Cydistomyia casuarinae (English, Mackerras & Dyce), 1989

Mackerras, I. M., Spratt, D. M. & Yeates, D. K., 2008, Revision of the horse fly genera Lissimas and Cydistomyia (Diptera: Tabanidae: Diachlorini) of Australia, Zootaxa 1886 (1), pp. 1-80 : 16-18

Cydistomyia casuarinae (English, Mackerras & Dyce)

( Figs. 1 , 13 )

* Chalybosoma casuarinae English, Mackerras & Dyce, 1957: 292 , figs 1–21, plate XIII, figs 1–4; Mackerras 1959: 166. Holotype female and paratype male (as allotype), NSW, Merricumbene, bred from pupae, Dec.1954 and 1955, A.L. Dyce (ANIC). Subsequent detailed study of the Papuan species ( Mackerras 1964: 107–108) showed that allocation of casuarinae and cyanea to Chalybosoma was not justifiable.

Cydistomyia casuarinae (English, Mackerras & Dyce) Daniels, 1989: 286 ; Bickel & Elliot, 1998 -2005: 3.

Other material examined. 6 ♀, 2 ♂.

Diagnosis. A thickset dark metallic blue-green species; related to C. cyanea but readily distinguished by the entirely black antennal flagellum and spotted wings. Length 10.0– 12.5 mm.

Female. Head. Eyes in life dark metallic green, with short sparse hairs just visible at 15X magnification. Frons medium, index 4.0–4.5, parallel or slightly divergent, covered with thick silvery white tomentum through which dark ground colour shines at certain angles, hairs black, short, inconspicuous; vertical triangle prominent, somewhat swollen, shiny dark blue, with black hairs; puncture at anterior angle, but no ocellar tubercle; callus greenish black, shiny, lower part somewhat swollen and wrinkled, about four-fifths width of frons at base. Subcallus rather prominent, shiny, blackish brown, with faint tomentose overlay; parafacials dark brown, somewhat shiny, with black hairs; face more definitely shiny, with some thin white tomentum in middle below antennae and with black hairs; tentorial pits large, deep and prominent; beard black. Antennal scape shiny, blue-black, with black hairs; pedicel black, with black hairs; basal plate dull blackish brown, of unusual shape, style short, same colour as plate. Palpi shiny, blue black, with black hairs.

Thorax. Scutum and scutellum metallic dark blue-green with thin ashy dusting, more purplish blue laterally, indications of median line anteriorly, hairs black. Pleura somewhat shiny, bluish to brownish black, with black hairs.

Legs. Black with dark purple reflections, except for cream fore distal femur and proximal tibia and more brownish mid and hind distal femur and proximal tibia; hairs black, except for pale antero-ventral zone on fore tibiae and reddish brown zone ventrally on tarsi; pulvilli cream, prominent. Fore tibiae markedly swollen, mid and hind less so.

Wings. Clear over most of membrane; stigma blackish; veins dark brown. There are the following conspicuous dark brown marks: one filling cells at extreme base of wing and extending a little into basal cells, small one on Rs just beyond fork of R, transverse band covering apices of basal cells, one extending from costa through stigma and R 2+3 (which is curiously sinuous) to reach R 4+5 and five small spots apically and posteriorly at tip of R 2+3, tip of R 4, fork of R 4+5, fork of M 1+2, and tip of A1+CuA2.Vein R 4 angulate, sometimes with rudimentary appendix. Basicosta bare.

Abdomen. Dark metallic bluish green above and almost blue-black below, with brownish hue at lateral edges of 1 st and 2 nd tergites in older specimens; hairs entirely black. Sternite 8 narrower than in cyanea , with much narrower, deeper gonapophyses; spermathecal bulbs slender, pale.

Male. Similar to female. Eyes with upper facets distinctly enlarged, bright orange with yellow reflections, lower and posterior small facets rich blue, with purple zone at margin of upper facets; hairs more evident than in female, especially on upper facets. Antennae more slender; palpi short, acorn-shaped. Swelling of tibiae may be slightly less than in female, hind tibial fringes better defined. Genitalia without distinctive characters.

Remarks. English, Mackerras & Dyce (1957) gave an excellent description of the larva and pupa of this species, which were found in cavities made by a longicorn beetle, Agrianome spinicollis (Macquart) in the trunks of Casuarina cunninghamiana Mig. The larvae are like those of other Diachlorini , but the pupae have the lateral arms of the posterior spiracles (= aster) greatly enlarged (see their Text-fig. 21).

Distribution. Atherton region of NE QLD and Merricumbene in NSW. QLD: Kuranda, A.P. Dodd; Imbil, Feb., F.A. Perkins; Boomer Range, Sept., C.J. Burwell and G.B. Monteith (raised from pupae); 22 km SE Yarraman, Jan., C.J. Burwell and D.C. Darling. NSW: Merricumbene, bred, Nov.–Dec., A.L. Dyce.

Figures

FIGURES 1–8. Habitus images 1. Cydistomyia casuarinae (English, Mackerras & Dyce) wing length 11 mm. 2. Cydistomyia cyanea (Wiedemann) wing 12 mm. 3. Cydistomyia nigropicta (Macquart) wing: 18 mm. 4. Cydistomyia doddi (Taylor) wing 13.5 mm. 5. Cydistomyia magnetica (Ferguson & Hill) wing: 14 mm. 6. Cydistomyia alternata (Ferguson & Hill). 7. Cydistomyia victoriensis (Ricardo) wing: 16mm. 8. Cydistomyia rivularis (Ferguson & Hill) wing: 9mm.

FIGURES 13–15. 13. Cydistomyia casuarinae (English, Mackerras & Dyce) frons, palp, antenna, female terminalia, sternite 8. 14. Cydistomyia cyanea (Wiedemann) frons, palp, antenna, female terminalia, sternite 8, spermathecal bulb. 15. Cydistomyia torresi (Ferguson & Hill) frons, palp, antenna, female terminalia, sternite 8.