Pointed Snakes
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| Wagler , 1830 |
The pointed snakes ( Oxybelis ) are an American genus of snakes .
features
Pointed snakes are characterized by an extremely slender body and an elongated, pointed head. They usually reach a length between 100 and 150 cm. The head shields are partially modified according to the elongated head shape. The body scales can be smooth or slightly keeled. The eye has a rounded pupil when exposed to light. The coloration of some species is very variable, the basic color being mostly brownish or greenish. Oxybelis fulgidus and Oxybelis wilsoni are typically greenish, while Oxybelis aeneus is brownish in color. The anal scutum can be divided or undivided.
Pointed snakes have a venom apparatus consisting of venom glands (modified salivary glands), venom canals and immobile fangs located in the rear upper jaw ( opistoglyph tooth position ). In humans, the toxic effects are limited to local effects (slight pain, edema , erythema , paresthesia ).
Way of life
Norway snakes colonize a multitude of habitats from sea level up to 2,500 m altitude, whereby a large part of the habitats is represented by tropical and subtropical woody stocks, for example in gallery forests and savannas . There are also occurrences in semi-arid to arid areas. A largely arboreal (tree-dwelling or climbing) way of life is led, with the animals moving skillfully and quickly in the branches of trees and bushes. The prey spectrum primarily includes lizards, sometimes also small mammals and birds. Some authors also list insects as food. Prey animals are immobilized by the poison secretion. The propagation is done by oviparity so oviparous.
Pointed snakes often freeze when in danger and rely on their camouflage: the structure and color of the branches give the impression of a branch. When provoked, the front body is placed in S-shaped loops and the mouth is opened wide. If the provocation continues, the animals defend themselves with bites.
Systematics
Types and distribution
- Ore snake , Oxybelis aeneus ( Wagler , 1824); North America (north to south Arizona , USA) as well as large parts of Central and South America
- Oxybelis brevirostris ( Cope , 1861); Central and South America
- Oxybelis fulgidus ( Daudin , 1803); Central and South America
- Oxybelis wilsoni Villa & McCrainie , 1995; Roatan , Honduras
Phylogenetics
In view of the large distribution area and the large number of habitats, the question of the taxonomic status of the genus and its species arises. In this context, molecular biological studies of mitochondrial genes (mtDNA: Cyt b (cytochrome b), ND4 (NADH dehydrogenase subunit 4)) and nuclear genes (nDNA: cmos (oocyte maturation factor), PRLR (prolactin receptor)) of Central American populations were carried out and evaluated. It was after Bayesian inference and maximum likelihood methods. The results suggest that the genus Oxybelis evolved during the Miocene about 20.5 mya and separated from the sister genus Leptophis . The position of Oxybelis within the Colubrinae is unclear.
The results of Jadin et al. (2019) contradict those of Pyron et al. (2011, 2013), after which Oxybelis a Schwestertaxon of Opheodrys ( opheodrys was). A clade comprising the genera Chironius , Dendrophidion , Drymobius , Leptophis , Opheodrys and Oxybelis is described by Jadin et al. however supported.
Two main clades are described within Oxybelis that separated during the Middle Miocene before 14.5 mya :
- O. aeneus
- O. fulgidus and O. wilsoni
In O. aeneus is probably a species complex , whose precise phylogenetic systematics is unclear; an evolutionary diversification of the as yet unclear lineages probably took place during the Pliocene (5.7 to 3 mya). The speciation of O. fulgidus and O. wilsoni took place about 3 mya.
etymology
The generic name “Oxybelis” is derived from the Greek “Oxy” for “pointed” and “belas” for “arrow”. This name is based on the elongated shape of the head.
Individual evidence
- ↑ The Reptile Database: Oxybelis aeneus (accessed April 18, 2019)
literature
- Jadin et al .: Hiding in the lianas of the tree of life: Molecular phylogenetics and species delimitation reveal considerable cryptic diversity of New World Vine Snakes , Molecular Phylogenetics and Evolution 134 (2019), 61-65. ( PDF )
- Trutnau: snakes in the terrarium; Non-toxic snakes , Vol. 1, Part 2, Verlag Eugen Ulmer, 2002. ISBN 3-8001-3223-0 .
- Schmidt: Atlas snakes; Species, attitude, care , bede Verlag, 2006; published by Nikol-Verlag, 2009.
- Mattison: Encyclopedia of Snakes , BLV Buchverlag, 2007.
Web links
- University of Adelaide, Clinical Toxinology Resources: Oxybelis aeneus (accessed April 19, 2019)