FAO Species Identification Guide for Fishery Purposes Western

Penaeidae 903
9a. Adrostral crest extending behind last postrostral
tooth (Fig. 51); postrostral crest distinctly
grooved (Fig. 53a); hepatic crest
extending well behind antennal crest
(Fig. 51) . . . . . . . . . . . . . . .Penaeus semisulcatus
9b. Adrostral crest at most extending to last postrostral
tooth (Fig. 52); postrostral crest without
a distinct groove (Fig. 53b); hepatic crest
not extending behind antennal crest (Fig. 52)
. . . . . . . . . . . . . . . . . . . . . Penaeus esculentus
adrostral crest
hepatic crest
carapace (lateral view)
Fig. 52 Penaeus esculentus
10a. Third maxilliped of males with distal segment about half as long as second segment
which bears a tuft of hairs at tip (Fig. 54a, rostral crest high and broadly triangular in
both sexes; body yellowish to greenish, antennal flagella reddish brown) . . . Penaeus merguiensis
10b. Third maxilliped of males with distal segment longer or as long as second segment . . . . . . → 11
11a. Rostrum slightly curved at tip and
sigmoidal shaped; antennal flagella
yellowish (third maxilliped of
males with second segment as
long as distal segment and bearing
a tuft of long hairs at tip, Fig. 54b;
rostral crest slightly elevated in
both sexes; body yellowish white to
greyish green) . . . . . . . . . Penaeus indicus
11b. Rostrum nearly horizontal straight;
antennal flagella reddish brown . . . . . . → 12
12a. Third maxilliped of males with distal
segment 1.5 to 2.5 times longer
than second segment which bearing
a tuft of very long hairs at tip
(Fig. 54c); rostral crest slightly elevated
in males and moderately
high in large females; body somewhat
greenish . . . . . . . Penaeus penicillatus
distinct
groove
a) Penaeus
merguiensis
a) Penaeus
semisulcatus
b) Penaeus
esculentus
Fig. 53 dorsal view of carapace
b) Penaeus
indicus
c) Penaeus
penicillatus
d) Penaeus
silasi
Fig. 54 distal part of third maxilliped in adult males
12b. Third maxilliped of males with distal segment as long as second segment which only bears
a rudimentary tuft of hairs at tip (Fig. 54d); rostral crest slightly to moderately elevated in
males but broadly triangular in large females; body yellowish white to pinkish . . . . . . Penaeus silasi
Key to the species of Trachypenaeus occurring in the area 3/
Remarks on key characters: occasionally, spermatophores or sperm sacs (a white or yellowish cement-like
mass) are attached to the thelycum of mature females, making observation difficult. Nevertheless, they can
be easily removed by using a pin, forceps, or finger nail.
1a. Second leg with epipod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . → 2
1b. Second leg without epipod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . → 6
3/ The taxonomic status and relationships of some species of this genus are still unclear, and this genus is sometimes
subdivided into many genera by some authors.