FAO Species Identification Guide for Fishery Purposes Western

Key to Brachyura 1073
strongly
recurved
a) Camptandriidae b) others
Fig. 66 male first gonopod
Fig. 67 Camptandriidae
(after Shen, 1932)
37a. Carapace squarish to longitudinally rectangular, posterolateral margins subparallel,
dorsal surface flat or gently convex; free-living intertidal, estuarine, or fresh-water crabs
(Fig. 68) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grapsidae (in part) (p. 1138)
37b. Carapace shape not as above; dorsal surface usually convex; posterolateral margins
gently to strongly converging; sublittoral to deep-water crabs . . . . . . . . . . . . . . . . . . → 38
38a. Legs with special dactylo-propodal articulation (formed by a rounded, submedian
extension of the lateral margin of the propodus, sliding underneath a projecting button
on the subproximal edge of the dactylus; Fig. 69a) . . . . . . . . . . . . . . . . . . . . . . . → 39
38b. Legs without special articulation between propodus and dactylus (Fig. 69b) . . . . . . . . . . → 41
projecting button
of dactylus
a) special dactylopropodal
articulation
propodus
b) normal articulation
Fig. 68 Grapsidae (subfamily Varuninae)
Fig. 69 distal end of walking leg
(from Alcock and Anderson, 1899)
39a. Fingers of chelipeds distinctly spoon-tipped (Fig. 70a); male abdominal segments 3 to
5 always immovable, completely fused although sutures may be partially visible
(Figs 71a and 72) . . . . . . . . . . . . . . . . . . . . . . . . . . . Xanthidae (in part) (p. 1098)
39b. Fingers of chelipeds with sharp tip, not distinctly spoon-tipped (Fig. 70b); male abdominal
segments 3 to 5 freely movable (Fig. 71b) or fused . . . . . . . . . . . . . . . . . . . . . → 40
fingers
spoon-tipped
a)
tip sharp
Fig. 70 pincer
b)
segments 3-5 fused
(sutures completely absent)
6
5
4
3
2
1
6
5
4
3
2
1
segments 3-5 fused
(sutures visible
laterally)
segments
3-5 freely
movable
a) Xanthidae b) others
Fig. 71 abdomen
6
5
4
3
2
1