Dexia basifera Walker, 1859

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 : 15-16

Dexia basifera Walker, 1859

Dexia basifera Walker, 1859: 129 . — Crosskey 1967: 103 (designation of lectotype). — Crosskey 1976: 178 (catalog). Calotheresia orientalis Baranov, 1932: 214 . — Crosskey 1967: 101 (as syn. of D. basifera ).

Diagnosis. Tegula dark brown; lower calypter with short fringe on outer margin; 3 supra-alar setae; abdominal sternite 1 with pale yellowish hairs; abdominal tergite 3 widened at posterior margin.

Description. Body length. 9.4−15.7 mm.

Male. Head with dense yellow pruinosity, golden on fronto-orbital plate; antenna yellowish; palpus yellowish, somewhat reddish yellow at apex. Frons about 0.19 times as wide as head width; frontal vitta about 1/2 as wide as fronto-orbital plate at middle; parafacial slightly widened below, slightly more than twice width of 1st flagellomere; gena about 0.4 times as wide as eye height; face well concave, facial carina developed, longer than antenna, weakly pointed on upper 1/2 and flat on lower 1/2, continuous to produced lower margin of face. Inner vertical seta rather fine, about 2/5 as long as eye height; outer vertical seta fine but distinct, about 3/4 length of inner seta; ocellar seta longer than inner vertical seta; 7 frontal setae, lowest seta nearly level with upper margin of lunule; fronto-orbital plate with only a few fine hairs among row of frontal setae; parafacial with very minute black hairs on upper 1/2−2/3, which are only visible at high magnifications; gena bare; vibrissa inserted slightly above level of lower margin of face. Antenna falling short of lower margin of face by about twice length of pedicel; 1st flagellomere about 4.3 times as long as pedicel; total width of arista including plumosity about 2.5 times as wide as 1st flagellomere. Prementum slender, about 3/5 as long as eye height; palpus subequal in length to 1st flagellomere.

Thorax black in ground color, broadly reddish on postpronotal lobe, notopleural area and scutellum except base, with dense yellowish white pruinosity; supra-alar region, postalar callus, posterior 1/4 of postsutural scutum and anterior 1/4 of scutellum with bronwish pruinosity; 1 pair of broad outer and 1 pair of narrow inner longitudinal black vittae, outer vitta obscure marginally with brownish pruinosity on inner portion, outer and inner vittae merged on postsutural scutum. All thoracic hairs black; 2−3 postpronotal setae; 1 postsutural acrostichal seta; 2 presutural and 3 postsutural dorsocentral setae; 2 postsutural intra-alar setae; 3 supra-alar setae, pre-alar seta fine but distinct; 2 katepisternal setae, katepisternum only with a row of fine hairs in front of mid coxa; scutellum with fine hair-like discal setae, sometimes without them (absent in lectotype). Wing hyaline, brown-black on anteroproximal area between costa and stem vein R from base to level of costagial break, pale yellowish white to brownish on other portion; tegula and basicosta black; lower calypter pale brownish. Costal spine slightly longer than r-m crossvein; relative lengths of 2nd, 3rd and 4th costal sectors approximately 3.5:9.5:3; vein R 4+5 with 4 setae dorsally extending to 1/3 way to r-m crossvein; vein M from dm-cu crossvein to its bend about 3.5 times distance between the bend and wing margin, appendix about 3/5 as long as r-m crossvein. Lower calypter with short fringe. Legs reddish yellow, tibiae brown. Mid tibia with 2 posterodorsal setae; hind tibia with 2 anterodorsal, 2 posterodorsal and 1 ventral setae.

Abdomen translucent reddish yellow, narrow posterior margin of syntergite 1+2, posterior 1/5 of tergite 3, 1/6 of tergite 4 and very narrow anterior margin of tergite 5 brown-black, mid dorsal triangular area brownish black on posterior 2/3 of syntergite 1+2, 1/2 of tergite 3 and 1/3 of tergite 4; thin yellowish pruinosity on narrow dorsomedian anterior margin of tergite 3, narrow anterior margin and mid dorsal longitudinal area of tergite 4 and anterior 1/2 of tergite 5. Long ovate in shape, widest at posterior margin of tergite 3. Hairs black except on sternite 1 which bears pale yellowish hairs, fine short dense and recumbent on tergites 2 to 4, suberect on tergite 5 and longer on venter. Syntergite 1+2 with 1 pair of fine median marginal and l rather long lateral marginal setae, median marginal setae sometimes absent; tergite 3 with 2 fine irregularly set median discal, 1 pair of strong median marginal and 1 strong lateral marginal setae, median discal setae sometimes indistinct; tergite 4 with 2 pairs of rather fine and irregularly set median discal and a row of strong marginal setae; tergite 5 with 2 regular rows of strong discal and marginal setae.

Female. Frons about 0.32 times as wide as head width; frontal vitta about 3/5 as wide as fronto-orbital plate at middle; parafacial about 3 times as wide as 1st flagellomere; all head setae strong, inner vertical seta about 3/4 eye height, 1 outwardly directed prevertical seta, 2 strong proclinate frontal setae; inner and outer vittae of thoracic scutum merged on posterior 1/2 of presutural area of scutum; wing more distinctly tinged, brownish area expanded almost to whole cells r 4+5 and dm and contrasting to pale basal area; distal portion of femora darkened; abdominal tergites without discal setae.

Type material examined. Lectotype male of Dexia basifera Walker (by designation of Crosskey 1967: 103), INDONESIA, Macassar, Celebes (= Sulawesi), A.R. Wallace ( BMNH) . Paralectotypes 2 males, 1 female; same locality as lectotype ( BMNH) .

Distribution. Indonesia (Sulawesi).

Remarks. This species is similar to D. flavida , but is distinguished from it in having dark tegula, 3 supraalar setae, abdominal sternite 1 with pale yellowish hairs, tergite 3 with yellowish pruinosity on anterior margin, and with 2 fine irregularly set median discal setae.