Saola
The saola, also called spindlehorn, Asian unicorn, or infrequently, Vu Quang bovid, is a forest-dwelling bovid native to the Annamite Range in Vietnam and Laos. It was first described in 1993 following a discovery of remains in Vũ Quang National Park by a joint survey of the Vietnamese Ministry of Forestry and the World Wide Fund for Nature, Saolas have since been kept in captivity multiple times, although only for short periods as they died within a matter of weeks to months.
The first photograph of a living saola was taken in captivity in 1993. The most recent one was taken in 2013 by a movement-triggered camera in the forest of central Vietnam, which represents the most recent record of the saola.
There is concern that the species may already be extinct. It is the only species in the genus Pseudoryx and the earliest diverging member of the tribe Bovini, placing buffalo and cattle as its closest relatives.
History of research and taxonomy
In May 1992, the Ministry of Forestry, Vietnam sent a survey team to examine the biodiversity of the newly established Vu Quang National Park. On this team were Do Tuoc, Le Van Cham and Vu Van Dung ; Nguyen Van Sang ; Nguyen Thai Tu ; and John MacKinnon. On 21 May, the team procured a skull featuring a pair of strange, long and pointed horns from a local hunter. They came across a similar pair in the Annamite Range in the northeastern region of the reserve the following day. The team ascribed these features to a new bovid species, calling it the "saola" or the "Vu Quang ox" to avoid confusion with the sympatric serow. The WWF officially announced the discovery of the new species on 17 July 1992.According to biodiversity specialist Tony Whitten, though Vietnam boasts a variety of flora and fauna, many of which have been recently described, the discovery of as large an animal as the saola was quite unexpected. The saola was the first large mammal to be discovered in the area for 50 years. Observations of live saola have been few and far between, restricted to the Annamite Range.
The scientific name of the saola is Pseudoryx nghetinhensis. It is the sole member of the genus Pseudoryx and is classified under the family Bovidae. The species was first described in 1993 by Vu Van Dung, Do Tuoc, biologists Pham Mong Giao and Nguyen Ngoc Chinh, Peter Arctander of the University of Copenhagen and John MacKinnon. The discovery of saola remains in 1992 generated huge scientific interest due to the animal's special physical traits. The saola differs significantly from all other bovid genera in appearance and morphology, enough to place it in its own genus.
Since its physical traits are so complex to classify, Pseudoryx had been classified variously as member of the subfamily Caprinae and as belonging to any of the three tribes of the subfamily Bovinae: Boselaphini, Bovini and Tragelaphini. DNA analysis has led scientists to place the saola as a member of the tribe Bovini, the group which includes buffalo, cattle, bison and yaks, among others. Recent genetic research has placed it as the most primitive and earliest diverging member of the tribe Bovini.
Below is a cladogram based on Yang et al.'', 2013 and Calamari, 2021:
The saola is suggested to have diverged from the ancestor of other members of Bovini between 10.8 and 16.2 million years ago, during the Middle Miocene. A 2021 study suggested that it was closely related to the extinct genus Miotragocerus'', known from the late Miocene of Eurasia.
A genomic analysis of historical saola specimens published in 2025 revealed that the saola split into two lines at least 20,000 years ago, but no later than 5,000 years ago, one of which became the northern population in the area of the Vũ Quang National Park, the Pù Mát National Park, both in Vietnam, and the Nakai-Nam-Theun National Park in Laos, and the other became the southern population in the area of Huế, Đông Giang and Tây Giang, all in Vietnam. The separation may have been caused by climatic changes at the end of the last ice age and the associated changes in the landscape and vegetation. This may also have been influenced by the beginning of sedentarisation in the region. This separation was accompanied by a steady reduction in effective population size, with the effective population size suggested to have not have exceeded 5,000 individuals in the last 10,000 years. Within the genome of the respective evolutionary lines, there are areas with a lack of diversity, but these are variably distributed and are therefore not shared by the two populations.
