Acatopygia pulchella Kröber

Winterton, Shaun L., 2007, Revision of the Australian stiletto fly genus Acatopygia Kröber (Diptera: Therevidae: Agapophytinae), Zootaxa 1405, pp. 51-62 : 58-61

Acatopygia pulchella Kröber

( Figures 3–4 )

Acatopygia pulchella Kröber, 1912a: 149 . – Kröber 1913: 17, figs 15–16 (listing); Mann 1928: 43 (redescription); Irwin & Lyneborg, 1989: 353 (catalogue); Winterton et al. 2001: 195, 210, fig. 6 (listing).

Holotype male, AUSTRALIA: NEW SOUTH WALES: “ Australien ”, A.L. Schrader leg. ded., 25.ix.1896 (MEI 90753) ( DEIC). Condition: poor; specimen damaged.

Other material examined. AUSTRALIA, NEW SOUTH WALES: female, Minnamurra Falls, [­34.632, 150.717], 18.xii.1968, mv light, C.E. Chadwick (MEI 025309) ( NSWA). QUEENSLAND: 3 males, Brisbane, [­27.465, 153.017], 3.ix.1927, J. Mann (MEI 109628­30) ( ANIC); female, Brisbane, [­27.465, 153.017], 20.viii.1927, J. Mann (MEI 109636) ( ANIC); male, Bribie Island, [­27.05, 153.15], 4.ix.1980, M. G. Jefferies (MEI 109802) ( MGJC / ANIC).

Diagnosis

Antenna and foreleg brown; eye with transverse furrow; scutum overlain with brown pubescence, distinct white­grey dorsocentral stripes; femora with dark ventral setae; abdomen overlain with silver velutum; epandrium large, cerci elongate.

Redescription

Male: Body length: 6.0– 7.5 mm.

Head. Frons flat, bulbous around antennal base ( Figs 3 A–B), narrower than ocellar tubercle at narrowest point; frons and face glossy black; frons overlain brown pubescence tending towards silver in lower portion, admixed with elongate, dark setae; bulbous area above antennal base glabrous; silver pubescence around base of antenna and on face, admixed with several elongate dark setae; eye with facets slightly larger in upper portion, transverse furrow present; ocellar tubercle raised, black, overlain with brown pubescence admixed with elongate, dark setae; occiput concave, overlain with light­grey pubescence, single row of relatively long, black, postocular setae dorsally; gena overlain with silver­white pubescence, admixed with white setae; mouthparts light orange­brown, covered with dark setae; antennal length approximately equal to length of head, antenna orange­brown, overlain with brown pubescence, admixed with erect, elongate, dark setae on scape and pedicel; flagellum turbinate, slightly shorter than combined length of scape and pedicel.

Thorax. Glossy black; scutum overlain with brown pubescence, anterolateral corner of scutum and dorsocentral stripes of white­grey pubescence, admixed with long, erect setae; postalar callus glabrous; scutal macrosetae black; scutellum overlain with matte, black pubescence anteriorly, glabrous posteriorly; pleuron and coxae with dense, silver pubescence except on anepisternum, anepimeron and katatergite, admixed with long, pale setae on postpronotum, proepisternum, anepisternum, katatergite and coxae; legs dark brown, bases of tarsomeres and anterior surfaces of mid and hind tibia dark yellow; single row of dark macrosetae on ventral surfaces of mid and hind femora and on anteroventral surface of fore femur; wing hyaline with brown or black banding, bands across cells bm and d respectively, third band across subcostal and radial fields; venation brown in infuscate areas, dark yellow in hyaline areas; haltere crème­white colour; macrosetae difficult to discern from regular setation of scutum; scutal chaetotaxy (pairs): np, 3; sa, 1; pa, 1–2; dc, 2–4; sc, 1.

Abdomen. Glossy brown­black with scattered, erect, pale setae; setae longer laterally; setae on terminalia dark; dense, silver, velutinous pubescence tergite 1–5 and epandrium; intersegmental membrane of segments 2–4 white; terminalia dark.

Male genitalia. Epandrium large, quadrangular, length slightly shorter along midline than greatest width, posterolateral corners rounded ( Fig. 4 A), extending laterally and ventrally to partially conceal gonocoxites; cercus greatly elongate; tergite 8 narrow, band­like with round lateral lobes ( Fig. 4 B); sternite 8 broad with few setae along posterior margin ( Fig. 4 E); gonocoxite ( Figs 4 C–D) wedge­like in profile; gonocoxal process narrow, much shorter than inner gonocoxal process, elongate setae on posterior surface; medial atrium present with membranous area covered with velutum; hypandrium large, fused laterally to gonocoxites, large, posteriorly projecting setae along posterior margin; ventral lobe elongate, projecting dorsally, broadly club shape apically with velutum present at apex; gonostylus curved medially towards apex, erect setae on medial surface; inner gonocoxal process equal in length to gonostylus, curved medially towards apex, short setae on ventral surface of apex; gonocoxal apodeme approximately equal to length of gonocoxite; distiphallus straight ( Figs 4 F–G), ventral apodeme of parameral sheath elongate, narrow, approximately equal in length to ejaculatory apodeme; dorsal apodeme of parameral sheath reduced; lateral ejaculatory apodeme small and tapered; ejaculatory apodeme narrowed anteriorly, projecting dorsally at apex.

Female: Body length: 6.5–8.0 mm.

Similar to male except: Frons wider than ocellar tubercle at narrowest point, extensively covered with brown pubescence dorsally; shorter setae on head, thorax and abdomen; abdominal tergites without velutum covering, silver­grey pubescence extensively on tergite 1.

Female genitalia. Spermathecal sac present, spherical in shape; spermathecal sac duct thickened at common junction with spermathecal ducts; spermathecae spherical.

Comments

Acatopygia pulchella is the type species for the genus. It is readily differentiated from other species of Acatopygia based on furrowed eyes, row of macrosetae on the femora, brown legs and antennae, scutum colouration, and abdominal velutum covering and enlarged epandrium in the male. This species is known from central, eastern Australia and has been associated with coastal heath habitats. Mann (1929) noted that males of this species are found hovering in swarms in sandy habitats.

Figures

FIGURE 3. Acatopygia pulchella Kröber, male head: A, dorsal; B, same, lateral. Scale line = 0.5 mm.

FIGURE 4. Acatopygia pulchella Kröber, male genitalia: A, epandrium, dorsal view; B, tergite 8, dorsal view; C, gonocoxites lateral view; D, same, ventral view; E, sternite 8, ventral view; F, aedeagus, lateral view; G, same, dorsal view. Scale line = 0.5 mm.