Taxonomic notes: The differentiation between this species and Acanthocercus cyanogaster has long been uncertain, and prior to Spawls et al. (2002) most authors followed Parker (1942), who formally synonymized the two taxa under the older name A. cyanogaster (although the concept of A. cyanogaster applied by Largen 1997 - which restricts the species to Ethiopia and Eritrea - suggests that this author recognized A. atricollis as distinct). Spawls et al. (2002) considered the two taxa "doubtfully distinct". Largen and Spawls (2006) opin that, despite variability in certain characters, two distinct phenotypes are diagnosable within this complex, supporting the recognition of two species rather than one; Largen and Spawls (2010) further recognize the "completely ignored" A. zonurus, and these authors' division of the A. cyanogaster complex into three species (A. atricollis, A. cyanogaster and A. zonurus) is followed here. Largen and Spawls (2010) also suggest that research is needed to clarify whether Ethiopian records of A. atricollis are genuinely conspecific with those from the South African type locality, or whether they represent a separate species for which the name A. minuta is available (Largen and Spawls 2010). It is likely that molecular research will be required to resolve the taxonomy of North African Acanthocercus (Largen and Spawls 2006), as the scheme adopted here is based largely on museum records and "do not resolve all outstanding issues" (Largen and Spawls 2010).

This wide-ranging lizard occurs from Ethiopia and northwestern Somalia (where it is known only from West Galbeed, a record possibly attributable to the subspecies A. a. minutus - Lanza 1990), south through East Africa to coastal KwaZulu-Natal, eastern Botswana and northern Namibia (Branch 1998, Largen and Spawls 2006). Records of this species from Eritrea (Spawls et al. 2002) appear to represent confusion with A. cyanogaster. In Tanzania and most of Kenya it is represented by scattered, sporadic records; its distribution is more continuous in Uganda and northern Rwanda (Spawls et al. 2002). The western limit of the distribution is the western Democratic Republic of the Congo (Spawls et al. 2002). No records of this species complex appear to exist for Sudan or South Sudan (P. Wagner pers. comm. 2012). This species occurs from sea level to 3,000 m above sea level, although in East Africa it is most common from 1,300 to 2,000 m above sea level (Spawls et al. 2002; Largen and Spawls 2010).
CHECK NEW DISTRIBUTION MAP FROM WAGNER AND CORRECT TEXT ABOVE.
OBTAIN UPDATED ACANTHOCERCUS ATRICOLLIS PAPER FRON PW AND AMEND TAXONOMY. ETHIOPIA = minutus, Kenya = gregorii, Tanzana = loveridgei, cyanogaster apparently synomyised.

Patterson (1987) reported that this species appears to be common in Kruger National Park. A resident pair was found on almost every tree, including those in human-disturbed areas. The species seems to be anthropophilic, occurring in higher densities in villages than in natural habitats, despite some human persecution of this lizard (Whiting et al. 2009, Wagner et al. 2012). It is "common in wooded suburbs of Nairobi, Nakuru and Kitale" (Spawls et al. 2002).
minutus: Quite common, tolerant of urbanisation and habitat degradation. Rupiculous in Ethiopia (although it can be arboreal), where A. lionotus and other rupicolous species are absent; in Kenya mostly arboreal (Spawls pers. comm.)

This species inhabits open savannah, woodland and forest clearings (Spawls et al. 2002). In East and southern Africa it is almost exclusively associated with large trees (Branch 1988, Spawls et al. 2002), however in Ethiopia it occurs in open areas with rocks or burrows for shelter (Largen and Spawls 2006). 
SPECIMENS FROM SERENGETI AND NGORONGORO ARE GROUND DWELLING KNOWN TO SIT ON SMALL TERMITE MOUNDS OR BUFFALO SKULLS IN OPEN SAVANNAH WITH FEW TREES (WAGNER PERS  COMM)
Due to the taxonomically complex nature of this species concept, it is not clear whether these reports reflect a single, highly adaptable species, or whether ecological differentiation reflects cryptic species divisions (Largen and Spawls 2006).

A study on the southern African A. atricollis atricollis found that this subspecies preferentially inhabits thorn trees, followed by common sugarbush and dead trees. It was also found to select trees with larger diameters, denser canopy cover (Reaney and Whiting 2003). In disturbed areas, this subspecies may be associated with marula trees (Whiting et al. 2009). Within Semuliki National Park, A. atricollis was often found in the vicinity of human settlements (Necas et al. 1997); outside protected areas it also occurs in high densities around villages and in communal rangelands (Smart et al. 2005, Whiting et al. 2009, Wagner et al. 2012).

Where this agamid is predominantly arboreal, it comes to the ground only to cross to another tree or to feed. This species is diurnal and oviparous, with clutch sizes of 4-15 (Spawls et al. 2002). It feeds principally on ants and beetles, but other arthropods also form important components of the diet (Reaney and Whiting 2002). It occurs in structured colonies consisting of a male and several females and juveniles (Reaney and Whiting 2003).

A questionnaire-based study in South Africa found that 12% of interviewees believed this species possessed medicinal properties (Whiting et al. 2009), but there is no evidence that this species is actively harvested. SPECIMENS OF UGANDENSIS AND LOVERIDGEI ARE OFTEN IN TRADE.

No substantial threats are thought to exist to this species. This species can be more abundant in artificial than in natural habitats in southern Africa, and its apparent preference for large fruit trees in these areas may make it somewhat resilient to the effects of timber extraction that might otherwise pose a risk to this LARGELY arboreal species (Whiting et al. 2009). Negative traditional beliefs are associated with this lizard across much of its range, including a widespread belief in highland East Africa that it is venomous (Spawls et al. 2002), and Whiting et al. (2009) found it to be subject to heavy persecution in the area they studied. The species remains abundant in plantations and villages despite this pressure, and it may be that mortality from persecution is offset by hypothesized reduced numbers of natural predators in anthropogenic habitats (Whiting et al. 2009).

• 5.4.5 Persecution/control

There are no known species-specific conservation measures in place for this species. It is known from a number of protected areas, including Kruger (Patterson 1987), Semuliki (Necas et al. 1997) and Masai Mara (Wagner et al. 2012) National Parks. SERENGETI. minutus is commonly seen in Awash and Abiatta-Shalla National Parks in Ethiopia (Spawls pers. comm.)

Acanthocercus atricollis is listed as Least Concern in view of its large distribution across eastern and southern Africa, its tolerance of anthropogenic environments, and the absence of any major widespread threat.
TRUE OF ALL HORN AND E AFRICAN FORMS

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• Griffin, M. 2003. Annotated Checklist and Provisional National Conservation Status of Namibian Reptiles. Namibia Wissenschlaftliche Gesellschaft (NWG), Windhoek.
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• Reaney, L.T. and Whiting, M.J. 2002. Life on a limb: ecology of the tree agama (Acanthocercus a. atricollis) in southern Africa. Journal of Zoology 257: 439-448.
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• Spawls, S., Howell, K.M., Drewes, R.C. and Ashe, J. 2002. A Field Guide to the Reptiles of East Africa. Academic Press, Elsevier Science.
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