Cydistomyia wentworthi (Ferguson & Hill)

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 : 55-56

Cydistomyia wentworthi (Ferguson & Hill)

( Fig. 39 )

* Tabanus wentworthi Ferguson & Hill, 1922: 259 ; Hardy 1939: 42, 1944: 84. Holotype female, paratype male from Leura, Blue Mountains, NSW (AM).

Cydistomyia wentworthi ; Mackerras 1959: 168; Daniels, 1989: 288; Bickel & Elliot, 1998 -2005: 5.

Other material examined. 15 ♀, 3 ♂.

Diagnosis. A medium to large species closely resembling C. doddi , C. magnetica and C. alternata but distinguished from them by wider frons, much less pronounced dorsal angle with smaller upward pointing tooth on basal plate of antennal flagellum, and absence of discrete brown cloud in apical half of wing. Length 13–17 mm.

Female. Head. Eyes (relaxed) black, bare (short hairs visible at 35X magnification). Frons relatively narrow, parallel or slightly divergent, index 4.0–4.6, with dull fawn-brown tomentum and short black hairs; vertex not hollow; vertical triangle greyish, with long black hairs; ocellar tubercle well defined, raised, brown, slightly shiny, ocelli not visible; callus quadrate, almost full width of frons at base, with tapering extension which at its base is about one-third width of upper edge of callus and extends almost to ocellar tubercle. Subcallus with greyish cream tomentum, yellowish above base of antennae, without hairs; parafacials and face with grey tomentum, with predominantly dark hairs; beard greyish white, with a few black hairs. Antennal scape and pedicel with greyish fawn tomentum, with black hairs, moderate dorsal prolongation on pedicel; basal plate slender, brownish black, with weak dorsal angle and small upward pointing dorsal tooth which does not project anteriorly. Palpi brown, more yellowish at tip, with black hairs on segment 2 and mixed black and greyish white or all greyish white on palpal segment 1.

Thorax. Scutum and scutellum greyish brown, with traces of darker median and dorsocentral lines, lighter brownish grey on lateral margins, with short black and scanty appressed yellowish hairs; marginal hairs black in front of wing root, white to yellowish behind it. Pleura pale grey, hairs creamy white, some black ones on upper mesopleural convexity.

Legs. Femora dark brown, with mixed short black and longer white hairs, fore femora generally darker than others; tibiae brown at least on basal half, with entirely black hairs; tarsi generally darker, with black hairs.

Wings. Greyish, costal cell brown; all veins narrowly margined with brown and with clear window in basal portion of cell R 1 extending apically to basal edge of stigma. There is no discrete brown cloud in apical half of wing as is found in preceding three species but rather more uniform suffusion in cells of basal twothirds of wing.

Abdomen. Blackish brown, first tergite dark brown in middle basally, grey along hind margins, ashy grey laterally; subsequent tergites brownish black in middle third, dark brown laterally, with paler apical margins; small white-haired semilunar median and lateral apical spots on tergites 1–5, elsewhere hairs black. Venter dark brown, greyish in centre of 1 st and 2 nd sternites, with grey to fishy white haired apical margins and white haired lateral areas on sternites 1–5, elsewhere hairs black.

Male. Similar to female but more brown in colour. Eyes (relaxed) black, contiguous, bare (short hairs easily visible at 35X magnification), upper facets not appreciably enlarged nor differentiated from lower. Ocellar tubercle prominent, projecting above level of eyes, with three small but distinct brown spots representing ocelli. Palpi subcylindrical, tapering rather abruptly to point, bright brown, with fairly dense black and some creamy hairs. Legs somewhat more brownish than in female. Dark markings along wing veins less evident. Abdomen brown, darker in median area, with dense pale hairs on median triangles, apical edges, and lateral triangles of tergites.

Remarks. Four specimens from Wilson’s Promontory, Vic., are here placed as variants of C. wentworthi . They differ mainly in the shape of the callus which is not quadrate but rather with gently tapering shoulders, although the extension usually reaches the ocellar tubercle. In addition, the cream to creamy white hairs forming median and lateral apical spots on the tergites extend along the pale apical margins forming incomplete haired bands approaching those seen in C. pruina . In some specimens the dorsal prolongation on the antennal pedicel is pronounced and similar to that seen in C. victoriensis . The brown costal cell and brown suffusion along the wing veins, as well as dark femora contrasting with lighter brown tibiae, immediately distinguish these specimens from C. pruina . The smaller size, abdominal markings, colour of legs, and shape of basal plate distinguish them from C. victoriensis .

Distribution. Inland NSW from near Glen Innes to Wilsons’ Promontory VIC. NSW: Washpool Nat. Pk., nr Glen Innes, Jan., J. and A. Skevington; Leura, Jan., W.W. Froggatt; Wentworth Falls, F.H. Taylor, Nov., A. Tonnoir; Blackheath, Feb., A.J. Nicholson, I.M. Mackerras; Katoomba, Dec., S.S. Sekhon; Blue Mountains, Jan., C. Deuquet. VIC: Wilson's Promontory, Jan.–Feb., G.W. Douglas, Jan., A.J. Nicholson.

Figures

FIGURES 37–39. 37. Cydistomyia magnetica (Ferguson & Hill) frons, palp, antenna, female terminalia, sternite 8, spermathecal bulb. 38. Cydistomyia alternata (Ferguson & Hill) frons, palp, antenna, female terminalia, sternite 8, spermathecal bulb. 39. Cydistomyia wentworthi (Ferguson & Hill) frons, palp, antenna, female terminalia, sternite 8, spermathecal bulb.