Identifying features
Wingspan 36–44 mm. The upper side of the wing is yellowish-brown with a somewhat diffuse pattern of large black spots, which means that many specimens are very dark on the upper side. The underside of the hindwing is less contrasting than in the other Boloria species. It is brown or yellowish-brown with a greenish-yellow transverse band in the inner half, and lacks entirely white or silvery-white spots.
Similar species
No competing species have been described for the species handbook; the species is characterised by the subtly coloured underside of the hindwing, which lacks any white or silvery-white markings. Frigga Fritillary exhibits an underside pattern that may resemble that of Thor’s fritillary.
Distribution
Northern Europe, the Alps, and mountain ranges in Russia from Kamchatka to Japan. Locally quite common from Dovre through eastern parts of Trøndelag, Nordland, and Troms, to Alta in Finnmark.
Biology
The larvae live on violets (Viola), most likely primarily on mountain violet. It is black with yellowish branched thorns and brownish-yellow longitudinal stripes. It grows to 33 mm and overwinters twice.