Sisyromyia decorata ( Walker, 1849 )

Li, Xuankun & Yeates, David K., 2019, Revision of the Australian bee fly genus Sisyromyia White, 1916 (Bombyliidae, Bombyliinae, Acrophthalmydini), Zootaxa 4711 (2), pp. 201-244 : 212-216

4. Sisyromyia decorata ( Walker, 1849)

( Figs 7–9 )

Bombylius decoratus Walker, 1849: 291 . Type-locality: Australia (WA); 2 syntypes, BMNH.

Type specimen. Syntype of Bombylius decoratus Walker , ♂ Western Australia ( NHMUK 010921894 ) ( Fig. 7 ) .

Other specimen examined. Australia, WA, ♂ -31.9648 116.5125, York , open woodland, 10 Aug 2018, J & F Hort . ♂ (2) ♀ (4) -31.9648 116.5125, York , open woodland, 11 Aug 2018, J & F Hort . ♂ (2) ♀ (1) -31.9648 116.5125, York, open woodland, 12 Aug 2018, J & F Hort . ♂ -31.9648 116.5125, York, open woodland, 24 Aug 2018, J & F Hort . ♀ 34°46’36.3”S 116°18’56.4”E, D’Entrecasteaux NP, Deeside Coast Road, malaise, 81 m, C Lambkin, J Recsei, J Hamilton, 5-14 Nov 2003, ANIC Buck Sample 2201

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Diagnosis. Medium-sized fly, body with mostly brownish hairs. Wing membrane dark brown on anterior half and clear on posterior half. Male eyes dichoptic, narrowly separated by 0.3 x width of ocellus. Gap between inner apices of gonocoxites wide. Inner apex of gonocoxite long.

Redescription. Male. Body length 7.4–10.5 mm, wing length 7.0– 8.4 mm.

Head. Head about 2.4 x wider than long, mostly blackish with thick pale pruinescence and covered in admixed white to black hairs and scales. Eyes dichoptic, narrowly separated by 0.3 x width of ocellus. Frons short, 1.9 x length of ocellar tubercle, upper narrow and black; lower half triangular, 0.6 x length of upper half, with thick pale pruinescence and black hairs admixed with few pale scales. Ocellar tubercle slightly raised, blackish brown to black with thick grey pruinescence, with long black hairs and some golden scales. Face with thick pale pruinescence and golden scales admixed with long black hairs; parafacial area with long white scales. Gena with thick pale pruinescence and dense long white to yellow hairs, admixed with few brown hairs. Clypeus with thick pale pruinescence and otherwise bare. Occiput with thick pale pruinescence and yellow scales and black hairs. Posterior eye margin slightly convex. Antennal scape and pedicel brown with thick pale pruinescence, scape with long black hairs admixed with few white scales ventrally, pedicel with short black hairs; flagellum black without pruinescence, subapex with 3–5 long hairs. Scape 3.1 x as long as wide, and 3.2 x as long as pedicel, uniform from base to apex. Pedicel 1.1 x as long as wide. Flagellum 12.0 x as long as wide, 1.7 x as long as scape + pedicel, 2.3 x as long as scape, conical and slightly laterally compressed, one-segmented with apical stylus ( Fig. 8c ). Palpus long, just extending beyond oral cavity, dark yellow with black hairs, one-segmented, without palpal pit. Mouthparts slender, 4.5 x as long as eye length, 3.3 x as long as head length, labellum thin and filiform ( Fig. 8h ).

Thorax. Integumental colour of scutum mostly black with thick brown pruinescence except two median wide white pruinescent stripes, postalar callus brown with sparse pale pruinescence. Scutum covered with short pale yellow to brown hairs, admixed with few short black hairs, lateral stripe consisting of short white to pale yellow scales, and posteriorly with few short white and golden scales. Seven brownish yellow notopleural setae present. Scutellum black with sparse pale pruinescence, anterior margin with an indistinct band consisting of short white scales, posterior margin with long brown hairs admixed with some long black hairs. Pleura black with thick pale pruinescence, mostly covered in long white to pale yellow hairs admixed with few black hairs, except dorsal half of anepisternum with brown hairs, anepimeron, meron, laterotergite and mediotergite bare.

