1. Introduction

 

Uromastyx thomasi has been described in the year 1930 by PARKER on the basis of two specimens. The holotype originated from Bu Ju’ay, Rub’al Khali, Dhofar and is now in „The Natural History Museum“, London [BM 1946.8.14.43 (old number: BM 1930.6.30.2)]. Since its description only few has been published about this species (see also BARTS & WILMS 1997), including faunal lists (PARKER 1931, WERMUTH 1967, ARNOLD 1986, WELCH 1994) as well as publications on the zoogeography of Arabia (ARNOLD 1987) and on the phylogeny of the genus Uromastyx (MOODY 1987). WILMS (1995) compiled all available data on U. thomasi or the first time and prepared a distribution map for the species. At that time the knowledge on morphology, distribution and especially ecology was very limited. Ecological observations of U. thomasi have been published by ARNOLD (1980), WILMS & HULBERT (2000) and WILMS, LÖHR & HULBERT (2002). Uromastyx thomasi lives in coastal Oman. The status of the wild population is unknown, but preliminary investigations suggest, that this species is not common in wide parts of the range (WILMS, unpublished). The distribution area of U. thomasi has a length of approx. 600 km and a maximum width of 230 km. Obviously not all types of landscape (e.g. mountainous areas) represented in the natural range of the species are suitable for them as habitats. In the year 1998 the author was able to examine 19 preserved specimens in museum collections [„The Natural History Museum“, London (BMNH) and Zoologischen Forschungsinstitut und Museum A.Koenig, Bonn (ZFMK)]. Some more specimens are kept in the collections of he Museum of Natural History, Muscat, Oman; the University of Muscat, Al Khod; the California Academy of Science, San Francisco and the Museum of the Bombay Natural History Society. WILMS et al. (2002) estimated the number of Uromastyx thomasi known to science of not more than 30 specimens (until the year 1998).

 

2. Studbook population

 

The captive population of Uromastyx thomasi consists today (January 2007) of 33 specimens. The founders of this population have been imported to Germany in accordance with national and international laws in 1998 for breeding project. First captive breeding occurred in 2000 (WILMS et al 2002). The animals are beeing kept at six locations. Four locations left the breeding programme befor 2006 because of loss of all specimens. In 2006 breeding occurred at one location. The sex ratio within the population is: 12.4.17.

 

3. Imports

 

No imports of this taxon occurred since 1998.

 

4. Natural history notes

 

According to WILMS & HULBERT (2000) and WILMS et al. (2002) Uromastyx thomasi lives in stony and sandy plains with sparse vegetation. At the end of November the specimens where active from 11 a.m. to 4 p.m. The temperature of the surface and air temperature one meter above ground was measured. The surface temperature ranged from 37.5-51.1 °C, while the air temperature was 29.2-35.8 °C.  The body temperature of 24 specimens ranged from 33.1-39.4 °C. The temperature was measured within 10 and 35 min. after the first sighting of the respective animal (for details see WILMS et al. 2002). The temperature in the burrows was between 30.3-33.6 °C at a depth of 20-41cm. In four burrows temperature at a depth of more than 53 cm was measured. The data are 34 °C at  53.5 cm, 31.4 °C at  47.5 cm, 29.7 at  67 cm and 29.6 °C at 77.5 cm. The length of the burrows varied between 45 and 165 cm. One specimen played dead after capturing. A total of 38 faecal samples have been analysed and despite the fact, that six plant species were found in the habitat, only two different plant species could be found in the droppings: Indigofera sp. (Fabaceae) and Plantago albicans (Plantaginaceae). Remains of insects or other animals could not be found in the faecal samples (WILMS et al. 2002).

 

5. Reproduction in captivity

 

