(Fig. 9)
Gigantalcis flavolinearia: Beljaev & Mironov 2019: 244 (Sakhalin); Vasilenko & Dubatolov 2021: 256 (Yasnomorskoe).
Material examined. 5 ♂, 1 ♀, S Kholmsk, 11, 12, 13, 15.IX.2017; 1 ♂, S Kholmsk, 14.IX.2022.
Distribution. Russia (S RFE: SW Sakhalin, S Kurils—Kunashir (Rybalkin 2020)), Japan (Hokkaido, Honshu, Shikoku, Kyushu).
Remarks. The finding of G. flavolinearia in Sakhalin significantly expands its general distribution range to the north. The host plants of the species in Japan are woody Rosaceae (Cerasus, Malus, Sorbus) (Sato 2011), which are common in S Sakhalin. The moths fly during September. Genus Gigantalcis Inoue contains only two species, distributed far apart from each other: G. flavolinearia (the type species of the genus) and G. gomphica (Wehrli), distributed in N and SW China (Shaanxi, Sichuan), and northern Laos (Sato 2017).