Confirming of the occurrence of three intertidal xanthid crabs (Crustacea: Decapoda: Brachyura: Xanthidae) in the Gulf of Oman

Abstract

Three brachyuran species of the family Xanthidae, Atergatis ocyroe, Macromedaeus voeltzkowi and Macromedaeus quin-quedentatus are recorded from the Iranian coast of the Gulf of Oman. These specimens were collected in 2009 and 2010 from the Iranian waters of the Gulf of Oman. Among these species, A. ocyroe is a new record for the Gulf of Oman and M. quinquedentatus is a new record for the Iranian coast. This is the second record of M. voeltzkowi from the Iranian coast, whereas there is still no record from the Arabian coast of the Gulf of Oman. The diagnostic characteristics of the species and some taxonomic remarks are reported upon in this paper.

Full text

Confirming of the occurrence of three
intertidal xanthid crabs (Crustacea:
Decapoda: Brachyura: Xanthidae) in the
Gulf of Oman
negar ghotbeddin
1
and reza naderloo
2
1
Department of Fisheries, College of Agriculture and Natural Resources, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran,
2
School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, 14155-6455
Tehran, Iran
Three brachyuran species of the family Xanthidae, Atergatis ocyroe,Macromedaeus voeltzkowi and Macromedaeus quin-
quedentatus are recorded from the Iranian coast of the Gulf of Oman. These specimens were collected in 2009 and 2010 from
the Iranian waters of the Gulf of Oman. Among these species, A. ocyroe is a new record for the Gulf of Oman and
M. quinquedentatus is a new record for the Iranian coast. This is the second record of M. voeltzkowi from the Iranian
coast, whereas there is still no record from the Arabian coast of the Gulf of Oman. The diagnostic characteristics of the
species and some taxonomic remarks are reported upon in this paper.
Keywords: Crustacea, Brachyura, Xanthidae, New records, Gulf of Oman, Iran
Submitted 14 August 2013; accepted 21 May 2014
INTRODUCTION
Decapod crustacean fauna of the north-western Indian Ocean
have received more attention in the last decades.
Comparatively, the fauna of the Pakistani waters (e.g.
Tirmizi & Siddiqui, 1982; Tirmizi & Kazmi, 1988; Tirmizi &
Ghani, 1996) and the Persian Gulf (Stephensen, 1946; Apel,
2001; Naderloo & Tu¨rkay; 2012, Naderloo et al., 2013) have
been well documented. The Gulf of Oman fauna generally
have been less studied by marine biologists, therefore few
data are available on the decapod crustaceans of this connect-
ing corridor of the Arabian Sea to the Persian Gulf. For filling
the data gap, more attention must be paid to the sampling of
crustaceans from the Gulf of Oman, which was started in
recent years from the Iranian sides (e.g. Siddiqui et al., 2003;
Yazdani et al., 2008; Asgari et al., 2012;Nget al., 2012;
Momtazi & Sari, 2013; Shahdadi et al., 2014).
Xanthid crabs are common animals in shallow marine com-
munities in temperate (McDermott, 1960;Sinclair,1977)and
tropical regions (Havens, 1974). Because of the paucity of faunistic
and taxonomic work in the area, the exact number of species of
the family Xanthidae MacLeay, 1838,isnotknown.Inhisunpub-
lished thesis, Apel (2001) reported 19 species of the family from
theGulfofOman,ofwhichfourhaveoccurredontheIranian
coast. Generally, intertidal brachyuran fauna of the northern
Gulf of Oman are generally unknown. There are only few
records of the brachyuran crabs from the Iranian coast of the
region. Stephensen (1946) recorded four xanthids from the Gulf
of Oman collected by the ‘Danish Expedition’ in 1937/1938
from Iranian waters including: Medaeops granulosus (Haswell,
1882); Atergatis integerrimus (Lamarck, 1818); Dentoxanthus ira-
nicus Stephensen, 1946;andActaea cavipes Alcock, 1898 (cur-
rently known as Psaumis cavipes (Dana, 1852); see Apel (2001)).
During 2009 and 2010, the brachyuran crabs have been col-
lected at 8 sites in the subtidal zone and 10 sites in the intertidal
zone from the northern Gulf of Oman along the Sistan–
Baluchistan Province (Figure 1). In the subtidal zone, specimens
were collected using a fisheries vessel (‘Ferdous I’) by a beam-
trawl. Specimens in the intertidal area were collected mainly
using hand and sometimes using a scoop net.
In this study, one species Atergatis ocyroe (Herbst, 1801)
from the subtidal zone and two species Macromedaeus voeltz-
kowi (Lenz, 1905) and Macromedaeus quinquedentatus
(Krauss, 1843) from the intertidal zone are reported from
the Gulf of Oman. Short morphological diagnosis is provided
for these three species. Specimens of the study have been
deposited in the Zoology Museum, University of Tehran
(ZUTC) and the Senckenberg Museum of Frankfurt (SMF).
Abbreviations used: CL, carapace length; CB, carapace
breadth; mm, millimetre, cm, centimetre.
RESULTS
systematics
Infraorder BRACHYURA
Family XANTHIDAE MacLeay, 1838
Subfamily XANTHINAE MacLeay, 1838
Corresponding author:
N. Ghotbeddin
Email: Ghotbeddiny2005@gmail.com
1
Marine Biodiversity Records, page 1 of 5. #Marine Biological Association of the United Kingdom, 2014
doi:10.1017/S1755267214000712; Vol. 7; e98; 2014 Published online

