Gracillaria sapporella Matsumura, 1931: 1101. TL: Japan.

Caloptilia sapporella (Matsumura): Inoue, 1954: 26; Kumata, 1982: 79; Liu & Yuan, 1990: 183; de Prins & de Prins, 2005: 123; Bai & Li, 2012: 54.

Caloptilia rhodinella (Herrich-Schäffer): Esaki et al., 1957: 29. Misidentification.

Diagnosis. This species is similar to C. sapporella on the forewing patterns, but can be distinguished from the latter by the yellow pattern on forewing extending to near apex on costa, the valva dilated on distal part and the phallus having about 14−15 cornuti. In C. sapporella, the yellow pattern on forewing extends to 3/4 on costa, the valva is almost parallel-sided on the distal part and the phallus lacks any cornutus in the male genitalia.

Description. Adult. Wingspan 10.3 mm. Head, face and thorax yellowish white and light brown between two antennae. Maxillary palpus yellowish white, with white end. Labial palpus yellowish white, 3rd segment white with dark brown apex. Scape yellowish white, slightly dark brown at base; flagellum yellow, with brown rings dorsally. Fore legs dark brown, with inner side white except tarsus; mid legs dark brown, femur and tibia covered with long scales; fore and mid tarsus white and end of each segment brown; hind legs yellowish white, base of coxa and end of femur dark brown, gray on end of tibia, second to fourth tarsal segments slightly brown at end. Tegula and forewing brown with purple luster. A rectangle lemon yellow spot occupying basal 1/4 of dorsum, slightly narrower than half of wing width; a lemon-yellow spot occupying costal 1/4 to 7/8, widest in middle of wing, about 3/4 width of wing, with 3–5 dark brown dots on costa; cilia on termen light brown, with 2–3 dark brown lines, cilia on dorsum gray. Hindwing and cilia gray.

Male genitalia. Tuba analis with a linear sclerotization with unclear boundary. Tegumen slightly dilated apically, both sides densely setose. Valva reniform, dorsal and ventral margin obviously depressed, with distal part remarkably enlarged and covered with long setae, apical margin densely covered with short setae. Vinculum + saccus V-shaped, narrow and long. Phallus short, with about 14−15 cornuti inside, a larger hook-like thorn on apex.

Material examined. Shandong: 1♂, Yaoxiang National Nature Reserve, Jinan, 36.328°N, 117.122°E, 700m, 2017.VI.14, leg. Tengteng Liu, Zhenquan Gao & Nan Wang, genitalia slide no. LIU0038, registration no. SDNU. Ent 170088.

Host plant. Quercus mongolica Fisch et Ledeb., Q. dentata Thunb., Q. serrata Thunb., Q. acutissima Carr., Q. cerris Linn., Castanea crenata Sieb. et Zucc. (Liu & Yuan, 1990) (Fagaceae).

Distribution. China (Anhui, Beijing, Gansu, Guizhou, Henan, Heilongjiang, Hunan, Jilin, Jiangxi, Ningxia, Shandong, Shanxi, Tianjin, Yunnan, Zhejiang) (Liu & Yuan, 1990; Bai & Li, 2012), Korea (Park, 1983), Japan (Kumata, 1982), Russian Far East (Sinev, 2019).