Diversity and Distribution of Reptiles in Al Qiddiya, Southwest Riyadh, Saudi Arabia

The reptiles and amphibians of Saudi Arabia are rich with at least 135 species. Aloufi et al. (2019) [1] gave a detailed account of the diversity of the herpetofauna of Saudi Arabia, along with the proposed conservation status and imposed threats. Al-Sadoon (1988, 1989) [2,3] gave a detailed list of reptilian species recorded from Ar-Riyadh Province (Table 1), some considered threatened, such as the Egyptian Spiny-tailed Lizard, Uromastyx aegyptia. Tilbury (1988) [4] reported on the reptiles around Ar Riyadh. It included records for 33 species. Tamar et al. (2023) [5] recently described a new species, Pseudotrapelus tuwaiqensis, from around Ar Riyadh area. This species is endemic to central Saudi Arabia occurring within the study site. Other studies included records from Al-Zulfi area, close to the study area (Al-Sadoon et al., 1991) [6]. The snakes of Saudi Arabia were extensively studied with records from the vicinity of Ar Riyadh area (Gasperetti, 1988) [7]. Also, Arnold (1986) [8] presented a list of lizards of the Arabian Peninsula, where some of the listed species require taxonomic revision.

Table 1: Reptiles reported to occur in the Ar-Riyadh Province.

Two detailed studies on the feeding behaviour of Eryx jayakari and Diplometopon zarudnyi collected from Ar Riyadh area were published by Al-Sadoon and Al-Otaibi (2014) and Al-Sadoon et al. (2016) [9,10]. Also, the feeding behaviour of the Arabian Horned Viper, Cerastes gasperettii, was studied based on specimens collected around Ar Riyadh (Al-Sadoon and Paray, 2016) [11]. The Arabian horned viper seems to be common around Ar Riyadh area, Al-Sadoon and Kandeal (2015) [12] collected 100 specimens from Ar Riyadh while studying its reproductive biology. Recent studies dealt with the herpetofauna and its richness in different parts of the Arabian Peninsula (Šmíd et al., 2021) [13] and analyzed the reptiles of King Abdulaziz Royal Nature Reserve, close to Ar Riyadh (van Huyssteen et al., 2024) [14]. In this study, we report on the reptiles observed at Al Qiddiya region, located about 40 km from Riyadh over a period of five months during 2023–2024.

Study area

The study area is divided into two distinct parts. The upper plateau, part of the Tuwaiq Mountains, is characterized by rocky terrain composed of fossilized corals and high mountain cliffs. In contrast, the lower plateau consists of a gravelly, stony, and sandy desert interspersed with scattered vegetation, several wadis, and streams (Figures 1 and 2). These wadis serve as channels for rainwater and support a rich diversity of flora, predominantly Vachelia trees along with various other plant species. At the base of the high mountains, the landscape transitions to fields of large and small fallen rocks. During the rainy season, depressions and artificial reservoirs temporarily collect water. However, due to the intense sunlight, these water bodies evaporate quickly. The climate of Ar Riyadh represents hot desert climate, characterized by long, extremely hot summers with average temperatures reaching around 43°C and short, very mild winters with minimum temperatures reaching around 10°C. Temperatures can fluctuate significantly between day and night, especially during the summer months. Rainfall is minimal, about 14 mm annually occurring mostly between November and May.

Data collection

Fieldwork was conducted during October and November 2023, and January, April, and May 2024. Twenty daytime transects were conducted in search of reptiles. A total of 137 reptiles were observed and photographed for later identification to the species level as possible, and geographic coordinates were recorded. Additionally, reptiles were checked under bushes, crevices in rocky areas, and under left furniture and wooden boards. Night-time search for nocturnal species was performed from 18:00hr–23:00hr. Fecal remains of the Egyptian Spiny-tailed Lizard were identified for its presence.

Table 2: Reptiles recorded from the study site during the study period and their conservation status.

NA = Not Assessed, VU = Vulnerable, LC = Least Concern.

Twelve species of reptiles were identified to occur within the study area, including two species of the family Lacertidae, two species of the family Agamidae, one species of the family Phyllodactylidae, one species of the family Gekkonidae and one species of the family Scincidae. Four species of snakes belonging to four families were observed (Elapidae, Colubridae, Psammophiidae, and Viperidae) (Table 2). This expands distributional data for the little-known species and adds additional locality records for Walterinnesia aegyptia around Ar Riyadh area.

