Pseudotrapelus tuwaiqensis, Tamar & Uvizl & Shobrak & Almutairi & Busais & Salim & AlGethami & AlGethami & Alanazi & Alsubaie & Chirio & Carranza & Šmíd, 2023

Tamar, Karin, Uvizl, Marek, Shobrak, Mohammed, Almutairi, Mohammed, Busais, Salem, Salim, Al Faqih Ali, AlGethami, Raed Hamoud M., AlGethami, Abdulaziz Raqi, Alanazi, Abdulkarim Saleh K., Alsubaie, Saad Dasman, Chirio, Laurent, Carranza, Salvador & Smid, Jiri, 2023, A new species of Pseudotrapelus (Reptilia: Squamata: Agamidae) from Central Arabia, Vertebrate Zoology 73, pp. 1033-1045 : 1033

Pseudotrapelus tuwaiqensis sp. nov.

MorphoBank, project 4714, M862812-M863071 Figures 1 , 2 , 3 , 4 , 5 , 6

Chresonymy.

Agama ( Pseduotrapelus [sic]) Pseudotrapelus sinaita in Al-Sadoon (1988)

Agama (Pseudotrapelus) sinaita in Al-Sadoon et al. (1991)

Pseudotrapelus sinaitus in Kordges (1998)

Pseudotrapelus sp. in Tamar et al. (2019b)

' Pseudotrapelus sp Riyadh’ in Šmíd et al. (2021)

Holotype.

NMP-P6V 76634 (sample CN6252), adult male, a hill in a wadi, north-west to Thumamah, Saudi Arabia (25.592°N, 46.401°E; 670 m elevation), collected by Laurent Chirio on 25th March 2016 (Fig. 4 ; MorphoBank accessions M862812-M862870).)

Paratypes.

NMP-P6V 76635 (sample CN13348), adult female, foothill of Jebel Baloum, Saudi Arabia (23.699°N, 46.173°E; 800 m elevation), collected by Laurent Chirio on 27th April 2018 (Fig. 5A ; MorphoBank accessions M862871-M862941). NMP-P6V 76636 (sample CN15766), adult female, north west of King Khalid Royal Reserve, north of Riyadh, Saudi Arabia (25.45933°N, 46.56276°E, 630 m elevation), collected by Salvador Car-ranza, Jiří Šmíd, and Mohammed Shobrak on 14th June 2019 (Fig. 5B ; MorphoBank accessions M862992-M863071)

Other examined specimen.

NMP-P6V 76637 (sample CN15755), juvenile, west of Al-Kharj, south of Riyadh, Saudi Arabia (24.15093°N, 46.9317°E, 530 m elevation), collected by Salvador Carranza, Jiří Šmíd, and Mohammed Shobrak on 15th June 2019 (MorphoBank accessions M862942-M862990)

Etymology.

The species epithet tuwaiqensis is derived from the geographic feature the species is associated with, the Tuwaiq Escarpment, that cuts through central Saudi Arabia from the southwest of the country to slightly north and northwest of the city of Riyadh.

Diagnosis.

A Pseudotrapelus species forming a clade together with P. sinaitus and P. chlodnickii , with the following combination of morphological and genetic characters: (1) large size with a total length of 200-203 mm and SVL 70.7-76.6 mm; (2) 14-19 upper and 14-18 lower labial scales; (3) ear opening very large, oval, rimmed anterodorsally by conical scales of different sizes that give it a serrated appearance; (4) scales in the occipital area predominantly not enlarged; (5) heterogeneous dorsal scales with the mid-dorsals being distinctly keeled and larger than the scales on the flanks; (6) one continuous row of 4-7 precloacal pores in both sexes; (7) 3rd toe longer than the 4th; (8) tail scales not arranged in whorls; (9) body and tail beige-brown in life with dark brown or orange transverse bars, the first on the nape, the second and the most prominent one in the scapular region, the third at midbody, the fourth in front of the insertion of the hind limbs, the fifth at the tail base; and the tail with regular dark bars down its length; (10) three unique mutations in the MC1R alignment: position 264 C instead of T, position 508 G instead of A, position 562 G instead of C; (11) one unique mutation in the c-mos alignment in position 202 C instead of G (see Appendices 5, 6).

Differential diagnosis.

