Breeding program for Socotri reptiles [Archives:2004/797/Culture]

December 9 2004

The Socotra Archipelago is home to a large number of endemic reptiles. Of the 22 types lizards, six types snakes, and a species of worm-like lizards (Trogonophidae), 26 are found only in the archipelago.
The geckos are the most diverse of the archipelago's reptiles, with 18 species, 15 of which are considered endemic. Seven species belong to the genus Pristurus, nine to the genus Hemidactylus and two to the genus Haemodracon.
Little is known about the biology and ecological needs of these species.

The Genus Haemodracon
The Haemodracon riebeckii was described by Peters (1882) as Diplodactylus riebeckii, based on three specimens collected by the two German naturalists Dr. George Schweinfurth and Dr. E. Riebeck, who spent six weeks on Socotra in 1881.
It grows up to 30 cm in length, and is the largest gecko species on Socotra. It has relatively small, flat scales, and is distinguished by a dark streak from the nostril to ear, that is interrupted by the eye.
The Haemodracon trachyrhinus was described by Boulenger (1899) as Phyllodactylus trachyrhinus based on two specimens recorded by the British zoologists W. R. Ogilvie-Grant and H. O. Forbes, who visited Socotra and Abd al Kuri in 1898.
It grows to be about 9 cm, and resembles a dwarf Haemodracon riebeckii, with larger scales, although the scales on the snout are distinctly larger and conical.
Bauer et al. (1997) reviewed and revised the genus Phyllodactylus and created the new genus Haemodracon for the two taxa from Socotra.
A few years ago, forms of Haemodracon were also recorded on the island of Samha. The species there are similar to large H. riebeckii of Socotra, but further taxonomic study is needed to clarify the status of this population.
On Socotra, H. riebeckii seems to be more common than H. trachyrhinus. They are predominantly nocturnal and if disturbed, take refuge in the deep crevices of the rock, living a predominantly solitary existence. All our specimens of H. trachyrhinus were located during the day in an inactive state.

Captive maintenance and breeding
Two male and two females specimens were kept in the laboratory terrariums, with a floor covered with a larger layer of mixed sand and loam. Nesting boxes, similar to those used for birds were offered, and the temperature and humidity was carefully controlled food. They were fed crickets, locusts, cockroaches, and fruit.

Egg laying
The female digs a small vertical pit in which she usually lays two white and sticky soft-shelled eggs. The eggs are laid next to each other and the shells harden in the air, becoming fragile. Immediately after the eggs are laid, the female closes the pit with substrate and leaves them for the unusually long time before they hatch. Eggs are incubated at 20-28 degrees centigrade, and the young hatched after 176 to 270 days.
Another peculiarity is the time difference between the hatching of the young within one clutch of two eggs. If both eggs are kept under identical conditions, in most young geckos on, or nearly on the same day. However, in case of H. riebeckii the difference in hatching times can range from between 4 to 27 days.

The young break the shell with their paired egg-teeth and form a hole through which they hatch. They usually then have to dig themselves out through the substrate.
Young specimens are more colorful than the adults. Immediately after hatching they shed their skin and consume the exuviae and eat their first food after 3-5 days.