Atheris is a genus of venomous vipers found only found 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 vipers of Asia and South America. Eight species are currently recognized.
Relatively small in size, with adults ranging in size from 40 cm (A. katangensis) to a maximum of 78 cm (A. squamigera).
All species have a broad, triangular head that is distinct from the neck. The canthus is also distinct and the snout is broad. The crown is covered with small imbricate or smooth scales, none of which are enlarged. The eyes are relatively large eyes with elliptical pupils. The eyes are separated from the supralabials by 1-3 scale rows and from the nasal by 2-3 scales.
The body is slender, tapering and slightly compressed. The dorsal scales are overlapping, strongly keeled and have apical pits. Laterally these are smaller than the middorsals. Midbody there are 14-36 rows of dorsal scales. There are 133-175 rounded ventral scales. The subcaudal scales are single and number 38-67. The tail is strongly prehensile and can support the body while suspended from a branch or a twig.
Members of this group come in an amazing variety of colors and patterns, often within a single species. A. ceratophora and A. squamigera are particularly variable.
Relatively small in size, with adults ranging in size from 40 cm (A. katangensis) to a maximum of 78 cm (A. squamigera).
All species have a broad, triangular head that is distinct from the neck. The canthus is also distinct and the snout is broad. The crown is covered with small imbricate or smooth scales, none of which are enlarged. The eyes are relatively large eyes with elliptical pupils. The eyes are separated from the supralabials by 1-3 scale rows and from the nasal by 2-3 scales.
The body is slender, tapering and slightly compressed. The dorsal scales are overlapping, strongly keeled and have apical pits. Laterally these are smaller than the middorsals. Midbody there are 14-36 rows of dorsal scales. There are 133-175 rounded ventral scales. The subcaudal scales are single and number 38-67. The tail is strongly prehensile and can support the body while suspended from a branch or a twig.
Members of this group come in an amazing variety of colors and patterns, often within a single species. A. ceratophora and A. squamigera are particularly variable.
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