Rhabdophis

Rhabdophis
Rhabdophis subminiatus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Subfamily: Natricinae
Genus: Rhabdophis
Fitzinger, 1843
Species

30, see text.

Rhabdophis is a genus of snakes in the subfamily Natricinae of the family Colubridae. Species in the genus Rhabdophis are generally called keelback snakes, and are found primarily in Southeast Asia. The best-known species is Rhabdophis tigrinus; few other species have been studied in detail.

Toxicity

Colubrid snakes are often thought of as completely harmless, but there are a handful of notable exceptions, including some species of Rhabdophis. Bites from both Rhabdophis tigrinus and Rhabdophis subminiatus have caused cases of severe envenomation.[1][2][3][4] There are several reports of fatal bites from R. tigrinus.[5][6] Between 1971 and 2020, 5 of 43 R. tigrinus bites in Japan were fatal,[7] all of which occurred in cases not treated with antivenom. Antivenom is manufactured by the Japan Snake Institute [8] and is an effective treatment for R. tigrinus bites,[9][10] but is an unapproved drug. The venom is highly hemorrhagic.[11][12]

While the term "poisonous snake" is often incorrectly used for a wide variety of venomous snakes, some species of Rhabdophis are in fact poisonous as well as venomous. Many species of Rhabdophis have specialized nuchal glands on the back of the neck [13] that are used to store cardiotonic steroids (bufadienolides) sequestered from their diet,[14] mostly from toads but also from firefly larvae.[15] Rhabdophis are resistant to the toxic effects of these chemicals.[16] This is different from their venom, which is produced in oral glands and is not known to contain bufadienolides or other sequestered toxins. Female Rhabdophis tigrinus can pass sequestered chemicals to their offspring, both by deposition in egg yolk and by transfer across the egg membranes within the oviduct, late in gestation.[17]

Recent taxonomic changes

In 2018, Balanophis ceylonensis and three of the four species in the genus Macropisthodon were reassigned to Rhabdophis on the basis of three genes indicating a common ancestor for all species possessing nuchal glands.[18] At least two species, “R”. conspicillatus and “R”. chrysargos, are more distantly related and might be assigned to other genera in the future. The same analysis suggested that Rhabdophis might contain several undescribed species.

Species

These species are recognized as being valid:[19]

Nota bene: A binomial authority in parentheses indicates that the species was originally described in a genus other than Rhabdophis.

