 Pseudoryx
nghetinhensis
Saola |
Taxonomy | Description
| Reproduction | Ecology
| Behavior | Distribution
| Conservation | Remarks
| Literature |
| Taxonomy
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Pseudoryx nghetinhensis [Dung, Giao, Chinh, Tuoc, Arctander and MacKinnon,
1993].
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Citation: Nature, 363: 443.
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Type locality: Vu Quang Nature Reserve, Vietnam
18o15' N by 105o25'E.
One of the most recently discovered large mammals, the saola excited a flurry
of scientific interest due to its unique characteristics, including its long
horns and unique facial glands. Its discovery required the creation
of a new genus, and considerable controversy raged as to the evolutionary
affinities of Pseudoryx. Based on morphological characters,
various authors have allied the saola with the subfamily Bovinae (including
it in each of the three tribes: Boselaphini (nilgai and chousingha), Bovini
(cattle and buffalo), and Tragelaphini (spiral-horned antelope)) and the
subfamily Caprinae (specifically the Rupicaprini, closest to serows and gorals)
(Schaller and Rabinowitz, 1995). Genetic analysis (based on mitochondrial
DNA and rRNA genes) by Hassanin and Douzery (1999) appears to have set the
debate to rest: Pseudoryx is strongly nested within the subfamily
Bovinae. While these authors suggest that the saola should be
placed within the tribe Bovini, the current consensus is to place
Pseudoryx in its own tribe - Pseudorygini (Hernandez-Fernandez and Vrba,
2005).
General Characteristics
Few measurements of the saola have been made in life. Weight is
approximately 100 kg, body length around 150 cm, and shoulder height between
80 and 90 cm. There does not appear to be any noticeable sexual dimorphism
(Schaller and Rabinowitz, 1995).
Reported measurements for saola (Pseudoryx nghetinhensis) |
| Source |
Adult Weight |
Head & Body Length |
Shoulder Height
|
Tail Length |
| Dung et al., 1993 |
est. 100 kg |
~150 cm |
~80-90 cm |
13 cm + tassle |
| Robichaud, 1998 |
est. 85 kg 
(n=1) |
150 cm
(n=1) |
84 cm
(n=1) |
23 cm
(n=1) |
The general color of the saola is a deep chestnut brown, with individuals
varying from a rich reddish brown to almost black (Dung et al., 1993;
Schaller and Rabinowitz, 1995). The hair on the upper parts is
short (1.5-2.5 cm long), fine, and glossy, being shortest on the head and
neck (Dung et al., 1993; Robichaud, 1998). Considering
the cool, damp weather in at least part of its range, the coat of the saola
is surprisingly soft and thin (Robichaud, 1998). The underparts are
also brown, but are paler than the upper body, and are covered in fluffy,
almost wooly hairs about 3.5 cm in length (Dung et al., 1993; Robichaud,
1998). The anal area and inner flanks (including the scrotal skin
of males) is white (Dung et al., 1993). The same pale coloration
of the underparts is seen on the neck (beginning from the shoulders), and
this appears as a conspicuous patch when seen from the side (Robichaud, 1998).
There is no dorsal crest, but a thin (0.5 cm wide) black stripe runs
along the spine from between the shoulders to the top of the tail, where
it fades out (Dung et al., 1993; Robichaud, 1998). A white
horizontal stripe runs across the rump, including the tail in its relaxed
position against the rump (Dung et al., 1993; Robichaud, 1998).
This white stripe splits the tail into three bands of color - brown
above, white in the middle, and black towards the fluffy terminal tassle
(Dung et al., 1993; Robichaud, 1998). The legs are darker than
the main body, accented by two white spots above the hooves which are separated
by a fine band of black (Dung et al., 1993; Schaller and Rabinowitz,
1995).
