Metriochroa symplocosella Kobayashi, Huang & Hirowatari

Kobayashi, Shigeki, Huang, Guo-Hua, Nakamura, Akihiro & Hirowatari, Toshiya, 2013, Four new species of Gracillariidae (Lepidoptera) from China and Japan, and description of the pupal morphology of the genera Corythoxestis, Eumetriochroa, Guttigera, and Metriochroa, Zootaxa 3619 (2), pp. 101-129 : 103-110

Metriochroa symplocosella Kobayashi, Huang & Hirowatari sp. nov.

Figs. 2 A–B, 3, 7, 14

Diagnosis. All Metriochroa species possess a forewing without veins R1 and CuA2 ( Fig. 4 A). The forewings of most species are ochreous white with brown scales ( Fig. 2 A, B). This species is superficially very similar to M. pergulariae Vári , but it is distinguished from the latter by the following characters:

Male genitalia with tubular aedeagus without juxta ( Fig. 3 E). Female genitalia without a signum on the corpus bursae ( Fig. 3 F).

Adult. ( Fig. 2 A, B) Wing expanse 8.0 mm in holotype, 6.2–8.0 mm (7.32 mm in average of 19 specimens) in paratypes. Head smooth; frons and vertex lustrous ochreous white mixed with brown scales centrally and laterally. Maxillary palpus pale ochreous; labial palpus pale ochreous to whitish brown, with blackish brown apically. Antennae 9/10 of forewing, lustrous white annulated with dark brown. Thorax ochreous white. Abdomen ochreous to dark grey. Anal tuft whitish brown to grey. Forewing: white to ochreous white scattered with brown scales and with dark brown obscure patches; one obscure line from base to 1/4, one patch at costal 2/5, another at costal 3/5, apical patches at 7/10 of wing. dorsal area white scattered with brown or dark brown scales. Hindwing whitish grey or grey; cilia white. Wing venation ( Fig. 3 A, B).

Male genitalia ( Fig. 3 C–E). Tegumen round apically. Vinculum Y-shaped, round laterally, with saccus oblong clavate. Valva about 3/ 4 in length, clavate in lateral view with an apex obliquely curved toward middle; a group of partite scales occurring along apex. Aedeagus ( Fig. 3 E) tubular, slightly longer than valva in length; vesica with several small spines densely concentrated at middle.

Female genitalia ( Fig. 3 F). Apophyses anterioris and apophyses posterioris slender. Ostium bursae membranous; antrum very short, ring-shaped; ductus bursae short, tubular; inception of ductus seminalis on the posterior part of ductus bursae. Corpus bursae pyriform, without a signum, posterior part wrinkled.

Pupa. ( Figs. 7 G–I, 14). Dark brown, 3.5–3.6 mm in length, 0.5–0.6 mm in diameter ( Fig. 7 G–I). Vertex with a stout, spade-like frontal process (cocoon cutter) ( Fig. 14 B, E). Dorsum of A2–A8 with a pair of long, lateral setae, and a concentration of small spines ( Fig. 14 F, I); A9–10 prominently furcated with a pair of perianal, dorsal and caudal processes ( Fig. 14 J–L); one pair of very small spines from anal area; second pair of digital processes from caudal apex with small processes at apex; third pair of anterior curved, small caudal processes dorsally.

Distribution. China (Hunan).

Host plant. Symplocos anomala Brand, S. sumuntia Buch. -Ham. ex D. Don, ( Symplocaceae ).

Specimens examined

Type material. 25 (133 12Ƥ)

Adults: Holotype 3, China: Tianpingshan, Badagongshan NNR, Sangzhi, Hunan, 20.iv.2011 em., T. Hirowatari & Guo-Hua Huang, Host: Symplocos sumuntia , 28–29. iii. 2011 (ex larva) in OPU. Paratypes 123 12Ƥ. Same locality as holotype, 18–27.iv.2011 em., Host: Symplocos anomala and S. sumuntia , 28–29.iii.2011 (ex larva), (genitalia slide no. OPU-SK340–346) in HUNAU and OPU.

