| Philodryas olfersii | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Serpentes |
| Family: | Colubridae |
| Genus: | Philodryas |
| Species: | P. olfersii |
| Binomial name | |
| Philodryas olfersii (Lichtenstein, 1823) | |
| Synonyms [2] | |
| |
Philodryas olfersii is a species of venomous snake in the family Colubridae. The species is endemic to South America.
Common names for P. olfersii include Lichtenstein's green racer, [3] [4] South American green racer, [5] and eastern green whiptail, [6] [7]
The specific name, olfersii, is in honor of German naturalist Ignaz von Olfers. [8]
P. olfersii is native to southern South America, including northern Argentina, Brazil, Bolivia, and northwestern Paraguay. [3]
P. olfersii reaches 1 to 1.5 meters (about 40 to 60 inches) in maximum total length (including tail). [4]
Dorsally, it is green in color; [9] ventrally, it is yellowish. [2]
The dorsal scales are smooth, without apical pits, and are arranged in 19 rows at midbody. [2]
P. olfersii can be found in many habitat types, including the Cerrado, Caatinga, forest, forest transition, [10] and restinga. [11] It has been found at altitudes from sea level to 1,700 m (5,600 ft). [1]
The species P. olfersii is often arboreal, [7] but it also forages on the ground. [6] It is diurnal, [7] though it has been observed mating late in the evening. [12]
Prey items of P. olfersii include small rodents, lizards, amphibians, and birds, [1] [7] especially nestlings. [6] They will also eat other snakes, including ones almost as large as themselves. [13]
P. olfersii is oviparous. [1] [3] Each egg measures about 5 centimeters (about 2 inches). [7] The clutch size is 4 to 11 eggs, with larger females producing more eggs than smaller ones. [14]
P. olfersii is a venomous snake, and there have been reports of serious bites causing local and systemic effects requiring medical treatment. [15] The venom of P. olfersii is highly hemorrhagic, fibrinogenolytic, edematic, and has proteolytic activity 208% higher than Bothrops jararaca , in addition to containing neurotoxic properties. In mice, doses such as 5.6 μg / 20g resulted in neurotoxic effects, which included dyspnea, equilibrium alterations, posterior limbs paralysis, flaccid paralysis, and relaxation of the urinary sphincter. In laboratory mice, the venom of this species has an LD50 of 2.79 ± 0.58 mg / kg (intraperitoneal), equivalent to the lethality of Bothrops asper . However, due to the anatomy of their inoculating teeth located in the posterior region of the maxilla, these snakes have difficulty in inoculating venom, sometimes giving a "dry" bite. [16] [17] [18] The most common symptoms are pain, swelling, erythema, and ecchymosis. [19] There may be a pulsing sensation or numbness at the bite site. Some pus can develop and nearby lymph nodes may enlarge. Bruising or other discoloration can appear quite a distance from the wound site, sometimes occurring far up the arm after a hand wound, [15] even progressing to the neck, chest, [10] and abdomen. [5] Stiffness may affect the entire limb. [9] Patients complaining of snakebite may be given an antivenom for Bothrops snake venom, which is inappropriate for the treatment of Philodryas bites. [15] [20] Philodryas does not cause the coagulopathy that Bothrops does. [10] Only one fatality has been reported, and that in a child. [4]
The secretion that causes death to prey (or injury to bite victims) is produced in the snake's Duvernoy's gland at the rear of the mouth, and ”chewed” into its prey via a grooved tooth; this unique method of envenomation takes considerably more physical effort, from the snake, than it would with a more lethally venomous species (such as vipers, cobras, mambas, etc.). The majority of other venomous snakes will deliver one, swift bite of venom (via two frontal fangs, shaped like needles) before retreating and waiting for the venom to take effect on their prey in question. In the same way, a rear-fanged snake is less likely to bite a human, because it doesn’t view such a large potential predator as prey, and therefore is less inclined to exert the needed force to envenomate—this does not mean they will NOT bite, it is simply less common in rear-fanged snakes than other, more lethal, species. Nevertheless, their venom is myotoxic, causing muscle damage; muscle tissue hemorrhages and becomes necrotic. [20] The secretion contains toxins such as serine proteases, metalloproteases, C-type lectins, cysteine-rich secretory proteins, and a C-type natriuretic peptide. [21] Since Philodryas olfersii has difficulty in inoculating venom and produces small amounts of venom, accidents by this species are generally not serious, having a protein content of only 932 micrograms, and generally, 75 to 90% of the venom is composed of proteins. More recently, there was a severe case for this species, in which the victim let the snake bite for a long time, allowing it to inject a significant amount of venom. The symptoms started with a lot of swelling and bruises. The accident at first was not taken seriously as bites by Philodryas aren't serious in general. At the beginning, the victim only had pain and swelling. However, over time, the pain intensified, and the victim reported that she was in severe pain from the fingertip to the chest. Examinations showed that the venom caused clotting problems, affected liver enzymes and 50% of the liver. Swelling in the two arms was severe, with risk of thrombosis, and fasciotomy or even amputation was almost necessary. [22] [23] [24]
P. olfersii is host to a newly described species of parasitic protozoan, Caryospora olfersii . This snake has also been recorded carrying C. braziliensis . [11]
Some sources do not recognize any subspecies of P. olfersii. [13] [25] However, other sources recognize the following three subspecies, including the nominotypical subspecies: [9] [3] [26]
Colubridae is a family of snakes. With 249 genera, it is the largest snake family. The earliest fossil species of the family date back to the Late Eocene epoch, with earlier origins suspected. Colubrid snakes are found on every continent except Antarctica.
