KEY TO GENERA CARDISOMA LATREILLE, 1828, DISCOPLAX A. MILNE- EDWARDS, 1867 AND TUERKAYANA N. GEN.

1. Orbit with a large lateral gap closed by an obliquous margin; suborbital ridge, forming a pars stridens; plectrum on the inner margin of cheliped merus. Subhepatic, subbranchial and posterolateral regions heavily striated. Median line on sternites 8 and 7 ............................................................ Discoplax A. Milne-Edwards, 1867

— Orbit closed laterally by right-angled margin; no suborbital ridge, no stridulatory apparatus. Subhepatic and subbranchial areas without striae. Posterolateral striae either absent or faint and lost at largest size .............. 2

2. Proepistome prominently dome-shaped. No posterolateral striae; anterolateral margin not delimited, unarmed. Sternite 4 wide and short. Pleonal somite 6 narrow and conspicuously elongated; telson elongated. Median line on sternites 8, 7 and 6 ............................................................................................ Cardisoma Latreille, 1828

— Proepistome dome-shaped wide but low. Weak but distinct posterolateral striae, may disappear in largest adults. Sternite 4 wide and short. Pleonal somite 6 broad and short; telson short, bluntly tipped. Median line on sternites 8 and 7 .................................................................................................................... Tuerkayana n. gen.