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Freshwater Crab
Diversity
Major
projects | Further readings
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Freshwater crabs are medically important
as vectors of the deadly disease Paragonimiasis which
affects about 20 million people worldwide. The identification
of the correct crab vector is important for the control
of this disease. Freshwater crabs are also important
as environmental markers (especially for rainforests)
and water quality indicators. This necessitates that
they are identified correctly.
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The terrestrial crab, Terrapotamon abbotti,
from Thailand is often traded as an aquarium pet.
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Scientifically,
freshwater crabs are important as markers for the
study of biogeography, plate tectonics and animal
evolution. Some colourful species are also important
in the aquarium trade.
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The Southeast Asian freshwater crab
diversity project is terminating after several years
of university funding and also represents the end
of some 15 years of work on the group for the region.
The Southeast Asian freshwater crab fauna is one of
exceptional diversity. Of the some 160 named species,
more than half were described only after 1970, and
some 90 (i.e. almost 50%), were discovered only over
the last 15 years. This number, however, will probably
increase by another 10-20% after the collections from
various parts of Thailand, Philippines, Sumatra, Kalimantan
and Sulawesi are studied. The actual number of freshwater
crab species present in Southeast Asia is probably
in the neighbourhood of 200 species.
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An endemic forest swamp crab, Johora punicea
(Potamidae), from Pulau Tioman.
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The unusual terrestrial crab (right), Geosesarma
notophorum (Grapsidae),
from the Lingga islands off Sumatra
which carries the baby crabs on its back. |
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The beautiful spider-like cave crab, Stygothelphusa
bidiensis (Gecarcinucidae), from Sarawak.
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For the Southeast Asian fauna, work
is now being completed on several genera of gecarcinucoid
crabs (including a revision of the genus Stygothelphusa),
as well as the fauna of the Philippines (with M. Takeda)
and Sulawesi.
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The laboratory emphasis has shifted
in recent years from Southeast Asia to continental
east Asia, mainly the countries of Thailand, Laos,
Cambodia, Vietnam and Burma. A graduate student is
currently studying the diversity of the crab fauna
in these countries. Many of the species belong to
difficult species-complexes, making the study slow
and tedious. The potamid genus Demanietta has
just been revised, and a study on members of the very
difficult Potamon tannanti species group from
Vietnam, China and Laos, has just been completed.
The study has been helped a great deal by specimens
obtained by H. Morioka and M. Kottelat from Laos,
and Hanoi University and Vietnamese Medical Research
Centre from Vietnam. Most of the work on the Thai
fauna is being done with P. Naiyanetr from Chulalongkorn
University, based in part on the very extensive collections
in his laboratory.
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A beautiful species of Demanietta (Potamidae)
from southern Thailand ( of P. Naiyanetr).
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The spectacular terrestrial queen crab of Thailand (right),
Thaiphusa sirikit (Potamidae) ( of P. Naiyanetr).
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On another front, the study of the
freshwater crab fauna of Sri Lanka has been completed,
and work is in progress (with the Wildlife Heritage
Trust of Sri Lanka) to publish a monograph of the
group. A large amount of material has also been assembled
of southern Japanese freshwater crabs (Geothelphusa)
and the terrestrial crabs of Southeast Asia (Geosesarma),
and work is planned for the revision of these groups.
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The beautiful terrestrial crab, Geothelphusa albogilva
(Potamidae), from Taiwan.
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The ricefield crab, Sayamia bangkokensis (Parathelphusidae),
of Thailand. |
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The beautiful Terrathelphusa
kuchingensis from Bako National Park, Sarawak.
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