Iranian Journal of Fisheries Sciences
DOI: 10.22092/ijfs.2021.124446
20(4) 1128-1137
2021
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Research Article
Confirmed records of Japanese blunthorn lobster Palinustus
waguensis (Decapoda: Palinuridae) from the northern coastal
waters of Oman
Chesalin M.1*; Al-Abri N.2; Al-Marzouqi A.2; Al-Shajibi S.3
Received: February 2019
Accepted: May 2019
Abstract
The Japanese blunthorn lobster Palinustus waguensis was recorded in the coastal
waters of Oman in April and May 2015, and November 2018. The total length of
lobsters ranged from 11.4 to 14.0 cm, weight was 48-109 g. The present report
represents the first record of this rare species from the Gulf of Oman and expands its
known range to the north-west of the Indian Ocean. Descriptions, illustrations, and
morphometric data for specimens caught in 2015 are presented.
Keywords: Lobster, Palinustus waguensis, Morphometrics, Oman
1-A.O. Kovalevsky Institute of Biology of the Southern Seas of the Russian Academy of
Sciences, Sevastopol, Russian Federation
2-Marine Science and Fisheries Centre, Ministry of Agriculture and Fisheries Wealth, Muscat,
Sultanate of Oman
3-Fisheries Research Center-Dhofar, Ministry of Agriculture and Fisheries Wealth, Salalah,
Sultanate of Oman
*Corresponding author’s Email: mike.chesalin@gmail.com
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1129 Chesalin et al., Confirmed records of Japanese blunthorn lobster Palinustus waguensis...
Introduction
Spiny lobsters of genus Palinustus have
five recognized species including one
species P. truncatus known from the
Caribbean Island of the western
Atlantic, and four Indo-West Pacific
species: P. holthuisi (Taiwan and
Japan), P. mossambicus (Mozambique,
Somalia), P. unicornutus (South Africa
to Îles Glorieuses, Comoro Islands,
Japan, Indonesia, and New Caledonia),
and P. waguensis which is widely
distributed from Japan to Taiwan,
Philippines, Indonesia, Thailand, India,
and Madagascar (Chan and Yu, 1995).
Along the Oman coast in the Gulf of
Oman (Sea of Oman), the first
specimen
of
blunthorn
lobster,
Palinustus waguensis was caught by a
local fisherman using a bottom set
gillnet at about 80 m depth in April
2015. We captured three more
individuals at the same place using the
same fishing gear in May 2015. In
November 2018, a fisherman caught
several more specimens in a fishing
cage at the depth of 70–85 metres off
Muscat (Seeb area). This finding was
about 130 km to the southeast from the
first records. The total length of these
lobsters ranged from 11.5 to 14.0 cm,
and weight varied between 48–109
grams. The information about the
second group of lobsters was published
in the “Times of Oman” and “Muscat
Daily” newspapers.
The present paper describes the
morphology and morphometrics of P.
waguensis based on the measurements
of four specimens, which were
collected for the first time in the Omani
waters.
Materials and methods
On 27 April 2015 an unusual lobster
specimen was caught by a local
fisherman from the Omani waters near
Shinas (Fig. 1) and transferred to the
Fisheries Research Center in Salalah for
identification. On 7 May 2015, three
more specimens were collected by the
second author (NMA) in the same place
off Shinas (24o41´17 N, 56o32´6 E) by a
bottom gillnet which was set at about
80 m depth on a rocky and sandy
bottom.
These four lobsters were measured
in the laboratory using an electronic
vernier calliper to the nearest 0.01 mm
and weighed using electronic balance to
the nearest 0.01 g.
Terminology
and
description
generally follow Chan and Yu (1995).
Morphometric measurements were
taken based on the picture of Chan
(1998), on the general shape of a spiny
lobster, which we are slightly modified
(Fig. 2), as follows: total length middorsally from the anterior margin of the
carapace between the frontal horns to
the posterior margin of telson; carapace
length from the anterior margin to the
posterior carapace edge; carapace width
as the maximum width; abdominal
length as total abdominal length
excluding the telson; first to six
abdominal segment width dorsally as
dimension between margin spines;
antennular length; length of antenna and
separately antennal peduncle and
Iranian Journal of Fisheries Sciences 20(4) 2021
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antennal flagellum lengths; lengths of
1–5 walking legs. All measurements
were calculated as a percentage of
carapace
length
(CL).
