o_19ko2dt161ng2j4e1tgnoqv1s45a.pdf

STATUS OF BIOLOGICAL DIVERSITY IN MALAYSIA &
THREAT ASSESSMENT OF PLANT SPECIES IN MALAYSIA
MALAYSIAN FRESHWATER CRABS:
CONSERVATION PROSPECTS AND
CHALLENGES
1
Peter K. L. Ng & 2 Darren C. J. Yeo
ABSTRACT
Of the over 150 species of true freshwater crab species now known from Sundaic Southeast
Asia, more than half occur in Malaysia. Currently, 24 genera and 102 described species from
four families; Potamidae, Gecarcinucidae, Parathelphusidae and Sesarmidae, are known. Many
species of freshwater crabs, however, have very restricted geographic ranges, a consequence
of their relative low fecundity cum direct development, poor dispersal abilities, and nichespecialisation.
This makes freshwater crabs highly susceptible to anthropogenic activities.
While there is no clear evidence that any one species has been made extinct as a result, the
threats facing many known species are critical. The conservation status of Malaysian freshwater
crabs are reviewed and assessed using the criteria established by the IUCN (2001), and the
problems and challenges associated with these discussed. The report serves as a starting point
for determining appropriate conservation strategies for these animals.
INTRODUCTION
Of the estimated 6,500 known species of brachyuran crabs, over 1,000 are known to be wholly
freshwater in habit. Freshwater crabs are one of the most important organisms inhabiting
Southeast Asian freshwaters, but are relatively poorly known because of their secretive habits.
They are present in almost all clean freshwater bodies, from lowlands to high mountains.
Some species have also become terrestrial and semi-terrestrial, moving about or burrowing
into the forest floor. Their direct development and freshwater habit have resulted in rampant
speciation, with a large number of species occurring in this part of the world. Malaysia alone
has one of the highest densities of freshwater crab diversity in the world, with 24 genera and
102 known species from four families (Potamidae: 41 species; Parathelphusidae: 40 species;
Gecarcinucidae: 3 species; and Sesarmidae: 18 species), many of them endemic, and more
than half of them described between 1990 and 2000 (Ng 1988, 1990a, 2004; Cranbrook &
Furtado 1988; Ng & Ambu 1998).
Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 119260, Republic of
Singapore; 1 dbsngkl@nus.edu.sg; 2 darrenyeo@nus.edu.sg
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