosteoides.
However, Cerastium fontanum only identified to the species level is still called Cerastium fontanum and is now automatically incorrect in most cases, as Cerastium fontanum s.str. is an alpine species that does not occur in many countries.
An additional problem is that in many countries the old nomenclature still prevails in the identification books and indexes. As a result, the name C. fontanum is still frequently used incorrectly for the common species.
The challenge now is to re-identify as many Cerastium fontanum as possible. This is quite difficult because in many areas there are other similar species. (e.g. Cerastium lucorum; Cerastium semidecandrum, Cerastium dubium u.a.).
As a result, the identifier may only be able to confirm the genus Cerastium or the Komplex Cerastium fontanum, causing the observation to revert to genus or Complex level. If you think it is the common Cerastium species you should correct the name to Cerastium holosteoides.
It would be nice if someone could be found in the individual countries where this problem exists to help re-identify the observations of Cerastium fontanum.
If Cerastium fontanum disappears as a species name from many areas, it will no longer be suggested by the AI and Cerastium holosteoides will be suggested instead. It would also be important to update the common names of C. fontanum and C. holosteoides to prevent mis-selection.
Comments
thanks for this helpful summary, Wolfgang!
Thanks for this. Is there an illustrated key to differentiate these species?
Hello @jasongrant There is a key with photos at blumeninschwaben. http://www.blumeninschwaben.de/Zweikeimblaettrige/Nelkengewaechse/fontanum_agg.htm
However, it is not possible for me to distinguish the 2 species with certainty by means of this key.
My main criterion is the distribution, because C. fontanum s.str. is an alpine species which occurs according to Infoflora "pastures, Lägerstellen / (subalpine-)alpine / GR, scattered AN and VS".
Do you have a link to a publication giving more informations on this change ?
@plantoine sorry, I don't have that at hand.
iNat just follows POWO here https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:920635-1
In some excursion floras this nomenclature is also followed, like the German Rotmahler and Schmeil-Fitschen. I don't know when this taxon change was made at iNat. I think it was some time ago. I myself was only made aware of it by @karsten_s, since my observations were also misnamed. My intention is to support karsten in his ambitious task to review the Cerastium fontanum observations. I hope to find a few more comrades-in-arms. :-)
Thanks for the info on this species. This issue with elevated subspecies has happened a lot in the past 10 years with all the recent molecular work.
@plantoine the species page of POWO is giving an overview of all synonyms incl. the reference literature for these synonyms.
POWO Cerastium holosteoides page, for example:
@epsilon has already posted the link to the species page of for the last one which also gives some literature.
Thanks for this.
I also want to mention the poorly known Cerastium dubium (=Dichodon viscidum) that's basicaly Cerastium fontanum vulgare with glandular hairs in inflorescence
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