First, I need to apologize since this swap was probably caused by the discussion here: https://www.inaturalist.org/observations/19989732 -- and I did not suspect that an immediate action will follow.

Secondly, the issue seems not to be that easy. Probably it is reasonable to ask (and somehow answer) the following questions:

1) Are the taxa ichnea (Boisduval, [1833]) and intermedia (Menetries, 1859) really synonymous? If yes, what should be the valid name?

2) (similar to 1 but not quite the same) Are European (Alps) and Asian populations of the entity in question belong to the same species?

For question 1, notice that ichnea is older. However, I recall reading somewhere that ichnea is treated as a nomen nudum. I will try to locate the source. If this is "true", than obviously not all researchers follow this.

Some examples from the literature. In Tscikolovets et al, 2009, Butterflies of Altai, Sayans and Tuva, the valid name is ichnea Boisd. (type locality: "Le nord de la Lapponie et de Siberie"); intermedia Men. (with the type locality "Khotoum" -- I assume this is also in Siberia) is under synonyms. The general distribution is given as "Alps, Urals, temperate Asia" (so here the answer to my question 2 is also yes).

On the contrary, in Tscikolovets, 2011, Butterflies of Europe and Mediterranean, the valid name is intermedia! The general distribution is the same -- "Alps, Urals, temperate Asia"... So either he changed his mind, or just tried to be "good" to his mostly European readers this time.

Probably it is unreasonable to provide here the names usage in all the literature (available to me), but it seems that intermedia as a valid name prevails in European publications, while in modern Asian ichnea prevails.

If I will find any useful information (eg. why an older name ichnea at least CAN be treated as a synonym to intermedia) I will post it here.

OK, something is getting clearer (at least to me :)).

This is from Gorbunov, 2001, Butterflies of Russia, p. 170: "Melitaea ichnea was described by Boisduval from material from Lapland and northern Siberia as a species intermediate between maturna and cynthia. Later Boisduval's name was synonymized with either cynthia (Staudinger, 1861, 1871, Higgins, 1950, etc.) or intermedia (Ershov, Field, 1870, Staudinger, 1901, Korshunov, 1996, Tuzov etal., 2000). The former identification with cynthia seems to me unacceptable since this Alpine species is absent from both Lapland and Siberia. The only species of Euphydryas known simultaneoulsy from extreme North of Europe and from Siberia is iduna, which is absent from the iconography by Boisduval (1832). Both his picture and description do not contradict with identification of ichnea with iduna rather than with intermedia."

My comments:

1) Of course those who synonymize ichnea with intermedia use ichnea (the older name) as valid. On the contrary, those who synonymize ichnea with iduna, use iduna as valid, since iduna is the oldest of all three names in question. So under the latter point of view ichnea goes to synonyms of iduna, and Gorbunov in particular follows this approach.

2) It seems that Boisduval's description is indeed inadequate since it does not unambigously point to a particular species (i.e. ichnea can indeed be treated as a nomen nudum!). Moreover, Gorbunov's arguments concerning the type locality seems reasonable, and if one wants to apply Boisduval's name to a species, this should be iduna, and not the species we are discussing now (since it is absent from Lapland -- or at least there are no reliable records).

Summarizing, I would prefer to use the name intermedia instead of ichnea here. Notice that my arguments are not of "political correctness", but rather of scientific (or taxonomic, if you prefer not to call it science :)) nature.

@sunwenhao90 Could you please consider this and comment about your thoughts and opinion?

@kharkovbut I apologize for this arbitrary change made by me and thanks for the helpful discussion from you and @chrisvanswaay. These discussions make things clearer and I will recover the status of E. intermedia based on the facts we have here.

@sunwenhao90 Thank you!