Legs. Legs mostly yellow, except femora black. Femora with long black hairs admixed with some brown scales. Mid femur with two anterior bristle on apical half; hind femur with one row of anteroventral bristles and one row of posteroventral bristles, more separate bristles on apical half. Bristles and other hairs on legs brown. Fore tibia 2.0 x longer than fore basitarsus, mid tibia 2.6 x longer than mid basitarsus, hind tibia 2.4 x longer than hind basitarsus.

Wings. Wing membrane dark brown on anterior half and clear on posterior half, darker towards wing base. Cell r 5 open, M 1 close to R 5; cell br nearly as long as cell bm, crossvein r-m arising from base of cell dm; crossvein m-m nearly as long as crossvein r-m; cell cup open ( Fig. 8d ). Haltere stem brown, and knob yellow.

Abdomen. Integumental colour of tergites black mostly with sparse pale pruinescence. Tergite 1 with thick pale pruinescence and dense brown hairs; tergites 2 with brown hairs, posterior half admixed with some black hairs, hairs denser laterally; tergites 3–7 with short golden scales and sparse long black hairs in dorsal face, and pale yellow to white scales laterally, best viewed from posterodorsal side, laterally with dense long brown hairs admixed with black hairs; tergites 2–7 with median stripe consisting of dense, decumbent short white scales.

Sternites black except posterior margin yellow, with thick pale pruinescence, covered with pale brown hairs and scales, admixed with few black hairs. Genitalia. Epandrium anterior margin strongly concave, posterior margin straight ( Fig. 9d ). Lateral margin of gonocoxite nearly straight ( Figs 9a,b ); lateral ejaculatory process wide; inner apex of gonocoxite long and acute, outer apex of gonocoxite long and sharp; gap between inner apices of gonocoxites wide; phallus shorter than gonocoxite ( Fig. 9c ).

Female. Body length 5.7–7.7 mm, wing length 6.9–9.1 mm. Very similar to male, except frons black with thick pale pruinescence, 4.0 x as wide as ocellar tubercle, frons with long black hairs admixed with few short white and golden scales ( Fig. 8l ). Body hairs paler than male. Around 30 acanthophorite spines present on each side of tergite 9+10 ( Fig. 9g ).

Remarks. Bombylius decoratus was first described based on two specimens from WA. Twenty years later, the species Bombylius scutellaris was described from NSW. As Bombylius scutellaris is very similar to Bombylius decoratus externally, it was considered a synonym of the latter by Roberts (1928: 429). However, this arrangement was not recognised in the catalog ( Evenhuis & Greathead, 1999). We compared the specimens from NSW and WA, and agree with Evenhuis & Greathead’s decision to keep two valid species (also see ‘9. Sisyromyia thomsoni Evenhuis & Greathead, 1999 ’ later).

Sisyromyia decorata is similar to Sisyromyia thomsoni , but differs as follows: male eyes dichoptic; gap between inner apex of gonocoxite wide; inner apex of gonocoxite long.

Distribution. Australia (WA).

Figures

FIGURE 7. Sisyromyia decorata (Walker, 1849). Syntype of Bombylius decoratus Walker, 1849, NHMUK 010921894: (a) dorsal; (b) lateral. Scale bars = 1 mm.

FIGURE 8. Sisyromyia decorata (Walker, 1849). External (a–i (♂); j–o (♀)): (a, j) dorsal; (b, k) lateral; (c) antenna, lateral; (d) wing; (e, l) head, dorsal; (f, m) head, frontal; (g, n) head, profile; (h, o) head, lateral; (i) abdomen, dorsal. Scale bars = 1 mm (a, b, d–o); = 0.1 mm (c).

FIGURE 9. Sisyromyia decorata (Walker, 1849). Genitalia (a–e (♂); f, g (♀)): (a) genitalic capsule, dorsal; (b) genitalic cap- sule, ventral; (c) genitalic capsule, lateral; (d) epandrium, dorsal; (e) epandrium, lateral; (f) sternite 8, ventral; (g) genitalia and spermathecae. Scale bars = 0.1 mm.