Any thoughts or concerns regarding this taxon swap, @dhobern @hkmoths @hughmcguinness @jasondombroskie?

Not sure how to handle the general treatment of Deltote / Protodeltote across the Holarctic Region...

in Hong Kong there is Protodeltote distinguenda, so I'll need to check publications as to the correct use of Deltote R.L. [Reichenbach], 1817 and Protodeltote Ueda, 1984- If I recall correctly they're distinct genera, not synonyms, and are separate on the Moths of Japan website, as well as the MPG website.
As to the placement of pygarga..... that requires further searching, too. On MoJ, pygarga is placed in Protodeltote. http://www.jpmoth.org/Noctuidae/Acontiinae+Eustrotiinae/Protodeltote_pygarga.html

There is evidence in Lafontaine & Schmidt, 2010. Annotated check list of the Noctuoidea (Insecta, Lepidoptera) of North America north of Mexico
ZooKeys 40: 1–239 (2010). (doi: 10.3897/zookeys.40.414). See notes 216 & 217 (appended here)

216 Deltote bellicula - Generic combination from Ueda (1984).
217 Protodeltote Ueda - Ueda’s (1984, 1987) revision of the Deltote R. L. [the name of the author “R. L.” is unknown] group of genera was restricted to the fauna of Japan and Taiwan, although the North American species Lithacodia bellicula was included because it is the type-species of Lithacodia Hübner, a synonym of Deltote R. L. Th e valves of “Lithacodia” muscosula (Guenée) and “L.” albidula (Guenée) are similar to those of Deltote bellicula, but the wing pattern and vesica characters are similar to those of the Eurasian species “Lithacodia” pygarga (Hufnagel, 1766), which Ueda (1984) made the type-species of Protodeltote Ueda, so these two North American species are transferred to Protodeltote as P. muscosula (Guenée), comb. n. and P. albidula (Guenée), comb. n.

So that was the state of play in 2010.

In 2015 there was a review of Chinese species of Deltote (abstract at - http://mapress.com/zootaxa/2015/f/z04007p587f.pdf)
Reading between the lines, this publication regards Protodeltote as valid, and as there is no mention of pygarga I assume it was considered combined with Protodeltote.

I can't find any other recent relevant publications. Looks like the European listers may need bringing up to speed on this one. So for now, I would recommend using Protodeltote pygarga rather than Deltote pygarga. I will ask Martin Honey, retired (ex BMNH) Noctuid specialist and see what his opinion is. Will report back as and when.

We should await advice from noctuid specialists (I have asked already).
Just because something is commonly used does not necessarily mean it is taxonomically correct.
I don't know what the correct answer is, but on the limited evidence available, Protodeltote looks to be the correct placement.
Incidentally, GBIF has entries for both combinations!

In Europe, from the map above for GBIF data, there appears to be no consensus of binomial combination by country:

European GBIF data for Deltote pygarga:
UK, France, Austria, Germany, Denmark, Norway, Sweden, Finland, Russia, Italy, Switzerland

European GBIF data for Protodeltote pygarga:
Ireland, UK (Wales, Cornwall, N. Ireland), France, Spain, Portugal, Netherlands, Belguim, Switzerland, Austria, Italy, Denmark, Sweden, Germany, Slovakia, Bulgaria, Belarus, Finland, Georgia, Estonia, Latvia, Russia

hmm !

that's due to politics - ecology and taxonomy doesn't attract many people due to relatively poor pay. Pay is better in jobs that are at odds to the survival of life (including Homo sapiens) on earth - developers, builders, engineers, finance...... and because of that, vested interests do not support ecology and taxonomy as they are perceived as counter to "development" industries.
So where there is a need to still provide a baseline inventory of life on earth, the "powers that be" decide this isn't a need and conflicts with their personal greed, so doesn't get funded.

reply from Martin Honey
from p. 61 of the above "The type-species of the taxon Protodeltote Ueda, 1984, pygarga (Hufnagel, 1766) shares all apomorphies with Deltote, although in different character states, so Protodeltote is downgraded to subgenus level, revised status".
so all species previously considered under Protodeltote should new be referred to in Deltote (Protodeltote).
I'll get on to it with the iNat database.
@jakob - please go ahead and commit your taxon change.

According to Fibiger et al. (2009) [Noctuidae Europaeae Volume 11] and Fibiger et al. (2011) [Check List of the Quadrifid Noctuoidea of Europe, in Noctuidae Europaeae Volume 13] in Europe there are 4 species of Deltote with two subgenera:
Deltote (Protodeltote) pygarga
Deltote (Deltote) deceptoria
Deltote (Deltote) uncula
Deltote (Deltote) bankiana