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 1st 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, 1st 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 1st 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, 1st postsutural intra-alar seta very small; 3 postsutrual supraalar setae, anterior seta shorter than notopleural seta and longer than 1st 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 R2+3; costagial seta not extending beyond humeral crossvein; costal spine indistinct; base of R4+5 with 2–3 fine setulae dorsally, 1– 2 shorter setulae ventrally; vein R4+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 CuA1 slightly shorter than dm-cu crossvein; vein A1+CuA2 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; 3rd and 4th tergites without median discal setae; female 5th 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; 6th sternite asymmetrical, articulated with 6th 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; 6th tergite in the form of a long hemitergite; 6th and 7th sternites normal, not modified; 8th 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 R4+5 and M ending at wing apex, fore tibia with 2 posterior setae, female 5th 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 1st 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 1st 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 R4+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 R4+5 and M end at or near the wing apex, but in Paracraspedothrix these veins end much far apart.