Last year this was published:
Genetic analysis reveals Finnish Formica fennica populations do not form a separate genetic entity from F. exsecta.
Sanja Maria Hakala, Perttu Seppä, Maria Heikkilä, Pekka Punttila, Jouni Sorvari, Heikki Helanterä.
https://peerj.com/articles/6013/
or
https://peerj.com/articles/6013.pdf and supplemental files
But here is the reaction of...… B. Seifert:
The Rubens morph of Formica exsecta Nylander, 1846 and its separation from Formica fennica Seifert, 2000 (Hymenoptera, Formicidae).
https://dez.pensoft.net/article/34868/
or
https://dez.pensoft.net/article/34868/download/pdf/305045