Genus Macromedaeus Ward, 1942
Macromedaeus voeltzkowi (Lenz, 1905)
(Figure 2A)
material examined
2 females (ZUTC Brach1310), Djod Village, Sistan –
Baluchestan, 25827′N59830′E, rocky bed, boulder, sandy, 15
November 2005, coll. R. Naderloo, A. Kazemi; 2 females (1
ovigerous) (SMF 40799), Djod Village, Sistan – Baluchestan,
25827′N59831′E, rocky bed, boulder, sandy, 23 April 2007,
coll. R. Naderloo, H. Salehi, A. Sari; 1 female (ovigerous)
(SMF 40777), Djod Village, Sistan–Baluchestan, 25827′N
59831′E, rocky bed, boulder, sandy, 23 October 2006, coll. R.
Naderloo, A. Kazemi; 2 males CL 6 – 9 mm, CB 9–12 mm
(ZUTC Brach1797), Tiss, Chabahar Bay, Sistan –
Baluchestan, 25821′N, 60835′E, intertidal, rocky shores,
under stone, 1 May 2010, coll. N. Ghotbeddin.
diagnosis
Carapace hexagonal, broader than long; posterior surface
moderately convex, markedly uneven, regions well-defined
with deep grooves, short setae sparsely set on areoles, long
setae densely on lateral margins. Frontal region deflexed
downward; front wide, about 2/3 as wide as carapace,
bi-lobed, lobes nearly sinuous, separated from orbits by
V-shape furrow. Eyestalks stout, short, reaching to end of
exorbital angle. Upper orbital margin rounded, one cleft
near exorbital angle. Anterolateral margin with four teeth
(excluding exorbital angle), all teeth triangle, wide based,
first tooth smaller than others. Chelipeds unequal, stout,
covered with irregular granules in outer surface, inner
surface smooth, granules getting smaller from upper
margins to lower margins; palm relatively long, tip of fingers
spoon-shape.
Walking legs with long setae along anterior margin of
merus; posterior margin of merus with long setae in proximal
Fig. 1. Map of sampling areas along the Iranian coasts of the Gulf of Oman.
2 negar ghotbeddin and reza naderloo