The form of the saola is similar to that of other forest-dwelling ungulates,
such as duikers, with a compact neck and body with a hunched back adapted
for moving through dense cover (Schaller and Rabinowitz, 1995). As
a result, the shoulders sit low in comparison to the arch of the spine -
an adult female examined by Robichaud (1998) had a shoulder height of 84
cm but a height of 96 cm at the tallest part of the back. The skin
is 1-2 mm thick over most of the body, but thickens significantly (to around
5 mm thick) on the nape of the neck (Schaller and Rabinowitz, 1995).
Schaller and Rabinowitz suggest this thick skin, which extends to between
the shoulders, may act as a shield to protect saola from being punctured
by a rival's horn during intraspecific conflict (Schaller and Rabinowitz,
1995). There are no known glands on the legs (Robichaud, 1998). The
dark grey hooves are approximately 6 cm in length and have rounded tips,
resembling those of the lowland anoa (Bubalus
depressicornis) (Schaller and Rabinowitz, 1995). The dew claws
are vestigial calluses (Dung et al., 1993). Females have four
mammae (Robichaud, 1998).
The head is described by Schaller and Rabinowitz (1995) as being "delicately
shaped", with a narrow muzzle and distinctly arched nasal bones which give
the appearance of an almost bulging face (Dung et al., 1993; Schaller
and Rabinowitz, 1995). The ears are relatively small (each being about
10 cm long), are brown behind and whitish inside, and are covered with short
hair except for a long tuft on the inside (Dung et al., 1993). The
eyes have dark brown irises and round pupils, and in a flashlight beam they
reflect a glowing orange (Robichaud, 1998). The rhinarium (naked
flesh of the nose) is dark brown (Robichaud, 1998). The tongue is unusually
long, and can extend up to 16 cm to reach the eyes and upper face (Robichaud,
1998). The lips are white, as is the underside of the chin and
upper throat (Robichaud, 1998). On the underside of the muzzle is a
cluster of whiskers about 2 cm long (Robichaud, 1998). The faces of
both males and females are distinctly marked with white to buff patches,
the most distinctive of which is a long, thin stripe above each eye ("eyebrow")
(Dung et al., 1993). A variable pattern of spots and slashes
runs from beneath the eye to under the jaw, while a single white spot may
be present on the cheek (Dung et al., 1993). On close
examination, Robichaud (1998) found each white cheek mark to conceal dermal
nodules, measuring 1 or 2 mm high, which were found nowhere else on
the face (Robichaud, 1998). Black whiskers 2.0-2.5 cm long protrude
from most of these nodules, and the presence of a single pore on the top
of most of the nodules indicate that they may have a secretory function
(Robichaud, 1998)
The maxillary glands, located just in front of the eye, are extremely well
developed (Dung et al., 1993; Dung et al., 1994). Indeed,
Robichaud (1998) suggests that the saola may have the largest
maxillary-preorbital gland of any extant mammalian species. The fleshy
external part of the gland comprises a rectangular, shallow depression along
the upper muzzle measuring approximately 9 cm long by 3.5 cm wide by 1.5
cm deep (Robichaud, 1998). This gland secretes a thick, grayish-green
paste with a foul, pungent odor reminiscent of the musk of mustelids (Robichaud,
1998). Covering this depression is a muscular flap 0.8 cm thick, which
can be raised like an awning to expose the gland (Robichaud, 1998). This
unusual flap of skin has been misinterpreted in the common media, with the
result that the saola is sometimes referred to as an antelope with "gills".
The horns of the saola, being the most frequently encountered evidence of
this species, have received much attention with respect to description. In
adults, the two horns are long, slender, and nearly straight, with a slight
curve backwards (Dung et al., 1993; Schaller and Rabinowitz, 1995).
The horns are swept backwards following the profile of the face, and
rest on the back if the head is tilted upwards (Dung et al., 1994).
