New record of a freshwater crab Phricotelphusa callianira
(De Man, 1887) (Decapoda: Brachyura: Gecarcinucidae) from
Thailand
Vachira Lheknim 1 & Pimonpan Leelawathanagoon 2
1,2 Department of Biology, Prince of Songkla University, PO Box 3 KoHong, Songkhla 90112, Thailand
Email: 1 vachira.l@psu.ac.th
Date of publication (online): 26
September 2009
Date of publication (print): 26
September 2009
ISSN 0974-7907 (online) |
0974-7893 (print)
Editor: Stephan Gollasch
Manuscript details:
Ms # o1901
Received 05 December 2007
Final received 08 September 2009
Finally accepted 11 September
2009
Citation: Lheknim, V. & P. Leelawathanagoon (2009). A new
record freshwater crab Phricotelphusa callianira (De Man, 1887) (Decapoda:Brachyura: Gecarcinucidae)
from Thailand. Journal of Threatened Taxa 1(9): 461-465.
Copyright: © Vachira Lheknim & Pimonpan Leelawathanagoon2009. Creative Commons Attribution 3.0 Unported License. JoTT allows
unrestricted use of this article in any medium for non-profit purposes,
reproduction and distribution by providing adequate credit to the authors and
the source of publication.
Author Details: Vachira Lheknim is an Assistant Professor in the Department of
Biology and Chief Curator of Prince of Songkla University
Zoological Collection (PSUZC) at Prince of SongklaUniversity. He is keenly interested in
marine and freshwater biology and local fauna. Currently, he is engaged in ichthyologicalsurveys of freshwater fishes in all river basins of southern Thailand.
Pimonpan Leelawathanagoon is an Assistant
Professor in the Department of Biology and Curator of Crustacean Section of
Prince of Songkla University Zoological Collection
(PSUZC) at Prince of Songkla University. She has long experience in study of both
marine and freshwater decapod crustaceans in southern
Thailand. Currently, she is
investigating the diversity of freshwater crabs of southern Thailand.
Author Contribution: VL is involved
in specimen collection, identification and preparing descriptions in the
present study. PL is responsible for identification and preparing descriptions
in the present study.
Acknowledgement: This
is the Prince of Songkla University Zoological
Collection Contribution No. 5. Logistic
support for transportation and working at Ko Tachai and Ko Bon from Naval
Special Warfare Unit, Naval Fleet Command, the Royal Thai Navy and Plant
Genetic Conservation Project under the Royal Initiative of Her Royal Highness
Princess Maha Chakri Sirindhorn are greatly appreciated by VL. We would like to thank Prof. P.K.L. Ng and
Dr. Darren Yeo of Raffles Museum of Biodiversity
Research (ZRC), Department of Biological Sciences, National University of
Singapore for suggestions and help in examining our specimens from
Thailand. Dr. Harold K. Voris and Jeniffer Mui of the Field Museum of Natural History (FMNH) kindly
read and correcting the early draft of this manuscript. Three anonymous reviewers who greatly
improved this manuscript are also acknowledged.
Abstract: An
expedition by scientists participating in a Plant Genetic Conservation Project
under the Royal Initiative of Her Royal Highness Princess Maha Chakri Sirindhorn to Tachai Island, off the coast of Changwat Phangnga, Andaman Sea, southern Thailand in April
1999, revealed a new record of the freshwater crab Phricotelphusa callianira (De Man 1887). The new distribution data is considered
indicative of a lack of freshwater biota surveys in the area studied, and
emphasizes the need for further biogeographicalstudies.
Keywords:Freshwater crab, Mergui Archipelago, Phricotelphusa callianira,
plant genetic conservation project, southern Thailand.
For Figures, Images &
Tables – Click here
Introduction
Several joint scientific expeditions of
botanists, zoologists and marine biologists participating in the Plant Genetic
Conservation Project under the Royal Initiative of Her Royal Highness Princess Maha Chakri Sirindhorn,
supported by the Royal Thai Navy, explored the flora and fauna associated with
the islands in Thailand´s jurisdiction between 1999 and 2008. One of the expeditions was organized between
2 & 11 April 1999 to visit the lesser known islands, Ko Tachai (Tachai Island) and Ko Bon (Bon Island) in the Andaman Sea. These islands are under the jurisdiction of
the Royal Thai Navy. The purpose of the
expedition was to make preliminary studies of the fauna and flora of the
islands and surrounding areas.
