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.

Figures

FIGURES 9–12. Silba bambesa sp. nov. 9. Epandrium and associated features, lateral view (hypopygium removed). 10. Same, internal view. 11. Phallus, lateral view. Figure 12. Silba virescens Macquart, 1851. Phallus, lateral view.

FIGURES 13–16. Silba figurata MacGowan, 2005. 13. Epandrium and associated structures, lateral view (hypopygium removed). 14. Same, ventral view, pps = posterior projection of surstylus. 15. Inner surface of surstylus. 16. Phallus, lateral view.

FIGURES 3–5. Silba akola sp. nov. 3. Epandrium and associated features, lateral view. 4. Same, ventral view, Prg = pregonite, Pog = postgonite, Ph = phallus, E = epandrium, Sur = surstylus, Pren = prensisetae, Cer = cerci. 5. Phallus, lateral view.

FIGURES 17–20. Silba kakamega sp. nov. 17. Epandrium and associated features, lateral view. 18. Same, ventral view. 19. Inner surface of surstylus. 20. Phallus, lateral view.

FIGURES 31–33. Silba tsifama sp. nov. 31. Epandrium and associated structures, lateral view. LP = lateral process. 32. Same, ventral view. 33. Internal view of surstylus.

FIGURES 25–27. Silba otanjobo sp. nov. 25. Epandrium and associated structures, lateral view (hypopygium removed). 26. Same, ventral view. 27. Phallus, lateral view.

FIGURES 28–30. Silba togoensis sp. nov. 28. Epandrium and associated structures, lateral view (hypopygium removed). 29. Inner surface of surstylus. 30. Phallus, lateral view.

FIGURES 21–24. Silba media sp. nov. 21. Epandrium and associated structures, lateral view. 22. Same, ventral view. 23. Inner surface of surstylus, 24. Phallus, lateral view.

FIGURES 34–38. Silba zogbegani sp. nov. 34. Epandrium and associated structures, lateral view. 35. Same, ventral view. 36. Inner surface of surstylus. 37. Hypopygium and associated structures, posterior view. 38. Phallus, lateral view, TP = translucent projection.

FIGURES 6–8. Silba sp. of the Silba arcana McAlpine, 1960 species-group. 6. Epandrium and associated features, lateral view. 7. Same, internal view. 8. Phallus, lateral view.