FAO Species Identification Guide for Fishery Purposes Western

Grapsidae 1139
2a. Carapace squarish; frontal margin entire, without lobes or teeth; third maxilliped with
broad exopod and long flagellum (Fig. 2a); male abdomen with all segments movable
(Fig. 3a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Varuninae
2b. Carapace circular; third maxilliped with slender exopod and no flagellum (Fig. 2b); male
abdomen with segments 3 to 6 immovable, with suture between segments 3 and 4 still
evident (Fig. 3b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plagusiinae
(a single species of interest to fisheries, Plagusia tuberculata, occurring in the area)
broad
exopod
with
flagellum
a) Varuninae b) Plagusiinae
Fig. 2 third maxilliped
narrow
exopod
without
flagellum
3a. Merus and ischium of third maxillipeds with ridge (Fig. 4a); pterygostomial region with
network-like (reticulated) pattern of very short, stiff setae (Fig. 5a); carapace usually
squarish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sesarminae
3b. Merus and ischium of third maxillipeds without hairy oblique ridge (Fig. 4b); pterygostomial
region may be setose but no network-like pattern discernible (Fig. 5b); carapace
usually circular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grapsinae
ridges on
merus and
ischium
no clear
ridges
a) Sesarminae b) Grapsinae
Fig. 4 third maxilliped
Key to food species of Grapsinae occurring in the area
1a. Front gently deflexed, margin weakly serrated
(Fig. 6a); inner angle of carpus of cheliped
with acutely triangular spine (Fig. 7a); pectinated
fingertips of chela longitudinally broad
(Fig. 8a); adult male sixth abdominal segment
shorter than fifth segment (Fig. 9a) . . . . .
. . . . . . . . . . . . . . . . . . . .Grapsus albolineatus
1b. Front strongly deflexed and appears almost
vertical from frontal view, margin serrated
(Fig. 6b); inner angle of carpus of cheliped
with subtruncate base (Fig. 7b); pectinated
fingertips of chela longitudinally narrow
(Fig. 8b); adult male sixth abdominal segment
distinctly longer than or subequal in length to
fifth segment (Fig. 9b) . . . . . . . Grapsus tenuicrustatus
6
5
4
3
segments 3-6
movable
6
5
4
3
a) Varuninae b) Plagusiinae
Fig. 3 male abdomen
dense
network of
hairs
a) Sesarminae b) Grapsinae
Fig. 5 body in frontal view
weakly serrated
a) Grapsus albolineatus
distinctly serrated
b) Grapsus tenuicrustatus
segments
3-6
immovable
scattered
setae
Fig. 6 frontal margin of carapace