Cymo, de Haan, 1833

P. - H & Ng, Peter K. L., 2005, On a new species of coral-symbiont crab of the genus Cymo de Haan, 1833 (Crustacea: Decapoda: Brachyura: Xanthidae), from the South China Sea, Zootaxa 1029, pp. 31-38 : 36-37

Key to species of Cymo

1. Front margin bilobed, margin almost straight, lined with denticles, acute granules or spines; dorsal surface of carapace, cheliped carpus and palm with acute granules, sometimes spinose; carapace region 1M smooth, indistinct ........................................ 2

­ Front bilobed, margin almost straight or concave (appearing quadrilobed), lined with coarse, blunt granules of irregular sizes; dorsal surface of carapace, cheliped carpus and palm with similar­shaped granules which are usually in clusters; carapace region 1M distinct, with granular tubercles ............................................................................. 7

2. Each frontal lobe gently convex, margin with at least 3 curved, acute spines, with similar spine on inner supraorbital angle; carapace longitudinally ovate, not distinctly circular, with smooth dorsal surface, without transverse row of granules on anterior margin of 2M; anterolateral margins with single acute granule; superior and external surfaces of cheliped palm (especially larger cheliped) with some long, spaced spines 3

­ Each frontal lobe straight, margin with numerous small, acute granules that are also found on the exorbital angle; carapace not noticeably elongate, more rounded, dorsal surface and anterolateral margins with similar­shaped blunt granules, especially on anterior margin of 2M where they are arranged in a transverse row; chelipeds with coarse and finer granules interspersed, especially on superior and external surface of larger palm .................................................................................................................... 4

3. Frontal margin with proportionately longer frontal spines; fingers of cheliped white or pale­coloured; male telson triangular ....................................................... C. deplanatus

­ Frontal margin with distinct frontal spines; fingers of cheliped pigmented brown throughout or almost to tips; male telson semicircular ................................ C. barunae

4. Fingers of larger cheliped entirely white .................................................. C. andreossyi

­ Fingers of larger cheliped black but distally white, black coloration on pollex extending onto male palm ....................................................................................................... 5

5. Carapace relatively broad, appearing almost rounded, dorsal surface with relatively small granules ............................................................................................... C. cerasma

­ Carapace comparatively narrower, appearing more longitudinally ovate, dorsal surface with relatively larger, coarser granules ........................................................................ 6

6. Frontal and anterolateral margins uneven, lined with low and high granules ................ ........................................................................................................... C. melanodactylus

­ Frontal and anterolateral margins entire, lined with very low granules, without prominent granules or spines ........................................................................... C. lanatopodus

7. Margin of each frontal lobe concave, front appears quadrilobed; carapace not much longer than broad, subcircular; dorsal surface with 1 M, anterior margin of 2 M, adjacent regions of anterolateral margins and cardiac regions well demarcated by groups of relatively coarse granules; outer surface of chelipeds with coarse granules ............. ............................................................................................................. C. quadrilobatus

­ Margin of each frontal lobe almost straight, front appears bilobed; carapace prominently longer than broad, longitudinally ovate; all groups of granules on dorsal surface of carapace and chelipeds comparatively weak .................................... C. tuberculatus