They range from nearly parallel to moderately diverging - villagers
have even reported one individual with crossed horn tips - but there does
not appear to be a significant difference in divergence between males and
females as initially reported by Dung et al. (1993) (Schaller and
Rabinowitz, 1995). In cross-section, the horns are round to ovoid,
with neither the horn cores nor the outer sheaths presenting a keel (Dung
et al., 1993; Schaller and Rabinowitz, 1995; Robichaud, 1998). For
the majority of their length, the horns are smooth, although corrugations
(annual rings) are often found within a few centimeters of the base (7 cm
according to Dung et al., 1993; 2-4 cm from Schaller and Rabinowitz,
1995). The lateral and medial surfaces of horns of many individuals
are rough and pitted, and it has been suggested that the smoothness of the
horn sheath is the result of animals sharpening their horns by rubbing them
against small trees (Dung et al., 1994; Robichaud, 1998). The
horn cores extend close to the horn tips (over 80% of the horn length in
both specimens measured by Schaller and Rabinowitz, 1995), and suggest that
they serve a real fighting purpose, possibly as defence against predators
(Dung et al., 1993; Dung et al., 1994).
The horns of most adults of both sexes are 35-50 cm long, with the longest
reported set having a maximum length of 52 cm (Schaller and Rabinowitz, 1995).
In Laos, eight sets of adult horns examined by Schaller and Rabinowitz
(1995) had a length of 36.2-50.4 cm, averaging 44.2 cm. Eighteen sets
of horns measured by Dung et al. (1993) varied in length from 32-52
cm, with an average of 41 cm. Due to the difference in horn divergence
among individuals, the width between the horn tips shows considerable variation.
Dung et al. (1993) reported horn tip distances of 7.5-20 cm, with
an average of 13.3 cm (n=17), while skulls examined by Schaller and Rabinowitz
(1995) measured between 3.5 and 18.4 cm between the horn tips (average
9.6 cm, n=7). The living female observed by Robichaud (1998) did not
follow this trend - the distance between the tips of her horns was 25 cm.
The basal circumference shows much less plasticity among individuals,
ranging from 10.8 to 13.0 cm (average 11.7 cm, n=8) (Schaller and Rabinowitz,
1995).
Ontogeny and Reproduction
A surprising amount of information on the reproductive cycle of P.
nghetinhensis has been gathered and inferred, giving its newness to science
and the remoteness of its range. Most of the data is from a single
pregnant female observed in life by Robichaud (1995), who was found to be
carrying a male fetus upon her death in January 1996. Based on its
size (38 cm from nose to rump along the contour of the spine) and weight
(800-1,000 grams), the fetus was estimated to be in its second trimester.
By inferring a 33 week gestation length from similarly sized spiral-horned
antelope (the nyala Tragelaphus angasii and sitatunga Tragelaphus
spekii), Robichaud (1998) estimated that the fetus would have been conceived
between late August and mid-November (the mid-rainy to early dry season in
Viet Nam). Likewise, the birth would be expected to occur between mid-April
and late June (the late dry season to mid wet season), an estimate which
is supported by observations made by Schaller and Rabinowitz (1995).
Based on horn length variation among animals within the same cohort, Schaller
and Rabinowitz (1995) suggested that the birthing season spreads over 2 to
3 months. .All of the data collected to date suggests that the saola is a
seasonal breeder, with births timed to coincide with the onset of the monsoon
(Robichaud, 1998). No estimate of life expectancy is available, but
the adult female examined by Robichaud (1998) was estimated to be between
8 or 9 years old.
Ecology and Behavior
Pseudoryx nghetinhensis inhabits a wide variety of habitats in the
Annamite mountains. At higher elevations (with peaks up to 2,000
m), the forests are dominated by conifers, notably Fokenia hodgsoni
(Dung et al., 1993). As altitude declines, rich lowland forests
comprised of mixed-broadleaf, evergreen trees take over, often dominated
by the dipterocarp Hopea mollissima (Dung et al., 1993).
