Two new and one newly recorded species of Gracillariidae from China (Lepidoptera)

Abstract The paper presents four Chinese species belonging to the genera Metriochroa Busck, Eumetriochroa Kumata, and Gibbovalva Kumata & Kuroko (Lepidoptera, Gracillariidae), including two new species: Metriochroa alboannulata Bai, sp. n. and Gibbovalva clavata Bai, sp. n. Eumetriochroa hiranoi Kumata, 1998, is newly recorded from China. Photographs of adults and figures of the genital structures are provided, along with keys to the Chinese species of Metriochroa, Eumetriochroa, and Gibbovalva.

The genus Metriochroa contains twelve described species worldwide. There are seven species in the Afrotropical region, three in the Palearctic region, and one each in the Oriental and Nearctic regions. Metriochroa was not recorded in China until M. symplocosella Kobayashi, Huang & Hirowatari, 2013 was described on the basis of Chinese material (Kobayashi et al. 2013). A total of twenty plant species in twelve genera of six families are known as host plants of Metriochroa. Eleven species in five genera of the family Oleaceae serve as the most common host plants for the larvae of Metriochroa (Kumata 1998;Kobayashi et al. 2013;De Prins and De Prins 2015).
The genus Gibbovalva Kumata & Kuroko, 1988 is one of the smallest genera of the subfamily Gracillariinae, and is represented by eight species worldwide. The majority of them (five) occur in the Palearctic and Oriental regions, the remaining two species were recorded from the Australasian region and one from the Afrotropical region. Host plants of Gibbovalva comprise thirty-four species in ten genera under four families, the majority of which (twenty species in six genera) belong to the family Lauraceae, followed by the Magnoliaceae (ten species in two genera), the Typhaceae (three species in one genus), and the Apocynaceae (one species) (Kumata et al. 1988;Bai and Li 2008;Bai et al. 2009;Triberti andJaworski 2014, De Prins andDe Prins 2015). Six species of Gibbovalva were recorded in China, mainly distributed in Guangdong, Guangxi, Hainan, Fujian, Guizhou, Zhejiang, Anhui, Yunnan, Hunan, Liaoning and Hong Kong (Bai and Li 2008).
Of the four gracillarid moth species treated in the present paper, Eumetriochroa hiranoi is newly recorded from China, and Metriochroa alboannulata sp. n. and Gibbovalva clavata sp. n. are new to science.

Methods
All adult specimens were obtained after by rearing from immature stages. Adult external morphology was examined by using a Leica M-205C stereomicroscope, and photographs were taken with a Leica DFC-450 digital camera connected to a Leica M-205C stereomicroscope. Genitalia were prepared following the methods of Li and Zheng (1996). Dissections of genitalia were conducted under an Olympus SZX-7 stereomicroscope. Genital morphology was examined with an Olympus BX-53 microscope, and the illustrations were prepared by using an Olympus DP-26 digital camera connected to the Olympus BX-53 microscope. Terminology follows Kumata (1998) and Kumata et al. (1988).
All specimens studied are deposited in the Insect Collection, Department of Bioscience and Biotechnology, Changzhi College, Changzhi, Shanxi, China (ICCC).

Key to the Chinese species of Eumetriochroa
Remarks. In all four specimens examined the fore wing markings were poorly preserved, but the genital characters (Figs 5,9) well agree with the description given by Kumata (1998). First record from China. Kumata, 1998 Figs 2, 6, 10 Eumetriochroa hederae Kumata, 1998, Insecta Matsumurana  Distribution. China (Hunan, Jiangxi), Japan. Remarks. Specimens from China do not fully agree with the original description (Kumata 1998), especially in fore wing markings. Their fore wing has a white stripe situated between the third and fourth fasciae which extends from the dorsal edge of the third fascia towards costa to the middle of the fourth fascia. This character was not recorded by Kumata (1998) in the original description based on Japanese specimens. In addition, instead of the fourth fascia as described by Kumata, it is the apex of the fifth fascia which is edged with remarkable darker spots. However, the structures of the male (Fig. 6) and the female genitalia ( Fig. 10) are in accordance with the original description, which provides us confidence to assign the specimens reared in China to this species.
Type species. Metriochroa psychotriella Busck, 1900. References. Busck (1900: 245, pl. 1, fig. 13). Diagnosis. The new species is a member of Metriochroa by the characteristics of venation and male genitalia. Fore wing of M. alboannulata sp. n. has nine veins ( Fig. 11), M 3 and CuA are absent, M 1 is stalked with R 5 , R 4 is connate or shortly stalked with stalk of M 1 and R 5 ; 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.

