Oratostylum crenum, Torsten Dikow & Jason G. H. Londt, 2000

Torsten Dikow & Jason G. H. Londt, 2000, A review of the genera Anasillomos Londt, 1983, Oratostylum Ricardo, 1925, and Remotomyia Londt, 1983, with description of a new genus and two new species (Diptera: Asilidae: Stenopogoninae), Ann. Natal Mus. 41, pp. 107-121 : 113-114

Oratostylum crenum sp. n.

(Figs 8-10, 14-15, 19)

Etymology: L. crena = rounded projection. Refers to the rounded appearance of the facial swelling.

Description (based on all material examined):

Head: Antenna orange-brown; postpedicel clubbed (Fig. 15) and longer than scape and pedicel combined; scape and pedicel with anteriorly directed yellow setae; style cylindrical, black; face orange-brown with dense golden (♀) or silvery (♂) pruinescence; mystax yellow, some black setae on upper margin; facial swelling pronounced, not ending abruptly in upper part (Fig. 14); vertex black and silver-gold pruinose, yellow setae laterally, ocellarium prominent with 4-6 yellow setae; occiput black with silvery pruinescence, yellow and white setae; proboscis black, stout, ventrally with white setae; palpi black, longer than half length of proboscis, white setae ventrally.

Thorax: Orange-brown; pronotal setae yellow and white; propleuron with white setae only; postpronotal lobe with yellowish setae of different lengths; mesonotum: ♀ brown pruinose, ♂ grey pruinose, 2 longitudinal stripes not reaching hind margin (♀ brown, ♂ black), covered with short white and brownish setae (longer in ♂), 1-2 pairs dorsocentral setae may be present anterior of transverse suture, macrosetae yellow; scutellar pruinescence similar to that of mesonotum, disc with yellow setae, margin with 6-8 yellow setae; mesopleura: ♀ dorsally brown pruinose and ventrally grey pruinose, ♂ entirely grey pruinose, white setae only; katagergal setae yellow; anatergal setae yellowish; legs: coxae orange-brown with silvery pruinescence and white setae; fore femur orange-brown, posteroventrally black, fore and hind tibiae with dense short yellow setae on inner margin which extend onto basitarsi, these setae only on distal half of hind tibia; mid and hind femora orange-brown, black ventrally, all tibiae proximally orange-brown, black distally; tarsi black; all macrosetae of legs pale yellow; claws brown basally and black distally, pointed; pulvilli large, pale yellow; empodium needle-like, black; wing: membrane transparent; veins yellow basally and on anterior margin, distally brown; r 5 open, m 3 open; halteres pale yellow.

Abdomen: Brown; T1 with long white setae and a few pale yellow setae laterally; remaining terga with white and yellow setae; pruinescence silver-brown with silvery hind margin, apruinose diagonal stripes laterally; sterna weakly silver pruinose with white setae; T6-8 of ♀ apruinose, brown with white, erect fine setae; macrosetae of acanthophorites reddish-brown; ♂ genitalia orange with white setae, hypandrium without distal projection (Figs 8-10).

Material examined: SOUTH AFRICA: 1♂ holotype, 'S Africa: N-W Province / Pilanesberg National Park / Manyane Trail 15.xi.1999 / 25°15'12"S: 27°13'25"E / J.G.H. Londt 1200 m’ ( NMSA); 3♂ 2♀ paratypes, 'S Africa: N-W Province / Pilanesberg National Park / Manyane Trail 15.xi.1999 / 25°15'12"S: 27°13'25"E / J.G.H. Londt 1200 m’ ( NMSA); 1♀ paratype, 'S Africa: N-W Province / Pilanesberg National Park / Bakubung 12-19.xi.1999 / 25°20'40"S: 27°03'25"E / J.G.H. Londt 1170m camp’ ( NMSA); 1♂ 1♀ paratypes, 'S Africa: N-W Province / Pilanesberg National Park / Bakubung 12-19.xi.1999 / 25°20'40"S: 27°03'25"E / J.G.H. Londt 1100m gate’ ( NMSA).

Remarks: The sexual dimorphism displayed by this species is remarkable. The pruinescence of the mesonotum, mesopleuron, and face differs - females tend to be more golden pruinose whereas males are silver-grey pruinose.