FAO Species Identification Guide for Fishery Purposes Western

926 Shrimps and Prawns
Penaeus silasi Muthu and Motoh, 1979
Frequent synonyms / misidentifications: None / Penaeus indicus H. Milne Edwards, 1837;
P. merguiensis De Man, 1888; P. penicillatus Alcock, 1905.
FAO names: En - False white prawn.
(after Muthu and Motoh, 1979)
Diagnostic characters: Carapace rather smooth, lacking gastrofrontal
and hepatic crests; adrostral crest extending to
about epigastric tooth; tip of rostrum horizontally straight;
rostral crest slightly to moderately elevated in youngs and
adult males but high and broadly triangular in large females,
with 7 to 9 upper teeth (including those on carapace) and 4or5
lower teeth; postrostral crest extending near to posterior margin
of carapace; gastro-orbital crest distinct, extending over
posterior 3/5 to 2/3 of distance between hepatic spine and
orbital margin. In adult males, third maxilliped with distal
segment about as long as second segment which bears
only a rudimentary tuft of hairs at tip. Petasma of males
with distomedian projections slightly bent and not overhanging
distal margin of costae. Thelycum of females formed by 2 semi-
distal 2 segments of
third maxilliped
(male)
posterior
process
lateral plates
thelycum
anterior
process
distomedian projection
ventral
costa
petasma
(ventral view)
(after Muthu and Motoh, 1979)
circular lateral plates, with their median margins forming tumid lips; anterior process rounded and slightly
concave, generally distinct and not obscured by hairs (more clear in adults); posterior process elongated
and inserted between anterior part of lateral plates.Telson without lateral spines.Colour: bodysemi-translucent,
somewhat yellowish white (small specimens) to pinkish (large specimens) and covered with numerous
minute dark brown dots (dots becoming obscure in large specimens); eyes light brown and covered with
some dark brown mesh-like stripes; rostral and abdominal dorsal crests reddish brown to dark brown; antennal
flagella reddish brown; antennular flagella of same colour as body and covered with many dark spots; legs
translucent and somewhat whitish, while pleopods yellowish to pinkish; distal part of uropods yellowish with
red margins; young specimens often with short longitudinal black broken lines on abdomen.
Size: Maximum body length 20 cm in females (carapace length 4.8 cm) and 15.3 cm in males (carapace
length 4.1 cm), commonly between 12 and 16 cm.
Habitat, biology, and fisheries: Found on muddy bottom in shallow waters to a depth of about 36 m. Caught
by trawlers and probably artisanal gear. An abundant species in the markets of Singapore and of commercial
importance. Probably also common in Thailand, Malaysia, and Indonesia, where it is often confused with
Penaeus indicus. Marketed fresh and frozen,
mainly for local consumption.
Distribution: Indo-West Pacific; so far only
reported from Thailand (Andaman Sea and
Gulf of Thailand), Indonesia, Malaysia, and
Singapore. Since this shrimp can be easily
confused with P. indicus, P. merguiensis,
and P. penicillatus, its actual distribution is
likely to be wider in the Indo-Malay region.