Metriochroa alboannulata Bai

Bai, Haiyan, Xu, Jiasheng & Dai, Xiaohua, 2016, Two new and one newly recorded species of Gracillariidae from China (Lepidoptera), ZooKeys 559, pp. 139-150 : 142-145

Taxon classification Animalia Lepidoptera Gracillariidae

Metriochroa alboannulata Bai sp. n. Figs 3, 7, 11

Diagnosis.

The new species is a member of Metriochroa by the characteristics of venation and male genitalia. Fore wing of Metriochroa alboannulata sp. n. has nine veins (Fig. 11), M3 and CuA are absent, M1 is stalked with R5, R4 is connate or shortly stalked with stalk of M1 and R5; the valva is covered with partite scales.

Flagellum of Metriochroa alboannulata sp. n. has six white rings on distal part. Forewing has two silvery white fasciae: one placed at the basal 1/4 and is slightly outwardly angulate on wing fold, the other situated preapically; forewing possesses white costal and dorsal specks, two of them at the middle, and opposite each other, and one near the tornus. Valva is divided into dorsal and ventral portions by a sclerotized ridge, the former shorter than the ventral one. Aedeagus is tubular, and with a clavate cornutus on vesica.

Forewing markings of Metriochroa vary notably. Metriochroa alboannulata sp. n. is similar to Metriochroa argyrocelis Vári, 1961 and Metriochroa celidota Bradley, 1965 in forewing with obvious white or silvery white markings. These characteristics easily distinguish these species from other members of the genus.

Metriochroa alboannulata is close to Metriochroa celidota in forewing with two silvery white fasciae, especially as the first fascia is present at the basal 1/4 in both species. However, in Metriochroa alboannulata the first fascia is evident and joins with dorsum, and the second fascia is closer to the apex of forewing than in Metriochroa celidota ; in addition, Metriochroa alboannulata has a silvery white speck near tornus, which does not occur in Metriochroa celidota .

Both Metriochroa alboannulata and the female of Metriochroa argyrocelis (forewing markings of male Metriochroa argyroscelis are clearly dissimilar from those of Metriochroa alboannulata ) have a silvery white fascia at the basal 1/4 of forewing, and a silvery white speck near tornus, but they differ in the following characteristics: in Metriochroa alboannulata , the fascia is of uniform width, and is narrower than that of Metriochroa argyrocelis , in which it gradually widens towards dorsum; in addition, in place of the fascia near the apex of forewing and the silvery white bar-shaped specks at the middle of costa and dorsum present in Metriochroa alboannulata , Metriochroa argyrocelis has two silvery white specks at the middle and basal 3/4 of costa, respectively.

Description.

Adult (Fig. 3). Wingspan 6.5-7.5 mm. Head fuscous with metallic luster. Antenna fuscous, flagellum with six white rings on distal part. Labial palpus whitish-yellow, with the outer side of second and third segments fuscous. Thorax, tegula, and fore wing fuscous. Fore wing shining with purple; two silvery white fasciae present, first fascia at the basal 1/4, and slightly outwardly angulate on wing fold, second fascia at subapex and outwardly oblique; costa and dorsum with an outwardly oblique bar-shaped silvery white speck each at the middle, costal speck longer than the dorsal one; dorsum with a silvery white speck near tornus; cilia grayish-brown, those on termen with median and apical fringe lines of black spots, which run parallel with termen. Hindwing and its cilia fuscous. Legs fuscous. External surface of profemur and mesofemur, internal surface of metafemur ochreous white; protibia basally, mesotibia and extremities of metatibia ochreous white; both ends of first tarsomeres, apical tarsomeres and the apex of other tarsomeres white. Abdomen dorsally fuscous, ventrally ochreous white, anterior margin of each sternite fuscous.

Male genitalia (Fig. 7). Tegumen ca. 100 μm in length, with widely rounded apex. Tuba analis bilobed apically, with setae on each lobe. Vinculum Y-shaped; saccus ca. 180 μm in length, clavate, with pointed apex. Valva ca. 160 μm in length, about three times as long as wide; inner surface with a sclerotized longitudinal ridge which divides the valva into dorsal and ventral portions; dorsal portion slightly shorter than ventral one, with obliquely truncated apex, and covered with a group of partite scales on its distal part; ventral portion with spine-like setae on its rounded apex. Aedeagus tubular, ca. 700 μm long, obliquely truncated along apical 2/7, pointed apically; vesica with a clavate cornutus, which is approximately 160 μm long.

Female. Unknown.

Type material.

Holotype ♂. China. Wuzhifeng, Shangyou County, Jiangxi Province, 2 January 2013, leg. Chengqing Liao; genitalia slide No. B13051, in ICCC. Paratypes 2♂♂. China, with same data as holotype; genitalia slide Nos B13050, BX15001, in ICCC.

Etymology.

The specific name is composed of “albus” and “annulatus”, meaning "with white ring", referring to the flagellum of antenna with white rings on its distal part.

Distribution.

China (Jiangxi).