Dung et al. (1993) report that the saola uses all forest levels
in differing seasons, even entering secondary lowland forests along large
rivers with an altitude of only 200 m (Dung et al., 1994). These
authors suggest that these seasonal movements are dependent on water, in
that the saola inhabits high hills during the summer months when highland
streams have plenty of water, but retreats to lower elevations in the winter
when the same streams dry up. Most hunted specimens have been taken
in winter, when saola are in more accessible lowland terrain (Dung et
al., 1994). Even so, most sightings made by locals occur in steep
- but not precipitous - hills, with vegetation strata including a closed
canopy of evergreen broad-leaved trees and an understorey with saplings,
bamboo, and palms (Schaller and Rabinowitz, 1995). While typically
encountered in primary forest, the saola may also frequent secondary forest
(Schaller and Rabinowitz, 1995). Pseudoryx is reportedly
very shy, and never enters agricultural lands (Dung et al., 1994)
P. nghetinhensis appears to be a solitary species based on reports
collected from locals by Schaller and Rabinowitz (1995). Adult pairs
(male and female) are known, but most pairs appear to be a female with her
most recent young (Schaller and Rabinowitz, 1995). Dung et al.
(1994) reported that the saola travels in small groups of two or three
animals, rarely as large as six or seven (Dung et al., 1994).
The captive individual studied by Robichaud (1998) is the source of the majority
of behavioral data on this species. Except where noted, all following
data comes from this paper. The captive saola was primarily diurnal,
or diurnal and crepuscular, although the author noted a potential bias due
to day-time human activity. Nonetheless, this individual fed at most
times during the day and only rarely at night, and was observed to rest her
chin on the ground with eyes closed most frequently during the hours of darkness.
Interviews with Laotian locals indicate that this species is most active
during the morning, late afternoon, and at night, but not when the sun is
overhead. While resting, the forelegs are tucked under the body as
seen in other members of the tribe Bovini.
The observed female spent a significant amount of time grooming with
her tongue, the main function of which was to disperse gathering flies.
The eyes and face were licked most, followed by the flanks, shoulders,
and forelegs. Licking of the muzzle was also observed after feeding,
drinking, and ruminating. Scent-marking was observed five times; in
each instance the flap of the facial gland was raised and the inner portion
of the flap touched to protruding rocks around the enclosure. The only
known vocalization is a soft, monotone bleat, around one second in duration.
The postures utilized for urination and defecation were very similar,
both of which involved squatting with the rear legs spread wide and the rump
low to the ground. This squatting posture was sometimes held for 0.5-3
minutes before and after passing urine or feces (as is typical of bovids,
passing of urine and feces were performed separately). Fecal deposits
were composed of boluses (around eight deposited per episode), each measuring
about 7.5 cm long by 4.5-6.0 cm in diameter. In turn, each bolus was
formed of smaller ovoid pellets (each about 1 cm by 2 cm by 0.75 cm - one
bolus examined contained 46 pellets).
Pseudoryx is surprisingly tame in the presence of humans - an observation
made from captive individuals as well as local reports observations (Robichaud,
1998). While neither obstinate nor excitable with people, dogs provoke
a strong reaction. In the presence of canines, Robichaud (1998) observed
the captive female to face the threat, arching her back by bringing her four
feet together and bowing her head such that the tips of her horns pointed
towards the dog (Robichaud, 1998). While posturing as such, the maxillary
glands were flared, accompanied by snorting. When chased by dogs in
the wild, saola are said to run to the nearest stream, making a similar stand
with the sharp tips of the horns facing the dogs (Schaller and Rabinowitz,
1995). Predators of the saola potentially include leopard
(Panthera pardus) and tiger (Panthera tigris), while the
above-described defensive stance is similar to that used by other ungulates
in the region when preyed upon by dhole (Cuon alpinus) (Dung et
al., 1994; Schaller and Rabinowitz, 1995).
Villagers' reports suggest P. nghetinhensis feeds on the leaves of
fig trees and other riverside bushes, an observation supported by the relatively
short incisors, which suggest a browsing diet (Dung et al., 1994).
This species is a rather delicate feeder - the captive female observed
by Robichaud (1998) rarely jerked or pulled on vegetation while feeding,
but rather chewed the petioles to separate the leaves from the stem before
chewing the leaves themselves. This saola only occasionally pulled
leaves into mouth using her tongue, a surprising observation given its length
and mobility. This captive individual was fed Homalomena sp.
