Pachydactylus bicolor HEWITT 1926
Distribution and biotope
Pachydactylus bicolor is endemic to north-western
Habitat at the coast of Namibia
P. bicolor is a crevice specialist and inhabits rocky habitats (e.g. Erongo-Mountains and Spitzkoppe), as well as rocks lying on the ground of plains. What’s astonishing, are the few isolated localities at the coast. The landscape consists of gravel- or sand plains with hardly any vegetation, where the geckos inhabit large pieces of rock which show small, loose chips that are used as hiding places. These rocks build a 300 to 500 meters wide band, which reaches to the inland and probably enables the geckos to reach the coast. In this habitat they live sympatric with the nocturnal gecko Chondrodactylus turneri laevigatus and the diurnal geckos Rhoptropus afer and R. bradfieldi. Due to their smaller and flat body dimensions, they are able to house smaller crevices than the larger geckos, which provides a certain security.
Captivity and breeding
Various pairs of the species were kept over several years. Pachydactylus bicolor is a very agile gecko. In a habitat which mostly consists of insular rocks, we observed that a flushed gecko will never leave its rock. While the rock was rotated several times, the gecko always flew to the far side. However, this behaviour couldn’t be confirmed with different populations which inhabit rocky locations (e.g. Spitzkoppe), where multiple hiding places were available.
Male of the coast population
Pachydactylus bicolor from Kamanjab, Namibia.
© J. Marais.
Juvenile Pachydactylus bicolor from Kamanjab, Namibia.
© J. Marais.
Copula bite of Pachydactylus bicolor. © F. Müller
Diet consisted of Drosophila, crickets, wax moths and their larvae, Buffalo-worms and similar invertebrates, which where dusted with minerals and vitamins (e.g. Korvimin ZVT®, Calcamineral). From time to time, the water was mixed with liquid vitamins (e.g. Multibionta®). Mussel grit was offered as well and was particularly consumed by the females during breeding season. Starting in spring, the females produced 3 to 5 clutches each in eight month, which were burrowed in loose sand. Our clutches always consisted of 2 oval, white eggs of 7.5 to 9.1 x 5.3 to 5.8 mm. The shell is 0.0041 mm thick. Eggs found in the natural habitat were 9.2 to 6.0 mm.
Female lay eggs. Foto: © F. Müller
Pachydactylus bicolor clutch
Hatchling of the inland population
Hatchling of the coast population
5 months old juvenile of the coast population
5 months old juvenile of the coast population
P. bicolor reaches its sexual maturity after 2 years. Early mating is likely to cause egg binding. A therapy of such a small gecko is usually unsuccessful.
6 months old juvenile of the inland population
Originalbeschreibung / Original description
Types.—Two specimens in the collection of the South African Museum (No. 17297), collected at Kaross, in the Kaokoveld, S.W.A., by Mr. E. F. Lawrence. These specimens are possibly immature and their characters a little uncertain, but the very striking colour pattern seems to warrant a distinctive name for the form, especially as there are minor structural peculiarities—the number of labials, etc.
The characters are as follows: Nasorostrals in contact, nostril well separated from rostral and first labial, rostral twice as broad as high, 8 upper labials, 7 quite distinct lower labials, snout scarcely more than 11/2 times as long as the eye; scales on the snout twice as large as those on occiput; a swelling above the loreal region on each side of the snout; symphysial shield nearly twice as long as broad ; ventral scales larger than the dorsals ; a circular area just in front of the vent with considerably enlarged scales, which are separated by much smaller scales from the strip of enlarged scales under each thigh ; dorsal scales not very strongly flattened; distal expansion of digits with 5 adhesive lamellae, the most distal lamella smallest and divided in the middle ; scales along the middle of the digit inferiorly all transversely enlarged.
Colour.—Head above greyish white, with some dark mottlings, and surrounded by an elliptical blackish stripe which arises at the nostril and passes backwards through the eye on each side and around the back of the occiput; this stripe is bordered behind by a white stripe arising on the upper lip and broadening a little over the neck; fore-limbs and greater portion of dorsal surface of body quite black, but changing suddenly to greyish white over the lumbar region; a dark transverse patch or band between the hind-limbs dorsally ; hind-limbs and base of tail greyish white, the tail with faint dark cross stripes.
Length from snout to vent 25 mm. ; tail imperfect.
Mr. Lawrence informs me that he noticed this gecko at other localities (Warmbad and Caimaeis), and that all specimens seen were similar in colour and size to those above described. They were found under logs or amongst decaying leaves.
Dr. Werner has given some notes on the coloration of the young of the related species, brunnthaleri, from which it is evident that the form now described cannot be referred to that species. It is, however, possible that fully adult specimens may be differently marked from the types : that such is the case in purcelli was pointed out by Methuen and myself in AnnalsTransvaal Museum, Vol. IV, p. 132, fig. 15, 1913. P. serval Wern., from Chamis in Great Namaqualand, seems to differ in the higher rostral and the greater number of subdigital lamellae (6), as well as in coloration, but the characters of immature specimens are unknown.
Lastly, P. pardus Sternf., from Warmbad, the only other western species of this group, differs in the greater number of labial shields (10-11 and 9) and in the rostral entering the nostril. Although the type locality is not more fully indicated, I presume that the particular Warmbad is that in the south of Great Namaqualand.