Dexia major ( Malloch, 1935 )

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 : 54-55

Dexia major ( Malloch, 1935)

Calotheresia major Malloch, 1935: 590 .

Dexilla major: Crosskey 1967: 106 .

Dexia major: Crosskey 1976: 179 . — Crosskey 1977: 603 (catalog).

Diagnosis. Thoracic pleura and venter of abdominal base with pale yellowish hairs; inner and outer black thoracic vittae merged on anterior half of postsutural scutum; abdominal tergites without discal setae and tergite 3 without median marginal setae in male.

Description. Body length. 14.6−17.1 mm.

Male. Head with grayish white pruinosity; frontal vitta dark brown; upper fronto-orbital plate and upper occiput yellow; gena reddish brown in ground color, with thin grayish white pruinosity. Antenna reddish yellow, with arista brown. Prementum dark brown; palpus reddish yellow, darkened basally. Frons about 0.18 times as wide as head width; frontal vitta wider than fronto-orbital plate; parafacial weakly widened below, 3−3.5 times as wide as 1st flagellomere at middle height; face well concave, facial carina developed, widened below and flattened on ridge; lower margin of face slightly produced forward; gena about 0.4 times as wide as eye height. Inner vertical seta 0.25−0.35 times as long as eye height, slightly longer than ocellar seta; outer vertical seta 3/4 as long as inner vertical seta; 12−14 inclinate frontal setae; lowest seta nearly level with base of antenna; fronto-orbital plate almost bare; gena with a few hairs on lower portion; vibrissa inserted above level of lower margin of face by about 3/4 length of pedicel. Antenna falling short of lower margin of face by about length of 1st flagellomere; 1st flagellomere 3.0−3.5 times as long as pedicel; total width of arista including plumosity 3−4 times as wide as 1st flagellomere. Prementum about 0.38 times as long as eye height; palpus subequal in length to pedicel and 1st flagellomere combined.

Thorax black in ground color, postpronotal lobe, notopleura and apical 1/2 of scutellum reddish; scutum with dense whitish, somewhat pale yellowish, pruinosity, 2 broad outer and 2 narrow inner longitudinal black vittae on presutural scutum, outer vitta about 5 times as wide as inner one, broadly brown-black on area between outer vittae of anterior 1/2 of postsutural scutum, posterior 1/3 of supra-alar area, posterior margin of postsutural scutum and basal 1/2 of scutellum; pleura with rather dense whitish pruinosity. Thoracic hairs black on scutum, whitish on katepisternum except upper portion and pale yellowish on meron and anepimeron except upper portion. Prosternum about twice as long as wide; proepisternum bare; 3−4 postpronotal setae, basal 3 setae nearly in a straight line; usually 1 presutural and 2 postsutural acrostichal setae; 3 presutural and 3 postsutural dorsocentral setae; 1 postsutural intra-alar seta; 3 supra-alar setae, anterior one fine, short, and outwardly shifted; 2 katepisternal setae, katepisternum with dense white hairs; discal scutellar seta slightly shorter than scutellum. Wing hyaline, slightly pale yellowish from base to level of base of vein R 1 and pale brownish toward apex, the tinge dense along veins and on anterior portion; tegula and basicosta black; lower calypters pale yellowish, with short fringe on outer margin. Costal spine absent; relative lengths of 2nd, 3rd and 4th costal sectors approximately 3:5:2.5; vein M from dm-cu crossvein to its bend about 3 times distance between the bend and wing margin, appendix absent. Legs reddish yellow, femora darkened on distal 1/4−2/5 especially on ventral surface, tibiae brown except pale median portion, tarsi and claws black, pulvilli brownish. Hind leg longer than body length, hind femur about as long as abdomen, hind tibia sinuated near middle. Mid tibia with 2 posterodorsal setae; hind tibia with 1 anterodorsal, 1−2 posterodorsal and 1−2 ventral setae. Claws and pulvilli subequal in length to tarsomere 5.

Abdomen translucent yellow, tergite 5 reddish yellow to dark brown, mid dorsal longitudinal portion of syntergite 1+2 to tergite 5 rather narrowly black, posterolatral portion of syntergite 1+2 to tergite 4 triangularly brown-black, and posterior narrow margin of syntergite 1+2 and posterior 1/4−1/5 of tergites 3 and 4 darkened; narrow anteromedian portion of tergite 4 and entire tergite 5 with rather thin whitish pruinosity. Hairs dense short fine and recumbent, rather sparse and erect on tergite 5, pale yellowish white on sternite 1 and mid ventral portion of syntergite 1+2; syntergite 1+2 and tergite 3 each with a lateral marginal seta, without median marginal setae; tergite 4 with a row of strong marginal setae; tergite 5 with rows of discal and marginal setae.

Female. Head with dense yellowish pruinosity, golden yellowish on upper fronto-orbital plate; frons about 0.34 times as wide as head width; parafacial about 4 times as wide as 1st flagellomere; gena about 0.48 times as wide as eye height; head setae strong, inner vertical seta slightly more than 1/2 length of eye height, twice as long as outer vertical seta; ocellar seta about 3/4 as long as inner vertical seta; fine prevertical seta shorter than outer vertical seta; 2 strong proclinate oribtal setae; 8−9 frontal setae; antenna falling short of lower margin of face by about 4/5 length of 1st flagellomere, 1st flagellomere 4.5−5 times as long as pedicel. Thoracic pleura with dense pale yellowish white pruinosity, hairs mainly black except pale brownish ones on posterior portion of anepimeron; legs short, hind tibia not sinuate, claws and pulvilli very short. Abdomen more broadly black on mid dorsal longitudinal portion and posterior portion of tergites 3 and 4, with rather dense pale yellowish pruinosity on narrow anterior portion of tergite 3, anterior 2/3 of tergite 4 and entire tergite 5; tergite 3 with 1 pair of strong median marginal setae; tergite 5 without discal setae. Other characters almost same as in male.

Type material examined. Holotype male of Calotheresia major Malloch , MALAYSIA, N. Borneo, Bettotan, nr. Sandakan, 6.viii.1927 . Paratypes. MALAYSIA. 3 males, 4 females, same locality as holotype, 7−15.viii.1927 ( BMNH) .

Distribution. Malaysia (Sabah).

Remarks. The species is similar to D. extendens , but is distinguished from it in having pale white hairs on thoracic pleura and basal abdomen ventrally, lower calypter with short fringe on outer margin, and abdominal tergite 3 without median marginal setae.