Stenodactylus sharqiyahensis, Metallinou, Margarita & Carranza, Salvador, 2013

Metallinou, Margarita & Carranza, Salvador, 2013, New species of Stenodactylus (Squamata: Gekkonidae) from the Sharqiyah Sands in northeastern Oman, Zootaxa 3745 (4), pp. 449-468 : 456-462

Stenodactylus sharqiyahensis sp. nov.

( Figs. 4–8 ; Table 3 )

Stenodactylus arabicus Arnold, 1980b: 370 (part.); Arnold, 1986b: 422 (part.), Gallagher and Arnold, 1988: 407; Leviton, Anderson, Adler and Minton, 1992: 43 (part.); Sindaco and Jeremcenko, 2008: 312 (part.); van der Kooij, 2000: 118 (part.); Fujita and Papenfuss, 2011: 1 (part.)

Stenodactylus cf. arabicus Metallinou et al. 2012: 3

Holotype. NMP 6 V 74955 (sample code S7568), male, from Al Sharqiyah Sands, Oman, 22.45379N 58.67551E WGS84, collected on the 4th of May 2011 by S. Carranza, E. Gómez-Díaz and F. Amat ( Fig. 4 A,B).

Paratypes. NMP 6 V 74953 (sample code S7925); NMP 6 V 74954 (sample code S7965); ONHM3715 (sample code S7908); MCCI-R1809 (sample code S7993). All paratypes are female and were collected at Al Sharqiyah Sands, Oman, 22.44492N 58.66177E WGS84, on the 17th of October 2010 by S. Carranza and F. Amat ( Figs. 4 C, 6A, 8A).

Other material examined. Twenty-two vouchers listed in Appendix I under S. sharqiyahensis sp. nov., apart from holotype and paratypes. Photographic material from eleven vouchers from the BMNH and CAS listed in Appendix II, not included in the genetic or morphometric analyses. Finally, samples UAE 63, UAE 64, S3463, S3217 were included in the molecular analyses only (Appendix I).

Etymology. The species epithet “ sharqiyahensis ” is an adjective that refers to the desert where all the specimens that belong to this species have been found to date, and to where the species is probably endemic, Al Sharqiyah Sands, in northeastern Oman.

Diagnosis. A small-sized Stenodactylus characterized by the following combination of morphological characters: (1) maximum recorded SVL 34.97 mm (27.76–32.22 mm in males and 27.45–34.97 mm in females); (2) body distinctly depressed and not slender; (3) head narrow (4.94–6.68 mm); (4) relatively short limbs; (5) tail about the same length as SVL or slightly shorter (TL/SVL=0.86–1.07) and not slender; (6) 10–12 upper labials in males and 10–13 in females; (7) 8–11 lower labials in males and 10–11 in females; (8) snout relatively short and round; (9) moderately protuberant nostrils (92.60% of specimens); (10) webbing between fingers not very extended (100% of specimens).

Stenodactylus sharqiyahensis sp. nov. is generally similar to its sister taxon, S. arabicus , but may be differentiated from it by its smaller maximum SVL (34.97 mm versus 37.73 mm); snout relatively round and short (snout length 3.56 ± 0.05 mm versus 3.93 ± 0.06 mm, P <0.05; Fig. 5 C,D); limbs relatively short (versus relatively long and slender, in all four independent limb measurement characters, P <0.05; Fig. 6 ); tail thicker (1.57 ± 0.05 mm versus 1.27 ± 0.05 mm, P <0.05; Fig. 6 ) and shorter (30.33 ± 0.79 mm versus 35.56 ± 0.82 mm, P <0.05; Fig. 6 ); 10– 12 upper labials in males (versus 12–14, P <0.05); 10–13 upper labials in females (versus 14–17, P <0.05); 8–11 lower labials in males (versus 10–12, P <0.05); 11–10 lower labials in females (versus 13–10, P <0.05); upper profile of snout mainly straight or mixed (41.15% or 29.63%), often also convex (22.22%) but not concave ( Fig. 5 A) (versus straight in only 19.23% or concave in 61.54% of specimens but not convex; P <0.001; Fig. 5 B); most of the animals with moderately protuberant nostrils (92.60%) and very few with strongly protuberant nostrils (3.70%) (versus strongly protuberant nostrils in most of the animals (61.54%), P <0.001; Fig. 5 A,B); webbing between fingers not very extended (versus extended webbing; Fig. 7 ).

