I do not want to agree with @heinerziegler without independently verifying the observations. This includes looking at literature. I know that it is found in Welhri, 1941, but I cannot seem to find the source. The main quandary is that I cannot find any other reliable sources at all that accurately describes in detail what Biston betularia alexandrina looks like. The only other website that has pictures of this particular subspecies contains @heinerziegler’s pictures, euroleps. (Warning! The website is not https!)
Has anyone else been in this situation where they encounter an observation of something that cannot be verified independently, either by pictures from other sources, or by literature?
This type of situation occurs fairly frequently for areas and groups that lack an abundance of literature (try IDing central African moths for example).
If you agree with the species, but can’t confirm the subspecies, best to just leave an ID at the species level. When you make that ID don’t select that you disagree with the observers ID. This will confirm the species (and lead to a RG observation for the species), while leaving the subspecies unconfirmed.
You can also ask the observer for more information. In this case, it seems that they may be a specialist in this taxon, and might well be very happy to explain what makes these observations alexandrina to someone who has taken an interest.
I’m not making any commentary on this particular observation, but there are a significant number of subspecies level identifications done on the site solely based on range as documented in some external source. To my mind, those in particular require extra care and scrutiny.
To be precise, since the iNaturalist pop-up is misleading, click the green button that says “I don’t know, but I am sure this is Biston betularia” if you don’t want to explicitly disagree with the other user’s subspecies ID.