Meristic
characters were counted as the number
1130
of spines between horns on anterior
margin of the carapace, the number of
spines on anterior margin of frontal
horn and the number of spinules on the
anteromedian margin of epistome.
Figure 1: Map showing the new records of Palinustus waguensis in the waters of Oman (A,
squares) and the modified map of its previous records (B, circles) from Chan and Yu
(1995).
All measurements were calculated as
percentage of standard length (SL) and
head length (HL). The specimens are
deposited in the Fisheries Research
Center-Dhofar, Oman.
Results
Four specimens found in the coastal
waters of Oman in May-April 2015
were males, measured from 39.7 to 43.1
mm in carapace length, 113.9–126.2
mm in total length and 55.5-76.2 g in
weight (Fig. 3).
We identified this species following
Holthuis (1991) and Chan and Yu
(1995) as Japanese blunthorn lobster,
Palinustus waguensis Kubo, 1963 and
this identification was confirmed by Dr.
T.Y. Chan.
Systematics
Order DECAPODA Latreille, 1802
Infraorder ACHELATA Scholtz and
Richter, 1995
Family PALINURIDAE Latreille, 1802
Genus Palinustus A. Milne-Edwards,
1880
Species: Palinustus waguensis Kubo,
1963
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1131 Chesalin et al., Confirmed records of Japanese blunthorn lobster Palinustus waguensis...
Figure 2: Scheme of measurements and general shape of a spiny lobster, modified from Chan
(1998).
Description
Morphometric
measurements
and
counts of Palinustus waguensis from
Omani waters are presented in Table 1.
Total body length was about 3 times
longer than carapace length (295±2.5%
CL). Antenna long, antennal flagellum
was longer than total body length.
Proximal (1st) segment of antennular
peduncle was approximately 1.4 times
longer than antennal peduncle that is
distinguished characteristic for the
genus Palinustus (Holthuis, 1991;
Chan, 1998). Antennular flagellum was
shorter than the last segment of the
antennular peduncle.
The second
abdominal segment was the widest,
then the abdomen narrowed to the 5th
segment. Second and third pairs of
walking legs were almost equal in
length, the longest was third pair with
about 265% CL.
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Iranian Journal of Fisheries Sciences 20(4) 2021
1132
Figure 3: Palinustus waguensis, adult male, 43.1 mm CL, from the coastal waters of Oman.
Anterior margin of carapace between
frontal horns bearing 5−7 spines (Fig.
4). Frontal horns truncated, with 5−7
distinct spines on inner margins.
According to Holthuis (1991), the
presence of several distinct spines on
anterior margin of carapace as well as
inner margin of the frontal horns are
distinguished features of the species,
while following Chan and Yu (1995)
anterior margin of carapace between
frontal horns provided with 0 to 8
spines and inner margin of supraorbital
horn armed with 0−5 spines. Epistome
armed with 3 to 5 spinules on the
anteromedian
margin.
Antennal
peduncle armed with many spines with
one distinctly long spine on distal part.
Carapace was heavily pubescent with
rows of regular spines along lateral
edges. Postorbital spine is shorter than
antennal and branchiostegal spines.
Anterior margin of abdominal pleurons
are spinous, pleuron of II−VI somites
having 2 spines. Margin of abdominal
sternites distinctly serrated. Abdominal
sternite VI with medial spine and 7−9
spinules, while from Chan and Yu
(1995), sternite VI armed with strong
median tooth and 8−12 other teeth.
Dactylus of walking legs was simple.
Coloration
Body was generally reddish. Antennular
flagellum, antennal flagellum and
walking legs were with broad pale
bands. Eyes were dark brown.
Maxillipeds were covered with red
bands. Hinges between carapace and
abdomen, as well as inner bases of
endopods of uropods, were with a pair
of large white spots.
