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Xenophidion schaeferi From Das 2010, painted by Szabolcs Kókay |
Collection locations of the only specimens of Xenophidion acanthognathus (red) and Xenophidion schaeferi (green) |
Almost a year later, at 10:00 PM on November 5th, 1988, German amateur herpetologist Christian Schäfer collected and photographed a snake at the edge of a trail near Templer Park, about 12 miles north of Kuala Lumpur in peninsular Malaysia. Schäfer donated his specimen to the Zoological Museum in Berlin in the spring of 1993. Curators Rainer Günther and Ulrich Manthey recognized it as unique and asked esteemed herpetologists Van Wallach and Bob Inger to compare it to specimens at Harvard and Chicago. Inger recognized similarity between Schäfer's specimen and his own, and sent both specimens back to Berlin to be described as new species. The dissimilarity between the two new specimens and all other known snakes was so great that they chose to establish a new genus, which they tentatively placed into the family Colubridae (which at the time was much more inclusive). The genus was elevated into a new family after the dissection of the X. acanthognathus specimen by Wallach and Günther in 1998 failed to reveal an obvious affinity with any existing family.
Drawing and photograph of the jaw spine of X. schaeferi (labeled 'Pp') From Günther & Manthey 1995 |
The only photograph of a living Xenophidion schaeferi (FMNH 235170), taken by W. Grossmann. From Günther & Manthey 1995 |
Ventral view of the sole specimen of Xenophidion acanthognathus (ZMB 50534) From Günther & Manthey 1995 |
Snake family tree from Figueroa et al. 2016, showing Xenophidiidae + Bolyeriidae as sister to Caenophidia Click for a larger version |
UPDATE: Additional specimens have since been discovered in Malaysia, Sumatra, and Borneo including at least one male, bringing the total number of individuals known to six, potentially representing three species if the Sumatra specimen proves to be distinct. Some photos of one of the new specimens here.
1 The IUCN page for Xenophidion acanthognathus mentions a second specimen from Kinabalu, but I couldn't find any other references to this specimen. Instead, the IUCN references page pointed me, through a couple of intermediates, to a paper (published before the discovery of Xenophidion) that included a reference to the type specimen of Stoliczkia borneensis, which was collected on Mount Kinabalu. Since Stoliczkia borneensis is in the family Xenodermidae, I suspect there may have been some confusion around the somewhat similar family names. VertNet lists only the single Sipitang specimen of X. acanthognathus, as does Wallach et al.'s 2014 edition of Snakes of the World. Both species of Xenophidion are listed as Data Deficient by the IUCN. ↩
ACKNOWLEDGMENTS
REFERENCES
Thanks to Szabolcs Kókay, who painted the only color image of Xenophidion for A Field Guide to the Reptiles of South-east Asia.
REFERENCES
Chan-ard, T., Grossmann, W., Gumprecht, A. & Schulz, K.D. 1999. Amphibians and reptiles of Peninsular Malaysia and Thailand: an illustrated checklist. Bushmaster Publishing, Wuerselen, 240 pp. <link>
Das, I. 2010. A field guide to the reptiles of South-East Asia. New Holland Publishers, London, 376 pp. <link>
Das, I. 2012. A naturalist’s guide to the snakes of South-East Asia. John Beaufoy Publishing, Oxford, 176 pp. <excerpt/link>
Figueroa, A., A. D. McKelvy, L. L. Grismer, C. D. Bell, and S. P. Lailvaux. 2016. A species-level phylogeny of extant snakes with description of a new colubrid subfamily and genus. PLoS ONE 11:e0161070 <link>
Günther, R. & U. Manthey. 1995. Xenophidion, a new genus with two new
species of snakes from Malaysia (Serpentes, Colubridae). Amphibia-Reptilia 16:229-240 <link>
Lawson, R., J. B. Slowinski & F. T. Burbrink. 2004. A molecular approach to discerning the phylogenetic placement of the
enigmatic snake Xenophidion schaeferi
among the Alethinophidia. Journal of
Zoology 263:285-294 <link>
Pyron, R. A., F. Burbrink, and J. J. Wiens. 2013. A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC Evolutionary Biology 13:93 <link>
Wallach, V. & R. Günther. 1998. Visceral anatomy
of the Malaysian snake genus Xenophidion,
including a cladistic analysis and allocation to a new family (Serpentes:
Xenophidiidae). Amphibia-Reptilia 19:385-405 <link>
Wallach, V. W., Kenneth J. and J. Boundy. 2014. Snakes of the World: A Catalogue of Living and Extinct Species. CRC Press, Boca Raton, Florida, USA <link/sample>
Wallach, V. W., Kenneth J. and J. Boundy. 2014. Snakes of the World: A Catalogue of Living and Extinct Species. CRC Press, Boca Raton, Florida, USA <link/sample>
Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Once the information about the divided maxilla has been 'officially' published and properly documented, I can't see any obstacle to referring Xenophidion to Bolyeriidae. It doesn't change any of the facts about the desperate lack of knowledge of natural distribution, ecology, behaviour and morphology of any of these species, but those are things common to all four species anyway (Casarea a bit less so).
ReplyDeleteIndeed. It would be nice to get some time-calibrated estimates of divergence times between Xenophidion and Casarea, although whether you combine them into one family or leave them as two is really more a matter of philosophy.
ReplyDeleteNice post. I'd never made the connection between the Bolyeriid maxillary joint and skink specialization. This is a nice functional parallel to the flexible frontoparietal joint seen in the Lialis (pygopodid) skull, also a skink specialist!
ReplyDeleteThanks Dan! I didn't know about Lialis. Here's the link to the Casarea article:
ReplyDeletehttp://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1989.tb02512.x/full
Hinged teeth is another cool convergent adaptation for this same purpose, shared by at least three lineages of snakes:
http://science.sciencemag.org/content/212/4492/346
Very cool - thanks for the refs. In fact, I had forgotten entirely about hinged teeth in snakes, but Lialis also shares this. http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1986.tb01513.x/abstract
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ReplyDeleteHi Kurt, yes, I'd like to! Are your images of the 2018 animal on Flickr?
ReplyDeleteYes, just search on my Flickr steam and you'll find them!
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