Etymology
The name 'saola' has been translated as "spindle", although the precise meaning is actually "spinning-wheel post horn". The name comes from a Tai language of Vietnam. The meaning is the same in Lao language. The specific name nghetinhensis refers to the two Vietnamese provinces of Nghệ An and Hà Tĩnh, while Pseudoryx acknowledges the animal's similarities with the Arabian or African oryx. The Hmong people in Laos refer to the animal as saht-supahp, a term derived from Lao meaning "the polite animal", because it moves quietly through the forest. Other names used by minority groups in the saola's range are lagiang, a ngao and xoong xor In the press, saolas have been referred to as "Asian unicorns", an appellation apparently due to its rarity and reported gentle nature, and perhaps because both the saola and the oryx have been linked with the unicorn. No known link exists with the Western unicorn myth or the "Chinese unicorn", the qilin.Description
In a 1998 publication, William G. Robichaud, the coordinator of the Saola Working Group, recorded physical measurements for a captive female saola he dubbed 'Martha', in a Laotian menagerie. She was observed for around 15 days until she died from unknown causes. Robichaud noted the height of the female as at the shoulder; the back was slightly elevated, nearly taller than the shoulder height. The head-and-body length was recorded as. The general characteristics of the saola, as shown by studies during 1993–5 as well as the 1998 study, include a chocolate brown coat with patches of white on the face, throat and the sides of the neck, a paler shade of brown on the neck and the belly, a black dorsal stripe, and a pair of nearly parallel horns, present on both sexes.Robichaud noted that the hair, straight and long, was soft and thin–a feature unusual for an animal that is associated with montane habitats in at least a few parts of its range. While the hair was found to be short on the head and the neck, it thickened to woolly hair on the insides of the forelegs and the belly. Studies before 1998 reported a hint of red in the inspected skins. The neck and the belly are a paler shade of brown compared to the rest of the body. A common observation in all the three aforementioned studies is a thick stripe extending from the shoulders to the tail along the middle of the back. The tail, which measured in Robichaud's specimen, is divided into three horizontal bands, brown at the base, black at the tip and white in the middle. Saola skin is thick over most of the body, but thickens to near the nape of the neck and at the upper shoulders. This adaptation is thought to protect against both predators and rivals' horns during fights. Saolas weigh between approximately 80–100 kg.
The saola has round pupils with dark-brown irises that appear orange when light is shone into them; a cluster of white whiskers about long with a presumably tactile function protrude from the end of the chin. The specimen Robichaud observed could extend its tongue up to and reach its eyes and upper parts of the face; the upper surface of the tongue is covered with fine, backward-pointing barbs. Robichaud observed that either of the two maxillary glands had a nearly rectangular hollow with the dimensions, covered by a thick flap. The maxillary glands of the saola are probably the largest among those of all other animals. The glands are covered by a thick, pungent, grayish green, semi-solid secretion beneath which lies a sheath of few flat hairs. Robichaud observed several pores, used probably for secretion, on the upper surface of the lid. Each white facial spot shelters one or more nodules from which originate long white or black hairs. These secretions are typically rubbed against the underside of vegetation, leaving a musky, pungent paste. The spoor of the forelegs measured long by wide, and long by for the hindlegs.
Both sexes possess slightly divergent horns that are similar in appearance and form almost the same angle with the skull, but differ in their lengths. Horns resemble the parallel wooden posts locally used to support a spinning wheel. These are generally dark-brown or black and about 35–50 cm long; twice the length of their head. Studies in 1993 and 1995 gave the maximum distance between the horn tips of wild specimens as, but the female observed by Robichaud showed a divergence of between the tips. Robichaud noted that the horns were apart at the base. While studies prior to Robichaud's claim the horns are uniformly circular in cross-section, Robichaud observed his specimen had horns with a nearly oval cross-section. The sides of the base of the horns is rugged and indented.
Distribution and habitat
The saola has one of the smallest ranges of any large mammal. It inhabits wet evergreen or deciduous forests in eastern Southeast Asia, preferring river valleys. Sightings have been reported from steep river valleys at above sea level. In Vietnam and Laos, the species' range appears to cover approximately, including four nature reserves. During the winters, it migrates to the lowlands. In the northern Annamite Mountains, it was sighted mostly near streams at elevations of.Ecology and behaviour
Local people reported that the saola is active in the day as well as at night, but prefers resting during the hot midday hours. Robichaud noted that the captive female was active mainly during the day, but pointed out that the observation could have been influenced by the unfamiliar surroundings the animal found herself in. When she rested, she would draw her forelegs inward to her belly, extend her neck so that her chin touched the ground, and close her eyes. Though apparently solitary, saola have been reported in groups of two or three as well as up to six or seven. Grouping patterns of the saola resemble those of the Cape bushbuck, anoa and sitatunga.Robichaud observed that the captive female was calm in the presence of humans, but was afraid of dogs. On an encounter with a dog, she would resort to snorting and thrust her head forward, pointing her horns at her opponent. Her erect ears pointed backward, and she stood stiffly with her back arched. Meanwhile, she hardly paid any attention to her surroundings. This female was found to urinate and defecate separately, dropping her hind legs and lowering her lower body – a common observation among bovids. She would spend considerable time grooming herself with her strong tongue. Marking behaviour in the female involved opening up the flap of the maxillary gland and leaving a pungent secretion on rocks and vegetation. She would give out short bleats occasionally.