Abstract

The genus Pristurus Rüppell, 1835 currently consists of 26 described species, distributed mainly across Arabia, the Socotra Archipelago and north-east Africa, with one isolated species in Mauritania and another which extends from southeast Arabia to the southern coast of Iran (Arnold 2009; Sindaco & Jeremčenko 2008; Tamar et al. 2019; Uetz et al. 2022).
The study on the systematics and evolution of the genus Pristurus by Badiane et al. (2014) including partial sequences of one mitochondrial (12S rDNA) and four nuclear (ACM4, C-MOS, RAG1 and RAG2) genes, indicated that what was considered as P. rupestris Blanford, 1874 at that time was polyphyletic. According to the results, “Pristurus rupestris” comprised two phylogenetically unrelated clades: the eastern clade and the western clade, referring to their geographic distribution within Arabia (Fig. 1B).
On the one hand, the eastern clade included P. rupestris iranicus Schmidt, 1952, distributed across the southern coast of Iran and P. r. rupestris, distributed throughout the Hajar Mountain range in northern Oman and eastern UAE, with scattered populations outside the Hajar Mountains on the northern UAE coast, from Sharjah to Abu Dhabi, and also in Qatar, Bahrain and the eastern coast of Saudi Arabia. A later study by Garcia-Porta et al. (2017) revealed that the subspecies P. r. rupestris was a species complex composed of 14 putative species divided into five deep lineages that started diverging approximately 15 million years ago. More recently, Saberi-Pirooz et al. (2019) analyzed specimens across the distribution range of P. r. iranicus and showed that the Iranian subspecies branched within the deep lineage composed of specimens from the type locality of P. r. rupestris (Muscat, Oman), making P. r. rupestris paraphyletic. Considering these molecular results and the lack of morphological evidence, P. r. iranicus was synonymized with P. rupestris (Saberi-Pirooz et al. 2019). Still unpublished genomic data indicate that each one of the five deep lineages of Garcia-Porta et al. (2017) represents a species: P. rupestris (including the synonymized P. r. iranicus) plus four new species that are in the process of being described (work in progress).
On the other hand, the western clade of “P. rupestris” (Badiane et al. 2014; Fig. 1) was distributed from central coastal Oman, through Yemen, Saudi Arabia and north to southern Jordan, from where the subspecies P. r. guweirensis Haas, 1943 (fide Kluge 2001), initially described as P. flavipunctatus guweirensis Haas, 1943 and then assigned to P. rupestris sensu lato by Leviton et al. (1992), was described from the sandstone desert of Guweira (=Quweira), 10 km south of the city of Quweira, Jordan (Haas 1943). Haas (1943) referred in his description to two male and two female type specimens all deposited in the herpetological collections of the Natural History Museum Vienna, though only a single syntype, NMW 17468, is present and inventoried based on the collection’s recent type catalogue (Gemel et al. 2019). Apart from P. r. guweirensis and several specimens of the western clade from Arabia that could be included in the molecular analyses (Fig. 1), Badiane et al. (2014) suggested that one female of Pristurus from “Bender Cassim” (=Bosaso), described as Pristurus migiurtinicus Scortecci, 1933 and later synonymized with P. rupestris by Parker (1942), might also be part of the western clade of “P. rupestris” and therefore it could take precedence over P. r. guweirensis to name the western clade. Unfortunately, the holotype of Pristurus migiurtinicus housed at the Museo Civico di Storia Naturale di Milano under reference MSNM Re97 (formerly 1323) had been sent on loan to the Natural History Museum, London back in 1980 and the type was apparently lost. As a result of the impossibility of studying the holotype of P. migiurtinicus, it was not possible to know which of the two names, P. guweirensis (=P. r. guweirensis elevated to species) or P. migiurtinicus, should be applied to the western clade of “P. rupestris”. Therefore, until new material of P. migiurtinicus from the type locality in Somalia or the holotype was found, Badiane et al. (2014) suggested to refer to the western clade temporarily as Pristurus sp. 1 (Garcia-Porta et al. 2017; Carranza et al. 2018, 2021; Tejero-Cicuéndez et al. 2021a, 2022). Aloufi et al. (2021) recently indicated that the species name guweirensis might be available for this group, but still referred to Pristurus sp. 1 awaiting further clarification of its taxonomic status.
