Key to genera of Malagasy Therevidae and species of Rinhatiana gen. nov. and Tianarinha gen. nov.

1. Femora with regular filiform setae of varying lengths, lacking adpressed scale-like setae; costal vein ending between veins R 4 and CuA+CuP, never circumambient around wing; female terminalia with, at most, a single set of acanthophorite spines ..............................................................2 ( Therevinae)

– Femora with regular filiform setae of varying lengths, admixed with adpressed scale-like setae, especially on mid and hind legs; costal vein circumambient around wing; female terminalia with two distinct sets of acanthophorite spines on each side (A1 and A2) ...................................................... 3

2. Dorsal surface of wing vein R 1 with setulae; palpus with apical pit; female sternite 8 without strong macrosetae; genitalia with three spermathecae and no spermathecal sac ........................................... ........................................................................................ Rueppellia Wiedemann, 1830 ( Phycusinae)

– Wing vein R 1 without setulae; palpus without an apical pit; female sternite 8 with strong macrosetae; genitalia with two spermathecae and spermathecal sac is present ...................................................... ................................................................................. Microgephyra Lyneborg, 1972 ( Xestomyzinae)

3. Wing vein R 1 without setulae ............................................................................................................ 4

– Dorsal surface of wing vein R 1 with setulae ..................................................................................... 5

4. Sternum with setae present medially in furrow; mid coxae with setae on posterior surface .............. ................................................................................................................... Irwiniella Lyneborg, 1976

– Sternum with setae present laterally only, rarely in medial furrow; mid coxae without setae on posterior surface .................................................................................................. Stenopomyia Lyneborg, 1976

5. Prosternum with setae medially; one pair of scutellar macrosetae; frons with dark setae, pubescence grayish-brown with a dark band from base of antenna to eye margin (Fig. 14); gena with dark setae ventrally; abdomen predominantly brown .................................................. Tianarinha gen. nov. ...6

– Prosternum without setae; two pairs of scutellar macrosetae; frons usually lacking setae, pubescence silver or metallic tan around antennal bases, matte black above this and frequently grayish-silver dorsally to ocellar tubercle (e.g., Fig. 9); gena with pale setae; abdomen predominantly bright yellow, sometimes brown laterally along tergites ................................................... Rinhatiana gen. nov. ...7

6. Extensive dark setae on the lower part of occiput, gena (Figs 10; 14A–B) and coxae; flagellum style relatively elongate; few dark setae on frons just above antennae; setae on posterior surface of hind coxae (Fig. 11B) ..................................................................................... T. goodmani gen. et sp. nov.

– Setae on the lower head and coxae fewer in number and shorter (Fig. 12A, 13A); flagellum style relatively short; frons only with setae dorsally, no setae just above antennae; setae absent on posterior surface of hind coxae (Fig. 13A) ................................................................... T. micet gen. et sp. nov.

7. Two pairs of supra alar macrosetae; dorsocentral macrosetae present (Figs 5–6); Male frons width at narrowest point slightly wider than anterior ocellus (Fig. 9E); short, dark setae present dorsally on frons .................................................................................. R. distincta (Lyneborg, 1976) comb. nov.

– One pair of supra alar macrosetae; dorsocentral macrosetae absent; male frons width at narrowest point narrower than anterior ocellus, eyes almost contiguous (Fig. 9A, C, G); frons lacking setae .. ........................................................................................................................................................... 8

8. Frons with metallic-tan pubescence around base of antennae (Fig. 9C, D); abdomen dark brown (yellow dorsally in female), cream-white posteriorly on each segment, silver pubescence absent (Figs 3–4) ................................................................................................ R. cracentis gen. et sp. nov. – Frons with silver pubescence around base of antennae and matte black area medially (Fig. 9A, G); abdomen predominantly yellow, sometimes brown laterally along tergites, triangular patches of silver pubescence laterally on at least tergites 2 and 3 ............................................................................... 9

9. Male frons with matte-black pubescence relatively narrow, brown pubescence dorsally (Fig. 9A); female frons with dorsomedial stripe of matte-black pubescence relatively narrow, suffused with brown pubescence laterally (Fig. 9B); male terminalia black (Figs 1–2) ...... R. arctifestuca gen. et sp. nov.

– Male frons with matte-black pubescence broader, lacking brown pubescence dorsally (Fig. 9G); female with dorsomedial stripe of matte-black pubescence broader, mostly lacking brown pubescence in upper portion (Fig. 9H); male terminalia yellow (Figs 7–8) ............ R. latifestuca gen. et sp. nov.