Medaeus, Dana, 1851

Key to the species of Medaeus View in CoL (modified from Davie, 1997)

1. Front moderately to well-advanced beyond level of orbits, anterior margin of lobes distinctly concave in dorsal view...2

– Front weakly advanced beyond level of orbits, anterior margin of lobes straight in dorsal view ..............................................3

2. Front and anterolateral teeth well produced; ambulatory meri spinose on both anterior and posterior borders; chelipeds with meri covered with large, subconical granules on ventral and posterior surfaces, 4 granular nodules on dorsoexternal border of palm, tip of chelar dactyli truncated .................................... ............................................................. M. ornatus Dana, 1852 View in CoL

– Front and anterolateral teeth moderately produced; ambulatory meri spinose on anterior border only; chelipeds with 3 well-defined nodules on dorsoexternal border of palm, tips of chelar dactyli pointed, curved .. M. elegans A. Milne-Edwards, 1867 View in CoL

3. Transverse crest on carapace 1P region uninterrupted, fingers slender and as long as palm of chela .....................................4

– Transverse crest on carapace 1P region interrupted in the middle, fingers thick and shorter than palm of chela .............. ............................................................ M. grandis Davie, 1993 View in CoL

4. Dorsal carapace appearing rugose due to several short transverse rows of large granules fused at the base; chelipeds with dorsoexternal surfaces of palm and carpus marked by clumps of large granules.................................. M. alidae , new species

– Dorsal carapace finely granular or at most slightly rugose, but never with distinct rows of large granules; cheliped palm and carpus with smaller granules ..................................................5

5. Carapace anterolateral teeth narrow, acute; carapace region 4M thin; anterior margin of meri of P2–P4 armed with sharp conical tubercles; G1 with triangular subdistal lob ................. ................................................................ M. aztec Davie, 1997 View in CoL

– Carapace anterolateral teeth broad; carapace region 4M thick; anterior margin of meri of P2–P4 armed with smaller sharp granules; G1 without subdistal triangular lobe ........................ .......................................... M. danielita Mendoza & Ng, 2010 View in CoL