Frank
Wall entered the Indian Medical Service in 1893 and spent most of the next 33
years as a British Medical Officer in the Indian Empire, being stationed in
Ceylon, Burma, and peninsular India. In the First World War he joined an expeditionary
force in Iraq and also served in France. Wall was interested in all aspects of snakes,
and he wrote about 215 titles between 1898 and 1928. As he traveled, he
obtained specimens from others, sometimes paying local people small sums
for specimens, encouraging them to collect. In 1907, Wall described Natrix baileyi on the basis of two specimens he
obtained from Lieutenant F. M. Bailey. The only locality data Wall provided in
the original description was that the snakes came from Tibet and were collected at about 14,000 feet elevation. The
specimens were given to the British Museum of Natural History, with a note
saying they came from “above Gyantze, at 14,000 feet altitude.” Wall
reported that the specimens were found "in the sides of a hot spring, and are
never found as far as half a mile distant… they are reported not to enter the
water, and can be obtained in winter and summer alike." One female (903
mm) contained six eggs. Edward
Malnate moved Natrix baileyi to the new
genus Thermophis when he examined the
snake’s anatomy and found it quite distinct from other snakes in the genus Natrix. Guo et al. (2008) described a
second species of Thermophis, T. zhaoermii. Both species are
endemic to the Qinghai-Xizang Plateau, with Thermophis
baileyi on western side of Mt. Hengduan, while T. zhaoermii inhabits its eastern side. Both species occur at
relatively high elevations (about 4350 m). Thus, Thermophis may reach the highest altitude of any snakes and undoubtedly holds the altitude record for Asian snakes.
Huang
et al. (2009) conducted a phylogenetic analysis to identify the closest related
living relative of the Hot Spring snakes using mitochondrial DNA sequences from
eight specimens, together with sequences from 95 additional caenophidian and
five henophidian genera that were obtained from GenBank. Results showed the
hot-spring snakes, species adapted to high, cold environments, clustered in the
monophyletic, New World Xenodontinae (now in the family Dipsadidae). Their data
failed to provide any evidence that the New World xenodontines diverged from Thermophis
and dispersed into the New World, and also failed to suggest a colonization of
Asia by New World xenodontines by dispersal from the New World. But perhaps more importantly than shedding light on the ancient relationships of this snake, Huang et al. (2009) also showed the divergence of the
two species in Thermophis was caused by the barrier formed by the
Hengduan Mountains, and that speciation had almost occurred when Tibetan
Plateau attained present elevation.
Using both mtDNA and a nuclear gene, He
et al. (2009) suggested again that Thermophis does appear to be a
member of the Western Hemisphere Xenodontinae, And their molecular data
also indicate a large genetic distance between T. baileyi and T.
zhaoermii, which strengthened the validity of the recently described, T.
zhaoermii. In a more recent paper, He et al. (2010) used the complete mitochondrial genome sequence
of the Sichuan hot-spring keel-back (Thermophis zhaoermii), and recovered Thermophis as a Colubridae and the sister to the Colubrinae. In an early on-line view Pyron et al.
(2010) recovered Thermophis as the
sister taxon to the colubrid pseudoxenodontinae genera Plagiopholis and Pseudoxenodon,
(both South and Southeast Asian high elevation snakes, (being found up to 1300 m and 2000 m respectively - not nearly as high as Thermophis) and they consider Thermophis to be part of
Pseudoxenodontinae.Geographically, this is a much more satisfactory relationship.
What
is missing here is the natural history of Thermophis.
We think it lays eggs - but might Wall have only seen un-shelled, ovarian or oviducal eggs? Its diet, habitat use, and thermal ecology are unknown.
Wall's comment that it can be found year round (at at 14,000 ft - more than 4000 m) and that it never wanders far from hot springs is tantalizing. Is Thermophis able to survive the cold temperatures of winter at high altitudes
because of the geothermal energy in its environment? Could the two species of Thermophis be the first
known snakes to rely not on solar power, but on geothermal energy, for regulating body temperature?
This is not as farfetched as it may
seem. Recently Loval et al. (2010) described an aquatic moss (Fontinalis)
colony closely associated with vent emissions at the bottom of Yellowstone Lake
that considerably exceeded known temperature maxima for this plant. The moss
was colonized by animals, including crustaceans (Hyalella and Gammarus), a segmented worm in the Lumbriculidae
family, and a flatworm tentatively identified as Polycelis. The
presence of these invertebrates suggest a highly localized food chain derived
from the presence of geothermal energy and that support significant
biodiversity.
Literature
Guo, P., S.-Y. Liu, J.-C. Feng, M. He. 2008. The
description of a new species of Thermophis (Serpentes: Colubridae). Sichuan
Journal of Zoology, 27(3). [In Chinese, English summary].
He, M., J.- C.
Feng; S.-Y. Liu, P. Guo, E. Zhao. 2009. The
phylogenetic position of Thermophis (Serpentes: Colubridae), an endemic
snake from the Qinghai-Xizang Plateau, China. Journal of Natural History, 43:479-488.
He, M., J. Feng, and E. Zhao.
2010. The complete
mitochondrial genome of the Sichuan hot-spring keel-back (Thermophis
zhaoermii; Serpentes: Colubridae) and a mitogenomic phylogeny of the
snakes. Mitochondrial DNA 21:8-18. (I have only seen the abstract of this paper).
Huang, S. S. Liu, P. Guo, Y.
Zhang and E. Zhao. 2009. What are the closest relatives of the hot-spring
snakes (Colubridae, Thermophis), the relict species endemic to the
Tibetan Plateau? Molecular Phylogenetics and Evolution, 51(3):438-446.
Lovalo, D., S. R. Clingenpeel,
S. McGinnis, R. E. Macur, J. D. Varley, W. P. Inskeep, J. Glime, K. Nealson,
and T. R. McDermott. 2010. A geothermal-linked biological oasis in Yellowstone
Lake, Yellowstone National Park, Wyoming. Geobiology,
8:327–336.
Malnate, E. 1953.The
Taxonomic Status of the Tibetan Colubrid Snake Natrix baileyi, Copeia (2):92-96.
Pyron, A. R.,
F. T. Burbrink, G. R. Colli, A. N. Montes de Oca,
L. J. Vitt, C. A. Kuczynski and J. J. Wiens.
2010. The phylogeny of advanced snakes
(Colubroidea), with discovery of a new subfamily and comparison of support
methods for likelihood trees. Molecular Phylogenetics and
Evolution, In Press, doi:10.1016/j.ympev.2010.11.006.
Wall, F. 1907. Some new Asian
snakes. Journal of the Bombay Natural
History Society 17(3):
612-618.
Zhao, E. 2008. Hot-Spring Snakes, The Snakes
Endemic to Qinghai-Xizang Plateau. Journal
of the Central University for Nationalities (Natural Sciences) [in Chinese, abstract in English].