Dear @zebs,
Please, cancel this taxon split immediately and hence restore identifications of Sympetrum frequens from Russia!
I don't know what you were based, but:

In the extreme south-east of Russia, in the coastal southern Primorye, we definitely have two well differing species, depressiusculum and frequens. This is well published:
https://pisum.icgbio.ru/kosterin/pdf/idf_report_177_far_east.pdf
This does not contradict at all the concept that S. frequens is a Japanese species, since our indifiduals of S. freqauens could migrate from Japan, which is very close, and may not comprise
ise a local population. S. frequens is known to be highly migratory speces.
There is Kunashir Island close to the north-east side of Hokkaido. This is currently in Russia but belongs to the Japanese Archipelago. It is inhabited by the genuine S. frequens, which you have now misidentified as "S. depressiusculum".
Thank you in advance,
Oleg