Genetic and phylogenetic remarks. The phylogenetic analyses by Fujita and Papenfuss (2011) and Metallinou et al. (2012) clearly indicate that S. arabicus and S. sharqiyahensis sp. nov. (referred to as S. arabicus by Fujita & Papenfuss 2011 and as S. cf. arabicus by Metallinou et al. 2012) are two genetically well differentiated sister taxa. The phylogenetic and network analyses performed in this study support this hypothesis ( Figs. 2 and 3 ) and show that the level of genetic differentiation (p -distance) between S. sharqiyahensis sp. nov. and S. arabicus for the dataset assembled here is of 8.1 ±1.3% for the 12S and 4.6 ±0.8% for the 16S. A network analysis of the nuclear gene MC1R indicates that, despite the large amount of samples included (48 specimens, 96 alleles), there is no haplotype sharing between the two species ( Fig. 3 ).

Description of the holotype. NMP 6 V 74955. Data on 14 morphometric, five meristic and three categorical variables (see Material and Methods) are provided in Table 3 . Adult male, small (SVL 28.30 mm), body distinctly depressed. Tongue muscle removed completely for tissue sample; fourth upper labial scale from the right side slightly damaged (approximately 1/5 of the scale is cut transversally and folded inwards). Head relatively narrow (HW/SVL=0.19), with round and not very elongated snout. Rostral roughly rectangular with a median notch above. Nostrils moderately protuberant, directed outwards, forwards and slightly upwards, defined by rostral, upper labial (both entering broadly into lower nostril border), and three supranasals in contact with upper border; inner supranasals in contact with rostral and separated from each other by a minimum of two flat polygonal scales. Snout straight in lateral view; 12/12 (right/left) upper labial scales with slightly rounded contour, gradually diminishing in size away from the tip of the snout. Size and shape of head scales very variable: in areas adjacent to the upper labials small, almost granular and not imbricate; in the upper side of the snout relatively large, hexagonal or rounded, and not imbricate; above the head (interorbital region) relatively large, hexagonal or triangular, slightly imbricate; in the temporal region (between the eye and the ear opening) medium sized, not imbricate or slightly imbricate. Lower labials 11/11. Mental ovoid, broader than long. No postmentals. Left border of mental almost at the same level as the border between rostral and 1st left upper labial; right border of mental half way into the 1st right upper labial. Ear opening small, elliptical elongated, at an angle of approximately 25º towards the back of the head. Eyes very large, (ED/SVL = 0.084), pupil vertical, upper part of palpebral fold not very developed.

Scales on the body and extremities variable: on the dorsal and ventral surfaces of the hind limbs larger, keeled and distinctly imbricate, increasing in size towards the distal part of the limbs; gular and anteriormost ventral scales small, cycloid and juxtaposed or slightly imbricate, increasing in size and in the degree of imbrication towards the pelvic area; dorsal scales cycloid at sides and more elongated in the middle areas of the back, and like the gular, juxtaposed or slightly imbricate. Scales on the proximal parts of tail elongated, of similar size as those on hind limbs, imbricated, with up to three keels, and organized in transverse whorls. Hemipenial swellings very obvious, with two visible elliptical openings below the vent; three cloacal tubercles in one row. Fingers on forefeet elongated, with elongated scales on the sides (fringes), flat and with several (5–10) small scales underneath. Presence of webbing between the fingers but not very extended, up to a maximum of 30-40% of the total length of fingers. Toes on the hind limbs also elongated, fringed, flat or slightly rounded and with numerous small scales underneath.

Coloration in alcohol, whitish-yellow above and white underneath ( Fig. 4 A,B). Trunk region comprised between the forelimb and the hind limb whiter than the tail, hind limbs, gular and pelvic areas. Tail increasingly whiter towards the tip, with eight dark bands that increase in intensity distally, contrasting with similar sized pale interstices; the most distal four bands extend to ventral surface. Proximal parts of the underside of tail with dark blotches. There is a strong continuous (uninterrupted) dark band starting from the snout (crescent-shape in this area) and extending along both right and left sides to the eyes, over the ear openings, shoulders, across the back and up to the base or proximal part of the tail. Another hardly weaker, continuous dark band joins the fore and hind limbs across the lower lateral parts of the body. A further two dark bands run over the dorsal part of both hind limbs, although in this case the bands are interrupted at some points. Two other less conspicuous bands start over the eyes and run in the form of pale streaks or blotches on each side and very close to the vertebral area, up to the beginning of the tail. A transversal dark band across the back of the head that fades out when reaching these latter bands on the sides. Dorsal color in life (data not shown) much richer than in the fixed specimen from Fig. 4 A,B. Dorsal side pink-orange, almost identical to paratype NMP 6 V 74954 ( Fig. 8A ), and matching the color of the sands of the general area where it was collected (Appendix I and Fig. 8 C). Underside, white from neck to the anterior margin of the pelvic area; pink or slightly transparent elsewhere on the underside of the four limbs, gular and pelvic areas, as well as in a narrow band between the two upper arms (almost identical to specimen depicted in Fig. 8 B). Iris in life colorful, orange, with brown venation; the dark band that extends across the whole body crossing through it and being only interrupted by a yellow central vertical stripe. Again, almost identical in coloration to the eye of paratype NMP 6 V 74954 depicted in Fig. 8A .

