Billaea robusta Malloch, 1935

Zhang, Chun-Tian, Shima, Hiroshi, Wang, Qiang & Tschorsnig, Hans-Peter, 2015, A review of Billaea Robineau-Desvoidy of the eastern Palearctic and Oriental regions (Diptera: Tachinidae), Zootaxa 3949 (1), pp. 1-40 : 21-22

Billaea robusta Malloch, 1935

Fig. 101

Billaea robusta Malloch, 1935: 674 .— Crosskey 1976: 177 (catalog).— Crosskey 1977: 601 (catalog).

Diagnosis. Arista plumose, fore tibia with 1 posterior seta and abdominal tergites 3 and 4 each with a pair of triangular dark markings which are fused on posterior portion to a transverse band.

Redescription. Body length 13.5 mm.

Male. Head. With dense pale yellowish gray-white pruinosity; occipital dilation and occiput more whitish; antenna with scape, pedicel and basal 1/2–1/3 of flagellomere 1 reddish yellow, apical portion brown, arista reddish brown; palpus reddish yellow. Vertex about 0.19 of head width; frontal vitta strongly widened anteriorly, about 1.5 times as wide as fronto-orbital plate at middle; parafacial 2–2.5 times as wide as flagellomere 1 at middle height; face rather weakly concave, facial carina weak and short, at most 2/3 as long as antenna, lower margin well warped forward; genal height 0.4–0.45 of eye height; occiput weakly bulged. Inner vertical seta slightly shorter than 1/2 of eye height; ocellar seta fine, about 1/2 as long as inner vertical seta; lowest frontal seta nearly level with base of antenna; fronto-orbital plate with dense fine rather long hairs, of which 1–2 descend just below lowest frontal seta; gena with very dense fine short hairs. Flagellomere 1 about 3.5 times as long as pedicel; arista plumose, total width including plumosity subequal in length to flagellomere 1.

Thorax. Black in ground color, with dense grayish white pruinosity on scutum, 2 outer broad and 2 inner rather narrow longitudinal black vittae on presutural area, and 3 broad longitudinal vittae on postsutural scutum, the inner vittae of presutural area extending posteriorly to anterior 1/3 of postsutural scutum widening posteriorly; scutellum black on basal 2/3, covered with grayish pruinosity at apex. Postpronotal lobe with 3 setae, middle seta only slightly set forward; 1 presutural and 2 postsutural acrostichal setae; 3 presutural and 4 postsutural dorsocentral setae; 2 postsutural intra-alar setae; 4 supra-alar setae; 2 katepisternal setae. Wing. Hyaline, distinctly tinged with brown from base to level of bm-cu crossvein and pale brownish on anterior portion and along veins; tegula and basicosta black; lower calypter white. Relative lengths of 2nd, 3rd and 4th costal sectors approximately as 3:3.5:1.5; vein M from dm-cu crossvein to its bend about 1.5 times distance between the bend and wing margin. Legs. Black; pulvilli pale brownish. Fore tibia with 1 posterior seta; mid tibia with 2 anterodorsal, 2 posterodorsal and 1 ventral setae; hind tibia with a row of very closely set anterodorsal setae, 1 posterodorsal and 1 ventral seta. Fore claws and pulvilli shorter than 5th tarsomere.

Abdomen. Black, broadly reddish brown on sides of tergites 3 and 4, dorsum with dense whitish pruinosity on anterior 2/3 of tergites 3 to 5, the pruinose band triangularly narrowed on both sides of each tergite. Hairs on dorsum very dense, fine, short and suberect, erect and finer on tergite 5; syntergite 1+2 and tergite 3 without median and lateral marginal setae; tergite 5 at most with a row of fine hair-like marginal setae.

Type material examined. Holotype ♂ of Billaea robusta Malloch , MALAYSIA, Pine Tree Hill (101°41′E, 3°41′N), Fraser’s Hill 4600 ft., Papahng, 3.vii.1933 ( BMNH).

Distribution. Malaysia ( Malaya).

Remarks. This species is one of five species with bare parafacial, 4 or 5 narrow dark longitudinal on presutural scutum and a pair of triangular black markings on each tergites 3 and 4, the other species being B. atkinsoni , B. chinensis , B. steini and B. triangulifera . Within this group of five species, B. robusta and B.chinensis are the only two with one posterior seta on fore tibia and sides of tergites 3 and 4 broadly reddish brown. Billaea robusta differs from the latter in having short plumose arista, scutellum black on basal 2/3, the triangular dark markings on abdominal tergites 3 and 4 merged forming a dark band, and syntergite 1+2 and tergite 3 without lateral marginal setae.

Figures

FIGURES 100 – 101. Billaea spp., bodies of male in dorsal view. 100. B. malayana Malloch. 101. B. robusta Malloch.