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Table 1: Morphometric data for specimens of Palinustus waguensis collected in the coastal waters
of Oman, with average (± S.D.), minimum and maximum values in percent of carapace
length.
Character
Spec.
1
Spec.
2
Spec.
3
Spec.
4
Average ±
S.D. (%)
Min.
(%)
Max.
(%)
Total length (mm)
126.2
117.4
113.9
122.9
294.7 ± 2.5
293
298
Carapace length (mm)
43.1
39.7
38.9
41.3
100.0
─
─
Carapace width (mm)
37.3
34.2
33.9
35.9
86.7 ± 0.5
86
87
Abdominal length (mm)
53.9
51.1
48.1
51.5
125.5 ± 2.1
124
129
1st abdominal
segment width (mm)
28.7
26.6
25.2
26.5
65.6 ± 1.3
64
67
2nd abdominal
segment width (mm)
29.8
28.3
27.3
29.0
70.2 ± 0.9
69
71
3d abdominal
segment width (mm)
28.6
27.4
25.4
27.8
66.9 ± 1.6
65
69
4th abdominal
segment width (mm)
27.5
25.7
25.0
26.5
64.3 ± 0.4
64
65
5th abdominal
segment width (mm)
26.6
24.8
23.8
25.2
61.6 ± 0.6
61
62
6th abdominal
segment width (mm)
27.9
26.6
25.0
26.4
65.0 ± 1.4
64
67
Antenna length (mm)
Antennal peduncle
length (mm)
Antennal flagellum
length (mm)
Antennula length (mm)
1st segment of antennular peduncle (mm)
1st walking leg length
176.0
170.0
164.0
─
419.2 ± 10.0
408
428
33.3
31.4
29.2
33.82
78.3 ± 2.9
75
82
143.2
138.9
134.6
─
342.5 ± 9.3
332
350
99.8
93.3
88.6
95.4
231.3 ± 2.9
228
235
47.2
43.7
41.7
46.3
109.8 ± 2.1
107
112
95.9
89.9
86.0
87.8
220.7 ± 5.7
213
227
2nd walking leg length
111.5
106.0
103.3
107.2
262.7 ± 4.0
259
267
3d walking leg length
113.4
106.8
102.5
─
264.9 ± 3.3
263
269
4th walking leg length
100.9
99.2
94.4
97.0
240.4 ± 7.3
234
250
5th walking leg length
90.1
88.4
85.1
─
216.7 ± 6.9
209
223
No. spines between horns
of carapace
5
7
5
7
6.0 ± 1.2
5
7
No. spinules on inner
margin of frontal horn
4
6
7
5
6.0 ± 0.8
4
7
No. spinules on margin of
epistome
5
4
3
4
4.0 ± 0.8
3
5
76.16
59.92
55.48
62.71
63.6 ± 8.9
55.48
76.16
Total weight (g)
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Iranian Journal of Fisheries Sciences 20(4) 2021
1134
Figure 4: Dorsal view of carapace of P. waguensis from Oman.
Discussion
As reported by SeaLifeBase (Palomares
and Pauly, 2019) the lobster fauna of
Oman consists 13 species, including
five species of spiny lobsters (Panulirus
homarus, P. ornatus, P. penicillatus, P.
versicolor, Puerulus sewelli), five
slipper lobsters (Acantharctus ornatus,
Eduarctus martensii, Scammarctus
batei, Scyllarides squammosus, Thenus
orientalis), two clawed lobsters
(Nephropsis stewarti, N. suhmi), and a
blind lobster (Pentacheles gibbus)
However, common and known lobsters
in Oman represented by only four
species: scalloped spiny lobster P.
homarus, painted spiny lobster P.
versicolor, blunt slipper lobster S.
squammosus and flathead lobster
Thenus orientalis (Al-Abdessalaam,
1995). One more spiny lobster species
as Arabian whip lobster P. sewelli was
found recently (Al-Nahdi et al., 2008).
Therefore, the present records of
Palinustus
waguensi
improve
knowledge about biodiversity and
marine carcinofauna of Oman.
