Green bush viper
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Green bush viper ( Atheris squamigera ) |
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| Atheris squamigera | ||||||||||||
| ( Hallowell , 1856) |
The Green Buschviper ( Atheris squamigera ), also Rankschuppige Buschviper , is a kind of tree adapted to the life atheris ( Atheris ) within the vipers (Viperidae). This species has the largest range of all Atheris species and is distributed over a large part of Central Africa. Despite its established name, the snake, which is only around 50 cm long, can have a wide range of colors. The species is nocturnal and feeds mainly on small mammals.
features
The green bush viper is probably the largest species of bush vipers with a maximum body length of around 80 cm. The average body length is around 45 to 50 cm, with the females usually being larger than the males. In a study of a population in Nigeria , the longest male found was 67.0 cm and the longest female was 70.5 cm long.
The basic color of the species is very variable and can also be regionally different (strong polymorphism ). The back usually shows a shade of green that ranges from very light green to rich dark green. There are also blue-green, bluish, olive-green and much less often yellow, reddish and gray individuals. There are populations in which only one color occurs, and others in which several color variants are even present within one litter.
The individual scales are strongly keeled, with the keel often being lighter than the scale itself. Lighter scales also create bright transverse or angular bands, the latter being particularly pronounced on the tail. In total, a full-grown snake has around 30 transverse ligaments and 10 to 20 angular ligaments on the tail, which are more or less clearly recognizable. The spaces between the scales are black in color, which is especially visible when the skin on the back is stretched. The belly side and the underside of the tail are light to dark green or yellowish and can be evenly colored or have very strong black speckles. The throat can be colored yellow and at the tail end the underside is ivory colored; this color extends over about 10 subcaudalia . At the transition from the back to the abdomen, there are pairs of bright spots. Young snakes are dark olive green with wavy lighter stripes that are darker edged. Their ventral side is lighter olive green. The animals get the adult color after about three to four months.
The head is broadly triangular and flat with a mouth that can be opened very wide. It is clearly set apart from the slender body and covered with keeled scales like roof tiles. There are 7 to 9 interorbitalia between the eyes and 10 to 18 circumorbitalia are located around the eye . There are two scales between the nasal and the eye rims. The rostral on the front of the head cannot be seen from above and the small scales above the rostral are flanked by very large scales on both sides. The nostrils are on the side. The rim of the mouth is formed by 9 to 12 supra- and just as many sublabials . Between the circumorbitalia and the supralabialia there are one or two (rarely more) rows of scales. The underside of the head has 2 to 3 chin shields and the keeled gularia .
In the females 15 to 23 and in the males 11 to 17 rows of scales of strongly keeled scales lie around the middle of the body. The ventral side is formed by 152 to 175 ventralia and the tail has 45 to 67 under-tail shields ( Subcaudalia ). The average number of body scales may vary depending on the habitat or population; thus representatives of the southern forests have an average of 17 rows of body scales, 171 ventralia and 52 subcaudalia, while individuals of the northern steppe areas have an average of 21 rows of body scales, 168 ventralia and 58 subcaudalia.
distribution and habitat
The green bush viper has a range that encompasses large parts of sub-Saharan Africa . It extends from Ghana in the west via Nigeria , Cameroon and the Democratic Republic of the Congo in the east to Uganda and western Kenya and in the southwest to Angola . Two male individuals were also found in the Rumanyina Game Reserve in Karagwe Province in Tanzania . They represent the only evidence for Tanzania and are only a few kilometers away from the Mpororo swamp, in which the black- green bush viper ( A. nitschei ) lives.
As with all species of this tree-living genus, the habitat of the green bush viper mainly includes forest areas in the tropics. Accordingly, the habitat consists mainly of rainforest , but the snake can also be found in lighter forest areas and even in adjacent savannas. In primary forests the species is strongly arboricolous , in lighter areas it lives in bushes and also in tall grass. In Nigeria it was found in secondary forest areas in both drier and flooded areas.
Way of life
The green bush viper is primarily nocturnal and stays in the upper tree layers during the day to allow the sun to warm itself up. It is particularly active in high humidity, especially during the rainy seasons. She is very alert and aroused quickly when disturbed. In this case it will remain still or, if the disturbance persists, it will fall through the leaves. When directly harassed by potential predators, it also bites hard.
nutrition
The green bush viper feeds primarily on small mammals such as mice . Species of the genera Dendroma , Mastomys and Leggado were verified . Adult animals, especially males, also prey on small birds, while young animals also hunt for cold-blooded animals such as lizards and smaller snakes. Young animals also eat more regularly than adult snakes.
The snake hunts by hanging from a branch in wait for rodents and other prey passing in the layer of foliage below. In this posture, she also absorbs water, which condenses on her hanging body and flows down to her head.
Reproduction and development
The green bush viper mates mainly in the very humid months of the year; a mating season in Uganda has been described in October to November. Mating rituals and details of mating are not known.
