Phylogeny of Gekko from the Northern Philippines, and Description of a New Species from Calayan Island

—We use mitochondrial gene sequences to estimate relationships among Gekko populations from the northern Philippines. These data, plus morphological and biogeographical evidence, suggest that the Babuyan and Batanes island groups (north of Luzon Island) are inhabited by a minimum of six distinct evolutionary lineages, only two of which (Gekko porosus Taylor from the Batanes and Gekko crombota from Babuyan Claro) have been formally recognized as distinct species. In this paper, we provide a description of another new species, the endemic Gekko from Calayan Island. This geographically isolated species is diagnosed on the basis of a distinct color pattern, body size, scalation, and significant divergence in mitochondrial gene sequences. The new species has been found on rocky outcrops and limestone caves in forested areas and on trunks of mature forest trees #500 m above sea level, away from the island’s coast. Given the history of geological isolation of Calayan Island and the distinctiveness of the endemic Gekko populations there, we are confident in diagnosing this gecko as a unique evolutionary lineage; it is unlikely that this species will be found on neighboring land masses. The remaining major islands of the Babuyans group (Camiguin Norte, Fuga, and Dalupiri islands) each contain similarly distinct endemic species that await description; additional surveys throughout the Batanes and Babuyan islands will be necessary to arrive at an estimate of total species diversity for this isolated gekkonid radiation. The Philippine gekkonid lizard fauna consists of 10 genera and 40 described species: Cyrtodactylus (5 species); Gekko (10 or 11); Gehyra (1); Hemidactylus (5; including platyurus, a species formerly assigned to Cosymbotus); Hemiphyllodactylus (1); Lepidodactylus (6); Luperosaurus (7); Pseudogekko (4); and Ptychozoon (1) (Taylor, 1922a,b; Brown and Alcala, 1978; Brown et al., 1997, 2007, 2008, in press; Brown, 1999; Gaulke et al., 2007; Welton et al., in press). Philippine species of the genus Gekko include three taxa shared with neighboring countries (Gekko gecko, Gekko monarchus, and G. hokouensis; Taylor, 1922a,b; Brown and Alcala, 1978; Ota et al., 1989). Although G. gecko and G. monarchus are common in collections, Gekko hokouensis has been represented in the country’s gekkonid fauna by only a single specimen originally described by Taylor as Luperosaurus amissus (Taylor, 1922a,b), later considered to be Gekko japonicus (Brown and Alcala, 1978) and eventually determined to be G. hokouensis (Ota et al., 1989). The specimen was apparently collected from Tablas Island (Taylor, 1962), and no specimens matching its description or the holotype have been collected since Taylor, suggesting erroneous attribution to the archipelago (Brown and Alcala, 1978; Ota et al., 1989). Eight species of Gekko are confidently considered endemic to the Philippines; these include Gekko athymus, Gekko gigante, Gekko mindorensis, Gekko palawanensis, Gekko porosus, Gekko romblon (Taylor, 1922a; Brown and Alcala, 1978), Gekko ernstkelleri (Roesler et al., 2006), and Gekko crombota (Brown et al., 2008). All endemic Philippine Gekko share (1) moderate body size and longer, slender limbs; (2) near complete absence of interdigital webbing or cutaneous body expansions; (3) enlarged dorsal tubercles arranged in longitudinal rows on the dorsum (except G. athymus, dorsal tubercles absent); (4) scales of dorsum between tubercle rows minute, nonimbricate; (5) scales of venter enlarged, flat, imbricate; (6) differentiated postmentals elongate and slender; and (7) subcaudals enlarged, platelike (Brown and Alcala, 1978; Brown et al., 2007, 2008). During recent biological inventories of the Babuyan Islands (Fig. 1), we obtained new specimens and tissues, allowing for a study of the genetic variation exhibited by isolated 2 Corresponding Author. E-mail: [email protected] 4 E-mail: [email protected] Journal of Herpetology, Vol. 43, No. 4, pp. 620–635, 2009 Copyright 2009 Society for the Study of Amphibians and Reptiles