(Araceae) (local reports suggest that the saola is quite fond of the medicinal
herb Homalomena aromatica (Dung et al., 1994)),
Asplenium sp. (Aspleniaceae), and an unidentified broad-leaved plant
of the family Sterculiaceae, all of which are reported to be part of the
diet in the wild (Robichaud, 1998). Boluses of fresh dung were eaten
on one observed occasion, and rumination occurred most frequently in the
morning (Robichaud, 1998). Observations of the drinking habits of the
saola suggest that they can consumed large quantities of water at one time
- in one 4 minute span, the captive female observed by Robichaud (1998) took
nearly 60 draughts of water, pausing only five times to lick her nose and
muzzle.
Distribution
The saola is found in the forests along the Annamite mountain range on the
border between Viet Nam and the Lao People's Democratic Republic. Most
records of occurrence are from south of the Song Ca river in Viet Nam, although
a population to the north has also been found (Dung et al., 1994;
Kemp et al., 1997). In all, the total known range of the saola
encompasses only 4,000 square kilometers (Dung et al., 1994).
Countries: Lao People's Democratic Republic, Viet Nam (IUCN, 2004).
Range Map (Localities redrawn from Kemp et al., 1997)
Conservation Status
P. nghetinhensis is classified as endangered (Criteria: C1+2a(i))
by the IUCN (2004), and has been listed on CITES Appendix I since November
1994 (Editor's note in Schaller and Rabinowitz, 1995; CITES, 2003). "A
few hundred" individuals are estimated to survive in both Viet Nam and Laos,
but counts are difficult due to the remoteness and ruggedness of the
terrain (Schaller and Rabinowitz, 1995). The saola is severely
threatened by habitat destruction, with the forests within their range being
cleared by timber extraction practices and for small-scale agricultural use.
The creation of roads for logging trucks not only increases the among
of lumber which can be exported, but also fragments the remaining forest
patches and make these animals more accessible to hunters (IUCN, 2004). In
addition to eating the meat, villagers may use the facial glands of the saola
for medicinal purposes (Dung et al., 1994)
Of the 13 known saola which were captured and kept in captivity, none survived
longer than five months. In light of this, the Ministry of Forestry
in Viet Nam issued a ban on further capture, trade, or holding of saola,
and ordered that no financial compensation be paid to anyone found in possession
of a saola (Robichaud, 1998).
Remarks
The saola is generally considered to be the greatest animal discovery in
recent times, and is so different from any currently known species that a
separate genus was constructed for it. The first record of this species
came to the western world in the form of three sets of horns discovered in
1992 in the Vu Quang Nature Reserve, from which the saola takes its alternate
common name, the Vu Quang ox (Schaller and Rabinowitz, 1995). Very
few saola have been studied alive, and much of our present knowledge comes
from native villagers' tales and skeletons.
The common name "saola" [rhyming with "now, ha", and sometimes spelled "sao
la"] is a native Vietnamese name meaning "spindle horn" or "spinning-wheel
posts", referring to the long, straight horns characteristic of this species
(Robichaud, 1998). On a similar thread, the genus name Pseudoryx
comes from the Greek word pseudes, meaning false, and the genus
Oryx, whose members (the oryxes) have extremely long, straight,
rapier-like horns. The species name
nghetinhensis describes the range of this new species: Nghe
an and Ha tinh are two Vietnamese provinces (bordering on Laos)
in the core of the saola's range, with -ensis (Latin) being a suffix
meaning "belonging to" (Dung et al., 1993).
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Local names
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Sao La [Nghe An province, "spindle horn"] (Dung et al., 1994)
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Sun Duong [Ha Tinh province, "mountain goat"] (Dung et al.,
1994)
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Yang [Laotian locals] (Schaller and Rabinowitz, 1995)
-
-
French
-
Saola (IUCN, 2004)
-
-
German
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Vu Quang-Wildrindes (Nadler and Phuong, 1994)
-
-
Spanish
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Saola (IUCN, 2004)
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Literature
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