Dexia velutina ( Mesnil, 1953 )

Zhang, Chun-Tian, Shima, Hiroshi & Chen, Xiao-Lin, 2010, A review of the genus Dexia Meigen in the Palearctic and Oriental Regions (Diptera: Tachinidae) 2705, Zootaxa 2705, pp. 1-81 : 70-71

Dexia velutina ( Mesnil, 1953)

Figs. 89−92

Calotheresia velutina Mesnil, 1953: 174 .

Dexia velutina: Crosskey 1976: 179 . — Crosskey 1977: 603 (catalog). — Dear & Crosskey 1982: 115 (key).

Diagnosis. Black thoracic vittae merged to form 2 wide vittae on postsutural scutum; scutellum with silvery white pruinosity; wing dark brown on anterior and median portion along veins; alula and calypter white; and legs black.

Description. Body length. 13.0− 16.1 mm.

Male. Head with dense whitish pruinosity on lower half of fronto-orbital plate, parafacial and gena, upper 1/2 of fronto-orbital plate with yellowish pollinosity; frontal vitta brownish black; antenna with 1st flagellomere reddish yellow, pedicel and arista brown; palpus reddish yellow except for brown basal half. Frons 0.17−0.2 times as wide as head width; frontal vitta about as wide as fronto-orbital plate or slightly wider at middle; parafacial 3−3.5 times as wide as 1st flagellomere at middle height; gena about 0.5 times as wide as eye height; facial carina pointed on ridge; lower margin of face protruded forward. Inner vertical seta 1/2−1/3 eye height, about twice as long as hair-like outer vertical seta; ocellar seta longer than inner vertical seta, about as long as upper frontal seta; 11−12 inclinate frontal setae, lowest seta nearly level with base of antenna; fronto-orbital plate with a few fine short hairs; parafacial virtually bare, with several very minute black hairs on upper portion, which are not visible at low magnification; gena only with a few fine long hairs on lower portion; vibrissa inserted slightly above level of lower margin of face. Antenna falling short of lower margin of face by about 1/2 length of 1st flagellomere; 1st flagellomere 4−5 times as long as pedicel; total width of arista including plumosity 3−4 times as wide as 1st flagellomere. Prementum about 3/4 of eye height, 5−6 times as long as wide; palpus about as long as antenna.

Thorax black in ground color, scutum with dense yellowish pruinosity, scutellum with dense silver white pruinosity; 2 broad outer and 2 narrow inner longitudinal black vittae on presutural scutum, an inner vitta about 1/3−1/4 as wide as outer vitta and as wide as pruinose portion between inner and outer vittae, inner and outer vittae merged to form a broad vitta on postsutural scutum; broadly brown-black on supra-alar area, postalar callus, posterior portion of postsutural scutum and base of scutellum; pleura with silvery white pruinosity on anterior 2/3 of proepisternum, 2/3 of anepisternum, 2/3 of katepisternum, anterior and posterior 1/3 of meron and anatergite, other portion with brownish black pruinosity. Thoracic hairs black; proepisternum bare; postpronotal lobe with 2−3 setae, anterior one weak; 1−2 postsutural acrostichal setae; 2 presutural and 3 postsutural dorsocentral setae; 2 postsutural intra-alar setae; 3 supra-alar setae, anterior one shifted outwards, about 1/3 as long as posterior setae; 2 katepisternal setae. Wing tinged with pale brown on cell h and basal area from base to level of dm-cu crossvein, bronwish on apical area, especially dark brown on area between costa and vein R 4+5, alula white; tegula and basicosta black; lower calypter white, with short fringe on outer margin. Costal spine subequal in length to r-m crossvein; relative lengths of 2nd, 3rd and 4th costal sectors approximately 4.5:9:4; vein M from dm-cu crossvein to its bend about 3.5 times distance between the bend and wing margin, appendix short. Legs brownish black, with grayish white pruinosity on fore and mid coxae; claws brownish black, pulvilli yellow. Mid leg longest; hind tibia straight. Mid tibia with 3 posterodorsal setae; hind tibia with 3−6 anterodorsal, 1−2 posterodorsal and 1−2 ventral setae. Fore claws and pulvilli about as long as tarsomere 5.