part; anterior and posterior margins of dactylus, propodus and
anterior margin of carpus with long setae; propodus subquadrate;
dactylus long, about as long as propodus. Third maxillipeds
without any gap between them; ischium about 2 times as long
as merus, inner margin of ischium dentate, long setae along
inner margin; merus nearly quadrate, inner margin straight,
with long setae proximally, outer margin straight, without any
seta. Male abdomen with segments 3–5 fused, telson triangular
apically rounded and shorter than segment 6, segment 6 with
lateral margins straight on most of their length. Gonopods 1
(G1) slender, long, tapering distally, distal part deflexed laterally,
short setae along inner surface of distal part.
colour
Carapace, chelipeds and legs are cream; dactylus and pollex of
chelipeds are brown.
remarks
Macromedaeus voeltzkowi (Lenz, 1905) is very similar to
Macromedaeus quinquedentatus (Krauss, 1843) but differs
from it by having the carapace regions partially or completely
divided. The legs in M. quinquedentatus have spines, areoles
have thickly plumose setae (Tirmizi & Ghani, 1996) and the
granules on the carapace, legs and chelipeds are sparse com-
pared to M. voeltzkowi.InM. voeltzkowi, the legs without any
spines, areoles have only short setae, whereas carapace, legs
and chelipeds with granules, granules on chelipeds getting
larger from the lower margin to the upper margin. This is the
second record of the species from the Iranian coast of the
Gulf of Oman, but there is still no record from the Arabian coast.
distribution
Western Indian Ocean: South Africa, East Africa, Red Sea,
Somalia, Persian Gulf and Gulf of Oman (Naderloo &
Tu¨rkay, 2012).
Subfamily XANTHINAE MacLeay, 1838
Genus Macromedaeus Ward, 1942
Macromedaeus quinquedentatus (Krauss, 1843)
(Figure 2B)
material examined
1 female (ZUTC Brach1309), Djod Village, 25827′N59830′E,
rocky bed, boulder, sandy, 15 November 2005, coll. R.
Naderloo, A. Kazemi; 1 male CL 21 mm, CB 23 mm (ZUTC
Brach1486), Tiss, Chabahar Bay, Sistan – Baluchestan,
25821′N60835′E, intertidal, rocky shores, under stone, 1
May 2009, coll. N. Ghotbeddin.
diagnosis
Carapace hexagonal, broader than long; regions well-defined
with deep grooves, granules sparsely on carapace, legs and
chelipeds, areoles with thickly plumose setae. Frontal region
deflexed downward; front wide, about 1/3 as wide as carapace,
bi-lobed by deep groove, separated from orbits by V-shape
furrow. Anterolateral margins with five teeth (excluding exor-
bital angle), all teeth triangle, same sized. Eyestalks stout,
short, reaching to end of exorbital angle. Upper orbital
margin rounded, one cleft near exorbital angle. Anterolateral
margin with four teeth (excluding exorbital angle), all teeth
triangle, wide based, first tooth smaller than others.
Chelipeds unequal, stout, covered with irregular areoles, gran-
ules in outer surface, inner surface smooth; palm relatively
long, tip of fingers spoon-shape, cutting edges toothed.
Walking legs with long setae along anterior margin of
merus; posterior margin of dactylus and propodus with long
setae, propodus subquadrate, dactylus longer than propodus.
Male abdomen with segments 3 – 5 fused, telson triangular,
shorter than segment 6. G1 slender, long, tapering distally,
distal part deflexed laterally, short setae along inner surface
of distal part.
colour
Carapace, chelipeds and legs are cream; dactylus and pollex of
chelipeds are brown.
remarks
Macromedaeus quinquedentatus (Krauss, 1843) is very similar
to Macromedaeus voeltzkowi (Lenz, 1905). For detailed taxo-
nomic remarks see remarks about M. voeltzkowi explained
above. This species was recorded from the southern Gulf of
Oman in an unpublished thesis of Apel (2001), but this is a
new record from the Iranian coast, and meanwhile confirms
the occurrence of the species in the Gulf of Oman. Naderloo
&Tu¨rkay (2012) recorded the species from the Persian Gulf.
distribution
Indian Ocean: South Africa, Madagascar, Somalia, Gulf of
Aden, Dhofar, Gulf of Oman, Pakistan, Bombay, Sri Lanka,
Mergui Archipelago, Indo-Malaysian Archipelago and
Hawaii (Apel, 2001).
Subfamily ZOSIMINAE Alcock, 1898
Genus Atergatis De Haan, 1833
Atergatis ocyroe (Herbst, 1801)
(Figure 2C)
Fig. 2. (A) Macromedaeus voeltzkowi, Jod Village, Iran, Gulf of Oman; (B)
Macromedaeus quinquendatus, Jod Village, Iran, Gulf of Oman; (C) Atergatis
ocyroe, Chabahar, Iran, Gulf of Oman.
three intertidal xanthid crabs in the gulf of oman 3

