Rhabdogaster gracilis ( Engel & Cuthbertson, 1937 )

Londt, Jason G. H., 2006, A review of the Afrotropical genus Rhabdogaster Loew, 1858 with descriptions of new species (Diptera: Asilidae: Stenopogoninae), African Invertebrates 47, pp. 243-313 : 258-260

Rhabdogaster gracilis ( Engel & Cuthbertson, 1937)

Figs 34–39

Heteropogon gracilis Engel & Cuthbertson, 1937: 13 , 14, fig. 9 a Antenna; Hull 1962: 194; Oldroyd 1974:

47 (in key), fig. 37 entire female; 1980: 362 (catalogue). Type locality: Zimbabwe (Trefonen

Farm, Trelawney).

Afroholopogon gracilis: Londt 1994 a: 64 .

Rhabdogaster gracilis: Londt 2005: 228 .

Redescription: Based on holotype ơ.

Head: Dark red-brown to black, silver pruinose, white setose.Antenna dark red-brown, setae white. Face entirely pruinose. Mystax entirely white, occupying lower two-thirds of face. Frons extensively pruinose, vertex (including ocellar tubercle) entirely shiny apruinose. Occiput entirely pruinose. Proboscis and palpi red-brown, setae white.

Thorax: Dark red-brown to black, silver pruinose, white setose. Mesonotum pruinose except for apruinose central area, postpronotal and postalar lobes. Pleura extensively pruinose (single bare spot on anepisternum). Scutellum pruinose except for posterior margin, approx. 10 moderately developed, white, sctl s. Postmetacoxal bridge entirely silver pruinose. Legs: cx dark red-brown, silver pruinose (cx 2 and 3 extensively apruinose laterally), white setose; troc, fem, tib and tar dark red-brown, mainly white setose; fem and tib narrowly orange proximally; tib (ventrodistally) and tar with some black setae. Wing 4.0 x 1.3 mm, veins yellow-brown, membrane transparent, unstained, extensively lacking microtrichia (proximally). Discal cell lacking microtrichia proximally; costal cell entirely devoid of microtrichia.

Abdomen: Dark red-brown to black, dull silver-gold pruinose, white setose. Tergites apruinose along hind margins. Sternites entirely pruinose. Terminalia ( Figs 34– 36 ): epand in lateral view much longer than external lobe of goncx and of similar length to hypd, gradually tapering to fairly acutely-pointed tip; lobes separated medially but touching basally; hypd in lateral view fairly narrow, about same length as epand, slightly upcurved distally; broadly-rounded basally in ventral view, tapering to long, parallel-sided distomedial projection with rounded apex. External lobe of goncx much shorter than epand, terminating in acutely-pointed apex; wellsclerotised internal lobe clearly seen to be fused with external lobe, projecting beyond external lobe, with somewhat truncate apex. Gonostyli in ventral view with thick bases and slender apices, fairly straight, projecting to similar level attained by inner lobes of goncx.

Variation: Some variation is evident over the fairly extensive range of the species. The extent of mesonotal and tergal apruinosity varies, as does the extent of the orange coloration of legs. Setal coloration varies from white to brown. Some variation in genital morphology is shown in Figs 37–39 . The identification key works for most of the specimens, but some may prove difficult to identify without macerating the male terminalia.

Holotype: ơ ZIMBABWE: ‘Trefonen Farm / Trelawney [1730S:3027E] / S. Rhodesia. / Dept. Agric. / 22/ 11/1935 ’, ‘W.L. Williams / collector’, ‘Type von / Heteropogon / gracilis Engel’ [orange], ‘973’ (NMBZ). Note: In their paper, Engel & Cuthbertson (1937) record the type locality as ‘Trefonen farm near Trelawney, Lomagundi’ and the date of collection as ‘ December 1935 ’. Lomagundi [1710S:3005E] is not recorded on the specimen labels, while the month of collection (written by hand in black ink) may either be read as November or February (not December).