After almost a decade, new data has become available making it possible to revise the taxonomy of Pristurus sp. 1 with the objective of clarifying the name of one of the most abundant reptile species in Arabia. The holotype of P. migiurtinicus on loan from the Museo Civico di Storia Naturale di Milano (MSNM Re97), was finally located in the reptile collection of the Natural History Museum, London and could be studied morphologically. A total of 1,135 high quality photographs from 291 specimens of Pristurus, including 19 photographs of the holotype of P. migiurtinicus, were taken and deposited at MorphoBank project number P4514 (http://morphobank.org/permalink/?P4514)
Despite 10 expeditions (140 fieldwork days) to Somaliland carried out by one of the authors (T.M.), no specimens that could be assigned to P. migiurtinicus or specimens morphologically similar to “P. rupestris” (Scortecci 1933, 1935; Parker 1942) were found. In fact, all the specimens found in the areas where P. migiurtinicus and “P. rupestris” supposedly occurred corresponded to the P. flavipunctatus Rüppell, 1835 species complex. Interestingly, in these areas P. flavipunctatus was seen not only on the trees, but also on the ground and on rocks like “P. rupestris” (T.M. pers. observ.). As for the single male “P. rupestris” specimens reported by Scortecci (1935) collected in 1931 at Bio Culul (Bender Cassim), Somalia, it most probably belongs to the P. flavipunctatus species complex, which at the moment includes at least four undescribed species (P. sp. 6, P. sp. 8, P. sp. 10 and P. sp. 11 in Tejero-Cicuéndez et al. 2021a, 2022).
The close morphological examination of the single available female specimen of P. migiurtinicus, i.e. the holotype (MSNM Re97), indicated that it does not belong to Pristurus. sp. 1 (western clade of Badiane et al. 2014; Fig. 1) or to the Pristurus rupestris species complex. The main differences between the single female of P. migiurtinicus and Pristurus. sp. 1 and P. rupestris include: 1.- a larger snout-vent length (SVL) of P. migiurtinicus (28 mm) versus an average of 24.3 mm (σ = 2.5), with only one female out of the total of 50 Pristurus. sp. 1 females analyzed having an SVL larger than 28 mm (28.03 mm), and an average of 23.7 mm (σ = 1.77), in P. rupestris, with all the 81 specimens analyzed having an SVL smaller than 28 mm (Supplementary Table 1; SVL data from Tejero-Cicuéndez et al. 2021b); 2.- a round tail in P. migiurtinicus without any enlarged scales (crest) on the dorsal or ventral sides versus a laterally compressed tail sometimes with a few enlarged scales on the dorsal and/or the ventral side in Pristurus. sp. 1 females (very clear dorsal and ventral crests in males) and usually with enlarged scales (crest) on the dorsal and ventral sides of the tail in P. rupestris females (very clear dorsal and ventral crests in males) (Fig. 1; Supplementary Table 1); 3.- presence of two enlarged postmental scales in P. migiurtinicus versus 3–6 not enlarged, or slightly enlarged, postmental scales in both Pristurus. sp. 1 and P. rupestris (Fig. 1; Supplementary Table 1).