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The boomslang is a highly venomous snake in the family Colubridae. The species is native to Sub-Saharan Africa.
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Philodryas is a genus of colubrid snakes endemic to South America, commonly called green snakes.
Boiga dendrophila, commonly called the mangrove snake or the gold-ringed cat snake, is a species of rear-fanged venomous snake in the family Colubridae. The species is endemic to southeast Asia. It is one of the biggest cat snake species, averaging 8–9 feet in length. It is considered mildly venomous. Although moderate envenomations resulting in intense swelling have been reported, there has never been a confirmed fatality.
Rhabdophis subminiatus, commonly called the red-necked keelback or red-necked keelback snake, is a species of venomous snake in the subfamily Natricinae of the family Colubridae. The species is endemic to Asia.
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Venomous snakes are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow or grooved fangs, although some venomous snakes lack well-developed fangs. Common venomous snakes include the families Elapidae, Viperidae, Atractaspididae, and some of the Colubridae. The toxicity of venom is mainly indicated by murine LD50, while multiple factors are considered to judge the potential danger to humans. Other important factors for risk assessment include the likelihood that a snake will bite, the quantity of venom delivered with the bite, the efficiency of the delivery mechanism, and the location of a bite on the body of the victim. Snake venom may have both neurotoxic and hemotoxic properties. There are about 600 venomous snake species in the world.
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.
Bothrops insularis, commonly known as the golden lancehead, is a highly venomous pit viper species found exclusively on the Ilha da Queimada Grande, off the coast of São Paulo state, in Brazil. The species is named for the light yellowish-brown color of its underside and for its head shape that is characteristic of the genus Bothrops. No subspecies of Bothrops insularis are currently recognized. It is one of the most venomous snakes in Latin America.
The twig snakes, also commonly known as bird snakes or vine snakes, are a genus of rear-fanged venomous snakes in the family Colubridae. The genus is native to Africa. All species in the genus have a slender and elongated profile, a long tail, a narrow head and a pointed snout. The eye of all species has a horizontal pupil, shaped like a keyhole, which gives twig snakes binocular vision. Twig snakes are greyish-brown with faint light and dark markings. When threatened, they inflate the throat to display bold black markings between the scales. Twig snake bites are potentially deadly: the venom is hemotoxic, affecting the blood clotting mechanism and causing uncontrolled bleeding and internal hemorrhaging. Bites by twig snakes have caused death in humans; famous herpetologist Robert Mertens died after being bitten by his pet savanna vine snake. However, envenomed bites are extremely rare when not handling the snake, as the fangs can't breach the skin except in a few places like the web between the thumb and fingers.
Tachymenis is a genus of venomous snakes belonging to the family Colubridae. Species in the genus Tachymenis are commonly known as slender snakes or short-tailed snakes and are primarily found in southern South America. Tachymenis are rear-fanged (opisthoglyphous) and are capable of producing a medically significant bite, with at least one species, T. peruviana, responsible for human fatalities.
Most snakebites are caused by non-venomous snakes. Of the roughly 3,700 known species of snake found worldwide, only 15% are considered dangerous to humans. Snakes are found on every continent except Antarctica. There are two major families of venomous snakes, Elapidae and Viperidae. 325 species in 61 genera are recognized in the family Elapidae and 224 species in 22 genera are recognized in the family Viperidae, In addition, the most diverse and widely distributed snake family, the colubrids, has approximately 700 venomous species, but only five genera—boomslangs, twig snakes, keelback snakes, green snakes, and slender snakes—have caused human fatalities.
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Philodryas patagoniensis, also known as the Patagonia green racer, is a species of rear-fanged (opisthoglyphous) venomous snake in the family Colubridae. The species is endemic to cis-Andean South America from northern Argentina to northeastern Brazil; despite its name, most of its range is outside Patagonia.
Philodryas nattereri, the Paraguay green racer, is a species of venomous snake, endemic to South America.
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