| Carapace | Distinctly wider than long; posterolateral margins gently converging; subquadrate (Figs. 1A, 2A, B, 3A, 4A, F, 6A, 9A, D) | As long as wide or slightly wider than long; posterolateral margins strongly converging; subcircular or almost so (Fig. 1B) | Carapace much wider than long, commonly subcircular; posterolateral margins strongly converging (Fig. 1C) |
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| Carapace regions | Surface smooth or almost so; regions not demarcated except for epigastric region (Figs. 1A, 2A, B, 3A, 4A, D, F, I, 6A, 9A, D) | Surface granulose to almost smooth; regions weakly demarcated (Fig. 1B) | Surface granulose or smooth; regions distinctly demarcated (Fig. 1C) |
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| Subhepatic region and infraorbital margin | Infraorbital margin projecting anteriorly, clearly visible in dorsal view; subhepatic region gently swollen, tuberculate or granulate (Figs. 1A, 12A) | Infraorbital margin not projecting anteriorly, not visible in dorsal view (Fig. 1B) | Infraorbital margin not projecting anteriorly, not visible in dorsal view (Fig. 1C) |
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| Pterygostomial region | Gently swollen, with cluster of granules or tubercles (Figs. 1D, 4E, J, 5A) | Not raised, smooth (Fig. 1E) | Not raised, smooth or granulate (Fig. 1F) |
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| Chelipeds | Elongate; basis-ischium and merus long; chelipeds unable to appress against carapace (Figs. 2A, 4A, F, 9A, B) | Short; basis-ischium and merus very short; chelipeds closely appressed to carapace when retracted (Fig. 1E) | Short; basis-ischium and merus very short; chelipeds able to appress against carapace when retracted (McLay 1999: fig. 17e) |
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| Chela | Elongate, slender; outer surfaces almost smooth; proximal part of inner surface, near carpus, with prominent median tooth or spine (Figs. 2A, D–F, 3C, D, 4B, C, G, H, 5D, 9A, B, 12B) | Short, stout; outer surfaces granulate or tuberculate; proximal part of inner surface, near carpus, with low rounded tooth (Fig. 1I, J) | Short, stout; outer surfaces granulate or tuberculate; proximal part of inner surface, near carpus, with low tooth (McLay 1999: fig. 23c, d) |
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| Fingers of male cheliped | Fingers elongate, cutting edge of pollex smooth, unarmed (Figs. 2D, E, 4B, C, G, H, 9B, E) | Fingers short, curved; cutting edge of pollex with 1 large tooth and several smaller teeth (Fig. 1I, J) | Fingers short, curved; cutting edge of pollex with 1 large tooth and several smaller teeth or several large equal-sized teeth (McLay 1999: fig. 23c) |
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| Ambulatory legs | Merus, carpus and propodus distinctly more elongate (Figs. 2A, G, 3E–I, 4A, F, 6A, 9A, D) | Merus, carpus and propodus very short (McLay 1999: fig. 17a, b) | Merus, carpus and propodus very short (McLay 1999: 17e) |
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| Fused male thoracic sternites 1–3 | Relatively broad, forming a wide pentagonal structure (Figs. 1D, 3B, 5E) | Relatively narrower, forming a more quadrate structure (Fig. 1E) | Relatively narrower, lateral margins sinuous, forming bell-shaped structure (Fig. 1F) |
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| Male pleon | Very broad, with somites 2 and 3 prominently narrow, waist-like (Figs. 1G, 2L) | Distinctly narrower, somites 2 and 3 less narrow, no obvious waist visible (Fig. 1H) | Distinctly narrower, somites 2 and 3 less narrow, no obvious waist visible (Fig. 1F) |
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