KHA-NYOU

This unique animal is less related to a rat and is really its own distinct species. It is considered a living fossil. It is the only living member of the family Diatomyidae, with other species in this family having gone extinct over 10 million years ago and existing only in fossil records. It was described by science only in 2005, first from specimens collected from a local market in Thakhek district in central Laos in 1996 and subsequently from specimens trapped during field surveys in nearby karst forests in 1999.

Although it is listed as a species of Least Concern in the IUCN Red List, this is now a seven-year-old assessment based on distribution information from several years before, with many assumptions about its population size and threats. It is thought that this genus, Laonastes, might actually consist of many species that look similar. Further surveys and genetic analysis may provide clarity and lead to many distinct species being described. Such splitting of the species may change their Red List status. In any case, the forest in the limestone karsts continue to be degraded, and the species is hunted and traded frequently, meaning this unique animal may be more threatened than the current assessment suggests.

Some of the karst habitats it occupies are small, but the karst habitat occurring in Phou Hin Puon National Protected Area in Khammouane province, central Laos, is large and contiguous. A population of the kha-nyou is also known from the limestone karsts on the eastern border areas of Phon Nha-Ke Bang National Park in Quang Binh province, Viet Nam. However, some of the karsts in central Laos, particularly on the peripheries of Phou Hin Poun, are being quarried to make cement, which poses a threat to local populations of this species.

A more severe and immediate threat, however, is from heavy hunting and trade. Localized declines, particularly in the more isolated populations, could lead to extirpations of potentially unique species in this genus. This species is frequently traded in local wild meat markets, even though it is not thought to be a special or “luxury” meat. Surveys conducted in the markets around Phou Hin Poun often find this rodent being sold alongside other commonly found species such as Finlayson’s and red-cheeked squirrels.

There is a perception among conservationists that the incorrectly given English name terming it a “rat” (“Laotian rock rat”) diminishes the charisma and makes it difficult to get global public interest and conservation attention for this highly unique species.

Duckworth, J.W. 2016. Laonastes aenigmamus. The IUCN Red List of Threatened Species 2016: e.T136474A22199035. https://dx.doi.org/10.2305/IUCN.UK.2016-2.RLTS.T136474A22199035.en. Accessed 9 May 2023.