One should be ever mindful...while the guardians do not exhibit enlarged posterior teeth (rearfangs) they do possess the Duvernoys gland....
An appropriate re-naming of this forum....& a gift from the past....
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Posted by: regalringneck at Sun Feb 9 16:32:46 2003 [ Report Abuse ] [ Email Message ]
Greetings all, time to accept the change & start posting again...
The Duvernoys gland seems to be as much a cauldron for toxicity as the other venom glands. Necropsys I've done on ophidian prey from Diadophis (ringneck), Hypsiglena (nite), Clelia (musurrana), Trimorphodon (lyre), all indicate widespread hemolytic action with as little as 5-8 min. chewing. I would avoid a deep bite from all. Remember 2 well known herpetologists have been lost to colubrid bites!
Cheers & beers; jg
From my archived files; a timeless RFF masterpiece...
Re: A small note, Wolfgang.. More..
Posted by Matthew Scruggs on November 26, 1999 at 12:38:36:
In Reply to: Re: I want the truth on this matter. posted by Wolfgang Wuster on November 26, 1999 at 03:22:17:
Wolfgang,
I've heard rumors of one Thamnophis bite serious enough to require brief (overnight?) hospitalization, but cannot confirm. However, given the kinship with asian keelbacks, I'm looking at T. sirtalis with a hint of respect.
Also, Ernst & Zug (not sure if that's right) inicate Diadophis has marked at least one mild reaction in humans, however, efforts to track this down have also been futile to date..
Cheers & happy holidays.
Genera of rearfanged and nonvenomous snakes
known to produce "toxic" saliva
Ahaetulla - Asian (vine snakes)
Alsophis - South American and West Indian ("racers"
Amplorhinus - Africa
Boiga - Cat snakes, mangrove snakes, brown tree snake, etc.
Cerberus - Asia (dog-faced water snake)
Clelia - South America
Coluber - Asia, Europe (racers)*
Coniophanes - Central and South America
Conophis - Central and South America
Crotaphopeltis - Subsaharan Africa
Dendrelaphis - Australasian (vine snakes)
Diadophis - North American (ringneck snakes)
Dipsadoboa - Africa
Dispholidus - Subsaharan Africa (boomslangs)
Dryadophis
Elapomorphus - South America
Enhydris - Australasian (water snake)
Erythrolamprus - South America
Heterodon - North American (hognose snakes)
Homoroselaps - South Africa
Hydrodynastes - South American (false water cobras)
Hypsiglena - North America (night snake)
Langaha - Madagascar (leaf-nosed snakes)
Leioheterodon - Madagascar (hognose snakes)
Leptodeira - South America (cat-eye snake)
Leptophis - South America (vine snakes)
Macrelaps - South Africa
Madagascarophis - Madagascar
Malpolon - Europe and Asia (montpellier snakes)
Oxybelis - South America (vine snakes)
Philodryas - South America (whipsnakes)
Pliocercus - South America (false coral snakes)
Psammophis - Africa and Asia (sand or grass snakes)
Psammophylax - Africa
Rhabdophis - Asia (keelback snake, yamakagashi)
Stegonotus - Australia
Stenorrhina - South America
Tachymenis - South America
Telescopus - Africa and Asia
Thamnophis - North and South America (garter snakes)
Thelotornis - Africa (bird snakes, twig snakes)
Trimorphodon - North and Central America (lyre snakes)
Xenodon
Possible, but unconfirmed:
Spalerosophis - Africa, Mid-East, Asia
*Keep in mind - I have never heard of a report of envenomation by North American racers. Most likely, Minton is referring to Asian or European species which are now considered to be in their own genera by herpetologists.
These are from Sherman Minton (1996), and other papers I've come across.
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: I will give these a shot:
: : Q: Is a snake with a mildly toxic saliva the same thing as mildly venomous?
: In rear-fanged snakes, it is not the saliva that is toxic. Many colubrids (a large number, in fact) have a special gland called Duvernoy's gland, which secretes venom. Although this probably evolved from a modified salivary gland, snakes with a Duvernoy's gland do have "normal", unmodified salivary glands as well. The saliva routinely present in the snake's mouth is not venomous, only the secretion from Duvernoy's gland.
: : Q: Is there any truth to what I heard about the mildly venomous and rear fanged members of Thamnophis?
: All Natricines, including Thamnophis, have Duvernoy's gland. There have been a few cases of people developing mild localised envenomation after prolonged Thamnophis bites.
: : Q: What is the comparison of the venom/toxic saliva to that of Heterodon, Boiaga, and hyspeglena?
: Not sure about the direct toxicity. In snakes with Duvernoy's gland, the main factor determining the danger to man is the ability to actually get the venom into a person, and the quantity available. Some colubrids have very potent Duvernoy's gland secretions (on a par with various elapids or vipers), but they secrete so little, or have such difficulty actually injecting it, that they are, to all intents and purposes, harmless. I have never heard of anyone getting a non-trivial Hypsiglena bite. Heterodon and Thamnophis seem to be on a par, whereas at least some Boiga (esp. B. irregularis) are capable of causing more serious envenomation.
: : Q: What is the comaprison of the Rear Fang/enlarged Teeth to that of Heterodon?
: Not sure what you mean - are you referring to Thamnophis?
: : Q: Have there been any recorded fatalities that have occured from Thamnophis bites?
: No. All bites have been mild, with local swelling and pain.
: : Q: does the venom vary from Thamnophis species to species?
: Not really known. Recorded symptomatic bites have been from T. sirtalis and T. elegans.
: : II.
: : It was also brought to my attention that members of the Diadophis genus were also Rearfanged and venomous. It was also brought to my attention that they are starting to think that Diadophis is forming a kinship with Micrurus. I have never heard anything before this that would support this. This part II. of this post is in Q & A format as well for ease of answering.
: : Q; Is there truth behind what I heard about Diadophis being containing venom/mildly toxic saliva and rear fangs/enlarged teeth?
: That is correct, but they are nevertheless harmless to humans.
: : Q: Can sombody tell me if there is any truth behind what I heard abbout Diadophis forming a kinship with Micrurus?
: What kind of kinship???? They certainly do not hybridise, or anything like that. The only documented relationship between Micrurus and Diadophis that I can think of is a predator-prey relationship!
: : Q: If it is forming a kinship would that involve in the change of the venom components?
: : Q: Would this change in toxic components involve nerotoxic venom?
: : Q: What is the comparison of the current venom/mildly toxic saliva of Diadophis to that of Heterodon, Boiaga, Thamnophis (If Thamnophis falls under this category), and hyspeglena?
: I have never heard of a symptomatic Diadophis bite, so this genus would appear to be harmless.
: Hope this helps.
: Cheers,
: Wolfgang