The snake is ovoviviparous , the young are born after 6 to 7 months of gestation. The females give birth to 5 to 7 young snakes in one litter, whereby different color variants can occur in one litter. After observations in the terrarium, the juvenile snakes sometimes accept small frogs as food; no such observations from the field exist.
Taxonomy
The first description of the green bush viper was made by the herpetologist Edward Hallowell in 1856 and the name Echis squamigera . Peters 1864 and Boulenger 1896 placed the species in the genus Atheris established in 1862 by Edward Drinker Cope .
Systematics
Within the real vipers (Viperinae), the green bush viper is classified as a species within the genus of bush vipers ( Atheris ). The genus Atheris today contains 8 to 12 recognized species, depending on the observer.
The Green bush viper is both based on morphological studies, evaluations of plasma albumin, as well as by DNA tests as a sister species of Rauschuppen-bush viper ( A. hispida viewed), whereby a common ancestry of the two Atheris is TYPES probably strongly keeled scales :
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Internal system
Various subspecies have been described within the species. Of these, only the nominate form A. s. squamigera and A. s. robustus considered valid. The some time as a separate species A. laeviceps considered atheris with yellowish-green color from the central Congo and also still frequently as a separate species considered A. anisolepsis be than today Synonyms considered Buschviper to nominate the Greens.
The subspecies A. s. robustus is described as somewhat more massive in body shape and differs from the nominate form due to the scaling of the head and body. It is only known from the rainforest area of Ituri Province , Democratic Republic of the Congo .
Snake venom
The venom of the green bush viper acts very quickly on small mammals , which make up the majority of the snake's prey. A lethal dose LD 50 of 11 μg has been documented for mice with an average weight of 16 to 18 g . However, more detailed investigations into the composition, the amounts of poison and the toxic effects have not yet been described. As with all viper poisons, however, phospholipases are a central component.
Like most viper poisons, the poison of the green bush viper is primarily hemotoxic and accordingly primarily destroys cells of the blood and the tissues surrounding them with various proteases . The most effective components of the poison also include proteins that suppress blood clotting and thus together with the tissue-destroying components cause internal bleeding. In addition to these, there are also neurotoxic components that act on the victim's nervous system and cause paralysis and other symptoms.
The green bush viper is generally considered to be of little danger to humans, especially since encounters between it and the arboreal snake are very rare. The venom itself is also usually considered to be relatively harmless, mainly due to the small amounts that these small snakes inject with one bite. However, there are a number of documented bite accidents with more severe effects and at least one reported death from the snake's venom.
supporting documents
Evidence cited
The information available in the text is essentially taken from the monograph Mallow et al. 2003, which is listed in the literature, and the following sources are also cited:
- ↑ a b c d e f Lawson & Ustach 2000, Mallows et al. 2003.
- ↑ a b c d e f g Mallows et al. 2003.
- ↑ a b c d Luiselli et al. 2000.
- ↑ ITIS only distinguishes 8 types, Mallow and others list 12 types
- ↑ H.-W. Herrmann, U. Joger: Evolution of viperine snakes. Symp zool. Soc. London 70, 1997, pp. 43-61.
- ↑ P. Lenk, S. Kalayabina, M. Wink, U. Joger: Evolutionary relationships among the true vipers (Reptilia: Viperidae) inferred from mitochondrial DNA sequences. In: Molecular Phylogenetics and Evolution. 19, 2001, pp. 94-104. ( Full text PDF )
- ↑ S. Spawls, B. Branch: The Dangerous Snakes of Africa . Ralph Curtis Books, Sanibel Island, FL 1995, ISBN 0-88359-029-8 .
literature
- H.-W. Herrmann, U. Joger: Evolution of viperine snakes. In: Symp zool. Soc. London. 70, 1997, pp. 43-61.
- Dwight P. Lawson, Paul C. Ustach: A Redescription of Atheris squamigera (Serpentes: Viperidae) with Comments on the Validity of Atheris anisolepis . In: Journal of Herpetology. 35 (3), 2000, pp. 386-389.
- P. Lenk, S. Kalayabina, M. Wink, U. Joger: Evolutionary relationships among the true vipers (Reptilia: Viperidae) inferred from mitochondrial DNA sequences. In: Molecular Phylogenetics and Evolution. 19, 2001, pp. 94-104.
- Luca Luiselli, Francesco M. Angelici, Godfrey C. Akani: Arboreal habits and viper biology in the African rainforest: the ecology of Atheris squamiger. In: Israel Journal of Zoology. Volume 46, 4/2000, pp. 273-286.
- David Mallow, David Ludwig, Göran Nilson: True Vipers. Natural History and Toxinology of Old World Vipers. Krieger Publishing Company, Malabar, Florida 2003, ISBN 0-89464-877-2 , pp. 53-56.
