Silba, Macquart, 1851

Macgowan, Iain & Tschirnhaus, Michael Von, 2024, Records of Lonchaeidae (Diptera, Cyclorrhapha) from Togo and other African countries, with descriptions of new species, Zootaxa 5514 (1), pp. 1-27 : 20-21

Genus Silba (All characters are in the male genitalia)

1. Epandrium wider than high, surstylus with a rounded posterior projection extending beyond the shell of the epandrium bearing prensisetae, like a cat’s paw ( Figs. 9 & 10) ( virescens group)................................................... 2

- Epandrium higher than wide, surstylus without such a rounded posterior projection................................. 3

2. Phallus roughly J-shaped, basiphallus spiculate apically ( Fig. 12).................................... Silba virescens - Phallus with distiphallus emerging centrally from the basiphallus, basiphallus not spiculate ( Fig. 11)........ Silba bambesa

3. Surstylus posteriorly, at the base of each cercus, with a slightly projecting lobe, usually setulose, which bears one or more strong prensisetae ( Fig. 14 pps) ( figurata group).................................................................. 4 - Surstylus without such a setulose posterior lobe............................................................. 6

4. The two large posterior prensisetae located in a transverse row on the setulose posterior lobe of the surstylus ( Figs. 3–5)....

........................................................................................... Silba akola - The large prensisetae on the setulose posterior lobe of the surstylus in a longitudinal row ( Figs. 14 & 18)................ 5

5. Three prensisetae in a longitudinal row on setulose lobe, these not distinctly separated from the remaining prensisetae. Phallus not segmented, spiculate centrally. Figs. 13–16.................................................... Silba figurata

- Two prensisetae in a longitudinal row on setulose lobe, distinctly separated from the other prensisetae. Phallus bi-segmented, not spiculate ( Figs. 17–20).................................................................. Silba kakamega

6. A long, thin posteriorly directed process of the postgonite lying parallel to the phallus on each side ( Figs. 31–33)..........

.......................................................................................... Silba tsifama - Species without such processes..........................................................................7.

7. Inner margin of surstylus markedly emarginate ( Fig. 26, 28) ( adipata group)...................................... 8 - Inner margin of surstylus not emarginate ( Fig. 22)........................................................... 9

8. Phallus forming a tube of uniform diameter, distiphallus spiculate apically, basiphallus simple. Epandrium in lateral view approximately as long as it is wide ( Figs. 25–27)................................................. Silba otanjobo

- Basiphallus narrowing towards a spiculate apex, distiphallus slightly widening towards apex, without spicules. Epandrium in lateral view approximately twice as high as it is wide ( Figs. 28–30)................................... Silba togoensis

9. Epandrium twice as long as it is wide, inner surface of surstylus with one or two isolated prensisetae lying near margin at the mid-point anterior to the main row ( Fig. 21–24)..................................................... Silba media - Epandrium not twice as high as wide, prensisetae in a single compact row....................................... 10

10. Phallus unsegmented, with translucent lateral projections ( Fig. 38 -TP). Pregonite with inner spur ( Fig. 37 - spur)................................................................................................. Silba zogbegani

- Phallus bi-segmented, without translucent lateral projections ( Fig 6). Pregonites without inner spur ( Fig. 4).................................................................................... Silba sp. - Silba arcana species-group.