Atheris squamigera grows to an average total length of 46 to 60 cm, with a maximum total length that sometimes exceeds 78 cm. Females are usually larger than males. The head is broad and flat, distinct from the neck. The mouth has a very large gape. The head is thickly covered with keeled, imbricate scales. The rostral scale is not visible from above. A very small scale just above the rostral is flanked by very large scales on either side. The nostrils are lateral. The eye and the nasal are separated by 2 scales. Across the top of the head, there are 7 to 9 interorbital scales. There are 10 to 18 circumorbital scales. There are 2 rows of scales that separate the eyes from the labials. There are 9 to 12 supralabials and 9 to 12 sublabials. Of the latter, the anterior 2 or 3 touch the chin shields, of which there is only one small pair. The gular scales are keeled. Midbody there are 15 to 23 rows of dorsal scales, 11 to 17 posteriorly. There are 152 to 175 ventral scales and 45 to 67 undivided subcaudals. It is possible that there is a variation in morphometric characters related to habitat: The coloration is the same in some populations, but variable in [|others]. The dorsal color varies from sage green or light green to green, dark green, bluish, olive or dark olive brown. Rare specimens may be found that are yellow, reddish or slate gray. The scales have light-colored keels and sometimes yellow tips that form a series of 30 or more light crossbands or chevrons. On the tail, there are 10 to 19 chevrons: not always clearly defined, but usually present. The ventral edge of the dorsum has light spots in pairs. An interstitial black color is visible only when the skin is stretched. The belly is yellow or dull to pale olive; it may be uniform in color, or heavily mottled with blackish spots. The throat is sometimes yellow. The tail has a conspicuous ivory white tip, 7 to 12 mm long, extending back over 10 subcaudals. Neonates have a dark, olive coloration with wavy bars, paler olive or yellowish olive with fine dark olive margins, bars at intervals, and a belly that is paler greenish olive. The adult color pattern develops within 3 to 4 months.
Common names for A. squamigera include green bush viper, variable bush viper, leaf viper, common bush viper, bush viper, and tree viper, Hallowell's green tree viper.
Atheris squamigera requires a very high level of humidity to breed. In one case, males and females were kept separate from January to the end of November. Two females became gravid. Each produced eight young: a smaller percentage were yellow, most being green. In each brood, there was also one nonviable green specimen. Some of the neonates fed readily on frogs, while the others had to be force-fed pinkie mice. All fed independently after a few months.
Venom
Bites from A. squamigera have resulted in at least one report of severe hematological complications as well as two deaths. Although no specific antivenom is made for the genus Atheris, antivenom for the genus Echis has been shown to be partially effective in neutralizing Atheris venom.
Taxonomy
A number of subspecies of A. squamigera may be encountered in literature. These include:
Atheris squamigera squamigera, found in Ghana to Cameroon, DR Congo, Uganda, western Kenya and Angola.
Atheris squamigera robusta :fr:Raymond Ferdinand Laurent|Laurent, 1956, from the Ituri Forest in Province Orientale. It is sometimes described as growing larger, having a lower subcaudal count and only a single row of scales between the eye and the upper labials.
Furthermore, specimens from Dimonika and Menengue in Congo are sometimes treated as a separate species: A. laeviceps. It has been distinguished as having a group of small scales on top of the head, a row of scales that separates the suboculars and the upper labials, as well as a yellow coloration.
