Savanna, Nile, and Cape monitors
These lizards represent an entirely African
clade within the Varanidae. They are found over most of the continent excepting
the Sahara and northwestern portion. They are absent from Madagascar. A fossil
from the Miocene of Kenya is the earliest known member of the genus Varanus
and is remarkably similar to the living Nile monitor.
Features uniting the species of the subgenus
include:
- Enlarged posterior teeth in adults, the
teeth becoming molar-like crushing tools,
- Similar hemipenial structure,
- Nostrils located midway (or nearly so)
between the snout tip and the eye or very near the eye,
- Short, thick digits.
Key
to the Species of the Subgenus Polydaedalus.
1a.
Body black or dark brown, with cream or yellowish markings; tail more than 1.3
1b.
Body with few or no light markings; tail less than 1.3 times SVL; nuchal scales
2a.
Yellow dorsal markings large, solid and distinct, in 5-6 bands; tongue pink
V. ornatus
2b.
Light markings indistinct, or not yellow, or hollow; tongue dark blue or purple
V.
niloticus
3a.
Body gray, with dark gray or black ring-like dorsal markings; nostril about
midway
between
eye
and snout tip; nuchal scales nearly twice the diameter of other dorsal
scales; tongue blue or purple
V. exanthematicus
3b. Body not gray; nuchals about 1.5 times the diameter of other dorsal scales
4
4a.
Body tan or yellowish; nostril oval, about midway between snout tip and eye;
gular
region light
5
4b.
Body brown or dark brown; nostril much nearer eye than tip of snout; gular
region
V.
albigularis
5a.
Snout, forelimbs distinctly yellow; no distinct dorsal pattern; tongue dark
anteriorly, light behind
V.
yemenensis
5b.
Dorsal scales large, round, smooth; dorsal pattern of brown, hollow circles;
V.
ocellatus