Other material studied: BOTSWANA: 1ơ ‘Botswana: Serowe #56 / Farmer’s Brigade / 22 ° 25'S: 26 ° 44'E 1000m / Date: 28.xi.1990 / Coll: P. Forchhammer / Malaise Trap’; 1ơ ‘Malaise trap 3 / Botswana SE2226BD / Farmers Brigade / ca. 6 km SE of Serowe / Coll. P. Forchhammer / 20-v-1984 / A. tortilis woodland’; 1ơ ‘Malaise trap 1 / Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / 31-v-1984 / Mercury vapour lamp’; 1ơ ‘Malaise trap 1 / Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / 6-v-1984 / Mercury vapour lamp’; 1^‘Botswana SE2226BD / Farmers Brigade / ca. 5 km SE of Serowe / P. Forchhammer 13oom / A. tortilis woodland / Malaise trap 3 / Forestry 8-xi-84’; 2ơ ‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 3 / v-86’; 1ơ 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 2 / 4-xii-84 / Mercury vapour lamp’; 1ơ ‘Malaise trap / Serowe; Botswana / Forchhammer Leg. / Date 7-xi/83’; 2^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 2 / xi-86’; 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / M.T.2 xii-86’; 1ơ ‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 2 / vapona xi-85’; 1ơ ‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / 17-xi-84 / Malaise trap 1 / Mercury vapour lamp’; 1ơ ‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / 16-xi-84 / malaise trap 1 / Mercury vapour lamp’; 1ơ 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 1 / xi-85’; 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / 16-xi-84 / Malaise trap 2 / Mercury vapour lamp’; 2ơ ‘Botswana SE2226BD / Forestry nursery / ca. 6 km SE of Se- / rowe. Malaise trap 3. / Forchhammer. 13oom. / 27-xi-84’; 1ơ ‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 1 / 7-vii-1984 ’; 1ơ 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 3 / ix-86’; 1ơ ‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 3 / vi-86’; 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 2 / xi-86’; 2ơ 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 2 / vapona xi-85’; 1ơ ‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / xi-87’; 3ơ 2^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 2 / vapona xii-1985 ’; 3ơ 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 3 xii.1985 ’; 2ơ 1^‘Botswana SE2226BD / Farmers Brigade 5 km / SE of Serowe Hillside / N slope P Forchhammer / Malaise trap 3 i.1986 ’; 1^‘Botswana SE2226BD / Serowe. Farmer’s / Brigade. Malaise / trap. Forchhammer / 8 x-88’; 3^‘Botswana SE2226BD / Serowe. Farmer’s / Brigade. Malaise / trap. Forchhammer / 9 xi-88’; 2ơ 1^‘Botswana SE2226BD / Serowe. Farmer’s / Brigade. Malaise / trap. Forchhammer / xi-89’; 5ơ 1^‘Botswana: Central / Distrikt, Serowe / Farmer’s Brigade / SE2226BD, Mercury V.L. / xi.1989, Per Forchhamer leg.’ (NHRS); 10ơ 4^‘Botswana / Serowe / M.T.6.xi.78’; 5ơ 9^‘Botswana / Serowe / M.T.6.xii.78’. KENYA: 1ơ ‘Kenya Kampi-Ya- / Samai (Lake Baringo) / 00 ° 37'N: 36 ° 02'E 980m / 30.v.–2.vi.1980 / B/ Lamoral Malaise’; 1ơ ‘Kenya / 50 km S. / Maralal [0106N:3642E] / 24.xii.83 / A. Freidberg’; 1ơ 1^‘Kenya Eastern / Katulani [0132S:3738E] Kitui distr. / malaise trap 26.x.1990 / J.A.M. Jansen’; 1ơ ‘Kenya, Tsavo / West, Ngulia [0212S:3744E] / 6.xii.1989 / A. Freidberg / & F. Kaplan’. MALAWI: 1^‘Malawi Kasungu Nat. / Park Lifupa Camp / 1333Aa 9–10.xii.1980 / 1000m Stuckenberg & / Londt Brachystegia’. NAMIBIA: 1^‘Namibia 26.iii.1984 / 54 km S Khorixas. Rd. 76. 20 43'S: 14 49'E / Londt & Stuckenberg / Roadside grass and / flowers, sandy area’; ‘S.W. Africa (W56) / 16 mls. E Gobabis [2227S:1858E] / 11.iv.1972 ’, ‘Southern / African Exp. / BM. 1972-1’ (BMNH). SOUTH AFRICA: Mpumalanga: 1^‘Timbavat [? Timbavati] / SE2431Ac / v- 1979 / E. Holm. CH Scholtz’; North-West: 1ơ ‘S Africa: NW Province / Botsalano Game Reserve / Mogolodi Hide area / 25 ° 33'15"S: 25 ° 40'16"E / 1350m 18.iii.2003 J Londt / Rhus , Acacia savanna’; 1^‘Marico [Groot Marico 2536S:2625E] / Transvaal / Jan. 1918 ’ (NMNH), 12ơ 7^‘S Africa: N-W Province / Pilanesberg National Park / Bakubung 12–19.xi.1999 / 25 ° 20'40"S: 27 ° 03'25"E / JGH Londt Camp’; SUDAN: 1ơ ‘W. Darfur: / Jebel Murra, [? = Jabal Murrah 1419N:2227E] / Killing. [? = Jabal Killing 0410N:3012E] / 7000 ft. 7.iv.1932. / Miss. M. Steele’ (MBNH); TANZANIA: 2ơ ‘Tanzania, Mkomazi / Game Reserve, Ibaya Hill / 3º58.20'S 37º47.80'E. / 26.xi.1995, S. van Noort’, Sweep mk6. mixed grass / -land & shrubs in open / Combretum bushland & / Commiphora woodland’ (SAMC); 1ơ ‘Tanzania: / Same [0404S:3744E], Rt. B1 / 8–16.ix.1992 / A/ Freidberg’; 3ơ 1^‘Tanzania, Mkomazi / Game Reserve, / Kisima Plot. / 04º06.06'S 38º05.58'E.’, ‘ 25 Nov – 8 Dec 1995. / S. van Noort. / Malaise trap. Acacia / / Commiphora bushland’ (SAMC); 1ơ ‘Tanzania, Mkomazi / Game Reserve, / Kikolo Plot. / 04 ° 06.72'S 38 ° 01.37'E.’, ‘ 25 Nov – 8 Dec 1995. / S. van Noort. / Commiphora woodland. / Malaise trap’ (SAMC). ZAMBIA: 1^‘Zambia: 18mi. SW. / of Mkushi [1422S:2922E], 1300m. / 14-xi-1967 / E.S. Ross & / A.R. Stephen’ (CASC); ZIMBABWE: 1ơ ‘Birchenough / Bridge [1958S:3220E], S. Rhod. / 1- 1938, G. v. Son’.

