175 Mitochondrial phylogeny of the Darevskia saxicola complex: two highly deviant evolu tonary lineages from the easternmost part of the range David Tarkhnishvili, Mariam Gabelaia, Levan Mumladze & Marine Murtskhvaladze Biodiversity Research Center, Insttute of Ecology, Ilia State University, 3/5 Cholokashvili Ave., Tbilisi, 0162, Georgia Herpetological Journal FULL PAPER Correspondence: D. Tarkhnishvili (david_tarkhnishvili@iliauni.edu.ge) Volume 26 (April 2016), 175–182 Published by the Britsh Herpetological Society The rock lizards of the Darevskia saxicola complex are found exclusively in the west of the Greater Caucasus and in southern Crimea. The earliest split within this group occurred between D. saxicola from the northern and D. brauneri from the southern slopes of the Greater Caucasus, followed by the split between D. brauneri and the Crimean D. lindholmi, and the expansion of D. saxicola to the westernmost slopes of the Greater Caucasus. We collected nominal D. brauneri from the two easternmost populatons of the species range: the valleys of the Tekhuri and Enguri rivers in Georgia. Analysis of mitochondrial DNA showed that the lizards from both valleys are deeply diferentated from each other and from previously characterised D. brauneri. Lizards from Tekhuri keep a basal positon within the clade D. saxicola (excluding D. pratcola), and lizards from Enguri are closer matrilineally to the northern Caucasian D. saxicola than to either of the populatons of nominal D. brauneri. Tekhuri lizards have broader heads and more small scales between the inner and outer rows of supraoculars than the other populatons of the group. We suggest that the taxonomy of the group requires revision, considering the multple deeply divergent mitochondrial lineages and introgressive gene fow between the contnental populatons of nominal D. saxicola and D. brauneri. The D. saxicola complex in the Caucasus resembles a “ring species” arrangement as described for other taxa and mountain regions. Key words: Caucasus, cytochrome b, Darevskia, glacial refugia, mitochondrial DNA, scalaton, Species Nova INTRODUCTION C aucasian rock lizards (Darevskia) have been assumed to consist of three genetically distinct clades (Murphy et al. 2000). The clades “rudis” and “caucasica” are widespread throughout the Caucasus except its northwestern part as well as parts of Anatolia, and the clade “saxicola” is limited to the western part of the Greater Caucasus and southern Crimea (Murphy et al., 2000; Tarkhnishvili, 2012). This Western Caucasian clade most likely split from the reminder of the genus Darevskia approximately 6 million years ago, and is perhaps associated with the ancient Caucasus Island, which was isolated from the Asia Minor untl early Pliocene (Popov et al., 2004; Tarkhnishvili, 2012, 2014). The clade has fve to six nominal species, including the polytypic D. brauneri and D. saxicola (MacCullogh et al., 2000; Murphy et al., 2000; Ciobanu et al., 2003; Milto et al. 2010; Doronin, 2011; Tuniyev & Tuniyev, 2012; Doronin et al., 2013). Darevskia praticola, the most distant from the other species of the clade (Murphy et al., 2000), has a range between the southern Caspian Sea and the Balkans (Agasyan et al., 2009). Darevskia alpina occurs at alttudes above 1,650 m a.s.l. in the Greater Caucasus west of the valley of the river Baksan (Darevsky, 1967; Tuniyev et al., 2009a). Darevskia lindholmi is found in southern Crimea (Darevsky, 1967), D. saxicola occurs west of the valley of river Chegem north of the Greater Caucasus Range, below 1,500 m a.s.l. (Darevsky, 1967; Tuniyev et al., 2009b), and D. brauneri occurs at the southern slopes of the Greater Caucasus between the river Tekhuri valley in Georgia and Anapa in Russia, and at the northern slopes west of the river Kuban valley (Darevsky, 1967; MacCullogh et al., 2000). The genetcally distnct D. [brauneri] szczerbaki (a separate species according to Doronin et al., 2013) is found at the westernmost foothills of the Greater Caucasus. The subspecies D. brauneri darevskii from the north and the west of the river Psou valley was recently synonymised with the nominal form, and D. b. miusserica has been recently described from a small area in the north-westernmost Georgia (Doronin et al., 2013) (Fig. 1). Except for D. pratcola, neither of these species has diagnostc morphological characters that could easily distnguish them from their closest relatves. Darevskia alpina is morphologically intermediate between D. brauneri and D. caucasica, a representatve of another clade of Darevskia. The diferences among the remaining