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Laonastes aenigmamus 

Scope: Global
Status_ne_offStatus_dd_offStatus_lc_onStatus_nt_offStatus_vu_offStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Rodentia Diatomyidae

Scientific Name: Laonastes aenigmamus
Species Authority: Jenkins, Kilpatrick, Robinson & Timmins, 2005
Common Name(s):
English Kha-nyou
Taxonomic Notes: Originally placed in the family Laonastidae, this species is now assigned to the family Diatomyidae, which was previously represented only by species identified from the fossil record. It has been suggested that the genus might comprise multiple taxa, potentially species (Nicolas et al. 2012); if so, it is quite likely that one or more taxa will have a tiny range within which all its habitat is threatened.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2016-05-03
Assessor(s): Duckworth, J.W.
Reviewer(s): Amori, G.
Contributor(s): Aplin, K. & Lunde, D.P.
Facilitator/Compiler(s): Laginha Pinto Correia, D.
Justification:

Kha-nyou is listed as Least Concern because it does not come close to qualifying for a threat category under any criterion. The only potential exception is B1 using extent of occurrence (EOO). This is calculated as 10,942 km², which is within the threshold for Vulnerable, and the number of localities is dropping as marginal karsts are destroyed for raw material in cement manufacture, probably compounded in some surviving small karsts by hunting-driven extirpation. However, it is implausible that the species shows extreme fluctuations in population or range, it is not severely fragmented and it occurs in more than 10 locations; at least one of these latter subcriteria would need to be met for a listing as Vulnerable. The proportionate effects of current losses on population and range are likely to be too minor to warrant consideration of Near Threatened. There is a recent suggestion that the genus is a complex of cryptic taxa. Upon clarification of taxonomy, reassessment of the resulting species will be urgent, if any is confined to small karsts.

Previously published Red List assessments:

Geographic Range [top]

Range Description:

This recently described species is strictly endemic to the central Indochina limestone karsts, mostly in Khammouan Province (Lao PDR), but extending north into southern Bolikhamxai province (Lao PDR) and east into Viet Nam (Phong Nha Ke Bang Notional Park) (Jenkins et al. 2005, Nicolas et al. 2012, Nguyen et al. 2012). Nicolas et al. (2012) collected individuals from 38 Lao localities and mapped a number of others where they believed the species to occur. It remains known in Viet Nam from apparently only one (large) locality.

Countries occurrence:
Native:
Lao People's Democratic Republic; Viet Nam
Additional data:
Number of Locations:10
Lower elevation limit (metres):150
Upper elevation limit (metres):850
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:

Eight major geographic clades were identified based on DNA analysis by Nicolas et al. (2012), but this analysis did not cover the Viet Namese part of the range, there were some gaps within the Lao range, and the range of some Lao clades (notably A and E) is so large that they are likely to inhabit multiple locations as per Red List definitions. Overall, different karst blocks harbour distinct evolutionary significant units which may represent separate species (Nicolas et al. 2012). Some isolated karsts are of only a few square kilometres and if holding the genus, will hold only small an highly vulnerable population. By contrast the very large, contiguous karst overlapping largely with Phou Hinpoun (= Khammouan Limestone) National Biodiversity Conservation Area is likely to hold a huge population, mostly in areas never visited by people, even locals. Some isolates of karst are destroyed for cement-making and this occurs around the margins of the large blocks, but the total proportionate loss of habitat has been and will continue to be tiny (see Steinmetz et al. 2011). Hunting may also be causing localised declines, i.e. on small isolated karsts, but is unlikely to have any major effect on the overall population. An attempt in about 2009 to enter the interior of Phou Hinpoun NBCA, to survey the Lao Leaf Monkey Trachypithecus laotum, failed to find any villagers who had penetrated the area or were willing to try. The survey team pressed on alone but after several days wandering looking for water had to abort the attempt (J. W. Duckworth pers. comm. 2016). Even on small (thus accessible) isolated karsts in central Lao PDR, war scrap, one of the most lucrative non-timber forest products and thus one for which its presence is a good indicator of low human entry, could readily, as of 2008, be found within an hour’s walk of the karst edge (J. W. Duckworth pers. comm. 2016). On the assumption that the Kha-nyou occurs across the karst blocks which it inhabits, rather than just at their margins, the majority of the population is in areas not hunted, through their remoteness from human settlement.

Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:It was trapped in large limestone boulders varying in size up to several metres, on steep slopes surrounding karst formations, where traps were set on bare earth under and between boulders. The slopes were covered in both evergreen and deciduous trees, but with little ground vegetation. Low lying areas away from the karst had been cleared for the cultivation of paddy rice. Villagers reported that the animals were caught only in the vicinity of the karst (Jenkins et al. 2005). It is not clear whether the species is able to use the massive karst limestone formations themselves, nor whether it is able to exist in secondary scrub habitats. Believed to be nocturnal. Morphological features of the hypsodont molars, capacious stomach, a large caecum and appendix combined with evidence of plant remains in the stomach, suggest that it is primarily vegetarian in its diet. In an analysis of dietary toothwear by Gina Semprebon, which guages the probable diet of the last few meals, fine wear on the teeth suggested that leaves formed the diet of one individual, while there was evidence of grass and seed in the diet of a second specimen (Jenkins et al. 2005).
Systems:Terrestrial
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade:

Traditional hunters are known to capture this species and it is traded in local wildlife meat markets beside roads and in nearby villages/towns; its meat has no premium value over ‘average’ rodent meat and there is no significant trade to out of range meat markets, e.g. to Vientiane (Nicolas et al. 2012, J.W. Duckworth pers. comm. 2016)

Threats [top]

Major Threat(s):

Some isolates of karst are destroyed for cement-making and this occurs also around the margins of the large blocks, but the total proportionate loss of habitat has been and will continue to be tiny (see Steinmetz et al. 2011). Hunting may also be causing localised declines, for example through extirpations from small isolated karsts (as suggested by villagers to Nicolas et al. 2012), but is unlikely to have any major effect on the overall population. An attempt in about 2009 to enter the interior of Phou Hinpoun NBCA, to survey the Lao Leaf Monkey Trachypithecus laotum, failed to find any villagers who had penetrated the area or were willing to try. The survey team pressed on alone and after several days wandering looking for water had to abort the attempt (J. W. Duckworth pes. comm. 2016). Even on isolated karsts, war scrap, one of the most lucrative non-timber forest products and thus one for which its presence is a good indicator of low human entry, could readily, as of 2008, be found within an hour’s walk of the karst edge in central Lao PDR (Woxvold et al. 2009). On the assumption that the Kha-nyou occurs across the karst blocks which it inhabits, rather than just at their margins, the majority of the population is in areas not hunted through their remoteness from human settlements. Tree cover in peripheral and accessible karst areas is very vulnerable to loss due to logging and firewood removal. However, forest cover remained, as of 2008, extensive within Phou Hinpoun NBCA (Alström et al. 2009), most of this being outside the areas regularly entered by villagers. This species has, through its obligate karst association, a distribution including a number of small isolates as well as larg contiguousblocks; only very limited gene flow was detected between all populations (Nicolas et al. 2012). Although this is not a threat to the species as here defined, any taxonomically distinct populations confined to small (under 50 km²) karsts are at high risk, at least potentially.

Conservation Actions [top]

Conservation Actions:

It is present in the Phou Hinpoun (Khammouan Limestone) and Hin Namno National Biodiversity Conservation Areas of Lao PDR and in Phong Nha – Ke Bang National Park, Viet Nam (Jenkins et al. 2005, Nicolas et al. 2012, Nguyen et al. 2012). As a monospecific genus, there are no urgent conservation priorities, but clarification over the range of habitats used would be helpful, particularly in interior areas of large karsts remote from human use. Far more important than this is to resolve the genus’s taxonomy to determine if there are multiple cryptic species and, if so, whether any of them are restricted to small karst isolates; these may already be highly threatened and even if not yet so, the karsts are at permanent risk through destruction for cement manufacture, and even if surviving, the Kha-nyou populations upon them at risk through overhunting and forest degradation.


Citation: Duckworth, J.W. 2016. Laonastes aenigmamus. The IUCN Red List of Threatened Species 2016: e.T136474A22199035. . Downloaded on 01 October 2016.
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