Key to the Chinese species of Metriochroa
Forewing markings of Metriochroa vary notably. M. alboannulata sp. n. is similar to M. argyrocelis Vári, 1961 andM. 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 M. 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 M. alboannulata the first fascia is evident and joins with dorsum, and the second fascia is closer to the apex of forewing than in M. celidota; in addition, M. alboannulata has a silvery white speck near tornus, which does not occur in M. celidota.
Both Metriochroa alboannulata and the female of M. argyrocelis (forewing markings of male M. argyroscelis are clearly dissimilar from those of M. 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 M. alboannulata, the fascia is of uniform width, and is narrower than that of M. 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 M. alboannulata, M. 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.
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.

Diagnosis.
A new species of Gibbovalva, with antennal scape bearing a ventral flap and valva with a costal process as for other members of the genus, with which it also shares the fore wing markings and characteristics of vinculum and saccus. The basal 1/3 of the forewing of Gibbovalva clavata sp. n. is white in ground color and has four black costal specks; the distal 2/3 is ochreous yellow in ground color and has four white fasciae. The valva is blade-shaped, the costa possesses a clavate process at the basal 1/6; saccus is thumb-shaped with rounded apex; the aedeagus does not have a flap-like process, and its thorn-like cornuti are arranged in rows from basal 1/3 to subapex. Gibbovalva clavata sp. n. is similar to G. magnoliae and G. tricuneatella in the aedeagus lacking a flap-like process, but it is distinguishable by the forewing markings. In G. clavata, basal 1/3 of forewing is white with four black costal specks; apical 2/3 of forewing has four white fasciae, whereas in G. magnoliae forewing has a V-shaped speck at base and five white fasciae and in G. tricuneatella forewing has three white fasciae which markedly dilate towards wing fold. In addition, G. clavata resembles G. quadrifasciata (Stainton) in the male genitalia, as in both species the ventral surface of valva is covered with lanceolate setae, but it is distinguishable by other characters.
Description. Adult (Fig. 4). Wingspan 7.0 mm. Head white, with frons fuscous. Labial palpus white, second segment apically and third segment basally with a fuscous spot on their outer side. Thorax white, its sides edged with fuscous line; tegula fuscous with white apex. Basal 1/3 of forewing white, with four black specks along costa, of which the last one smallest; distal 2/3 of forewing ochreous yellow with fuscous band along costa and four white, nearly equally spaced fasciae which obliquely extend outwards from costa to dorsum; two basal fasciae, approximately twice the width of the two distal ones, enclose a black spot on costa. Cilia black from dorsal third fascia to costal fourth fascia, white at the apical angle, the remaining cilia pale grey. Hind wing and its cilia pale grey. Legs with coxae and tarsi white; tarsi with three fuscous rings, the last tarsomere ochreous yellow apically. Profemur fuscous; protibia white in basal 1/3, the remaining part fuscous. Mesofemur with external surface fuscous, internal surface ochreous white; mesotibia white, with three fuscous rings, of which one at the basal 1/3, two at the distal part. Metafemur white, external side with a fuscous spot at base and middle respectively; metatibia white, with a median fuscous ring, the last tarsomere fuscous apically.
Male genitalia (Fig. 8). Tegumen approximately 400 μm long, tongue-like, slightly wider on apical half, densely covered with fine setae on ventral and dorsal surfaces and with a sparse row of longer setae on each side. Valva approx. 600 μm long, bladeshaped, slightly narrowed at base, obliquely truncated at apex and almost parallelsided; costa straight with a clavate process at the basal 1/6, dorsum slightly upcurved near apex; inner surface covered with usual setae except for lanceolate setae clustered on distal part. Saccus thumb-shaped, rounded apically. Aedeagus nearly 650 μm long, tapering to a pointed apex from around the distal 1/4; vesica with acute, thorn-like cornuti arranged in rows from basal 1/3 to aedeagus subapex, some cornuti arranged between apical 1/5 and apex being larger than others. Antero-dorsal apodeme of the eighth tergite approx. 150 μm long, with slender sclerotization extending caudad to the middle of the eighth tergite; eighth sternite with a pair of very slender invaginations, nearly equal in length to dorsal apodeme.
Etymology. The species name is derived from the Latin "clavatus", meaning "clavate", in reference to the costal process of valva.