Chaco lance viper
| Chaco lance viper | ||||||||||||
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Chaco lance viper ( Bothrops diporus ) |
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| Bothrops diporus | ||||||||||||
| Cope , 1862 |
The Chaco Pitviper ( Bothrops diporus ) is a snake from the subfamily of the pit vipers . It inhabits large parts of the central south of South America. The animals there colonize a wide range of moderately moist to dry habitats such as the Gran Chaco , moist palm-grassland, subtropical deciduous forests, araucaria forests and the pampas . Up until a few years ago, the species was placed in the so-called " Bothrops neuwiedi complex" and was only separated as a separate species from Bothrops neuwiedi in 2004 .
description
anatomy
The Chaco lance viper is a relatively small, quite slender American lance viper , the broad head, as with all species of the genus, is clearly separated from the neck. The animals usually have total lengths of 60 to 70 cm, up to a maximum of 110 cm.
Scaling
The species shows 5 to 11, mostly 8 keeled intersupraocularia . The number of supralabials is 6 to 11, usually 8, the number of infralabials 7 to 13, usually 11. The number of ventral scales ( ventral shields ) varies between 166 and 187 in males and 173 to 189 in females, the number of divided subcaudalia between 44 and 59 in males and 38 to 56 in females. The number of dorsal rows of scales in the middle of the body is between 20 and 29, usually 25.
coloring
The basic color of the top is medium to dark brown. The upper side of the trunk shows on both sides of the back 10 to 28, mostly 21, white-rimmed, dark brown to black, trapezoidal or nearly triangular drawings, the wide and downwardly open base of which points to the stomach. The points of the drawings can meet in the middle of the spine, so that the spine shows a very conspicuous X-mark, or they can be partially or completely offset from one another. Each of the two basal forms of these drawing elements are bordered by two oval or round spots that form a row of spots on the back. Occasionally a number of brown spots are also present on the border with the abdomen.
The ventral side is pale whitish and less spotted than in other species of the Bothrops-neuwiedi complex. It shows irregular gray spots that are sometimes connected to one another and then form horizontal stripes. In young animals the tail end is white.
The top of the head always shows more or less symmetrically arranged, dark points or spots, these are bordered white and neatly delimited. This usually includes a spot on the mouth between the canthalia , often a pair of spots or spots near the supraocularia and a pair of spots in the temporal region. In most individuals, the rearmost pair of spots on the top of the head is fused with one another in front and drawn out in stripes towards the neck. A noticeable dark brown stripe (postocular stripe) extends from the eye to the corner of the mouth. This strip can be limited at the bottom by a pale area. The area of the canthus is mostly pale light brown and undrawn. The supralabials are undrawn or have large dark spots that cover more than half of the supralabials. The largest of these spots is just below the eye. Occasionally, these spots cover all of the anterior supralabials so that they are dark anteriorly and light posteriorly. The iris is bronze or light gold in color. The tongue is pinkish gray.
Systematics
After the first description up to a few years ago, the species was regarded as one of the up to 12 recognized subspecies of Bothrops neuwiedi or as part of the " Bothrops neuwiedi complex" and only in 2004 by da Silva based on morphological characteristics as one of a total of 7 species separated from Bothrops neuwiedi .
distribution and habitat
The relatively large distribution area of the species extends over large parts of the central south of South America. It includes southwestern Brazil , southern Paraguay, and northern to central Argentina . The animals inhabit a wide range of moderately moist to dry habitats such as the Gran Chaco , moist palm-grassland, subtropical deciduous forests, araucaria forests and the pampas .
Way of life
Like almost all species of the genus, the species is largely nocturnal and lives mainly on the ground. In northern Argentina, seasonal activity is greatest in autumn and least in winter and early spring. So far, there is hardly any information on nutrition. In the stomachs of 11 individuals from northeast Argentina, which can probably be assigned to the Chaco lance viper, three species from the genus of the real whistling frogs ( Leptodactylus ) and indefinite rodents were found. Reproductive data are also scarce so far; 4 females captured in northeast Argentina contained 13, 19, 20 and 22 embryos.
Poison
The toxin mixtures of pit vipers are by far komplexesten natural poisons. They contain a mixture of enzymes , low molecular weight polypeptides , metal ions and other components whose function has so far hardly been understood. The effects of these poisons are correspondingly diverse. Like many other species of the Bothrops genus, the venom of the Chaco lance viper causes a whole range of symptoms, a distinction being made between local and the whole body ( systemic ) symptoms.
Local effects
Typical local symptoms are primarily severe pain, redness, and swelling that quickly spread to the entire bitten limb and the adjacent trunk, as well as small or large blisters that contain clear or blood- serous fluid. Often necroses develop , especially of the muscle tissue.
Systemic effects
The poison has a hemolytic effect (destroys red blood cells) and, through metalloproteinases, has a hemorrhagic effect (destroys blood vessels). The poison causes a change in the blood coagulation precursor fibrinogen through thrombin-like enzymes and thereby a pathological activation of blood coagulation . This leads to the rapid consumption of the coagulation factors via further steps and therefore has an anticoagulant effect . As a result, normal blood clotting is no longer possible. The syndrome is known as Disseminated Intravascular Coagulopathy (DIC). The patients bleed from the bite site, from unhealed scars, mosquito bites and oral mucous membranes and internal bleeding occurs.
Epidemiology
Since the species was only separated from the B. neuwiedi complex as a separate species in 2004, little information is available on the epidemiology . In Argentina, however, the species is by far the most medically relevant snake, of 500 bite accidents per year in the years 1960–1975, 80% were attributed to the Chaco lance viper. However, fatal poisoning appears to be relatively rare.
Danger
The species has a relatively large range and is sometimes common there; it is therefore not viewed as endangered by Campbell and Lamar. The Chaco lance viper is not listed by the IUCN .
swell
Individual evidence
- ^ Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London; 2004: p. 414.
- ↑ VX da Silva, MT Rodrigues: Taxonomic revision of the Bothrops neuwiedi complex (Serpentes, Viperidae) with description of a new species. Phyllomedusa 7 (1), 2008: pp. 45–90, here pp. 65–66
- ^ VX da Silva: The Bothrops Neuwiedi Complex. In: Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London; 2004: pp. 410-422
- ↑ VX da Silva, MT Rodrigues: Taxonomic revision of the Bothrops neuwiedi complex (Serpentes, Viperidae) with description of a new species. Phyllomedusa 7 (1), 2008: pp. 45-90
- ^ Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London; 2004: pp. 345-355.
- ^ David A. Warrell: Snakebites in Central and South America: Epidemiology, Clinical Features, and Clinical Management . In: Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London. 2004: pp. 709-761, here p. 746. ISBN 0-8014-4141-2
- ^ Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London; 2004: p. 347
literature
- Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London; 2004: Plates 640 and 641, pp. 345-355 and 413-415. ISBN 0-8014-4141-2
- VX da Silva, MT Rodrigues: Taxonomic revision of the Bothrops neuwiedi complex (Serpentes, Viperidae) with description of a new species. Phyllomedusa 7 (1), 2008: pp. 45-90 online, pdf