Recently, several papers reported
findings of P. waguensis in the Indian
Ocean along the southeast coast of
India (Kizhakudan and Thirumilu,
2006; Kizhakudan et al., 2012) and in
the Arabian Sea along the southwest
and central west coast of India
(Chakraborty et al., 2014; Purushottama
and Saravanan, 2014). The several
findings of P. waguensis in the Omani
waters are the first and confirmed
record of the species in the Gulf of
Oman that extending knowledge on its
distributional range to the north-west of
the Indian Ocean.
According to Chan and Yu (1995),
the large variations in the distinguishing
characteristics of P. waguensis have
caused some confusion in the taxonomy
of Palinustus. Actually, a full revision
of the genus is needed using modern
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1135 Chesalin et al., Confirmed records of Japanese blunthorn lobster Palinustus waguensis...
biochemical and molecular genetic
methods.
The lobsters of genus Palinustus
mainly inhabit deep reef slopes,
generally considered to be very rare and
are difficult to collect (Chan and Yu,
1995). The specimens of P. waguensis
from India and Philippines were taken
in depths of 72−84 meters, and
juveniles from Ambiona (Indonesia)
were collected from a depth of about
180 m (Holthuis, 1991). Records of P.
waguensis along the southeast coast of
India were from trawler landings
operating in the depths ranging of
300−450 meters (Kizhakudan and
Thirumilu, 2006). The lobsters caught
in the Arabian Sea along the coast of
India were among the trawl landings
from a depth of 150−250 m
(Chakraborty et al., 2014), and also
from 80 m depth (Purushottama and
Saravanan, 2014). The specimens from
the Omani waters were caught by a
bottom set gillnet at about 80 m depth.
Hence, P. waguensis, which was
recorded in depths between 72 and 450
meters, maybe considered as a deep-sea
species inhabiting mainly the mid and
outer continental shelf, and continental
slope.
P. waguensis is a relatively smallsize spiny lobster. According to Chan
(1998), maximum total body length is
about 140 mm. A single specimen
caught off the Mangalore coast had 150
mm of total length and 70 g
(Purushottama and Saravanan, 2014).
Holthuis (1991) reported the largest
carapace length as 32 mm and Chan and
Yu (1995) 45.4 mm. The specimens
landed from the southeast coast of India
off Cuddalore measured 40−52 mm CL
(Kizhakudan et al., 2012). The larger
lobsters were found in trawler landings
at Chennai, where the specimens’ size
ranged 53−75 mm CL in August
(Kizhakudan and Thirumilu, 2006). The
specimens from Omani waters have size
close to a maximum known for the
species, reaching 43.1 mm CL or 126
mm TL in 2015 and 140 mm TL in
2018.
Currently, there is no commercial
fishery for this relatively rare species in
any country, although some lobster
catches in India were abundant
(Kizhakudan and Thirumilu, 2006). In
Japan when the fishermen, capture this
lobster in their nets, they sell them to
the public aquaria (Holthuis, 1991). The
present findings of P. waguensis in the
Omani coastal waters for the first time
during a long history of the intensive
lobster fishery indicate that this lobster
is unlikely to become a target species
for the fishery.
As mentioned above, 13 species of
lobsters reported in fauna of Oman,
however only five species, including P.
waguensis, was actually found. Sultana
et al. (2009) reviewed lobsters of
Pakistan and reported a total of 16
species assigned to eight genera. The
current list of known lobsters from
Indian coast includes 30 species from
16 genera (Radhakrishnan, 2015). In
view of the fact that the lobster fauna in
Oman is poorer studied than in the
neighbouring countries, it seems likely
Iranian Journal of Fisheries Sciences 20(4) 2021
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that new distribution and confirmation
records of lobsters await discovery.
Acknowledgments
We are grateful to the Agriculture and
Fisheries Development Fund of the
Sultanate of Oman and the A.O.
Kovalevsky Institute of Marine
Biological Research of the Russian
Academy of Sciences for the financial
support of our biological investigations.
Much appreciation is extended to Dr.
Chan Tin-Yam for his help with
identification of the specimens. We also
wish to thank a local fisherman for
provision of the lobster samples.
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