o_19ko2dt161ng2j4e1tgnoqv1s45a.pdf

PETER K. L. NG & DARREN C. J. YEO (2007)
some 1,500 km 2 . However, while the area it is known from appears to be relatively extensive,
it must be noted that the distribution consists of many pockets of populations, and this species
is known to show the greatest variation among the Johora species, facts that point to it probably
being a species complex (Ng 1988). Another probable species complex is the troglophilic
crab, Stygothelphusa bidiensis, which has an unlikely distribution of two disjunct cave systems
in Sarawak (Bau and Gua Serian). The available evidence suggests that the populations in the
two cave systems actually belong to two separate species (unpublished data). The same situation
is true of Lepidothelphusa cognetti, which occurs in the sandstone streams of Bau and Penrissen.
Another point to consider is that for freshwater crabs in developing countries, the line separating
a vulnerable or endangered species is a very fine one. This is mainly because of the very
restricted distributions of many species and the speed of development projects; the time lapse
between project conception and implementation, even for large scale ones, can be as short as
a year.
Using Peninsular Malaysia and Singapore as an example, 42 species of potamids and
parathelphusids are known at present. All the potamids (27 taxa) are found only in Peninsular
Malaysia and Singapore. Of the 15 parathelphusids, 10 are endemic to Peninsular Malaysia
and Singapore, the other five species also occurring in Sumatra or southern Thailand. The
endemic taxa are almost always highland species, or occur on isolated islands. The conservation
of this remarkable diversity is imperative (see also Ng 1988). There is thus, more than ever, a
need to establish more nature reserves and national parks. And careful planning, co-ordination
and supervision to minimise its destructive effects must temper development, inevitable though
it may be. At the same time, other broader, long term issues, those of water-shed conservation,
sufficient size of protected areas, and forest conditions (primary or secondary or disturbed)
must be given due consideration. Such matters if dealt with properly would not just be for the
benefit of freshwater crab diversity, but for the overall ecosystem as well.
ACKNOWLEDGEMENTS
The authors thank the organisers of the workshop for inviting this paper from them, in particular,
Saw Leng Guan, the chair of the organising committee.
REFERENCES
BAHIR, M.M., NG, P.K.L., CRANDALL, K. & PETHIYAGODA, R. 2005. A conservation
assessment of the freshwater crabs of Sri Lanka. Raffles Bulletin of Zoology Supplement
12: 121–126.
CRANBROOK, EARL OF, & FURTADO, J.L. 1988. Freshwaters–Decapod Crustacea. Pp.
225–250 in Earl of Cranbrook (ed.) Key Environments: Malaysia. Pergamon Press, Oxford.
IUCN (International Union for the Conservation of Nature and Natural Resources), 2001. The
IUCN Red List of Threatened Species: 2001 Categories & Criteria. Version 3.1. http://
www.redlist.org/info/categories_criteria2001.html [accessed 01.01.2004].
NG, P.K.L. 1988. The Freshwater Crabs of Peninsular Malaysia and Singapore. Department
of Zoology, National University of Singapore. Shinglee Press, Singapore.
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