o_19ko2dt161ng2j4e1tgnoqv1s45a.pdf

MALAYSIAN FRESHWATER CRABS: CONSERVATION PROSPECTS AND CHALLENGES
Much of this diversity and endemism is owed to the complicated topography and equally
diverse and heterogeneous habitats found in much of the country, ranging from rugged montane
habitats with waterfalls and torrential streams to moist lowland forests to subterranean
freshwaters; in both continental as well as insular landmasses. These provide plenty of
opportunities not only for allopatric speciation to occur by geographic isolation, but also for
sympatric speciation through niche specialization in the many ecological niches available.
Naturally, these are coupled with the freshwater crab characteristics of possessing low fecundity,
direct development and limited dispersal abilities.
The species distributions cover a wide gamut, from point endemics such as Johora johorensis
(Gunung Pulai, Johor) to localized taxa like Geosesarma nemesis (Gunung Pulai and Gunung
Panti, Johor, and Singapore) to wide ranging species such as Parathelphusa maculata
(throughout Peninsular Malaysia, southernmost Thailand, Singapore and southern half of
Sumatra).
The present paper aims to assess and discuss the conservation status of the 102 freshwater
crab species now known from Malaysia.
MATERIALS AND METHODS
For purposes of reference and discussion, certain geographical terms have been used in this
paper. These are defined below:
Sundaland/Sundaic - refers to the continental land masses and islands of the Sunda Shelf, i.e.,
Malay Peninsula, Borneo, Sumatra, Java and Lesser Sunda Islands. Palawan (including
Balabac) is included but Sulawesi and the southern islands of the Philippines (e.g.,
Mindanao and Mindoro) are excluded.
Malay/Malayan - pertaining to Peninsular Malaysia, inclusive of southernmost Thailand (south
of the Isthmus of Kra), and Singapore.
The terminology for morphological structure follows essentially that used by Ng (1988). Several
genera and species are in the process of being described or the descriptions are in press. In
such instances, no name has been applied. In this paper, the abbreviations G1 and G2 are used
for the male first and second pleopods, respectively.
Although Ng (1988) previously recognised the taxon of subspecies, a reconsideration of the
state of brachyuran systematics suggests that such a fine division is neither useful nor realistic,
especially considering the poor understanding we have of their mechanisms of speciation.
The phylogenetic species concept is utilised here as far as possible. Under this framework, all
taxa previously regarded as subspecies are recognised here as species.
With regards to the threat status, the most recent (IUCN 2001) guidelines (Red List Categories
& Criteria, version 3.1) were adopted for use in assessing the threat-levels of the various
freshwater crab species considered. These categories are: Critically Endangered (CR),
Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), or Data
Deficient (DD).
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