The genus Pseudotrapelus is mor-phologically very conservative, and it is virtually impossible to phenotypically distinguish one species from another without knowing precise locality data. Pseudotrapelus tuwaiqensis sp. nov. is no exception to this. While available literature and recent descriptions of new species indicate some key features that allow species identification, these do not hold when confronted with additional material (Table 1 ). For example, one of the diagnostic characters of P. jensvindumi was a small gap in the middle of the precloacal pores row ( Melnikov et al. 2013a). However, similar state is present in some other species including P. aqabensis (specimen CN15112, MorphoBank accessions: M862611-M862613), P. dhofarensis ( Melnikov and Pierson 2012, fig. 7 therein; JIR107, MorphoBank accession: M862670), and P. sinaitus (JOR22_75, MorphoBank accession: M862793; JOR22_85, MorphoBank accession: M862799). Similarly, P. neumanni is supposedly the only species with enlarged scales in the occipital area of the head ( Melnikov et al. 2013a), but our examination of specimens of the other species revealed that in fact all but P. aqabensis and P. sinaitus have these enlarged scales present, at least in some specimens. In line with the above-said, our morphological examinations of P. tuwaiqensis sp. nov. did not reveal any characters that would be unique for the species and allowed its unambiguous identification (Table 1 ). As a result, we advise caution and prudence when trying to key out Pseudotrapelus specimens on the basis of morphology alone.

With the currently available evidence, the safest and perhaps the only way to differentiate the individual Pseudotrapelus species is either based on the origin of the specimens, or by using DNA barcoding. The ranges of most species are allopatric or parapatric, with P. tuwaiqensis sp. nov. being the only species that occurs in central Saudi Arabia around the city of Riyadh and further to the north and south along the Tuwaiq Escarpment. The other species are distributed in the peripheral mountain ranges of Arabia and some of them overlap to a certain extent (e.g., P. neumanni and P. dhofarensis in Yemen, P. neumanni and P. aqabensis in southwestern Saudi Arabia, P. aqabensis and P. sinaitus in northwestern Arabia; Fig. 1 ). The most reliable species identification tool in Pseudotrapelus is thus DNA barcoding. All presently recognized species have multiple specimens sequenced for three mitochondrial genes, including the COI marker that is the most commonly used barcode for animal identification ( Vences et al. 2012) and show marked genetic differentiation in all these markers across species (Appendix 4). Pseudotrapelus tuwaiqensis sp. nov. can be clearly differentiated from its congeners at the genetic level by p-distances of 6.3-8.6% in 16S, 15.3-19.8% in ND4, and 13.6-15.9% in COI (Appendix 4). In addition, all Pseudotrapelus species have been sequenced for two nuclear genes, of which the MC1R has unique alleles for each species and the c-mos has unique alleles for P. tuwaiqensis sp. nov., P. sinaitus , and P. chlodnickii (Fig. 3 ; Appendices 5, 6). Pseudotrapelus aqabensis , P. dhofarensis , P. jensvindumi , and P. neumanni are genetically indistinguishable in the c-mos sequences.

Description of the holotype.

Total length 203.9 mm (SVL 70.7 mm; original tail 133.2 mm). Head and body depressed (Fig. 4A, B ). Three internasal scales, the middle one is triangular and contacts the rostral dorsally. Nostril tubular directed laterally and slightly posterodorsally, pierced in the posterior part of a large convex, smooth, pear-shaped nasal scale, which is situated on the anterior edge of the canthus rostralis. The nasal scale is partially visible from above and directly in contact with the first canthal scale. The first six canthal scales not in contact with the eye. Scales on the head smooth, somewhat polyhedral, interorbital scales as large or larger than the supraorbital scales; imbrications of temporal scales directed ventrally. Occipital pierced by a visible pineal foramen posteriorly, surrounded by irregular scales. Occipital scales are somewhat smaller than other head scales (Fig. 4C ). 19 (left)-17 (right) upper and 18 (left)-17 (right) lower labial scales (Fig. 4D, E ). Ear opening as large as the eye, surrounded at its border by several single short conical scales of different sizes, with one single conical scale at the lower anterior edge of ear opening (Fig. 4E ). Gular fold absent. Dorsal scales heterogeneous with a medial longitudinal rows of enlarged scales present. Medial dorsal scales diamond shaped and distinctly keeled, with the keel extending along the entire scale and not mucronate. Lateral scales not keeled. Gular and ventral scales smooth, becoming feebly keeled toward the lateral side of the body. Dorsal scales on limbs keeled and imbricate. Hind limbs long with the 3rd toe reaching to the nostril level when adpressed. The 3rd toe is the longest, reaching 9.3 mm (Fig. 4F ). Ten lamellae under the left 4th finger, 17 lamellae under the left 4th toe. Forelimbs long with digits reaching to the cloaca when adpressed. The 3rd finger is the longest, reaching 6.5 mm. One row of six continuous precloacal pores each about the size of two to three other precloacal scales (Fig. 4G ). Tail depressed at its base, with a small pit after the cloaca. Large hemipenial pockets are absent, but two small bulges on either side of the pit are present. Dorsal tail scales strongly keeled, slightly mucronate, somewhat larger than the body scales. Ventral tail scales keeled and slightly mucronate. Tail scales not arranged in whorls.

Coloration in life.

