Platygaster ingeniosus Matsuo & Yamagishi

Matsuo, Kazunori, Fujii, Tomohisa, Tokuda, Makoto, Ganaha-Kikumura, Tomoko, Yukawa, Junichi & Yamagishi, Kenzou, 2018, Descriptions of two new species of Platygaster Latreille that attack gall midges (Diptera, Cecidomyiidae) with notes on their biology (Hymenoptera, Platygastridae), ZooKeys 754, pp. 113-125 : 114-117

Platygaster ingeniosus Matsuo & Yamagishi sp. n.

Etymology.

The specific name is derived from its ingenious parasitoid strategy.

Type material. Holotype: Female, emerged on 16 March 2011 from a gall of Masakimyia pustulae on Euonymus japonicus collected by T. Fujii from Nijoshikaka, Itoshima, Fukuoka, Japan. Paratypes: 5 females and 5 males, same data as holotype.

Description.

FEMALE (Fig. 1). Body length 1.4-1.6 mm. Head, mesosoma, and metasoma black. A1 dark brown basally; A2-A4 dark brown to black; A5-A10 black. Fore wing slightly infuscate. All coxae black; all femora brown yellow to black; all tibiae brown yellow.

Head in dorsal view, 1.9-2.1 times as wide as long, 1.1-1.2 times as wide as mesosoma; occiput transversely striate; vertex between ocelli with transverse wrinkles, with reticulation between posterior ocelli (Fig. 2); POL: OOL: LOL = 2.5: 1.3: 1.0. Head in frontal view 1.3-1.4 times as wide as high; frons with transverse wrinkles (Fig. 3); gena smooth. A1 5.5-5.6 times as long as wide, 0.7-0.8 times as long as height of head; A2 2.4-2.6 times as long as wide; A3 1.2-1.3 times as long as wide; A4-A6 1.4-1.5 times as long as wide; A7-A9 1.4-1.5 times as long as wide; A10 1.7-1.8 times as long as wide (Fig. 4).

Mesosoma 1.3-1.4 times as long as wide, 1.1-1.2 times as high as wide; sides of pronotum reticulate, smooth along upper and posterior margins (Fig. 6); mesoscutum reticulate, smooth between notauli which are indicated in posterior half (Fig. 7); posterior margin of median lobe of mesoscutum overlapping base of mesoscutellum; posterior margin of lateral mesoscutal lobes hairy; scuto-scutellar groove smooth and bare; mesoscutellum evenly convex, smooth and covered with long hairs except median glabrous area (Fig. 8); mesopleuron with two setae anteriorly, with a coriaceous area below tegula; mesopleural carina absent; mesofurcal pit present; metapleuron completely pilose; propodeal carinae widely separated, parallel. Fore wing 2.3-2.4 times as long as wide; marginal cilia approximately 0.1 times as long as width of fore wing. Hind wing approximately 4.8 times as long as wide, with two hamuli; marginal cilia approximately 0.2 times as long as width of hind wing.

Metasoma as long as head and mesosoma combined; T1 evenly crenulated, 1.8-1.9 times as wide as long, 0.2-0.3 times as long as T2; T2-T5 with a band of shallow punctation along posterior margin; T2 weakly striated in basal half, with shorter striae medially (Fig. 9); T3 with a few setae; T4 with a row of setae which is broken medially; T5 with a complete setal row; T6 with a complete setal row, smooth.

MALE. Differs from the female as follows: Body length 1.5-1.6 mm. Antenna with erect setae; A4 distinctly widened (Fig. 5). Metasoma approximately 0.8 times as long as head and mesosoma combined, obtuse at apex.

Differential dagnosis.

Platygaster ingeniosus is similar to the two Palearctic species, P. rutilipes Buhl and P. yunnanensis Buhl, because they share the following morphological characteristics: notaulus indicated in posterior half; mesopleuron with a coriaceous area below tegula; posterior margin of mesoscutum reaching base of mesoscutellum; hind wing approximately 4.8 times as long as wide. Platygaster ingeniosus can be distinguished from P. rutilipes by having the stouter fore wing that is 2.3-2.4 times as long as wide whereas P. rutilipes has elongated fore wing, approximately 2.8 times as long as wide. Platygaster ingeniosus could be distinguished from P. yunnanensis because sides of pronotum are finely reticulate whereas smooth in P. yunnanensis .

Biological notes.

Platygaster ingeniosus is an egg-larval solitary parasitoid of Masakimyia pustulae in Japan ( Yukawa and Sunose 1976; Sunose 1983, 1984; Fujii et al. 2014). Although Masakimyia pustulae induces dimorphic leaf galls, thick and thin types ( Sunose 1983), Platygaster ingeniosus can attack gall midge larvae inhabiting both types of gall ( Sunose 1984; Fujii et al. 2014). Because the genus Masakimyia is monotypic and its tribal position in the supertribe Lasiopteridi has not been determined ( Gagné and Jaschhof 2017), the possible host range of Platygaster ingeniosus is restricted to Masakimyia alone at this moment.