Pupae: 12 exs, Same locality and data of type series, 19.iv.2011.

Etymology. The specific epithet, symplocosella , is derived from the generic name of the host plant, Symplocos .

Biology. The larvae mine the adaxial epidermis of the leaf forming a narrow, long serpentine mine; about 30~ cm in length, yellowish green in coloration, with old mines becoming white. The mines ( Fig. 7 A–C) were usually 1–2 mines per leaf. The late instar larva is 3.0–4.0 mm long and yellow in coloration ( Fig. 7 E). The pupal cocoon fold is bean-shaped, situated at the end of the mine, usually along the leaf margins ( Fig. 7 F). The species overwintered in the larval stage in the leaf mine.

Remarks. In the original description of the genus, the length of antennae was described as “a little longer than forewing”. However, the antennae are a little shorter than the forewings in the new species and M. fraxinella , and the same length in M. syringae ( Kumata 1998) . Vári (1961) did not mention the length of antennae of his new Metriochroa species. At least, that of M. pergulariae is shorter than the forewing judging from the photographs of adult specimens. In addition, the new species and M. fraxinella possess a forewing with vein M3 and distinct CuA, while the type species M. psychotriella and M. syringae possess a forewing without vein M3 ( Vári 1961; Kumata 1998).

Figures

FIGURE 2. Adult of Oecophyllembiinae species from China and Japan. A. Metriochroa symplocosella sp. nov., holotype 3. B. Paratype ♀. C. Guttigera schefflerella sp. nov., holotype 3. D. Paratype ♀. E. Eumetriochroa araliella sp. nov., holotype 3. F. Paratype ♀ mining Evodiopanax innovans. G. Paratype 3 mining Dendropanax trifidus. H. Paratype 3 mining Fatsia japonica. I. Corythoxestis tricalysiella sp. nov., holotype 3. J. Paratype ♀. K. Corythoxestis sunosei (Kumata, 1998) 3 in Japan. L. Corythoxestis yaeyamensis (Kumata, 1998).

FIGURE 3. The wing venation and genitalia of Metriochroa symplocosella sp. nov .. A. Forewing ♀. B. Hindwing ♀. C. Male genitalia, lateral view. D. Ventral view. E. Aedeagus, ventral view. F. Female genitalia, ventral view. va: valva; vi: vinculum; ae, aedeagus; ob: ostium bursae; an: apophysis posterioris; ds: ductus bursae; db: ductus bursae; cb: corpus bursae.

FIGURE 4. The wing venation and genitalia of Guttigera schefflerella sp. nov .. A. Forewing ♀. B. Hindwing ♀. C. Male genitalia, lateral view. D. Ventral view. E. Left valva, lateral view. F. Aedeagus, ventral view. G. Female genitalia, ventral view.

FIGURE 7. Biology of Metriochroa symplocosella sp. nov. and the hostplants. A, C, D – K. Symplocos. sumuntia. B. S. anomala. A – C. Mines on the adaxial epidermis of the leaf. A, E. Mine by young larva. B. Mines by later instar larvae. C, D. Cocoon fold and old mine. F. Later instar larva on adaxial epidermis. G. Cocoon fold. H. Pupa, ventral view. I. Dorsal view. J. Lateral view. K. Resting posture of the adult, dorsal view.

FIGURE 14. Pupa of Metriochroa symplocosella sp. nov .. A. Head, ventral view. B. Cocoon cutter, ventral view. C. Frons. D. Head, lateral view. E. Cocoon cutter, lateral view. F. Spines on 6 th abdominal tergum, lateral view. G. Head, dorsal view. H. Cocoon cutter, dorsal view. I. Spines on 7 th abdominal tergum. J. A 8 – A 10, ventral view. K. lateral view. L. dorsal view. ds: dorsal seta; sds: subdorsal seta; ls: lateral seta; dp: dorsal process of cremaster; pp: perianal process.