Abdomen reddish yellow, dark brown on median excavation and anterior and posterior margin of syntergite 1+2, mid dorsal triangular portion and posterior 1/3−1/4 of tergite 3, posterior 1/2−2/5 of tergite 4 and posterior 2/3 of tergite 5; thin grayish white pruinosity on anterior 1/5−1/4 of tergite 3, 1/3 of tergite 4 and 2/3 of tergite 5. Syntergite 1+2 with 2 strong median marginal and 1 lateral marginal setae; tergite 3 with 2 pairs of short median discal, 1 pair of median marginal and 1 lateral marginal setae; tergite 4 with 2−3 pairs of irregular median discal and a row of strong marginal setae; tergite 5 with 2 median discal and a row of marginal setae. Male terminalia. Posterior lobe of sternite 5 blunt apically; cerci long, slender and pointed at apex; surstylus strongly narrowed and pointed apically; postgonite shorter than basiphallus.

Female. Frons 0.28−0.32 times as wide as head width, widened anteriorly; frontal vitta 1.2−1.3 times as wide as fronto-orbital plate at middle; gena 0.45−0.52 times as wide as eye height. Inner vertical seta slightly more than 1/2 eye height; outer vertical seta about 3/5 as long as inner seta; ocellar seta about as long as inner vertical seta; 1 outwardly directed prevertical seta, nearly as long as inner vertical seta; 2 proclinate orbital setae, anterior seta stronger and longer than inner vertical seta; 6−8 inclinate frontal setae; 1st flagellomere about 3.9 times as long as pedicel. Costal spine about 1.5 times as long as r-m crossvein; relative lengths of 2nd, 3rd and 4th costal sectors approximately 3.5:8.5:3; vein M from dm-cu crossvein to its bend about 2.5 times distance between the bend and wing margin. Mid tibia with 2 posterodorsal setae; hind tibia with 3−4 anterodorsal setae. Abdomen reddish yellow on anterior 1/2−2/5 of each tergite, black on posterior portion, rather thin whitish pruinosity on anterior 1/2 of tergite 5 and anterior 1/3−2/5 of venter of tergites 3 to 5; tergites without median discal setae. Other characters almost same as in male.

Type material examined. Holotype female of Calotheresia velutina Mesnil , PHILIPPINES, Luzon , Banahao, vi.1914 ( ZMU).

Additional material examined. INDIA. 2 females, Maharashtra St. Ambavahe , 15 km, S. Lonavala, 4−6.vi.1989, H. Kurahashi ( BLKU) . PHILIPPINES. 1 male and 1 female (identified by Mesnil as Dexia (Barydexia) bivittata T.T. in 1951) . 1 male, Callao cave, Baggaba, Penabianca Cagayan, Luzon Is. , 22.viii.1982, N. Kashiwai leg ( BLKU) . 1 male, 1 female, Luzon Is., Mt. Prov. Ifugao, Mayoyao , 1000−1500 m, 4−6.vii.1966, H. M. Torrevillas ( BPBM) . SRI LANKA. 1 female, Kan Dist., Udawattakele, Sanct , 1800', 1−3.ix.1980, K.V. Krombein, P.B. Karunaratne, T. Wijesinhe, L. Jayawickrema, V. Gunawardane . 1 female, Kandy, Rose Nith Est. , 31.x.1966, J.F.G. Clarke, Thelma M. Clarke . 1 female, Noori Estate Noori , 3500', C.R., 6.viii.1966, P.P. Karunarada ( USNM) .

Distribution. India *, Philippines (Luzon), Sri Lanka *.

Remarks. This species is similar to D. atripes , but is distinguished from it in having silvery white scutellum, 1 postsutural acrostichal seta, alula and calypter white, and anterior part and area along wing veins dark brown.