Key to Grandidierella mahafalensis Coutière species-complex

1. Male gnathopod 2 carpus anterior margin with no or few setae.................................................. 2

- Male gnathopod 2 carpus anterior margin with dense brush of setae.............................. G. spinicoxa Myers

2. Male gnathopod 1 carpus subovoid, posterior margin weakly convex; dactylus not greatly elongate, swollen medially..................................................................................... G. bonnieroides Stephensen

- Male gnathopod 1 carpus subrectangular, posterior margin substraight; dactylus elongate, scythiform, not swollen medially...................................................................................................... 3

3. Male gnathopod 2 coxa ventral margin produced into a strong spine.... G. halophilus Wongkamhaeng, Pholpunthin & Azman

- Male gnathopod 2 coxa ventral margin without spine........................................................ 4

4. Male gnathopod 1 carpus posterodistal spine long and slender, female gnathopod 1 basis broad, little over 2 × as long as broad................................................................................ G. mahafalensis Coutière

- Male gnathopod 1 carpus postero-distal spine, short, triangular, female gnathopod 1 basis slender, 4 × as long as broad.......................................................................................... G. nioensis sp. nov.