Chalybion madecassum (Gribodo, 1882)

Revised key to the species of the Chalybion madecassum View in CoL group

The following key is expanded and revised from the key by Hensen (1988). Characteristics for the key were taken from the original descriptions of C. bonneti Leclercq ( Leclercq 1966), C. madecassum (Gribodo) ( Gribodo 1883) , C. frontale (Kohl) ( Kohl 1906) , C. gracile Hensen and C. polyphemus Hensen ( Hensen 1988), and the examination of C. gracile Hensen , C. dolichothorax Kohl , and C. iridescens Pham & Ohl , sp. nov.

1. Mesosoma more than three times as long as high; propodeal dorsum with pair of longitudinal furrows; occipital carina evanescent ventrally............................................................................................ 2

- Mesosoma less than three times as long as high; propodeal dorsum without longitudinal furrows; occipital carina complete ventrally. Malagasy Subregion........................................................................... 3

2. Clypeus with longitudinal carina; inner eye margin conspicuously curved dorsally; vertex behind posterior ocelli conspicuously sloping; occipital carina lowered far from apical area; sterna III and IV largely covered with dense, brown micro-pubescence; apical edge of sternum IV not depressed; terminal metasomal sternum somewhat curved apically; body dark blue, head and mesosoma not iridescent......................................................... C. dolichothorax ( Kohl, 1918)

- Clypeus without longitudinal carina; inner eye margin conspicuously curved at middle; vertex behind posterior ocelli moderately sloping; occipital carina highly raised near apical area; sterna III and IV not covered with brown micro-pubescence; apical edge of metasomal sternum IV conspicuously depressed; terminal metasomal sternum widely flat apically; body dark green, head and mesosoma iridescent.................................................... C. iridescens Pham & Ohl , sp. nov.

3. Mesoscutum punctate to reticulate punctate; supra-antennal plate moderately protruding; males with placoids on flagellum. 4

- Mesoscutum transversely striate, with shallow punctures between striae; supra-antennal plate conspicuously protruding; males without placoids on flagellum........................................................................... 5

4. Petiole shorter than hind basitarsus; pronotum depressed medially; clypeal foremargin of females with three teeth; metasomal sterna IV depressed, with dense, yellow micro-pubescence. Madagascar...................... C. bonneti Leclercq, 1966

- Petiole longer than hind basitarsus; pronotum not depressed medially; clypeal foremargin of females with five teeth; metasomal sterna IV undepressed, with sparse, silvery micro-pubescence. Madagascar and Mascarenes........................... C........................................................................... madecassum ( Gribodo, 1883)

5. Dorsal margin of propodeal orifice conspicuously raised like lamella, Celebes................... C. frontale ( Kohl, 1906)

- Dorsal margin of propodeal orifice moderately raised like carina................................................ 6

6. Ocelli reduced, equal to mesopleuron puncture diameter, nearly flat; clypeal foremargin of female with five teeth. Philippines............................................................................. C. polyphemus Hensen, 1988

- Ocelli usual, larger than mesopleuron puncture diameter, distinctly convex; clypeus of female with three teeth. Sri Lanka to Java and Borneo.................................................................... C. gracile Hensen, 1988