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Monday, April 30, 2012

Dwarf pipesnakes


The only photograph of Anomochilus monticola and
when I wrote this article, the only photo of any anomochilid
Photograph by Indraniel Das
Republished from Lillywhite 2014
A contest to be the most enigmatic snake would be like a contest to be the least well-known president serving between Jackson and Lincoln (seriously, name even one). But the dwarf pipesnakes (Anomochilidae) make even vice president Elbridge Gerry look like Marilyn Monroe by comparison.

Ok, not literally
It's hard to overstate how obscure anomochilids are. A paper published in 2007 using morphological and molecular data to examine the phylogeny of snakes was unable to incorporate the anomochilids because no molecular data on these snakes were available. This seems unbelievable in a day and age when it takes only a day and $1000 to sequence an entire human coding genome. Of course, it isn't inadequacies of technology that have kept the genes of anomochilids from us - it's lack of anomochilids, specifically fresh anomochilid tissue samples. In all museums in all the world, the Anomochilidae are represented by fewer than 15 specimens. Bigfoot has been seen more times than that.

But never collected
The first anomochilid was collected by Max Weber in Sumatra and described  in 1890 by Theodorus Willem van Lithe de Jeude, a curator of the Leiden Museum in the Netherlands (not to be confused with Erland of the same name, of Running Man fame). It was named Anomalochilus weberi after its collector, who also edited the volume in which its description was published, and it was one of only three snakes illustrated therein, out of 50 species covered. The spelling of the genus was changed from Anomalochilus to Anomochilus by Berg in 1901, because the former was already in use for a beetle.

Anomochilus weberi on the left (1, 2, & 3); on the right (4, 5, & 6) is Asthenodipsas malaccana, a pareatid 

The second anomochilid specimen was collected in 1915 by Edward Jacobson, also in Sumatra, and again described by van Lithe de Jeude in a 1922 paper in the journal Zoologische Mededelingen. He assigned it to the same species as the first, A. weberi. These two Sumatran specimens, together with one from Borneo, are all that we know of Anomochilus weberi.

Anomochilus weberi line drawing from de Rooij's 1917 book
The Reptiles of the Indo-Australian Archipelago
The second species of anomochilid wasn't discovered until 1940, when its description was published by Malcolm Smith of the British Museum in the Annals and Magazine of Natural History, the same journal in which Alfred Russel Wallace's 1855 paper "On the Law which has Regulated the Introduction of New Species" pre-empted Darwin's theory by four years. Smith named this species Anomochilus leonardi, again after its collector, G.R. Leonard, who may be the only person ever to have collected two anomochilidsIt is today known from five specimens collected in peninsular Malaysia (including the first, or holotype, and second, or paratype, specimens), and one from the Sabah province of northern Borneo. The Sabah specimen was collected by Raymond Goh in 1981, but sat undescribed in the Sabah Museum until 1993.

Figure from Smith 1940
Fast forward to 2002, when a snake collected in 1993 in northern Borneo was described in a book by Rudolf Malkmus and colleagues called Amphibians and Reptiles of Mount Kinabalu (North Borneo). The authors of the book called the snake Cylindrophis ruffus, which is a pipesnake in the family Cylindrophiidae. Although their book included photos of C. ruffus, the snake they described was in fact a third species of anomochilid, which was re-described in 2008 by Indraneil Das and colleagues. They named it Anomochilus monticola, because it was found in a mountainous area, and published the only photos of a living anomochilid known (above, in black and white). Based on the three specimens they had, they noted that A. monticola was far larger than either A. weberi or A. leonardi, and that it also differed in scalation and pattern. Their paper includes a nice history of anomochild discoveries, after which I have based most of this article.

Skull of Anomochilus leonardi imaged using high-resolution X-ray computed tomography
From Digimorph.org

One group of intrepid researchers, led by David Gower at the Natural History Museum in London, recently tried to extract DNA from three Anomochilus leonardi, with mixed success. Two of these were preserved over 50 years prior, and no genes could be recovered from their tissues. From one specimen collected in 2003, partial sequences of 12S and 16S rRNA mitochondrial genes were amplified, for a total of 221 informative sites. In their trees, Anomochilus leonardi formed a clade with Cylindrophis maculatus, rendering the latter's family, Cylindrophiidae, paraphyletic. However, this conclusion is based on limited data, and this study was done before the discovery of A. monticola, from which fresh tissue could presumably be obtained.

As early as 1890, van Lithe de Jeude noticed the similarities and differences between Anomochilus and other basal alethinophidians. He remarked that it was similar to Anilius scytale, a primitive snake from the Amazon rain forest, in that both lacked a mental groove (a structure on the chin that allows the lower jaw to open widely), but that the scalation of the head was more similar to Cylindrophis than Anilius. Respectively, Anilius, Anomochilus, and Cylindrophis are known as the red, dwarf, and Asian pipesnakes, and they were once treated as a single family together with shield-tailed (uropeltid) and sunbeam snakes (look out for future articles!), though today these are all separated into different families. In outward appearance, all of these snakes are have glossy scales, a result of their scale microornamentation, and a pattern of yellow or white spots with a red tail band against a dark ground color. They have blunt tails and few specialized head scales, with mostly undifferentiated ventral scales. These basal lineages have much to teach us about snake evolution, if we can find enough of them to learn from!

