Hemidactylus homoeolepis Blanford, 1881

Carranza, Salvador & Arnold, Edwin Nicholas, 2012, 3378, Zootaxa 3378, pp. 1-95 : 47-50

Hemidactylus homoeolepis Blanford, 1881

( Figs. 3, 5, 8, 19–21, Table 1; Appendix I; Appendix III)

MorphoBank M95683 – M95823 M100000–M100038 M102031–M102145

Hemidactylus (Liurus) homoeolepis Blanford, 1881: 464 . (Syntypes: BMNH1946.9.6.99 male, and 1946.9.7.1 female; Socotra Island, Yemen; collected by I.B. Balfour)

Hemidactylus homoeolepis: Arnold, 1977: 103 (part.); Arnold, 1980: 279 (part.); Arnold, 1986: 419 (part.); Schätti and Desvoignes, 1999: 50 (part.); van der Kooij, 2000: 111 (part.); Carranza and Arnold, 2006: 536; Sindaco and Jeremcenko, 2008: 115 (part.).

Material examined

Twenty-seven vouchers listed in Appendix I under the name H. homoeolepis . Juvenile specimens AO81, AO85, AO119 and samples S4209, S3399, S7091, JS5, JS6, JS8, JS75 were included in the molecular analyses only (Table 1).

Diagnosis

A small member of the H. homeolepis group with a maximum recorded SVL of 42 mm. Undepressed head; scaling fine without tubercles with the exception of specimen BMNH 1953.1.6.9 from Shaqara, Southwest Yemen, which presents large tubercles on the hind back, tail base and hind limbs. Lamellae under the 1 st toe of pes mean 4.7 (4–5); lamellae under the 4 th toe mean 8.4 (7–10); preanal pores mean 5.5 (3–6); expanded subcaudal scales beginning some way from tail base; dorsal pattern spotted. For differences from the three new species described herein formerly part of H. homoeolepis (clades E–G in Fig. 5 and Appendix III) see below.

Genetic and phylogeographic remarks

Hemidactylus homoeolepis is monophyletic in the phylogenetic analyses of Dataset 1 ( Fig. 5) and Dataset 3 (Appendix III). According to both Fig. 5 and Apendix III, H. homoeolepis is sister to a clade formed by two of the new species described below (clades F and G). This topology is very well supported and is maintained even if the two endemic Hemidactylus from the island of Abd Al Kuri ( Socotra Archipelago), H. oxyrhinus Boulenger, 1899 and H. forbesii Boulenger, 1899 are included in the analyses (Gómez-Díaz et al. in press). According to the analyses by Gómez-Díaz et al. (In press), the two endemics from Abd Al Kuri are sister taxa and branch within the “ H. homoeolepis group”, in a position between the new species from clade E (described below) and a monophyletic assemblage formed by clades F, G and H. homoeolepis . According to the results of the analysis of Dataset 2 (dates inserted in Fig. 5), H. homoeolepis split from its sister clade approximately 6.6 mya (95% HPD: 4.2–9.6) and the species colonized the Socotra Archipelago about 4.3 mya (95% HPD: 2.5–6.4). Since at that time Socotra was already close to its actual position ( Bosworth et al. 2005; Laughton 1966; Samuel et al. 1997), our data suggests that, similar to the skinks of the genus Trachylepis and the ancestor of the two endemic Hemidactylus from Abd Al Kuri, H. homoeolepis arrived to the archipelago by transmarine dispersal from Southeast Arabia (Gómez-Díaz et al. in press; Sindaco et al. in press.). The dates of origin of H. homoeolepis and colonization of the Socotra Archipelago by H. homoeolepis do not differ much from the inferred dates of these two events by Gómez-Díaz et al. (In press) using the same methods and calibrations but including H. oxyrhinus and H. forbesii (5.9 mya [95% HPD: 3.6–8.6] and 4.3 [95% HPD: 2.5–6.4], respectively).

Uncorrected genetic distances between H. homoeolepis and the other three members of the “ H. homoeolepis group” (described as new species below) are very high: H. homoeolepis vs. the new species from clade G ( Fig. 5, Appendix III) 13% in the cytb and 8.4% in the 12S; H. homoeolepis vs. the new species from clade F ( Fig. 5, Appendix III) 11.2% in the cytb and 8.8% in the 12S; H. homoeolepis vs. the new species from clade E ( Fig. 5, Appendix III) 11% in the cytb and 8.5% in the 12S. The results of the nuclear networks presented in Fig. 8 and a network analysis including all members of Dataset 1 (data not shown) clearly show that all alleles of H. homoeolepis for all three independent loci analyzed (c -mos, mc1r and rag2) are private (not shared with any other species included in the analyses).

The level of genetic variability within H. homoeolepis is rather high: 3.2% in the cytb and 1.3% in the 12S, and is the result of the relatively high level of genetic differentiation between mainland Arabia and Socotra Island populations of H. homoeolepis (uncorrected genetic distances of 10.4% in the cytb and 5.7% in the 12S). This genetic differentiation at the mtDNA level is also supported by differentiation at the nuclear level and by morphological differences in size, tuberculation, number of lamellae under the toes of pes, which suggests that Arabian mainland populations may, in fact, represent a new species (data not shown; work in progress). Although most specimens of H. homoeolepis across its distribution range in mainland Arabia are morphologically very uniform, one single isolated specimen from the coastal city of Shaqra (13.35’ N 45.70 ’E; Southwest Yemen, 850 km to the West of the main distribution range of the species; BMNH1953.1.6.9; see Appendix I; MorphoBank: M102031–M102050) presents several differences from Eastern H. homoeolepis . The main differences are: dorsal scales flatter and slightly more imbricate; ventrals markedly larger with distinct serrated edges; presence of numerous enlarged unkeeled tubercles on the hind parts, just in front of the pelvic region that increase in size and frequency posteriorly. These are much bigger than the intermediate scales and are irregularly arranged although they tend to form transverse rows on tail base (rest of the tail is missing). Similar large scales occur on the tibia. Although no material is available for genetic comparisons, all these differences suggest that the specimen from Shaqra, Yemen may be part of yet another undescribed species of the H. homoeolepis group.

Distribution

Hemidacytlus homoeolepis is found in Socotra, Samha and Darsa Islands ( Socotra Archipelago), Shaqra in Southwest Yemen, extreme Eastern Yemen, Dhofar region in South Oman and adjoining Central Oman and North Oman (Asylah) ( Fig. 3). Across its distribution range it has been recorded from sea level (4 m in Wadi Mughsayl) up to 670 m in Wadi Ayoun (Table 1).

Habits

Hemidactylus homoeolepis is a small and strictly nocturnal gecko found in usually dry places on rock surfaces near the ground and on sandy and stony substrates close by. At Wadi Ayoun it occupies stony ground and sloping rock pavements and at Thumrait was found on screes of small stones ( Fig. 19B). According to Arnold (1980), at these localities 62% of sixty-four animals checked were first sighted on the ground and all but one of the others were lower than 60 cm from it. At Wadi Ayoun H. homoeolepis is sympatric with three other nocturnal geckos: H. lemurinus , H. festivus and Ptyodactylus ; although only newborns and juveniles of H. festivus are found in the same microhabitat (stony ground). Hemidacytlus homoeolepis is very agile, often proceeding in a series of leaps when pursued.