Size The maximum snout-vent length recorded for females is 109 mm and for males 105 mm.
Description The flanks are entirely covered with granular scales. The tail is considerably longer than the body and only moderately spinose. This species has long toes, an indication of its sprinting abilities.
The head, body and tail are black in colour, often with yellow or light green blotches and vermiculations, particularly on the top of the head. The belly is uniform slate-grey. In some populations the throat may have a reddish colour which may be very prominent in juveniles.
Biology The graceful crag lizard is one of the most fascinating cordylids and also the most atypical. As its common name suggests, it is an agile lizard with long limbs, long tail, and smooth scales. It is one of several melanistic (black) cordylids that occur in the southwestern corner of the subcontinent. It is believed that melanism in cordylids is an adaptation to conditions of limited sunshine, in that it increases the rate of radiation absorption under such conditions. In experiments conducted in the laboratory, melanistic cordylids became active at least an hour earlier in the morning than closely related non-melanistic species. The metabolic rate of melanistic forms is also considerably lower than that of non-melanistic forms at corresponding body temperatures, giving them a greater survival potential under prolonged overcast or misty conditions when little activity is possible. The concentration of melanistic species in the southwestern corner of South Africa suggests that adverse climatic conditions prevailed here some time in the distant past. Today, most melanistic species survive as small relic populations in very specific microhabitats, either high up in the mountains, in insular or peninsular situations along the coast, or inland at canyons or waterfalls.
The graceful crag lizard displays higher activity levels than most other cordylids and is not afraid to move considerable distances away from its shelter. It is rock-dwelling and prefers vertical cliff faces. Before the evolution of melanism in this species, the gular region was probably brightly coloured, like in the closely related Blue-spotted girdled lizard, Cordylus coeruleopunctatus. Juveniles sometimes still display this bright coloration.
Females seem to attain larger body sizes than males. Generation glands are always present in males, but can be present or absent in females. The glands are usually absent in females at higher altitudes and present at lower altitudes. The generation glands start to develop in males on reaching sexual maturity. The function of these glands is still uncertain, but they probably play a role in chemical communication. Unlike in most other members of the genus, the reproduction cycles of males and females are synchronised. The species is live bearing and one to three babies are born during late summer or early autumn.
Distribution Occurs in isolated populations from Oorlogskloof (Nieuwoudtville) and Gifberg (Vanrhynsdorp) in the north southwards through the Cape Fold Mountains to Kamanassieberg near Uniondale.
Distribution in GCBC Occurrence within the Corridor appears to be extremely patchy and isolated populations probably occur throughout the Corridor.
Conservation status Not listed in the latest South African Red Data Book for reptiles and amphibians, or in the IUCN Red List of Threatened Species. Like all other cordylid species, it is listed internationally in Appendix II of the Convention on the International Trade in Endangered Species of Fauna and Flora (CITES); legislation which regulates the international trade in these animals.
Threats Being a cool-adapted species (melanistic), global warming presents a major threat to this species.
Current studies Dahné du Toit of the Department of Botany & Zoology, Stellenbosch University, is conducting a PhD study on the effective conservation of melanistic lizard species and populations in the greater Cederberg area. Her study includes a GIS analysis of the distribution of melanistic lizard populations in the Cederberg area. It also focuses on canyon populations of the graceful crag lizard. This is the only melanistic species making use of this unique habitat type. Doug and Maria Eifler of the Haskell Indian Nations University, USA, are conducting a study on foraging activity and spatial use by this species in the Hottentots Holland Mountains. Other recent studies include:
COSTANDIUS, E. 2005. The Landdroskop area in the Hottentots Holland Mountains as a refugium for melanistic lizard species: An analysis for conservation. Unpubl. M.Sc. thesis, University of Stellenbosch, Stellenbosch, South Africa.
VAN WYK, J.H. & MOUTON, P.LE F.N. 1998. Sexual dimorphism and reproduction in a montane cordylid lizard, Pseudocordylus capensis. South African Journal of Zoology 33: 156-165.