Hygiella Mesnil, 1957

Hiroshi Shima & Takuji Tachi, 2016, New species of Hygiella Mesnil (Diptera: Tachinidae), parasitoids of leaf insects (Phasmatodea: Phylliidae), Journal of Natural History 50 (25), pp. 1648-1668 : 1650-1652

Hygiella Mesnil, 1957

Hygiella Mesnil, 1957: 28 . Type species: Hygiella pygidialis Mesnil, 1957 , by monotypy.

Hygiella Mesnil : Crosskey, 1976, p. 116, 117 (key to Oriental genera), 216 (Oriental catalogue); Crosskey, 1977a, p. 649 (Oriental catalogue).

Description

Male and female. Head: Dichoptic; eye bare; parafacial bare; face weakly concave, lower margin at most weakly warped forward, without facial carina; one reclinate orbital seta; ocellar seta strong or weak; facial ridge with fine setae on lower quarter or less; vibrissa strong, nearly level with lower margin of face; occiput nearly flat, with many whitish hairs, upper occiput with or without black setulae behind row of postocular setae. Antenna level with middle of eye height, pedicel with a long seta which is 1.5 – 2 times as long as its own length, first flagellomere 3 – 3.5 times as long as pedicel; arista bare, first and second aristomeres shorter than wide. Prementum short, at most three times as long as wide; labella large; palpus well developed, clavate.

Thorax: Prosternum and proepisternum bare; three postpronotal setae set in shallow triangle; two to three presutural and three postsutural acrostichal setae; three presutural and three to four postsutural dorsocentral setae; one presutural and three postsutural intraalar setae; three postsutural supra-alar setae, anteriormost seta shorter than first postsutural intra-alar and notopleural setae; one or two proepisternal setae, lower seta very fine; one strong proepimeral seta; anepimeral seta developed, at most extending to posterior margin of upper calypter; anatergite bare or micro-haired; three or four pairs of marginal scutellar setae and one pair of discal setae, basal scutellar seta strong, subequal in length to subapical seta, lateral seta, if present, short and fine, apical setae crossed horizontally, about twothirds as long as subapical setae. Anterior spiracle with fine short hairs on both anterior and posterior margins; posterior spiracle with crescent-shaped anterior and rounded posterior lappets. Wing with costal spine very fine or well developed; second costal sector bare or haired below; vein M from dm-cu crossvein to its bend longer than that from the bend to its apex, and longer than distance between the bend and wing margin; bend of vein M obtuseangled; basal node of vein R4+5 with two to four setulae dorsally and one to three ventrally; vein A1+CuA2 not reaching wing margin. Lower calypter bare above, inner margin rather close to upper margin of anatergite and lower basal margin of scutellum and outer margin rounded, with short fringe. Fore coxa bare on anteroventral surface; hind coxa bare posterodorsally; fore tibia with one strong preapical dorsal seta, sometimes accompanying with very fine preapical anterodorsal and posterodorsal setae, a row of fine anterodorsal and one or two posterior setae; mid tibia with two or three anterodorsal, two posterodorsal and one ventral setae; hind tibia with two preapical dorsal and one apical ventral setae, preapical posterodorsal and apical posteroventral setae absent.

Abdomen: Syntergite 1 + 2 excavated dorsally to posterior margin; male fifth tergite with dense brownish nap of short very fine close set hairing; second to fourth sternites at most narrowly exposed in male, almost concealed under tergites in female; male fifth sternite with V-shaped or U-shaped posteromedian cleft on posterior half; discal setae absent on third to fifth tergite.

Male terminalia: Sixth tergite entire, free from syntergosternite 7 + 8; sixth sternite nearly symmetrical, closely connected on left side with syntergosternite 7 + 8; syntergosternite 7 + 8 weakly sclerotized on posteromedian circular area; bacilliform sclerite short but well developed; surstylus small, strongly constricted near middle in lateral view; cerci broad and high, in dorsal view strongly swollen on both sides as lobes, median portion of nearly straight lobes, narrowly separated apically; dorsal arms of hypandrium broad and fused, encircling base of phallus; pregonite flat, fused anteriorly with hypandrium; postgonite long, rounded at apex; basiphallus broad with narrow and long epiphallus near apex; distiphallus of a pair of narrow and long dorsal sclerites connected with membrane; phallic apodeme longer than hypandrium; phallic guide long, curved ventrally; ejaculatory apodeme small, sometimes very weakly sclerotized.

Female terminalia: Sixth sternite with dense short and strong spines; seventh sternite developed as strongly curved and sharply pointed piercer with a median groove.

Remarks

Mesnil (1957) treated this genus as a blondeliine, presumably because it is characterized by a weak first postsutural supra-alar seta (shorter than notopleural and first postsutural intra-alar setae) and has the marginal scutellar setae arranged as in blondeliines: subapical setae divergent and apicals strong and crossed horizontally. Although the prosternum is bare and the abdomen lacks discal setae on the third to fifth tergites, these character states are also found in some blondeliine genera. However, the male terminalia of Hygiella are peculiar among members of the Blondeliini and even among other Exoristinae , in lacking a developed lobe-like pregonite and in possessing a short phallus.