Materials and Methods
Ko Tachai is a small isolated island in the Andaman Sea, about
1.25km2 in area, lying on the edge of the continental shelf approximately 70km
from Phang-nga Province off the west coast of the
Thai peninsula, approximately 40km south of the Mu Ko Surin (Surin Islands) and
40km north of the Mu Ko Similan(Similan Islands). It is located south of the Myanmar border at 9o03.50’-9o05.00’N & 97o48.50’-97o49.25’E
(Fig. 1). The surrounding waters are
relatively shallow, but approximately 150-800m from the shoreline the water
exceeds 30m in depth. The terrestrial
part of the island is covered with tropical rain forest over a small hill
approximately 100m in height, and there is a thin zone of beach forest in the
sheltered area northeast of the island. There is a small creek near the beach forest, which flows during the
rainy season. The mature primary forest
extends as far as 20-50 m from the shoreline. The substratum is primarily granite and soil covered with dry
leaves. There is no evidence of human
settlement on the island. Very little
was previously known about the fauna of this relatively unexplored island,
probably due to the remote location.
During the expedition, the first author
visited the small dry freshwater creek on Ko Tachai to search for terrestrial crab specimens, Gecarcoidea lalandii(Gecarcinidae: Brachyura). He also encountered some small colorful
brachyuran crabs underneath rocks among leaf litter and mosses, approximately
100m from the shoreline to the upstream and at an elevation of approximately
3-5 m above the spring high water mark. Crabs were haphazardly collected, fixed
in 10% neutral formalin for two months and transferred to 70% ethanol. Specimens were examined and mainly deposited
at Prince of Songkla University Zoological Collection
(PSUZC), Thailand. Morphological terms
used basically follow those used by Ng (1988a).
The authors tentatively identified the
collected specimens as belonging to the genus Phricotelphusaof the family Gecarcinucidae Rathbun,
1904. So far, five species of the genus Phricotelphusa are known in Thailand (Naiyanetr, 1998), viz. P. aedes(Kemp 1923), P. limula (Hilgendorf1882), P. ranongi Naiyanetr,
1982, P. sirindhorn Naiyanetr,
1989, and P. deharvengi Ng, 1988b, none of
which correspond with the specimens collected from Ko Tachai. During
March 2001, the authors visited the Zoological Reference Collection, Raffles
Museum of Biodiversity Research, Department of Biological Sciences, National
University of Singapore (ZRC) and met Dr. Darren Yeo,
who had previously studied and examined various type specimens of freshwater
crabs from Indo-China. He confirmed that
the specimens collected are Phricotelphusa callianira (De Man 1887).
Results
Phricotelphusa callianira (De Man 1887), is a poorly-known
freshwater crab previously documented only from the MerguiArchipelago, Gulf of Bengal. Originally
this species was described from eight males and seven females obtained in the
mangrove swamps of Kesseriang and Sullivan Islands in
southern Myanmar (De Man 1887) (Fig. 1). As far as we know, this species has only been recorded from the type
locality (De Man 1887; Bott 1970). P. callianirais one of the two species of Phricotelphusa(the other is P. carinifera) which have been
found to inhabit relatively isolated islands. Other known species of the genus are found in the mainland (Ng 1988a).
Thus specimens from Ko Tachai, which is approximately 350km south of the
type locality “Sullivan Islands”, have become the first record of P. callianira (De Man 1887) in Thailand. The presence of the species is unexpected
since the two islands are far apart with a marine environment barrier. Previously, the macrofaunafrom the mangrove forest and adjacent biotopes from Ko Surin Nua (Surin Nua Island), approximately
45km north of Ko Tachai,
were surveyed and only hermit crabs (family Paguridae)
and grapsid crabs were recorded (Frith1977). Land crabs from Mu Ko Similan were also studied and
only decapod crustaceans belonging to the families Coenobitidae, Ocypodidae, Grapsidae and Gecarcinidaewere recorded (Frith & Alexander 1978). Pretzmann (1984) collected and studied crabs from the
freshwater part of the Andaman Islands, and he only found members of the familyGrapsidae in the rivers and freshwater creeks there.
