Cydistomyia silviformis (Taylor)

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 : 68

Cydistomyia silviformis (Taylor)

( Fig. 47 )

* Tabanus silviformis Taylor, 1919, p. 62 . Holotype female, from Stradbroke Island , south Qld (QM).

Cydistomyia silviformis ; Mackerras, 1959: 168; Daniels, 1989: 288; Bickel & Elliot, 1998 -2005: 4.

Other material examined. 2 ♀.

Diagnosis. A very small, slender, brown species, known only from the type series. Resembling a small C. musgravii forma rivularis from which it is distinguished by the brown colouration, narrower frons, brown shiny, callus not full width of frons at base and with uniformly tapering narrow extension reaching at least two-thirds length of frons, absence of dorsal prolongations on antennal scape and pedicel, and absence of dark median vitta on abdominal venter. To be distinguished from C. palmensis by smaller size, lighter colour, light fawn palpi, and light yellowish brown wing veins. Length 8 mm.

Female. Head. Eyes (relaxed) reddish brown, bare (few short hairs just visible at 35X magnification). Frons slightly divergent, index 4.3, covered with brown tomentum and hairs, light greyish fawn along eye margins; ocellar tubercle indefinite; callus brown, shiny, distinctly raised, about four-fifths width of frons at base, tapering to extension reaching two-thirds length of frons. Subcallus, parafacials, and face light greyish cream; subcallus not shiny, without hairs, parafacials and face with light brown hairs; beard creamy white. Antennal scape fawn, pedicel fawn to reddish brown, both with dark brown to blackish hairs; flagellum missing. Palpi relatively long, narrow (like in C. musgravii form and contrasting with fleshiness of C. rivularis form), light fawn, with dark brown to black hairs, some cream ones below.

Thorax. Scutum and scutellum brown, with indications of paler dorsocentral vittae and paler lateral margins, hairs brown, mixed with creamy gold, with some long dark brown ones laterally in front of wing root. Pleura pale greyish fawn, with white hairs, few brown ones on upper part of upper mesopleural convexity.

Legs. Bright brown, darkening on tarsi; hairs brown, creamy on mid and hind femora and basal half of fore tibiae laterally.

Wings. Faintly greyish, without brownish hue; veins light yellowish brown.

Abdomen. Brown, with brown hairs; apices of tergites with well-defined pale greyish fawn bands covered with creamy hairs, widening in mid line to form apical triangles on 2 nd, 4 th and 5 th tergites and at extreme lateral edges of all tergites. Venter brown, with greyish overlay, with paler apical margins to sternites, no indication of median vitta, hairs predominantly cream, dark brown on 6 th and 7 th sternites.

Distribution. Known only from type locality, Stradbroke Island, QLD.

Figures

FIGURES 46–48. 46. Cydistomyia atmophora (Taylor) frons, palp, antenna, female terminalia, sternite 8. 47. Cydistomyia silviformis (Taylor) frons, palp, antenna. 48. Cydistomyia innubilus Mackerras & Spratt, sp. nov. frons, palp, antenna, female terminalia, sternite 8, spermathecal bulb.