Key to the species of Spiralothelphusa

1. Postorbital cristae almost straight, gently sloping posteriorly towards lateral border; G1 terminal segment and distal portion of subterminal segment strongly twisted clockwise full turn...................................................... 2

- Postorbital cristae distinctly curved, sloping posteriorly towards postorbital region and then anteriorly towards lateral border; G1 terminal segment and distal portion of subterminal segment less strongly twisted clockwise half turn............... 3

2. Telson slightly longer than sixth male abdominal somite; G1 twisted portion long, two-third length of non-twisted portion; terminal segment tip gently curved downwards; non-twisted portion outer margin without hump.............. S. wuellerstorfi

- Telson equal in length to sixth male abdominal somite; G1 twisted portion short, half-length of non-twisted portion; terminal segment tip distinctly curved upwards; non-twisted portion outer margin with distinct setose hump............. S. parvula

3. G2 distal segment short, 0.25 times length of basal segment; G1 terminal segment tip gently curved upwards … S. hydrodroma

- G2 distal segment long, 0.4–0.5 times length of basal segment; G1 terminal segment tip gently curved downwards or almost straight............................................................................................ 4

4. G1 twisted portion long, two-third length of non-twisted portion; non-twisted portion outer margin with distinct setose hump...................................................................................... S. gibberosa n. sp.

- G1 twisted portion short, half length of non-twisted portion; non-twisted portion outer margin without hump............. 5

5. Chelipedal carpus of adults with inner distal spine only; G1 terminal segment tip narrow, gently hooked downwards to almost straight; subterminal segment not visible as hump on base of terminal segment from dorsal view................. S. senex

- Chelipedal carpus of adults with both inner distal spine and very low sub-basal granule; G1 terminal segment tip normal, straight; subterminal segment visible as hump on base of terminal segment from dorsal view................ S. fernandoi