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84 Family Penaeldae
Genus Penaeus Fabricius, 1798
Key to species of adults and subadults
[Adapted from Williams, 1984]
1. Lateral rostral grooves reaching only slightly beyond posterior rostral tooth (nongrooved
shrimps) P. setiferus
Lateral rostral grooves reaching nearly to posterior margin of carapace (grooved
shrimps) 2
2. (1) Petasma with distomesial projection long; distal fold expanded mesially forming
large spined lobe; ventral costa with apex free; thelycum with anteromesial corners
of lateral plates extended to cover posterior process of median protuberance
P. brasiliensis
Petasma with distomesial projection relatively short; distal fold not forming lobe;
ventral costa with apex attached to adjacent membraneous part; thelycum with
anteromesial corners not extended, exposing posterior process of median
protuberance 3
3. (2) Petasma armed with minute spines on ventral costa along terminal part of free
border; thelycum with anteromesial corners of lateral plates slightly divergent,
posterior process of median protuberance with undivided median carina
P. duorarum
Petasma unarmed on ventral costa along terminal part of free border; thelycum with
anteromesial corners of lateral plates widely divergent, posterior process of median
carina bifurcate anteriorly ,. P. aztecus
Key to species of juveniles between 17 and 47 mm total length
[Adapted from Williams, 1984]
1. Lateral rostral grooves reaching only slightly beyond posterior rostral tooth;
rostrum long and slightly upturned at tip in individuals exceeding 22 mm total
length; ground color light gray, sometimes with greenish cast in shrimp taken from
beds of vegetation; chromatophores (widely spaced except on spines, ridges, and
uropods) colored slate-blue and brown; uropods with reddish-brown to brown
areasdistally .....P. setiferus
Lateral rostral grooves reaching almost to posterior margin of carapace (shallow in
17-mm individuals); rostrum relatively short; color gray to light brown, sometimes
with greenish cast in shrimp taken from beds of vegetation; chromatophores
numerous and closely spaced, often in bands or patches 2
2.(1) Rostrum with toothed dorsal margin straight; tip attenuate and straight
P. brasiliensis
Rostrum with toothed dorsal margin slightly arched over eye; tip short or attenuate
and slightly upturned 3