material examined
1 male CL 43 mm, CB 63 mm (ZUTC Brach1798), 25808′N
25810′N60827′E, 60859′E, Chabahar Bay, Sistan – Baluchestan,
32–38 m, 2 July 2009.
diagnosis
Carapace suboval, broader than long; posterior surface dis-
tinctly convex, smooth, regions weakly defined. Frontal
region deflexed downward; front wide, about 0.3 as wide as
carapace, two-lobed, lobes separated by shallow furrow,
convex, extending beyond inner orbital angle, separating
from inner orbital angle by deep groove. Eyestalks stout,
short, reaching to end of exorbital angle. Upper orbital
margin rounded, with two fissures. Pterygostomial region
smooth. Anterolateral margins ridgy, arched, broader than
posterolateral margins, with three wide lobes, first lobe
shorter than second, third longest; distinct blunt tooth on pos-
terior part. Chelipeds subequal, stout; merus smooth in inner
and outer surface, anterior margin sharp, ridgy; carpus convex
in outer surface, smooth, with distal blunt tooth on inner
margin; manus and movable fingers proximally ridgy on
upper margin, inner surface of manus smooth, outer surface
with shallow fold; fingers with teeth on cutting edge.
Walking legs smooth, compressed laterally; posterior margins
of coxa and ischium with setal patch distally; merus without
any seta, posterior margin with two ridges except proximal
part; posterior margin of propodus with long setae near
distal part; dactylus with long brown patch of setae on anterior
and posterior margins. Third maxillipeds with ischium about
2.2 times as long as merus, long setae along inner and outer
margins, with indent near proximal part, tiny pores near
inner and outer margins; merus rectangular, anterior margin
indent in middle, short setae on anterolateral corner. Male
abdomen with segments 3– 5 fused; telson apically rounded,
shorter than segment 6. G1 slender, long, with tapering,
deflexed tip; long setae along inner surface, spinules along
inner and outer margins of tip.
colour
Carapace, chelipeds and legs are cream with cream-brown
patches of setae; dactylus and pollex of chelipeds are black
and cutting edges of fingers are white.
remarks
Atergatis ocyroe (Herbst, 1801) is very similar to Atergatis flor-
idus (Linnaeus, 1767) and has long been considered a
synonym of A. floridus. Ng & Davie (2007) separated
A. ocyroe and A. floridus using differences of the colour pat-
terns of the carapace, the degree of swelling of the carapace
branchial region and feature of the third maxilliped. They
defined A. floridus as common species in South-east Asia,
Australia and the western Pacific whereas the distribution
range of A. ocyroe is the northern and western Indian
Ocean. The specimen examined here is clearly similar to the
specimens from Phuket examined by Ng & Davie (2007).
There are small differences in the colour pattern; the carapace
of the present specimen is cream in background with cream-
brown setal patches but that of Phuket has reddish-brown to
brown patches.
distribution
Indian Ocean: South Africa, Pakistan, India, Thailand
(Phuket) and Gulf of Oman (see Ng & Davie, 2007).
ACKNOWLEDGEMENTS
We are thankful to Hasan Salehi (ZUTC) for providing the
material to the authors. The anonymous referees who carefully
edited the paper are also greatly acknowledged.
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Correspondence should be addressed to:
N. Ghotbeddin
Department of Fisheries
College of Natural Resources, Khuzestan Science and Research
Branch
Islamic Azad University, Ahvaz, Iran
email: Ghotbeddiny2005@gmail.com
three intertidal xanthid crabs in the gulf of oman 5