2b Wings without staining, unpatterned, transparent and entirely lacking microtrichia; scutellum with ca. 6 well -developed marginal setae; setae of prothoracic coxae and macrosetae of terga white; mystax extending from antennal bases to epistomal margin. Illustrations - Head (Fig. 2), Wing (Fig. 9), Hypopygium (Figs 19-21), T2 (Fig. 40), Scutellum (Fig. 47), Distribution (Fig. 48) ..................

leucothrix sp. n.

Etymology: Gr. Leukos = white + thrix = hair - refers to the many white setae possessed by this species.

Material examined: NAMIBIA: 1♀ paratype, ‘ Namibia: Ai Ais [27 ° 55'S: 17 ° 29'E] / Fish River Canyon / 7-8.x.1993, F. Koch’ (ZMHB); 1♂ paratype, ‘ Gt. Karas Mts. [27 ° 20'S: 18 ° 45'E] / SWA’ ~ ‘ Mus. Staff / Nov. 1936 ’ (SAMC). SOUTH AFRICA: 2♀ paratypes, ‘ Nieuveld / Escarpment / Rietvlei [32 ° 21'S: 21 ° 49'E]’ ~ ‘ Mus. Exped. Feb.1925 ’ (SAMC); 1♂ 1♀ paratypes, ‘ S Africa:Cape #21 / 70 km E of Laingsburg / 33 ° 06'S: 21 ° 35'E 500m / Date: 24.xi.1990 / Whittington & Londt / Dry Dwyka River area’; 1♂ holotype, ‘ Sth Africa: Cape Prov / Gamka River 40 km N / Prince Albert 3321BB / 11.xi.1986 500m / Londt & Quickelberge / Sandy area / Acacias’.

A. leucothrix: Known only from a few localities situated within the semi -arid plateau and desert climatic regions characterised by cool dry winters and hot summers with low rainfall.