Key to the known species of Regasilus

1. Femora red or brownish, if red then black ventrally.......................................................... 2

‾ Femora wholly black, at most a faint reddish stripe dorsally on hind femora...................................... 5

2. Scutellar disc white setose; hind femora with at most 10–12 anteroventral macrosetae, arranged in a single row.......... 3

‾ Scutellar disc black setose; hind femora with 14–15 anteroventral macrosetae, somewhat arranged in a double row................................................................................................. R. strigarius

3. Katatergal macrosetae black, although some yellowish ones may be present; femora red, black ventrally; tomentum golden cinereous; epandrium broad in lateral view, its apex blunt..................................................... 4

‾ Katatergal macrosetae pale yellowish; femora mainly brown although the base is reddish brown; tomentum predominantly cinereous, almost silvery; epandrium thin in lateral view, its apex pointing downwards (Fig. 12B)........ R. illapa sp. nov.

4. Thorax red, except pronotum and some anterior area of pleura, dark brown; male terminalia reddish; phallus strongly flattened laterally (i.e. wide in lateral view) (Fig. 16D).................................................. R. supay sp. nov.

‾ Thorax and male terminalia brown; phallus narrow (Fig. 19D)................................. R. uscovilca sp. nov.

5. Ocellar triangle with long macrosetae, although no longer than length of escape and pedicel together; epandrium straight, al- though the apex may have a pointing-down projection; phallus narrow, ejaculatory apodeme short to large.............. 6

‾ Ocellar triangle with quite long macrosetae, about 1.5 times the length of scape and pedicel together. Epandrium apex distinctly angled downwards; phallus strongly flattened laterally, ejaculatory apodeme medium sized.......................... 8

6. Mystacal macrosetae black on the upper face and yellowish bellow; katatergite yellowish setose; epandrium apex blunt; ejaculatory apodeme medium sized to short.................................................................... 7

‾ Mystacal macrosetae wholly black, katatergite as well; epandrium apex with a pointing-down projection (Fig. 10B); ejaculatory apodeme large (Fig. 10D)............................................................ R. huiracocha sp. nov.

7. Scutellar disc black setose; macrosetae on antepronotum pale to yellowish; abdomen cinereous tomentose, eighth sternite in males with black macrosetae, phallus quite narrow, ejaculatory apodeme medium sized (Fig. 6D)......... R. apu sp. nov.

‾ Scutellar disc yellowish setose; macrosetae on antepronotum black; abdomen golden tomentose, eighth sternite in males with yellowish macrosetae; phallus narrow and ejaculatory apodeme short (Fig. 14D) ......................... R. inti sp. nov.

8. One pair of apical scutellar macrosetae; microtrichia in m1 barely present, thus, at first glance the apical third of the wing appears to be not fully darkened; epandrium apex strongly angled, almost at 90° (Fig. 8B)............ R. chicamac sp. nov.

‾ 2 – 3 pairs of apical scutellar macrosetae; apical third of the wing fully darkened, microtrichia also abundant on sides of basal fourth of R 4+5, r–m, and m–cu (i.e. wing seems to have three central dark spots); epandrium apex broad, distinctly angled downwards, though less than 90° (Fig. 4B)...................................................... R. aiapaec sp. nov.