All specimens share the general coloration pattern (Figs 4H , 5 ). Body is light brown with faint light speckles scattered randomly on the body dorsum. Head is slightly darker than body and has a blue tint in females. The nape is dark. There are prominent dark brown transverse bars across the body, the first is behind the insertion of forelimbs and runs to about the middle of the flank. Another, shorter and less conspicuous dark band is situated before the hind limbs. In some specimens, another small transverse stripe is in the middle of the body, sometimes marked only as a small darker patch. The dark dorsal stripes are orange or have reddish outlines in females. All body parts are white from the ventral side except for the throat, which has a dark background with regular, white, and evenly spaced ocelli. In some specimens, the throat pattern is less discernible and the dark and light scales form a reticulated pattern.

Habitat and Distribution.

Pseudotrapelus tuwaiqensis sp. nov. is a rock-dwelling species inhabiting rocky areas, outcrops, isolated rock mounds and even dry riverbeds with large boulders (Fig. 6 ). Like all other Pseudotrapelus species, it perches on top of stones and rocks during the day. Individuals were found sleeping at night tucked in rock crevices or laying on the ground in the open.

Currently available distribution data indicate that the species is endemic to Saudi Arabia, where it is confined to central Saudi Arabia around the city of Riyadh (Fig. 1 ). Most records come from the Tuwaiq Escarpment that runs from southwestern Arabia northeastwards to Riyadh where it bends to the northwest. The escarpment is bordered by massive sand seas: Rub al Khali from the southeast, Ad Dahna from the east, and An Nafud from the north, which seem to form a barrier to dispersal for these rock-dwelling agamas. There are several records west of Tuwaiq, suggesting that the species’ range extends more to the west and is not confined to the escarpment. More field data are however needed to delineate the geographic limits of its distribution and its possible contact with P. aqabensis in the west and north-west, P. sinaitus in the northwest, and possibly P. neumanni in the southwest. Other reptile species observed to live in syntopy with P. tuwaiqensis sp. nov. were Bunopus tuberculatus , Stenodactylus doriae , Tropiocolotes wolfgangboehmei (all Gekkonidae ), Ptyodactylus hasselquistii ( Phyllodactylidae ), Acanthodactylus boskianus , Mesalina lineage 4 (sensu Sindaco et al. 2018; Lacertidae ), and Echis coloratus ( Viperidae ).

Figures

Figure 1. Geographic distribution of the genus Pseudotrapelus in Arabia and adjacent territories. The circles show distribution records, those in color have been confirmed genetically to belong to the respective species. The white circles can be identified with confidence only to the genus level. All known records for Saudi Arabia, Yemen, Oman, and the UAE are shown. The map is not exhaustive in terms of records of P. aqabensis, P. chlodnickii, and P. sinaitus from Jordan west to Africa. Locality details of the numbered localities of P. tuwaiqensis sp. nov. are given in Appendices 1 - 2.

Figure 2. Bayesian inference phylogenetic trees of Pseudotrapelus. The trees were reconstructed based on A the concatenated dataset (16 S, ND 4, tRNA, c-mos, MC 1 R) and B the barcoding COI marker dataset. Support values are indicated near the nodes (Bayesian posterior probabilities / SH-aLRT / UFBoot). Sample codes correspond to specimens in Appendices 1, 2. Letters in rectangles in the COI tree indicate type specimens - H: holotype, P: paratype, T: topotype.

Figure 3. Allele networks of Pseudotrapelus for the two nuclear markers. A c-mos and B MC 1 R. Circle sizes are proportional to the number of alleles. White circles represent mutational steps.

Figure 4. General appearance of Pseudotrapelus tuwaiqensis sp. nov. holotype (NMP-P 6 V 76634), adult male. A Habitus, dorsal view; B Habitus, ventral view; C Head, dorsal view; D Head, ventral view; E Head, lateral view; F Hind foot, ventral view; G Precloacal area, ventral view; H In life. Photos by Salvador Carranza (A-G) and Laurent Chirio (H).

Figure 5. General appearance of Pseudotrapelus tuwaiqensis sp. nov. A paratype NMP-P 6 V 76635, adult female. Photo by Laurent Chirio; B paratype NMP-P 6 V 76636, adult female. Photo by Jiri Smid; C Uncollected specimen from locality 25.45933 ° N, 46.56276 ° E. Photo by Marius Burger; D Uncollected specimen, locality Shaib-Luha, Saudi Arabia. Photo by Laurent Chirio.

Figure 6. Habitat of Pseudotrapelus tuwaiqensis sp. nov. A Locality of specimen NMP-P 6 V 76637 (24.15093 ° N, 46.9317 ° E). Photo by Jiri Smid; B Locality of paratype NMP-P 6 V 76636 (25.45933 ° N, 46.56276 ° E). Photo by Marius Burger.