Variation. Data on 14 continuous, five meristic and three categorical variables (see Material and Methods) for all four paratypes, NMP 6 V 74953, NMP 6 V 74954, ONHM 3715 and MCCI-R1809, are provided in Table 3 . A dorsal picture of the four preserved paratypes is presented in Fig. 4 C. All the specimens are very similar to each other, varying slightly in size related measurements, number of upper and lower labials and snout shape (holotype straight; NMP 6 V 74954, NMP 6 V 74953 and MCCI-R1809 mixed - convex from anteriormost point of the eye to mid-snout switching to concave from mid-snout to tip of the snout; and ONHM 3715 convex) ( Table 3 ). Paratype NMP 6 V 74953 has regenerated tail; paratypes NMP 6 V 74954 and MCCI-R1809 both have their tails broken at the base but severed pieces are preserved intact together with the specimens ( Fig. 4 C). Main coloration very similar to the holotype, with the same continuous strong dark bands across the body (crescent-shape across the snout), with paler vertebral blotches and interrupted band on the dorsal part of the four limbs.

Although very little variability has been detected in the main characteristics of S. sharqiyahensis sp. nov., in some specimens collected at the very southern tip of the Sharqiyah Sands (approximately 200 km south of the type locality) (IBECN208, IBECN2788, IBECN2819, IBECN2615, IBECN2813; see Appendix I), the dark bands across the body are less marked, less strong and with different degree of interruption (specimens IBECN2802 and IBECN2615 slightly interrupted; specimens IBECN2788, IBECN1819 and IBECN2813 with large interruptions).

Distribution. Despite intensive sampling across large areas of Oman carried out between 2004 and 2013, S. sharqiyahensis sp. nov. has only been found within the confines of the Sharqiyah Sands in northeastern Oman ( Fig. 1 ). It can be therefore considered endemic to this ecologically relevant, arid area of the country.

Natural History. Strictly nocturnal, S. sharqiyahensis sp. nov. is always found on soft sands with patchy vegetation ( Fig. 8 C). Although it usually sits still underneath small bushes like Zygophyllym sp., very common in the Sharqiyah Sands, it has also been found away from any bushes or plants, probably while moving from one spot to the other. It is most probably a sit-and-wait predator, ambushing small insects from underneath the plant coverage. In a full moon day of March 1986, it was observed at Qarhat Mu’ammar (21.63N 59.30E) near trees where one specimen was watched burrowing into soft sand (Gallagher & Arnold 1988). This behavior is very common in its sister species, S. arabicus , which uses its frontal extensively webbed feet as shovels to dig into the sand. As a result of its nocturnal habits, small size, and dorsal color matching the color of the sand where it lives, this lizard was not seen frequently in previous surveys in the Sharqiyah Sands (Gallagher & Arnold 1988). However, our own observations indicate that it is rather common and occurs in medium to high densities, especially in suitable areas like the ones around the locality where the holotype and the paratypes were collected (Appendix I). It has never been found under dead wood, stones, or any other material deposited on the floor, so it probably spends the day inside burrows or buries itself into the ground at the base of plants. It has been found right after sunset (dusk) through the night, but it has never been found after sunrise. It has been observed in sympatry with the much bigger in size Stenodactylus doriae and S. leptocosymbotes , on strictly sandy substrate or slightly harder one, respectively. Other reptiles found in the localities where S. sharqiyahensis sp. nov. has been collected include Acanthodactylus schmidti , Bunopus tuberculatus , Cerastes gasperetti , Diplometopon zarudnyi , Eryx jayakari , Hemidactylus homoeolepis , Lytorhynchus diadema , Pristurus carteri , Pristurus minimus and Scincus mitranus .

Figures

FIGURE 1. Map of localities of examined material in this study. Circles indicate samples used in the genetic analyses, squares indicate samples used in morphological analyses and diamonds indicate specimens examined through photographic material from museum collections. Arrows indicate type localities of S. arabicus and S. sharqiyahensis sp. nov. Exact localities of all specimens can be found in Appendices I and II.

FIGURE 2. ML tree of S. arabicus and S. sharqiyahensis sp. nov. inferred using 12 S, 16 S mtDNA and MC 1 R nuclear gene fragments. Bootstrap values ≥ 70 % are shown next to the nodes. Black circles on nodes indicate posterior probability values ≥ 0.95. The tree was rooted using S. pulcher. Information on the samples included is given in Appendix I.

