Abstract: A new species of skink in the genus Epibator is described from Ile Walpole, a small, isolated, raised vegetated limestone platform, ~200km ESE of southern New Caledonia. The new species is distinguished from its congeners Epibator nigrofasciolatus and E. greeri primarily by its coloration and pattern (both species), differences in scalation (greeri), and substantial genetic differentiation (nigrofasciolatus). The new species is the only extant endemic terrestrial vertebrate on Walpole. The island is small (<1.7 [km.sup.2]), and has a long history of past human occupation (over the last 2,500 years, including European-era exploitation for guano), resulting in degradation of the vegetation cover and introduction of invasive animal species, most significantly ants (Little Fire Ant, Yellow Crazy Ant) and rats (Pacific Rat). The species' very limited distribution in combination with the threats posed by invasive species place it at a level of risk sufficient to be considered as Critically Endangered under IUCN Red List criteria.

Keywords: Scincidae, Epibator, systematics, new species, island, conservation, Critically Endangered

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Research into the systematics of the predominately endemic New Caledonian skink and gecko fauna over the past 20 years has significantly increased our understanding of the species richness and generic diversity of both lizard groups, an outcome of morphological and genetic investigation utilizing collections made through extensive field studies in the region during this period. The most significant contribution to the increase in species richness has come through the delineation of cryptic lineages within genera distributed on ultramafic surfaces of the massifs and ranges of the Grande Terre, the main island of New Caledonia. Most notably, these increases have been in the scincid genera Caledoniscincus (Sadlier et al. 2013, Sadlier, Whitaker et al. 2014), Marmorosphax (Sadlier and Bauer 2000; Sadlier et al. 2009), Nannoscincus (Sadlier et al. 2002, Sadlier, Bauer et al. 2004, Sadlier, Bauer et al. 2006), and Sigaloseps (Sadlier and Bauer 1999; Sadlier, Bauer et al. 2014), and in the diplodactylid genus Dierogekko (Bauer et al. 2006a). Other significant additions have come from the discovery of "novel" and clearly undescribed species such as the skink Kanakysaurus viviparus (Sadlier, Smith et al. 2004) and gecko Oedodera marmorata (Bauer et al. 2006b). Most of these recently described species have very small ranges, the product of a history of regional isolation at a small geographic scale, with microendemism being the emerging trend for the region's fauna (Caesar et al. 2017).

By comparison, the lizard fauna of the major satellite islands of the Grande Terre (Iles Belep and the Ile des Pins), or the major outlying islands in the region (Iles Loyaute and Ile Walpole) has, until recently, received little attention. The Iles Belep and the Ile des Pins lie off the northern and southern end, respectively, of the Grande Terre, and both are essentially extensions of the main island's land surfaces with intervening areas now submerged. Field studies on the Ile des Pins in 1992 (Bauer and Sadlier 1994) provided the first comprehensive overview of that island's lizard fauna, and was expanded between 2000 and 2003 with...