Common names: Uzungwe viper, worm-eating viper, Barbour's short-headed viper, more.

Adenorhinos is a monotypic

Monotypic

In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 created for a venomous

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 viper

Viperinae

The Viperinae, or viperines, are a subfamily of venomous vipers found in Europe, Asia and Africa. They are distinguished by their lack of the heat-sensing pit organs that characterize their sister group, the Crotalinae. Currently, 12 genera and 66 species are recognized...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, A. barbouri. This is a small and exceptionally rare terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 species found only in the Uzungwe and Ukinga mountains of south-central Tanzania

Tanzania

The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

 in Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

. No subspecies are recognized.

Description

A small species reaching only 40 cm in length. The head is broad, triangular and distinct from the neck. The snout is short and rounded. The head is covered with small, strongly keeled, imbricate scales. The eyes are prominent; about 1.5 times larger than the distance to the mouth. The nostril is in an extreme forward position and is part of a single nasal scale that touches the preocular scale.

The body is moderately slender while the tail is relatively short—shorter than Atheris

Atheris

Atheris is a genus of venomous vipers found only in tropical subsaharan Africa, excluding southern Africa. Confined to rain forest areas, many members have isolated and fragmented distributions. In an interesting example of convergent evolution, they show many similarities to the arboreal pit...

 and not prehensile. Dorsal scales

Dorsal scales

In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales.When counting dorsal scales, numbers are often given for three points along the body, for example 19:21:17...

 strongly keeled

Keeled scales

Keeled scales refer to reptile scales that, rather than being smooth, have a ridge down the center that may or may not extend to the tip of the scale, making them rough to the touch...

, 20-23 rows at midbody. Outermost rows smooth. Ventral scales

Ventral scales

In snakes, the ventral scales are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that contacts the paraventral row of dorsal scales on either side...

 116-122 and rounded. Subcaudals 19-23, single. Anal plate single.

The color pattern consists of a brown to blackish brown ground color with a pair of zigzag stripes that run dorsolaterally from the back of the head to the end of the tail. These stripes may form an irregular chain of darker rhombic blotches down the back. The tail may have a faint, black checkering. The belly color is greenish white to olive.

Common names

Uzungwe viper, Barbour's viper, worm-eating viper, Barbour's short-headed viper, Udzungwa viper, short-headed viper, Uzungwe mountain bush viper.

Geographic range

Range extremely limited. Known only from the Uzungwe and Ukinga mountains of south-central Tanzania

Tanzania

The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

. The type locality is "Dabaga, Uzungwe Mountains, southeast of Iringa, Tanganyika Territory, altitude 6000 feet (1,828.8 m)" (Udzungwe Mountains, Tanzania).

Habitat

A terrestrial species found in bushes and bamboo undergrowth on mountain slopes at 1800 m. It would seem that moist forest habitats are preferred, but it has also been found in gardens of tea farms.

Behavior

Little is known. It was first thought to be a burrowing species, but this is not likely as it has no obvious morphological adaptations for even a semifossorial life.

Feeding

It is believed they are specialized in eating slugs, earthworms and other soft-bodied invertebrates -- possibly also frogs.

Reproduction

This species is apparently oviparous. In February 1930, three females were collected that each contained 10 eggs. The largest egg measured 1.0 x 0.6 cm.

Venom

No information is available regarding the composition of the venom, its toxicity or the effects of a bite. No cases of envenomation have been recorded. However, because of the very limited distribution, bites are unlikely to occur.

Taxonomy

A. barbouri was previously described as a member of the genus Atheris

Atheris

Atheris is a genus of venomous vipers found only in tropical subsaharan Africa, excluding southern Africa. Confined to rain forest areas, many members have isolated and fragmented distributions. In an interesting example of convergent evolution, they show many similarities to the arboreal pit...

 (bush vipers). It differs morphologically from the Atheris group, but recent research by Lenk et al. (2001) suggests that it is closely related to the sympatric species, Atheris ceratophora

Atheris ceratophora

Atheris ceratophora is a venomous viper species found only in a few mountain ranges in Tanzania. This is the only horned, arboreal viper in Africa. No subspecies are currently recognized.-Description:...

, even though it differs morphologically from all other members of the genus Atheris

Atheris

Atheris is a genus of venomous vipers found only in tropical subsaharan Africa, excluding southern Africa. Confined to rain forest areas, many members have isolated and fragmented distributions. In an interesting example of convergent evolution, they show many similarities to the arboreal pit...

. Future research will show whether A. barbouri should be moved back to Atheris, or that Atheris ceratophora and A. barbouri should form a separate clade

Clade

A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

.

This species is similar to Montatheris hindii

Montatheris

Montatheris is a monotypic genus created for a venomous viper species, M. hindii. This is a small terrestrial species found only at high altitude on Mount Kenya and the Aberdare mountain range in Kenya. No subspecies are currently recognized....

 and Proatheris superciliaris

Proatheris

Proatheris is a monotypic genus created for a venomous viper species, P. superciliaris. This is a small terrestrial species found in Tanzania, Malawi and Mozambique. No subspecies are currently recognized.-Description:...

, which are also both terrestrial, monotypic

Monotypic

In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

genera, as well as previous members of the Atheris group.