FIGURE 3. Haplotype network of the phased sequences of nuclear marker MC 1 R. Phase probabilities were set as ≥ 0.7. Information on the samples included is shown in Appendix I.

FIGURE 4. Holotype and four paratypes of Stenodactylus sharqiyahensis sp. nov. A-B) Male holotype NMP 6 V 74955; C) Female paratypes, from left to right: NMP 6 V 74953, NMP 6 V 74954, ONHM 3715 and MCCI-R 1809. Scale bars = 5 mm.

FIGURE 5. Comparison of head and snout of specimens of S. sharqiyahensis sp. nov. and S. arabicus. A, C) Profile and dorsal view of head of female of S. sharqiyahensis sp. nov. from the central-west margin of Al Sharqiyah Sands (21.62177 N 58.28301 E), Oman (IBECN 8135); B, D) Profile and dorsal view of head of male of S. arabicus from Ramlat bu Tabul, Oman (IBECN 8658). Scale bars = 3 mm.

FIGURE 6. Comparison of habitus in life and of 70 % alcohol-preserved specimens of S. sharqiyahensis sp. nov. (left) and S. arabicus (right). A) Female paratype of S. sharqiyahensis sp. nov. in life, from Al Mintrib, Al Sharqiyah Sands, Oman (NMP 6 V 74953); B) Subadult of S. arabicus in life, from Ramlat bu Tabul, Oman (IBECN 209); C) Female of S. sharqiyahensis sp. nov. from the central-west margin of Al Sharqiyah Sands (21.62177 N 58.28301 E), Oman (IBECN 8135); D) Male of S. arabicus from Ramlat bu Tabul, Oman (IBECN 8658). Scale bars = 5 mm.

FIGURE 7. Comparison of forelimb of specimens of S. sharqiyahensis sp. nov. (first and third from left) and S. arabicus (second and fourth from left). A, C) Dorsal and ventral view of right forearm of male from Al Mintrib, Al Sharqiyah Sands, Oman (IBECN 8160); B, D) Dorsal view of right forearm and ventral view of left forearm of male of S. arabicus from Ramlat bu Tabul, Oman (IBECN 8658).

FIGURE 8. A) Female paratype of S. sharqiyahensis sp. nov. in life, with nested detail of eye, from Al Mintrib, Al Sharqiyah Sands, Oman (NMP 6 V 74954); B) underside of live male from Al Mintrib, Al Sharqiyah Sands, Oman (IBECN 8160); C) Al Mintrib, Al Sharqiyah Sands, Oman (around the general area where the type material was collected). Specimens of S. sharqiyahensis sp. nov. were found during the night, on the sandy substrate, close to bushes.

Tables

TABLE 3. Morphometrical, meristic and categorical data for the holotype and the four paratypes of Stenodactylus sharqiyahensis sp. nov. (reg.: regenerated tail)

	Holotype Paratype Paratype NMP6 V 74955 NMP6 V 74954 NMP6 V 74953	Paratype ONHM 3715	Paratype MCCI-R1809
Sex	Male Female Female	Female	Female
SVL	28.30 34.38 34.06	27.45	33.36
Head-neck length (HNL)	12.57 14.76 14.10	11.14	13.69
Head length (HL)	7.44 8.62 8.70	7.13	8.34
Snout length (SL)	3.36 3.91 3.96	3.34	3.82
Snout height (SH)	2.99 3.05 3.13	2.45	3.17
Distance between eyes (EW)	2.53 2.95 3.24	2.48	2.44
Maximum head with (HW)	5.47 5.82 5.99	4.94	5.70
Eye diameter (ED)	2.37 2.38 2.39	2.08	3.31
Forearm length (FL)	3.84 4.63 4.42	3.91	4.57
Arm length (AL)	4.48 4.22 4.2	3.82	3.90
Tibia length (BL)	4.94 5.89 6.03	4.67	5.93
Femur length (ML)	5.29 5.88 6.41	4.81	6.33
Tail length (TL)	29.96 27.85 24.15 (reg.)	27.93	36.88
Tail width (TW)	1.41 1.60 1.56 (reg.)	1.51	1.63
Upper labial scales (ULS)	12 12 11	11	12
Lower labial scales (LLS)	11 10 10	10	11
Scales between supranasals (SS)	2 2 2	2	2
Cloacal tubercles row 1 (CT1)	3 2 2	3	3
Cloacal tubercles row 2 (CT2)	0 0 0	0	0
Perinarial protrusion (PP)	3 3 3	3	3
Snout shape (SP)	2 4 4	1	4
Extended webbing (WB)	1 1 1	1	1