Freshwater Crab Diversity

Major projects | Further readings

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.

The terrestrial crab, Terrapotamon abbotti, from Thailand is often traded as an aquarium pet.

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.

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.

An endemic forest swamp crab, Johora punicea (Potamidae), from Pulau Tioman.

The beautiful spider-like cave crab, Stygothelphusa bidiensis (Gecarcinucidae), from Sarawak.

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.

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.

A beautiful species of Demanietta (Potamidae) from southern Thailand ( of P. Naiyanetr).

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.

The beautiful terrestrial crab, Geothelphusa albogilva (Potamidae), from Taiwan.

The beautiful Terrathelphusa kuchingensis from Bako National Park, Sarawak.

Major projects:

• Freshwater Crab Diversity
• Freshwater Prawn Diversity
• Marine Crab Diversity

Further readings:

• Dissertations
• Publications

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