Notes: 1. Some Forchhammer specimens are labelled as being both from a Malaise trap and a mercuryvapour lamp. Wording relating to Malaise trap collections are hand written, while words relating to mercuryvapour lamp collections are printed as the last line of what was obviously meant to be a general-purpose label. I believe that in these cases the material was Malaise-trap collected, and that the last line of the label should have been removed. 2. Some female specimens from localities where males have not been collected may not be correctly identified.

Other material recorded: Oldroyd (1974) gives ‘? S.W.AFRICA: 25 km E. of Gababis (B.M.A.Afr. Exped., 1972)’ and Londt (2005), in reviewing Afroholopogon , stated ‘I have also examined a female in the BMNH which appears to be the specimen Oldroyd (1974) illustrated (his fig. 37). The label reads ‘S.W. Africa (W56) / 16 mls. E Gobabis / 11.iv.1972 ’, ‘Southern / African Exp. / BM. 1972-1’ and is therefore not exactly as cited by Oldroyd (see above)’. This specimen is listed above but in the absence of a topotypic male may not truly represent the species.

Distribution, phenology and biology (Tables 1, 2): Recorded from Botswana, Kenya, Malawi, Namibia, South Africa, Sudan, Tanzania, Zambia and Zimbabwe. Collected throughout the year (no records for February or August). Although diurnally active the species may have been found in mercury-vapour light traps.

Similar species: Distinctive.

Figures

Figs 31–42. Rhabdogaster species, male terminalia: (31–33) R. glabra sp. n., Windhoek holotype: (31) lateral, (32) dorsal, (33) ventral; (34–39) R. gracilis (Engel & Cuthbertson, 1937): (34–36) Trelawney holotype: (34) lateral, (35) dorsal, (36) ventral; (37, 38) Bakubung: (37) lateral, (38) ventral; (39) Mkomazi: lateral; (40–42) R. kalyptos sp. n., Grootfontein paratype: (40) lateral, (41) dorsal, (42) ventral. Scale bars = 1 mm.