Gecarcinucidae Rathbun, 1904
Phricotelphusa callianira (De Man, 1887)
Thelphusa callianira De Man, 1887: 96-100, Pl.6 figs 1-3
Potamon(Potamon) callianira(De Man, 1887) - Rathbun, 1904: 239 (list), 250
(key), 303 (locality).
Phricotelphusa callianira (De Man, 1887) - Alcock,
1910: 101-102 (with key)
Phricotelphusa callianira callianira (De Man, 1887)
- Bott, 1970: 52-53(with key), Pl.6 figs.66-68, Pl.27
fig. 30
Phricotelphusa callianira (De Man, 1887)- Chuensri, 1974: 7(key)
Phricotelphusa callianira (De Man, 1887) - Ng, 1988a: 85 (list).
Material
Examined: 6.iv.1999,
8 males (4.9-17.0mm CW), 3 females (7.4-8.9mm CW), 9o04.50’N & 97o49.00’E,
alt 3-5m., Ko Tachai, off Amphoe Khura Buri,Changwat Phangnga, coll. V.Lheknim, PSUZC-19990406-01.01.
Comparative
materials: Phricotelphusa ranongi Naiyanetr, 1982:
PSUZC-19980921-01.13, 18 males (6.5x7.7-13.4x16.7), 12 females (8.3-15.0),
9°43.86’N & 98o41.39’E, alt 200m., Haew Ho Lom Waterfall (Klong Lak Rek), watershed area of Lang Suan River, Amphoe Phato, Chumphon, coll. V. Lheknim & P. Leelawathanagoon,
21.ix.1998; PSUZC-20010524-04.10, 1 juv (6.0x7.3), 10o30.20’N
& 98o53.15’E, alt 80m., Chum Sang Waterfall, Ban Nam Tok,Amphoe Kra Buri, Changwat Ranong, coll. V. Lheknim & P.Leelawathanagoon, 24.v.2001.
Description
Carapace is relatively low, slightly
broader than long (Image 1a). Anterolateralmargin slightly convex. Posterolateral margins entire, gently concave, converging posteriorly. Frontal
margin nearly straight, almost at right angles with internal angle of orbits,
slightly more than a third of carapace width (Image 1b). Frontal region deflexed vertically downwards,
finely granulated. Exorbitalangle well developed, relatively triangular broad. Dorsal carapace surface depressed, somewhat
flattened. Epigastric crest slightly arcuated, relatively low, sharp, transversely rugose anteriorly (Image 1c). Postorbital crest sharp, nearly straight, not
reaching epibranchial teeth. Postorbital crest behind and distinctly
separated from epigastric crest by a notch,
approximately 1/3 length of epigastric crest. Epibranchial teeth acute, prominent. Short oblique rugae present between postorbital
crests and epibranchial teeth. Carapace regions poorly defined, only
semicircular H-shaped gastric groove distinct, which separates gastric region
from cardiac region. Branchialregions relatively smooth, faintly demarcated from gastric region by shallow
cervical groove anteriorly.
Mouthparts: Third maxilliped exopod extends beyond edge of merus,
flagellum absent; merus with very faint medial ischial sulcus (Fig. 2a). Posterior margin of epistome with broadly triangular median lobe.
Abdomen: Abdominal segments 1-5
gradually narrowing from anterior to posterior margins; segment 6 nearly
rectangular, slightly longer than broad; lateral margins nearly straight (Image
1d and Fig. 2e). Telsonslightly longer than basal width, tip round; lateral margins slightly concave
at ¼ of length, then gradually converging posteriorly.
Chelipeds unequal: Outer
and upper surfaces of merus and carpus rugose, inner margins are granular. Carpus with a small inner subdistal spine. Palm inflated, longer than high. Fingers of
large chela gaping, shorter than palm, tips hooked,
crossing one another when closed, both toothed along cutting edges (Fig.