The comparison of P. migiurtinicus with females of P. flavipunctatus showed that it is not a wrongly identified P. flavipunctatus. Although the dorsal pattern of P. migiurtinicus matches that of some female P. flavipunctatus, with a light dorsal continuous mid-dorsal stripe with blotches extending from the occiput to the tail base (or well into the tail in some specimens of P. flavipunctatus), and the SVL of P. migiurtinicus falls within the observed SVL range of P. flavipunctatus females (29.1 mm; σ = 4.2), there are the following differences: 1.- a round tail in P. migiurtinicus without any enlarged scales (crest) on the dorsal or the ventral sides versus a laterally compressed tail always with enlarged scales (crest) on the dorsal and ventral sides of the tail in P. flavipunctatus females (very conspicuous dorsal and ventral crests in males) (Supplementary Table 1; Baha el-Din 2006; Arnold 1986); 2.- absence of enlarged scales (crest) on the body in P. migiurtinicus versus presence of a mid-dorsal line of enlarged scales (an obvious crest in males) that extends anteriorly from the tail into the sacrum region in P. flavipunctatus females (or well into the body in some males) (Supplementary Table 1; Baha el-Din 2006; Arnold 1986); 3.- presence of enlarged postmental scales in P. migiurtinicus versus absence of enlarged postmental scales or presence of slightly enlarged postmental scales in in P. flavipunctatus (Supplementary Table 1).
Based on the morphological evidence, we conclude that P. migiurtinicus is clearly not a “P. rupestris” as suggested by Parker (1942) and following authors, and it is also not a P. flavipunctatus. Therefore, we suggest to resurrect this taxon from the synonymy of P. rupestris and to consider it as a valid Pristurus species. With respect to the valid name that should apply to the western clade of “P. rupestris” of Badiane et al. (2014) provisionally referred to as Pristurus. sp. 1 (Garcia-Porta et al. 2017; Carranza et al. 2018, 2021; Tejero-Cicuéndez et al. 2021a,b, 2022), we conclude that the name Pristurus guweirensis stat. nov. Haas, 1943 should be used from now on. Its redefinition, preceded by a short synonymy/chresonymy list, is given below:

Pristurus guweirensis stat. nov. Haas, 1943

Pristurus flavipunctatus guweirensis Haas 1943 ('Guweira, between Ma'an and Guweira Police Station', Jordan)
Pristurus rupestris guweirensis — Hoofien 1960
Pristurus flavipunctatus guweirensis — Fritz & Schütte 1987
Pristurus flavipunctatus guweirensis — Werner 1987
Pristurus rupestris guweirensis — Disi 1991
Pristurus rupestris guweirensis — Leviton et al. 1992
Pristurus rupestris guweirensis — Kluge 2001
Pristurus rupestris guweirensis — Rösler et al. 2008
Pristurus rupestris guweirensis — Sindaco & Jeremčenko 2008
Pristurus rupestris guweirensis — Sindaco et al. 2014
Pristurus rupestris guweirensis — Yousofi et al. 2015
Pristurus sp. 1 — Badiane et al. 2014; Garcia-Porta et al. 2017; Carranza et al. 2018, 2021; Tejero-Cicuéndez et al. 2021a, 2022; Aloufi et al. 2021

As shown by Badiane et al. (2014) and Carranza et al. (2018, 2021), the species now known as P. guweirensis is the most widely distributed species of Pristurus, extending across Oman, Yemen, Saudi Arabia and southern Jordan. It is also the most abundant species of Pristurus and most probably one of the most abundant reptile species in Arabia (S.C. pers. observ.). It is a mainly diurnal species, although it can also be seen active after sunset. It is very abundant on rocks, boulders, tree trunks, and human-made structures such as walls, houses, and gardens. It performs complex signaling including push-ups, inflating and laterally compressing the body and throat, and curling and waving the tail up over the back. It preys on ants and other arthropods. Females lay single hard-shelled eggs throughout the year. It plays an important ecological role and it is the most sighted species in biodiversity surveys carried out within its distribution range (S.C. pers. observ.). In view of the complex taxonomic situation within the P. rupestris complex in general, it is of high importance to have finally solved the taxonomic status of P. guweirensis.