Dwarf snakes
| Dwarf snakes | ||||||||||||
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Headband dwarf snake ( Eirenis modestus ) |
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| Systematics | ||||||||||||
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| Eirenis | ||||||||||||
| Jan , 1863 |
The dwarf snakes ( Eirenis ) form a genus of snakes from the family of the snakes , more precisely, the subfamily of the land and tree snakes . Compared to other closely related snakes of the genera Dolichophis and Hierophis , they are significantly smaller and have fewer scales.
features
The dwarf snakes are small snakes whose body length is usually well under 75 centimeters. They have round pupils, relatively small eyes and wide head shields. The nasal is not divided and there is no subocular. Eirenis have only 15 or 17 rows of dorsal scales at the level of the middle of the body and less than 100 tail scales ( scutum caudale ). Dwarf snakes have no fangs, so they are aglyphic.
Similarities with Hierophis and Dolichophis exist in the morphology of the Hemipenises as well as in the appearance of the young animals. These snakes, on the other hand, have a presubocular.
Internal system
Within the genus Eirenis , four sub-genera are distinguished: Eirenis, Pseudocyclophis, Eoseirenis and Pediophis . A total of 19 species are counted among the dwarf snakes. The type species is Eirenis modestus .
Subgenus Eirenis
This subgenus includes the relatively original dwarf snakes with fewer dwarfing characteristics. The body sizes of adult animals are between 55 and 65 centimeters. They have 6 temporal, 17, very rarely 19 rows of dorsal scales and fewer than 200 ventral scales . In addition, there are individuals in whom the nasals are half divided.
- Eirenis aurolineatus ( Venzmer , 1919)
- Headband dwarf snake ( Eirenis modestus Martin , 1838)
Subgenus Eoseirenis
This subgenus includes only one species, Eirenis decemlineatus ( Duméril , Bibron & Duméril , 1854), which has the lowest dwarfing characteristics of all dwarf snakes. Adults grow up to 75 centimeters long and have large eyes in comparison. They have 6 temporals, 17 rows of dorsal scales, and fewer than 200 ventral scales .
Subgenus Pediophis
This sub-genus contains most of the dwarf snakes with differently pronounced dwarfing characteristics. The body sizes of adult animals are between 30 and 60 centimeters. They have 4 or 6 temporals, 17 or 19 rows of dorsal scales, and fewer than 200 ventral scales .
- Eirenis africanus ( Boulenger , 1914)
- Eirenis barani Schmidtler , 1988
- Collared dwarf snake ( Eirenis collaris Ménétries , 1832)
- Eirenis coronella ( Schlegel , 1837)
- Eirenis coronelloides ( Jan , 1862)
- Eirenis eiselti Schmidtler & Schmidtler , 1978
- Eirenis hakkariensis Schmidtler & Eiselt , 1991
- Eirenis levantinus Schmidtler , 1993
- Eirenis lineomaculatus Schmidt , 1939
- Eirenis mcmahoni ( Wall , 1911)
- Eirenis medus ( Chernov , 1940)
- Eirenis punctatolineatus ( Boettger , 1892)
- Eirenis rechingeri Eiselt , 1971
- Eirenis rothii Jan , 1863
- Eirenis thospitis Schmidtler & Lanza , 1990
Subgenus Pseudocyclophis
This subgenus includes only one species, Eirenis persicus ( Anderson , 1872), which has very strong dwarfing characteristics. Adults grow up to 45 centimeters long. They have 4 temporal, 15 rows of back scales but mostly more than 200 ventral scales .
External system
The genus Hierophis includes the genus of the dwarf snakes ( Eirenis ) and is therefore paraphyletic . The following diagram shows the relationship based on the research by Nagy et al. 2004, which is why the Andreas Wrath Snake, which was not part of the genetic test, is missing .:
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distribution
The range of the snakes of the genus Eirenis stretches from Turkey in the west over Georgia and Dagestan in the north to the east to Turkmenistan , Pakistan and Afghanistan and includes the Arabian peninsula . Only Eirenis africana lives across the Red Sea between Sudan and Djibouti .
Eirenis coronella is the only dwarf snake that lives in the Arabian desert.
Way of life
While the closely related wrath snakes are large and fast and hunt lizards and rodents, most dwarf snakes live hidden and are crepuscular. Their diet consists of arthropods . This change in lifestyle may have resulted in dwarfism.
Individual evidence
- ↑ a b c d e ZT Nagy, JF Schmidtler, U. Joger, M. Wink: Systematics of dwarf snakes (Reptilia: Colubridae: Eirenis) and related groups based on DNA sequences and morphological data . In: Salamandra . tape 39 . Rheinbach 2003, p. 149-168 .
- ^ A b ZT Nagy, R. Lawson, U. Joger, M. Wink: Molecular systematics of racers, whipsnakes and relatives (Reptilia: Colubridae) using mitochondrial and nuclear markers . In: Journal of Zoological Systematics and Evolutionary Research . tape 42 , no. 3 . Blackwell Verlag, 2004, ISSN 0947-5745 , p. 223–233 , doi : 10.1111 / j.1439-0469.2004.00249.x ( uni-heidelberg.de PDF, 0.2 MB). uni-heidelberg.de ( Memento of the original from April 2, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b Eirenis in The Reptile Database