References

  1. ^ Mittleman, M.; Goris, R. (1974). "Envenomation from the bite of the Japanese colubrid snake Rhabdophis tigrinus (Boie)". Herpetologica. 30: 113–119.
  2. ^ Smeets, R.; Melman, P.; Hoffmann, J.; Mulder, A. (1991). "Severe coagulopathy after a bite from a 'harmless' snake (Rhabdophis subminiatus)". Journal of Internal Medicine. 230: 351–354.
  3. ^ Hoffmann, J.; Vijgen, M.; Smeets, R.; Melman, P. (1992). "Haemostatic effects in vivo after snakebite by the red-necked keelback (Rhabdophis subminiatus)". Blood Coagulation & Fibrinolysis. 3: 461–464.
  4. ^ Sawai, Y.; Honma, M.; Kawamura, Y.; Saki, A.; Hatsuse, M. (2002). "Rhabdophis tigrinus in Japan: pathogenesis of envenomation and production of antivenom". Toxin Reviews. 21: 181–201.
  5. ^ Mittleman, M.; Goris, R. (1978). "Death caused by the bite of the Japanese colubrid snake Rhabdophis tigrinus (Boie)(Reptilia, Serpentes, Colubridae)". Journal of Herpetology. 12: 109–111.
  6. ^ Ogawa, H.; Sawai, Y. (1986). "Fatal bite by yamakagashi (Rhabdophis tigrinus)". The Snake. 18: 53–54.
  7. ^ Hifumi, T.; Sakai, A.; Yamamoto, A.; Morokuma, K.; Otani, N.; Takahashi, M.; Ato, M. (2022). "Rhabdophis tigrinus (yamakagashi) bites in Japan over the last 50 years: a retrospective survey". Frontiers in Public Health. 9: 775458.
  8. ^ "Anti-Yamakagashi Antivenom". MAVIN Poison Center Munich. Retrieved 22 December 2024.
  9. ^ Morokuma, K.; Kobori, N.; Fukuda, T.; Uchida, T.; Sakai, A.; Toriba, M.; Ohkuma, K.; Nakai, K.; Kurata, T.; Takahashi, M. (2011). "Experimental manufacture of equine antivenom againt yamakagashi (Rhabdophis tigrinus)". Japanese Journal of Infectious Diseases. 64 (5): 397–402.
  10. ^ Hifumi, T.; Sakai, A.; Yamamoto, A.; Murakawa, M.; Ato, M.; Shibayama, K.; Kato, H.; Koido, Y.; Inoue, J.; Abe, Y. (2014). "Effect of antivenom therapy of Rhabdophis tigrinus (yamakagashi snake) bites". Journal of Intensive Care. 2 (1): 44.
  11. ^ Zotz, R.B.; Mebs, D.; Hirche, H.; Paar, D. (1991). "Hemostatic changes due to the venom gland extract of the red-necked keelback snake (Rhabdophis subminiatus)". Toxicon. 29: 1501–1508.
  12. ^ Chowdhury, A.; Lewin, M.R.; Carter, R.W.; Casewell, N.R.; Fry, B.G. (2022). "Keel venom: Rhabdophis subminiatus (red-necked keelback) venom pathophysiologically affects diverse blood clotting pathways". Toxicon. 218: 19–24.
  13. ^ Mori, A.; Burghardt, G.M.; Savitzky, A.H.; Roberts, K.A.; Hutchinson, D.A.; Goris, R.C. (2012). "Nuchal glands: a novel defensive system in snakes". Chemoecology. 22: 187–198.
  14. ^ Hutchinson, D.; Mori, A.; Savitzky, A.H.; Burghardt, G.M.; Wu, X.; Meinwald, J.; Schroeder, F.C. (2007). "Dietary sequestration of defensive steroids in nuchal glands of the Asian snake Rhabdophis tigrinus". Proceedings of the National Academy of Sciences (USA). 104: 2265–2270.
  15. ^ Yoshida, T.; Ujiie, R.; Savitzky, A.H.; Jono, T.; Inoue, T.; Yoshinaga, N.; Aburaya, S.; Aoki, W.; Takeuchi, H.; Ding, L.; Chen, Q.; Cao, C.; Tsai, T.-S.; de Silva, A.; Mahaulpatha, D.; Nguyen, T.T.; Tang, Y.; Mori, N.; Mori, Anna (2020). "Dramatic dietary shift maintains sequestered toxins in chemically defended snakes". Proceedings of the National Academy of Sciences (USA). 117: 5964–5969.
  16. ^ Mohammadi, S.; Gompert, Z.; Gonzalez, J.; Takeuchi, H.; Mori, A.; Savitzky, A.H. (2016). "Toxin-resistant isoforms of Na+/K+-ATPase in snakes do not closely track dietary specialization on toads". Proceedings of the Royal Society B: Biological Sciences. 283: 20162111.
  17. ^ Hutchinson, D.A.; Savitzky, A.H.; Mori, A.; Meinwald, J.; Schroeder, F.C. (2008). "Maternal provisioning of sequestered defensive steroids by the Asian snake Rhabdophis tigrinus". Chemoecology. 18: 181–190.
  18. ^ Takeuchi, H.; Savitzky, A.H.; Ding, L.; de Silva, A.; Das, I.; Nguyen, T.T.; Tsai, T.-S.; Jono, T.; Zhu, G.-X.; Mahaulpatha, D.; Tang, Y.; Mori, A. (2018). "Evolution of nuchal glands, unusual defensive organs of Asian natricine snakes (Serpentes: Colubridae), inferred from a molecular phylogeny". Ecology & Evolution. 8: 10219–10232.
  19. ^ Genus Rhabdophis at The Reptile Database. www.reptile-database.org.
  20. ^ a b Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Rhabdophis barbouri, p. 16; R. swinhonis, p. 258).

Further reading

  • Fitzinger L (1843). Systema Reptilium, Fasciculus Primus, Amblyglossae. Vienna: Braumüller & Seidel. 106 pp. + indices. (Rhabdophis, new genus, p. 27). (in Latin).