Scanning electron microscope photograph of ventral scale
microornamentation of Anomochilus leonardi: BMNH 1946.1.17.4

Despite all the mystery, we do know some intriguing things about anomochilids. Like some basal snakes, but unlike many, Anomochilus has pelvic girdle vestiges. However, it does possess vestiges of pectoral girdle muscle, unusual among snakes, none of which have any vestige of a pectoral girdle bone. In addition, Anomochilus is unique in having lost the left lung entirely, a structure which is vestigial, but still present, in most other snakes. Like other basal snakes, Anomochilus has only a few teeth - 3 in each upper jaw and 5 in each lower jaw. What they eat is a matter of pure speculation, as are most details about how they reproduce (one female specimen contained four eggs, so we know that they are probably all oviparous, with small clutch sizes). Most of these basal alethinophidians eat elongate vertebrates, such as caecilians, amphisbaenians, and other snakes, because they do not have sufficiently flexible skulls to consume the very large prey items eaten by the macrostomate snakes (boas, pythons, and caenophidians).

ACKNOWLEDGMENTS

I would like to thank exactly no photographers, because apparently no one has ever taken a picture of these things, except for Das et al., who thoughtfully published photos of the type specimen of Anomochilus monticola in 2008.

Update, 11 September 2014: Konrad Mebert recently made me aware of a second color photograph of an anomochilid, posted by a mountain biker in Kuala Lumpur on Project NOAH. What a remarkable find!

Anomochilus leonardi
Photo by ImranKz
Update 4 February 2015: I just learned of some relatively new photos of A. leonardi taken in Selangor, Malaysia, by Hock Ping Guek (Kurt/orionmystery). Check out the link for some awesome photos of pareatids, flyingsnakes, and a ton of other awesome southeast Asian snakes.

Anomochilus leonardi photos by Kurt/Orionmystery
Left: close-up of tail; Center: close-up of head with tongue extended; Right: whole snake
REFERENCES

Cundall D, Rossman DA (1993) Cephalic anatomy of the rare Indonesian snake Anomochilus weberi. Zoological Journal of the Linnean Society 109:235-273

Cundall D, Wallach V, Rossman DA (1993) The systematic relationships of the snake genus Anomochilus. Zoological Journal of the Linnean Society 109:275-299

Das I, Lakim M, Lim KKP, Hui TH (2008) New species of Anomochilus from Borneo (Squamata: Anomochilidae). Journal of Herpetology 42:584-591

de Rooij N (1917) The Reptiles of the Indo-Australian Archipelago. Il. Ophidia. E. J. Brill, Leiden. 334 pp. <link>

Gower D, Vidal N, Spinks J, McCarthy C (2005) The phylogenetic position of Anomochilidae (Reptilia: Serpentes): first evidence from DNA sequences. Journal of Zoological Systematics and Evolutionary Research 43:315-320

Greene HW (1997) Snakes: The Evolution of Mystery in Nature. University of California Press, Berkeley
<this is the single best book on snakes available - if you don't own it, shame on you>

Lee MSY, Hugall AF, Lawson R, Scanlon JD (2007) Phylogeny of snakes (Serpentes): combining morphological and molecular data in likelihood, Bayesian and parsimony analyses. Systematics and Biodiversity 5:371-389

Malkmus R, Manthey U, Vogel G, Hoffmann P, Kosuch J (2002) Amphibians and Reptiles of Mount Kinabalu (North Borneo). Gantner Verlag, Rugell. 424 pp. <link>

Smith MA (1940) A new snake of the genus Anomochilus from the Malay Peninsula. Annals and Magazine of Natural History, Series 11 6:447-449 <link>

Stuebing RB, Goh R (1993) A new record of Leonard's pipe snake, Anomochilus leonardi Smith (Serpentes: Uropeltidae: Cylindrophinae) from Sabah, northwestern Borneo. Raffles Bulletin of Zoology 42:311-314

Tsuihiji T, Kearney M, Rieppel O (2006) First report of a pectoral girdle muscle in snakes, with comments on the snake cervico-dorsal boundary. Copeia 2006:206-215

van Lidth de Jeude TW (1890) Reptilia from the Malay Archipelago. II. Ophidia. In: Weber M (ed) Zoologische Ergebnisse einer Reise in Niederlandischost-Indien, vol 1. E. J. Brill, Leiden, The Netherlands, pp 178-192; PL XV-XVI <link>

van Lidth de Jeude TW (1922) Snakes from Sumatra. Zoologische Mededelingen 6:239-253 <link>

Yaakob N (2003) A record of Anomochilus leonardi Smith, 1940 (Anomochilidae) from Peninsular Malaysia. Hamadryad 27:285-286

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Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

2 comments:

Connedro said...

Very much enjoying your blog - I hope you'll keep it up.

Kind regards

Conners

Andrew Durso said...

Thanks! I'll do my best...