Tetrigimyia, Shima, Hiroshi & Takahashi, Hajime, 2011

Shima, Hiroshi & Takahashi, Hajime, 2011, Tetrigimyia minor, a new genus and species of Tachinidae (Diptera) parasitic on Formosatettix larvatus (Orthoptera: Tetrigidae) in Japan, Zootaxa 2921, pp. 39-46 : 40-41

Tetrigimyia gen. nov.

Type species: Tetrigimyia minor sp. nov.

Male & female. Head: Vertex wide, about 1 / 3 as wide as head width; frontal vitta narrowed anteriorly, distinctly wider than fronto-orbital plate at middle; face weakly excavated; gena narrow, subequal in width to 1 st flagellomere; occiput flat. Inner and outer vertical setae well developed; ocellar seta fine, hair-like; 1 reclinate and 2 proclinate orbital setae; parafacial bare; base of vibrissa level with lower margin of face; 2–3 short and fine subvibrissal setae; occiput with several fine black setae on upper 1 / 3. Antennal base well above level of middle of eye height, 1 st flagellomere not extending to lower margin of face; arista bare, short pubescent only on thickened basal 1 / 5, basal 2 aristomeres not longer than wide. Prementum short, at most as long as 1 st flagellomere; palpus slender, weakly widened anteriorly.

Thorax: Prosternum with a pair of rather strong setae and a few fine hairs; proepisternum bare; postpronotal lobe with 2 setae; 1 or 2 presutural and 3 postsutural acrostichal setae; 2 presutural and 3 postsutural dorsocentral setae; 1 presutural and 3 postsutural intra-alar setae, 1 st postsutural intra-alar seta very small; 3 postsutrual supraalar setae, anterior seta shorter than notopleural seta and longer than 1 st postsutural intra-alar seta; 3 katepisternal setae, anteroventral seta fine; anepimeral seta short, at most extending to posterior margin of upper calypter; anatergite bare; scutellum usually with 3 pairs of marginal setae, apical seta usually absent, subapical setae long and strong, rather weakly divergent, lateral seta short. Wing: Costa setulose below from base to vein R 2 + 3; costagial seta not extending beyond humeral crossvein; costal spine indistinct; base of R 4 + 5 with 2–3 fine setulae dorsally, 1– 2 shorter setulae ventrally; vein R 4 + 5 ending at wing apex; vein M curved at obtuse angle, bend of M almost 3 times closer to wing margin than to dm-cu crossvein; last section of vein CuA 1 slightly shorter than dm-cu crossvein; vein A 1 +CuA 2 not reaching wing margin. Legs: Fore tibia with 2 preapical dorsal setae, anterior seta fine, 1 apical ventral seta and 2 submedian posterior setae; mid tibia with 1 anterodorsal, 2 posterodorsal and 1 ventral setae; hind tibia with 2 anterodorsal, 2 posterodorsal and 2 ventral setae, and with 2 preapical dorsal setae.

Abdomen: Syntergite 1 + 2 excavated to its posterior 1 / 2; 3 rd and 4 th tergites without median discal setae; female 5 th tergite conical, strongly curved downwards, without distinct discal and marginal setae.

Male terminalia: Sixth tergite entire, weakly constricted near middle, about 1 / 2 as long as syntergosternite 7 + 8; 6 th sternite asymmetrical, articulated with 6 th tergite on left side and separated from it on right side; basiliform sclerite long and narrow; hypandrial arms separated; aedeagal guide well developed; epiphallus present.

Female terminalia: Elongate, almost as long as abdomen; 6 th tergite in the form of a long hemitergite; 6 th and 7 th sternites normal, not modified; 8 th tergite absent; epiproct small.

Etymology. This is named after the family name of the host species, Tetrigidae , plus the Greek suffix, myia, meaning fly.

Remarks. Tetrigimyia is similar in general appearance to the Central and South American genus Calodexia Townsend. It differs from Calodexia in possessing a wide frons in both sexes, wing veins R 4 + 5 and M ending at wing apex, fore tibia with 2 posterior setae, female 5 th abdominal tergite conical and terminalia curved ventrally, instead of rounded apically with the terminalia directed forward as in Calodexia . The new species of Tetrigimyia lays unincubated eggs with a hard chorion on the host exoskeleton. In this respect it is also different from ovolarviparous Calodexia species.

First postsutural supra-alar seta is slightly longer than 1 st postsutural intra-alar seta in the type species. This appears to conflict with one of the main blondeliine character states, but it may be due to the unusually fine and short 1 st postsutural intra-alar seta in this species. The first postsutural supra-alar seta is smaller than the notopleural seta and other characteristics, such as long and divergent subapical scutellar setae, wing vein M rounded and obtuse at the bend, and wing veins R 4 + 5 and M ending near wing apex, correspond well to the criteria of the Blondeliini ( Wood 1985).

In the key to genera of the Palaearctic Tachinidae ( Tschorsnig & Richter 1998) , this genus keys to Paracraspedothrix . However, the female of Paracraspedothrix has a short, globose abdomen, lacking a telescopic ovipositor, and lays embryonated eggs with transparent chorion, while the male is peculiar in having a large antenna and an arista thickened on its basal 2 / 3. Paracraspedothrix is also different from Tetrigimyia in the wide gena and wing with crossvein dm-cu attached to vein M closer to crossvein r-m than to bend of vein M. In both genera veins R 4 + 5 and M end at or near the wing apex, but in Paracraspedothrix these veins end much far apart.