Key to adult females of Sri Lankan Onomastus

1. S irregular in shape, with inverted u-shaped epigynal bars (Benjamin 2010: fig. 10e)..................... O. nigricauda

- S otherwise, epigynal bars absent.........................................................................2

2. S rounded............................................................................................3

- S oval...............................................................................................4

3. S with shallow indentation on mid-lateral wall, broad AEB, sclerotized hood-like structure, curved atrium rim (Figs 5 C, D)................................................................................... O. corbetensis sp. nov.

- S without any indentation, rounded (Benjamin 2010: figs 26d, e)..................................... O. rattotensis

4. S bean-shaped, large with mid-longitudinal sclerotized bars, large atrium rim (Figs 2 C, D)......... O. jamestaylori sp. nov.

- S inverted pear-shaped.................................................................................5

5. Epigyne broad, well sclerotized, with broad AEB, large atrial rim (Figs 8 C, D)................... O. maskeliya sp. nov.

- Epigyne narrower, without AEB..........................................................................6

6. FD large and lanceolate (Benjamin 2010: figs 21b, c)............................................ O. pethiyagodai

- FD small and filamentous (Benjamin 2010: figs 24c, d)......................................... O. quinquenotatus