Microendemicity in the northern Hajar Mountains of Oman and the United Arab Emirates with the description of two new species of geckos of the genusAsaccus(Squamata: Phyllodactylidae)

Abstract

BackgroundThe Hajar Mountains of Oman and the United Arab Emirates (UAE) is the highest mountain range in Eastern Arabia. As a result of their old geological origin, geographical isolation, complex topography and local climate, these mountains provide an important refuge for endemic and relict species of plants and animals with strong Indo-Iranian affinities. Among vertebrates, the rock climbing nocturnal geckos of the genus Asaccus represent the genus with the highest number of endemic species in the Hajar Mountains. Recent taxonomic studies on the Zagros populations of Asaccus have shown that this genus is much richer than it was previously thought and preliminary morphological and molecular data suggest that its diversity in Arabia may also be underestimated.MethodsA total of 83 specimens originally classified as Asaccus caudivolvulus (including specimens of the two new species described herein), six other Asaccus species from the Hajar and the Zagros Mountains and two representatives of the genus Haemodracon were sequenced for up to 2,311 base pairs including the mitochondrial 12S and cytb and the nuclear c-mos, MC1R and ACM4 genes. Phylogenetic relationships were inferred using both Bayesian and maximum-likelihood approaches and the former method was also used to calibrate the phylogenetic tree. Haplotype networks and phylogenetic trees were inferred from the phased nuclear genes only. Sixty-one alcohol-preserved adult specimens originally classified as Asaccus caudivolvulus from the northern Hajar Mountains were examined for 13 morphometric and the five meristic variables using multivariate methods and were also used to diagnose and describe the two new species.ResultsThe results of the molecular and morphological analyses indicate that the species originally classified as Asaccus caudivolvulus is, in fact, an assemblage of three different species that started diversifying during the Mid-Miocene. The molecular phylogenies consistently recovered the Hajar endemic A. montanus as sister taxon to all the other Asaccus species included in the analyses, rendering the Arabian species of Asaccus polyphyletic.DiscussionUsing this integrative approach we have uncovered a very old diversification event that has resulted in a case of microendemicity, where three morphologically and ecologically similar medium-sized lizard species coexist in a very short and narrow mountain stretch. Asaccus caudivolvulus is restricted to a small coastal area of the UAE and at risk from heavy development, while the two new species described herein are widely distributed across the northern tip of the Hajar Mountains and seem to segregate in altitude when found in close proximity in the Musandam Peninsula (Oman). Similarly to other integrative analyses of Hajar reptiles, this study highlights the high level of diversity and endemicity of this arid mountain range, underscoring its status as one of the top hotspots of reptile diversity in Arabia.

Hidden in the Arabian Mountains: Multilocus phylogeny reveals cryptic diversity in the endemicOmanosauralizards

“…The main phylogeographic partition between the different lineages observed within O. cyanura strictly matches the biogeographic pattern recovered by previous studies on reptiles of the genera Asaccus (Carranza et al., ; Simó‐Riudalbas, Tarroso, et al., ), Trachydactylus (de Pous et al., ), and Ptyodactylus (Metallinou et al., ; Simó‐Riudalbas, Metallinou, et al., ). Historically, knowledge of biodiversity patterns was not equally distributed across the Hajar Mountains.…”

“…The Jebel Akhdar, which includes the highest peaks in the Hajar Mountains, and the eastern Hajars have received more scientific attention over the last decades and have recently been shown to be areas with maximum genetic diversity for the reptile genera Asaccus (Simó‐Riudalbas, Tarroso, et al., ), Hemidactylus (Carranza & Arnold, ), Pristurus Rüppell, 1835 (Badiane et al., ), and Trachydactylus (de Pous et al., ). Comparatively, less research effort has been devoted to the northernmost part of the Hajar Mountains and especially to the Musandam Peninsula until very recently, when the discovery of high genetic diversity and new species of other reptile genera such as Ptyodactylus (Metallinou et al., ; Simó‐Riudalbas, Metallinou, et al., ) and Asaccus (Carranza et al., ) highlighted this area as a hot spot of diversity within the Hajar Mountains. The processes that have shaped the distribution patterns of taxa in the Hajar Mountains remain unclear, although a relation with geological and climatic events could be suggested.…”

“…The lack of data normally culminates in a general underestimation of the local biodiversity levels. Case examples of regions with recently discovered hidden genetic variability are the arid mountains in North Africa and the Arabian Peninsula (e.g., Carranza, Simó‐Riudalbas, Jayasinghe, Wilms, & Els, ; Garcia‐Porta, Simó‐Riudalbas, Robinson, & Carranza, ; Metallinou et al., ; Rato, Harris, Carranza, Machado, & Perera, ; Rosado, Rato, Salvi, & Harris, ).…”

“…However, the deep gorges running between the peaks (wadis) have water and vegetation, at least intermittently, and are the places where the majority of fauna and flora can be found. The geological setting, together with a local microclimate and the presence of wadis, makes the Hajar Mountains an important refuge for endemic and relict species (Mandaville, ), including, among others, endemic species of plants (MacLaren, ) and of reptiles, such as two species of the lizard genus Omanosaura Lutz, Bischoff, & Mayer, ; several species of the geckos of the genus Asaccus Dixon & Anderson, 1973 (Carranza et al., ; Simó‐Riudalbas, Tarroso, Papenfuss, Al‐Sariri, & Carranza, ), Hemidactylus Oken, 1817 (Carranza & Arnold, ), Pristurus Rüppell, 1835 (Arnold, ; Badiane et al., ; Garcia‐Porta et al., ), Ptyodactylus Godfuss, 1820 (Metallinou et al., ; Simó‐Riudalbas, Metallinou, et al., ), and Trachydactylus Haas and Battersby, 1959 (de Pous et al., ), an agamid of the genus Pseudotrapelus Fitzinger, 1843 (Tamar, Scholz, et al., ), and a viper of the genus Echis Merrem, 1820 (Babocsay, ; Robinson, Carranza, & Arnold, ). With an increase in scientific attention given to the Hajar Mountains, the number of microendemic species or lineages in this area has increased remarkably over the last few years, particularly among reptiles (Carranza et al., ; Garcia‐Porta et al., ; Simó‐Riudalbas, Metallinou, et al., ), an indication of very high levels of cryptic diversity in a still understudied biodiversity hot spot.…”

Cutting the Gordian Knot: Phylogenetic and ecological diversification of the Mesalina brevirostris species complex (Squamata, Lacertidae)

“…Mesalina saudiarabica sp. n. described here from western Arabia contributes to the intensively growing knowledge on the evolution and systematics of the pan‐Arabian reptile fauna within the last years (Carranza et al, ; Kapli et al., ; Metallinou et al., , ; de Pous et al., ; Šmíd, Shobrak, Wilms, Joger, & Carranza, ; Šmíd, Carranza, et al., ; Šmíd, Moravec, et al., ; Šmíd et al., ; Tamar, Carranza, et al., ; Tamar, Scholz, et al., ). As some of the studies show, cryptic and previously unrecognised species are present along the western Arabian mountains, and more species descriptions from there may thus be expected.…”