2d). The teeth of
movable finger proximally large, distally small, those on fixed finger small. Fixed finger with a shallow
longitudinal groove on outer surface. Fingers of small chelarather slender, straight, not gaping when closed, but crossing at tips, cutting
edges with small teeth.
Ambulatory legs: Legs relatively long,
slender. Dorsal and ventral margins of meri of second to fourth legs convex, those on first one
almost straight. Dactylus elongate, slender. Upper margin of merus weakly serrated, subdistalspine weak.
G1: relatively stout; not twisted,
terminal joint subconical, straight, relatively short
about 0.3 times length of subterminal joint, tip
truncate, slightly bent outwards; subterminal joint
faintly sinuous (Fig. 2b & c).
Color: Large adult specimens with deep
brown carapace and orange-yellowish chelipeds with
brown tips. Ventral surfaces dirty
white.
Sizes: The largest carapace width in our
collection was 17.5mm. compared to the type specimens
which measure 14.0-16.0mm (De Man 1887). Measurements (in millimetres) of the largest
male specimen are given in Table 1.
Habitat: The present specimens were collected
under rocks covered with dry leaves from a seasonal creek in the beach forest
adjacent to an intertidal sandy beach. Observations indicate that they prefer areas near moist soil but are
very active on land. This is contrary to
the semiterrestrial to fully freshwater aquatic
habits of other Phricothelphusa spp. elsewhere
(Ng 1988a).
Discussion
Our specimens of Phricotelphusa callianira from Ko Tachai agree well with the description and figures given by
De Man (1887). In addition, Dr. Darren Yeo of Zoological Reference Collection (ZRC), Raffles
Museum of Biodiversity Research, National University of Singapore presented his unpublished photographs and
drawings of the types of the species including the structure of the gonopods, now in Instituut voor Systematiek en Populatiebiologie [formerly Zoological Museum, University
of Amsterdam, Amsterdam, the Netherlands (ZMA)] and Nationaal Natuurhistorische Museum [formerly Rijksmuseum van Natuurlijke Historie (RMNH)],
Leiden, the Netherlands. The morphology
and dorsal ridge patterns on the carapace of our specimens (Image 1), match the
drawing of P. callianira in De Man (1887, pl 6, Figs. 1 and 2). The G1 of the present Thai material (Fig. 3) also agrees well with the
figure given in Bott (1970, Pl. 27, Fig. 30). As such, we believe our specimens are conspecific. P. callianira appears to be most similar to P. ranongi Naiyanetr 1982, but
can be distinguished by the following characters: G1 subterminaljoint faintly sinuous compared to almost straight in P. ranongi(Ng & Naiyanetr, 1993) (see also Fig. 59B & C
in Bott, 1970), dactylusand pollex of small and large chela are relatively
thicker and stouter compared to the relatively slender fingers in P. ranongi, the small chela of P.callianira has a movable finger which is shorter
than the palm whereas this finger is longer than the palm in P. ranongi, and the 6th abdominal segment of P. callianira is slightly rectangular (lateral margins
longer than anterior and posterior margins) but is trapezoidal in P. ranongi.
It is interesting to note that of the 11
recognized species of Phricotelphusa known, P.callianira and P. cariniferawere known to be insular species, occurring on the edge of the Mergui Archipelago, while the rest of the species from
Thailand and Malaysia are more continental species. Recently, Voris(2000) reconstructed sea-level changes in the Southeast Asia shoreline by using
present-day bathymetric depth contours and indicated this part of the Mergui Archipelago has been disconnected from the rest of
the archipelago some 7,500yr BP. Some
questions remain. First, how did this
freshwater crab species end up being distributed only on the islands of the
archipelago? Second, how much genetic
variation exists between populations morphologically identified as P. callianira along the islands chain at the rim of the Mergui Archipelago. Finally, what adaptations enable the crabs to live on such small islands
with clear seasonality in the climate? More data on the activity of P. callianiraduring the dry period, and their adaptation to survive and reproduce on such a
small isolated island would be interesting (Hartnoll1988).
Due to limited information on the
population status of Phricotelphusa callianira in the Myanmar jurisdiction and only one presently
known locality in Thai’s jurisdiction at Ko Tachai, conservation measures for this species at this
locality are clearly necessary
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