A total of 137 observations from 12 reptile species were collected during the study period (Table 3). During October 2023, only five species were observed with a total of 16 observations. In November 2023, three species were observed with a total of 10 observations. The number of observations declined to as low as seven with only two species of reptiles in January. This is mainly due to low temperatures and hibernation of most reptiles during the winter season. Starting from the Spring months, the temperature increased rapidly, allowing reptiles to emerge to catch up with the breeding season. A total of 65 observations were recorded in April, accounting for nine species, and 39 observations during May, with six recorded species.

Within family Lacertidae A. boskianus (Figure 3A) was found in open areas with scattered vegetation, taking refuge during daytime under bushes, while M. cryptica (Figure 3B) was usually associated with gravelly areas around the edges of open areas close to rocky surroundings. A male and female were found attempting to copulate in April. The taxonomy of the Mesalina guttulata complex was revised recently by Šmíd et al (2021, 2025) [14,15]. They described a new species, Mesalina cryptica, from Tuwaiq Escarpment near Riyadh. Its distribution extends from Jordan, Saudi Arabia and Kuwait.

In the Scincidae, a single adult specimen of Eumeces schneideri (Figure 3C) was observed, suggesting that it is a rare species within the study area. Family Agamidae was represented by two species. Several active burrows of the Spiny-tailed Lizards, Uromastyx aegyptia (Figure 3D) was the most observed species with five and 14 observations during April and May, respectively. In addition, several active burrows were located in the study site. Adults usually emerge from their burrows and remain stationary, and others were observed under Acacia trees. Few droppings were observed scattered close to shrubs and in open areas. The Egyptian spiny-tailed lizard is a common species inhabiting gravel deserts and flat and firm substratum of Saudi Arabia and adjacent countries. The newly described species, Pseudotrapelus tuwaiqensis, is a rock-dwelling species that is associated with medium-sized boulders (Figure 3E). It was observed during mid-day basking exhibiting different coloration according to temperature.

In the geckos, Stenodactylus slevini (Figure 3G) was associated with sandy areas in open deserts. It has a wide range of distribution extending from the eastern Arabian Peninsula, Kuwait, southern Iraq, reaching as far as the southern deserts of Jordan. The rock-dwelling nocturnal gecko Ptyodactylus hasselquistii (Figure 3F) takes refuge in shady areas along rock crevices. It was the most common gecko species in the study site. It was active during October 2023, and April and May 2024. On some occasions, two individuals were observed together. This is a rather problematic species with several forms and colours, and further studies may reveal several new species across Saudi Arabia. Finally, Bunopus tuberculatus (Figure 3H) inhabits gravelly and rocky areas. A single adult specimen of Platyceps rhodorachis (Figure 4A) was observed over a cliff. This snake inhabits rocky areas and around edges on interface with open deserts, and displays diurnal or crepuscular behaviour, feeding mainly on lizards, amphibians, and rodents. Two road-killed Malpolon moilensis (Figure 4B) were found in open deserts near bushes and gravelly areas. It is a rather common diurnal species across arid regions of Saudi Arabia. A single observation of Walterinnesia aegyptia (Figure 4C) was made in a rocky area. This is a venomous species with a wide range of distribution across the Middle East.

Table 2 shows the global conservation status for the reptiles reported from the study area. Only the Egyptian Spiny-tailed Lizard is listed as Vulnerable (VU) according to the IUCN Redlist. This species is threatened in Saudi Arabia due to hunting and habitat modifications. All other species are listed as Least Concern (LC). However, the conservation status of the Tuwaiq Agama has not been assessed yet. It is considered an endemic species for central Arabia, and conservation measures should be adopted to protect this little-known species. Threats affecting the reptiles of the study area include bulldozing, levelling, and man-made changes that may reduce vegetation cover as well as destroying habitats for sensitive and threatened species such as the Egyptian Spiny-tailed Lizard, Uromastyx aegyptia. The conservation status of the newly described species, Pseudotrapelus tuwaiqensis is still undetermined. Road kills due to vehicle movement in the study site were documented. Two Molia snakes, Malpolon moilensis, were found dead alongside roads. Most of the study area is very much disturbed due to extensive levelling, bulldozing, and movement of heavy-duty vehicles. The vegetation cover, especially at the upper plateau, was disturbed, and perhaps burrows of the Egyptian Spiny-tailed Lizard were buried or destroyed. The most pressing issue is to protect this vulnerable species by translocating its individuals to areas where disturbance is at its minimum and having a suitable habitat where it can thrive again.

Table 3: Number of observations for reptile species encountered at the study site during the study period.

We wish to thank Mrs. Laya Majid, Geographic Information System Specialist, Royal Society for the Conservation of Nature, Jordan, for map preparation.

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