Pseudoxenodontinae Explained

Pseudoxenodontinae is a small subfamily of colubroid snakes, sometimes referred to as a family (Pseudoxenodontidae). They are found in southern and southeastern Asia, from northeast India to southern China (including Taiwan) and south into Indonesia as far east as Wallace's Line. There are 10 species in 2 genera.^[1] Most are very poorly known, such that Pseudoxenodontinae is one of the most poorly known groups of snakes.^[2]

Pseudoxenodontine snakes are small to medium-sized egg-laying^[1] snakes. Shared features of the hemipenes between Pseudoxenodon and Plagiopholis first described in 1987,^[3] were later backed up by evidence from DNA in the early-2010s.

There are many differences between the two genera. Pseudoxenodon seem to be found along streams in wet forests,^{[2] [4]} whereas Plagiopholis are apparently found in grasses, bushes, and riprap. Pseudoxenodon eat frogs and lizards and Plagiopholis eat earthworms.^[5] Plagiopholis (20 to 40 cm total length^[5]) are smaller than Pseudoxenodon (50 to 170 cm in total length^[6]). At least two species of Pseudoxenodon (P. bambusicola and P. macrops) have impressive threat displays, including flashing boldly banded ventral patterning and bright yellow coloration, spreading a hood, and playing dead.^{[6] [7]} Plagiopholis have no enlarged teeth,^[8] but Pseudoxenodon have the two posterior-most maxillary teeth enlarged.^[6] No bites to humans are known.^{[9] [10]}

In spite of these differences, several studies have placed these two genera in a group together at or near the base of either Dipsadinae or Dipsadinae + Natricinae,^{[11] [12] [13]} whereas one study suggested that at least Pseudoxenodon is nested within Dipsadidae and represents a reverse west-to-east colonization across the Bering Land Bridge, from South America to Asia.^[14]

Genera

• Plagiopholis Boulenger, 1893, 4 species of mountain snakes
• Pseudoxenodon Boulenger, 1890, 6 species of bamboo snakes, also sometimes called false cobras

Notes and References

1. Web site: Uetz. Peter. Pseudoxenodontinae. The Reptile Database. 15 May 2018.
2. Rahadian. R.. Das. I.. A new record of Pseudoxenodon inornatus (Boie In: Boie, 1827) from Gunung Gedeh National Park, West Java, Indonesia (Squamata: Pseudoxenodontidae). Hamadryad. 2012. 36. 174–177.
3. Book: McDowell. S. B.. Seigel. R. A.. Collina. J. T.. Novak. S. S.. Systematics in Snakes: Ecology and Evolutionary Biology. 1987. Macmillan Publishing Company. New York.
4. Stuart. B. L.. Heatwole. H.. Country records of snakes from Laos. Hamadruas. 2008. 33. 97–106.
5. Zhong. G. H.. Chen. W. D.. Liu. Q.. Zhu. F.. Peng. P.. Guo. P.. Valid or not? Yunnan mountain snake Plagiopholis unipostocularis (Serpentes: Colubridae: Pseudoxenodontinae). Zootaxa. 2015. 4020. 2. 390–396. 10.11646/zootaxa.4020.2.9. 26624106.
6. Book: Das. I.. A Field Guide to the Reptiles of South-east Asia. 2010. Bloomsbury. London. 376.
7. Bhosale. H. S.. Thite. V.. Death feigning behavior in Large-eyed False Cobra Pseudoxenodon macrops (Blyth, 1854) (Squamata: Colubridae). Russian Journal of Herpetology. 2013. 20. 190–192.
8. Inger. R. F.. Marx. H.. The systematics and evolution of the Oriental colubrid snakes of the genus Calamaria. Fieldiana Zoology. 1965. 49. 1–304.
9. Book: Weinstein. S. A.. Warrell. D. A.. White. J.. Keyler. D. E.. Venomous bites from non-venomous snakes: A critical analysis of risk and management of "colubrid" snake bites. 2011. Elsevier. London.
10. Weinstein. S. A.. White. J.. Keyler. D. E.. Warrell. D. A.. Non-front-fanged colubroid snakes: A current evidence-based analysis of medical significance. Toxicon. 2013. 69. 103–113. 10.1016/j.toxicon.2013.02.003. 23462380.
11. Pyron, R. Alexander. 2011. The phylogeny of advanced snakes (Colubroidea), with discovery of a new subfamily and comparison of support methods for likelihood trees. Molecular Phylogenetics and Evolution . 58 . 2. 329–342. https://web.archive.org/web/20131003095528/http://200.46.218.171/bds-cbc/sites/default/files/Pyron_et_al_2011.pdf. 3 October 2013. dead. etal. 10.1016/j.ympev.2010.11.006. 21074626.
12. Figueroa. A.. McKelvy. A. D.. Grismer. L. L.. Bell. C. D.. Lailvaux. S. P.. A species-level phylogeny of extant snakes with description of a new colubrid subfamily and genus. PLOS ONE. 2016. 11. 9. e0161070. 10.1371/journal.pone.0161070. 27603205. 5014348. 2016PLoSO..1161070F. free.
13. Zheng. Y. Wiens. JJ. Combining phylogenomic and supermatrix approaches, and a time-calibrated phylogeny for squamate reptiles (lizards and snakes) based on 52 genes and 4162 species. Molecular Phylogenetics and Evolution. 2016. 94. Pt B. 537–547. 10.1016/j.ympev.2015.10.009. 26475614.
14. Zhang. B.. Huang. S.. Relationship of Old World Pseudoxenodon and New World Dipsadinae, with comments on underestimation of species diversity of Chinese Pseudoxenodon. Asian Herpetological Research. 2013. 4. 3. 155–165. 10.3724/SP.J.1245.2013.00155.