Acrocercops transecta Meyrick, 1931: 169; Kuroko, 1982: 186; Kumata et al., 1988a: 59; Xu et al., 2013: 61.

Acrocercops lyoniella Kuroko, 1982: 186, 450. Synonymized by Kumata et al. (1988a).

Diagnosis. This species is closely related to A. leucophaea Meyrick, 1919, and A. defigurata Meyrick, 1928, both distributed in India, in the general forewing pattern and the male genitalia, but can be separated from the latter two species by the valva with its width at apical tooth of comb 1/6.2 to 1/6.3 length of valva based on a statistical analysis (Kumata et al., 1988a). In A. leucophaea the width of valva at the apical tooth of comb is 1/5.4 to 1/5.8 length of valva, and in A. defigurata the value is 1/7.2 (Kumata et al., 1988a).

Description. Adult. Wingspan 7.5–9.7 mm. Face and head bright white or yellowish white. Maxillary palpus white, tip black. Labial palpus smooth, inner side white, outer side yellowish white, with outer side of second segment brown. Antennae yellowish white, with smooth scape. Thorax yellowish white or white, silver white ventrally. Legs bright white, outer side of fore femur light brown, outer side of fore and mid tibiae dark gray and end of each segment of tarsus black. Forewing brown, gradually darkens to end; spots white, sometimes yellow, most of them edged with dark brown scales; a white spot bending inward from basal 1/4 of dorsum, usually not touching costa, a thin white or yellowish white stripe arising from former spot extending along dorsum to base of wing; a white transverse oblique fascia in middle, extending along dorsum to near tornus; a white spot on costa at apical 1/4, about half wing width; 5−7 white spots on apical area; cilia near apex dark brown, sometimes with a white broad line at extreme end, cilia on dorsum dark gray, white at white spot. Hindwing and cilia dark gray. Abdomen dark gray with silvery white luster dorsally, bright white ventrally.

Male genitalia. Tuba analis densely covered with micro spines. Tegumen linguiform, nearly parallel-sided, much sclerotized laterally, truncated apically, with about 7 long setae and many short setae on each side, and one long seta on both sides of apex. Valva slightly longer than tegumen, densely covered with small spines and short setae; dorsal margin slightly curved up at middle; with a comb of 56–60 teeth on apical half of valva near costa, bending towards dorsum basally; coremata at both sides of valva basally. Vinculum Y-shaped, saccus thin, about 1/3 as long as comb. Phallus about as long as valva, tubular, a sclerotized long horn apically with a minute thorn process at before its end, about 4 pairs of cornuti at crack, with distal pair bend. Eighth sternite shorter than 7th, widely cleft ventrally, dorsal apodeme about 1/2 as long as 7th abdominal segment, bilobed apically.

Female genitalia. Papilla analis densely covered with short setae. Apophysis posteriores as long as anteriores. Antrum pot-shaped, cavity and opening large; sometimes heavily sclerotized at opening, about half length of 7th abdominal segment. Ductus bursae long and membranous, with numerous micro granules; corpus bursae spherical or ellipsoid, with two signa surrounded by many lanceolate sclerites of various lengths.

Material examined. Shandong: 6♂ 2♀, Mt. Laoshan, Qingdao, 36.215°N, 120.601°E, 400 m, 2015. VII.9, leaf mines collected on Pterocarya stenoptera, emerged VII.18, leg. Tengteng Liu, genitalia slide nos. LIU15001 ♂, LIU0032 ♀, registration nos. SDNU. LS150701.1 − 8; 1♀, 1 ex. without abdomen, Mt. Laoshan, Qingdao, 36.211°N, 120.593°E, 390 m, 2017.VI.29−VII.07, leg. Tengteng Liu, Zhenquan Gao & Nan Wang, genitalia slide no. LIU0027, registration no. SDNU. Ent 170180, 290; 1 ex. without abdomen, Yaoxiang National Nature Reserve, Jinan, 36.328°N, 117.122°E, 700 m, 2016. VIII.8−9, leg. Tengteng Liu & Jiaxiang Li, registration no. SDNU. Ent 162720; 1♀, Yaoxiang National Nature Reserve, Jinan, 36.350°N, 117.103°E, 700 m, 2018. VIII.24, leaf mines collected on Pterocarya stenoptera, leg. Tengteng Liu & Zhongfeng Jiang, registration no. SDNU. Ent 001410; 4♂ 2♀, Mt. Laoshan, Qingdao, 36.211°N, 120.593°E, 390 m, 2015. VII.10, leg. Tengteng Liu, registration nos. SDNU. Ent 150084, 131, 656, 787, 822, 910; 3♀, Mt. Laoshan, Qingdao, 36.215°N, 120.601°E, 400 m, 2015. VII.8, leaf mines collected on Pterocarya stenoptera, emerged VII.22, leg. Tengteng Liu, registration no. SDNU.LS150704; 1♂, Yaoxiang National Nature Reserve, Jinan, 36.328°N, 117.122°E, 700 m, 2017.VI.14, leg. Tengteng Liu, Zhenquan Gao & Nan Wang, registration no. SDNU. Ent 170061.

Host plant. Pterocarya stenoptera (Juglandaceae).

Distribution. China (Anhui, Hainan, Hebei, Henan, Hubei, Hunan, Jiangxi, Shandong, Shanxi, Sichuan, Taiwan, Zhejiang) (Xu et al., 2013 for records except Shandong), Korea (Park, 1983), Japan and Russian Far East (Kumata et al., 1988a).