Fist captive breeding of Uromastyx thomasi occurred in the year 2000 (WILMS et al. 2002). The animals have been kept pair wise in enclosures with one square meter floor space. Substrate temperature was partially between 45 and 55 °C. Air temperature was between 35 and 40 °C at daytime and around 18 –23 °C at night time. Photoperiod was 10 hours. Courtship behaviour began late February. Pregnancy takes around 35 days and oviposition takes place between May and September. Clutch size is between 9 and 16 eggs. Animals hatched in August 2000 reproduced for the first time at an age of 24 month. The juveniles of the F2-generation hatched between 22-25, November 2002. In 2003 breeding occurred with one of the original (wild caught) pairs and a pair consisting of WC male and a CB 2000 female (F1). In total 58 Uromastyx thomasi have been bred in the years 2000, 2002, 2003 and in 2004. Unfortunately some of these CB U. thomasi experienced a high mortality at four locations, so that the number of specimens transferred into the ESF Studbook is much lower. Incubation period was between 81 and 101 days. The juveniles had an average snout-vent-length (tail length) of 45.7 (17,2) mm [Clutch 1] ; 49.8 (19,1) mm [Clutch 2] and 46,9 (20,2) mm [Clutch 3]. Mass was averaged 5,6 g [Clutch 1], 4,3 g [Clutch 2] und 4.87 g [Clutch 3]. Of the 34 hatchlings from 2000 only 4 specimens are females. Because of this fact we suggest, that in U. thomasi the sex of the hatchlings could be greatly influenced by the incubation temperature (temperature depending sex determination). Until today, there are no available data on the time of oviposition or hatching of wild Uromastyx thomasi. Only the collection dates of three very young juveniles in the Natural History Museum, London are known (BMNH 1973.403, BMNH 1973.2906 and BMNH 1973.2907), which were collected in November 1972 and March 1973. All three specimens are of similar size, which points to a elongated egg laying period of presumably 3-5 month. This fits with the observations on captive U. thomasi. The first clutch was laid 01.05 and the last one 23.09. Some of the captive females laid two clutches in one breeding season. If this is likewise possible in the wild is not known.

 

6. References

 

- ARNOLD, E.N. (1980): The Reptiles and Amphibians of Dhofar, Southern Arabia. Journal of Oman Studies. Special Report 2: 273- 332.

 

- ARNOLD, E.N. (1986) A Key and Annotated Check List to the  Lizards and Amphisbaenians of Arabia. Fauna of Saudi Arabia 8: 385-435.

 

- ARNOLD, E.N. (1987): Zoogeography of the Reptiles and Amphibians of Arabia. In: Proceedings of the Symposium on the Fauna and Zoogeography of the Middle East. KRUPP, F.; SCHNEIDER, W. & KINZELBACH R. (eds.): 245-256.

 

- BARTS, M. & T. WILMS (1997): Catalog of valid Species and Synonyms, Vol. 4, Agamidae, Leiopepidinae.- Herpprint International, Pretoria, South Africa: 398-418.

 

- CUNNINGHAM, P. (2000): Daily activity pattern and diet of a population of the Spiny-tailed Lizard, Uromastyx aegyptius microlepis, during summer in the United Arab Emirates. Zoology in the Middle East 21, 2000: 37-46.

 

- MOODY, S.M. (1987): A preliminary cladistic study of the lizard genus Uromastyx (Agamidae, sensu lato), with a checklist and diagnostic key to the species. – Proceedings of the Fourth Ordinary General Meeting of the Societas Europea Herpetologica, Nijmegen, Holland. S. 285-288

 

- PARKER, H. W. (1930): Three new Reptiles from southern Arabia.- Ann. Mag. Nat. Hist., 6 (Ser. 10): 594-598.

 

- PARKER, H. W. (1931): Some Reptiles and Amphibians from SE. Arabia.- Ann. Mag. Nat. Hist., 8 (Ser. 10): 514-522.

 

- WERMUTH H. (1967): Das Tierreich (Agamidae). Lieferung 86, Berlin, 1-127.

 

- WILMS, T. (1995): Dornschwanzagamen - Lebensweise, Pflege und Zucht. 130 pp. Offenbach; Herpeton-Verlag.

 

- WILMS, T. (2001): Dornschwanzagamen - Lebensweise, Pflege und Zucht.- 143 pp. Offenbach; Herpeton-Verlag.

 

- WILMS, T. & HULBERT, F. (2000): On the herpetofauna of the Sultanate of Oman, with comments on the relationship between Afro-tropical and Saharo-sindian faunas. Bonner zoologische Monographien 46: 367-380.

 

- WILMS, T., LÖHR, B. & HULBERT, F. (2002): Erstmalige Nachzucht der Oman- Dornschwanzagame- Uromastyx thomasi PARKER 1930 - (Sauria: Agamidae: Leiolepidinae) mit Hinweisen zur intraspezifischen Variabilität und zur Lebensweise. Salamandra 38 (1): 45-62.