New Loam-Swimming Skink, Genus Brachymeles (Reptilia: Squamata: Scincidae) from Luzon and Catanduanes Islands, Philippines

—We describe a new species of scincid lizard of the genus Brachymeles from the Luzon Faunal Region of the northern Philippines. We discovered the new species in the Camarines Norte Province of the Bicol Peninsula (Luzon Island) and Catanduanes Island. Until recently, the new species had been mistaken as Brachymeles talinis, a distantly allopatric yet morphologically similar, large-bodied congener from the central Philippines. The new species is the second-largest known species of Brachymeles and differs from its congeners by numerous external morphological features. It is the eighth known Brachymeles from the Luzon Faunal Region and the sixth pentadactyl species in the genus. Scincid lizards of the genus Brachymeles are one of only four lizard genera that possess both fully limbed and limbless species (Brachymeles, Chalcides, Lerista, and Scelotes; Lande, 1978; Wiens and Slingluff, 2001; Brandley et al., 2008). Currently, there are 17 recognized species, all endemic to the Philippines except for Brachymeles apus from northern Borneo (Brown and Alcala, 1980; Hikida, 1982; Siler et al., 2009, 2010). Five species are pentadactyl (bicolor, boulengeri, gracilis, schadenbergi, and talinis); eight are nonpentadactyl, with incompletely developed limbs and reduced numbers of digits (bonitae, cebuensis, elerae, pathfineri, samarensis, tridactylus, wrighti and sp. nov. tridactyl [Siler et al., 2009]); and four are limbless (apus, minimus, vermis, and sp. nov. [Siler et al., 2010]). Among the nonpentadactyl species (Taylor, 1917, 1918, 1922), there is a full range of limband digit-reduced states, including species with minute limbs lacking digits and those with moderately developed tetradactyl limbs (Brown and Alcala, 1980; Hikida, 1982). All species exhibit a semifossorial lifestyle and usually are found in dry rotting loam inside decaying logs or in loose soil and leaf litter. Members of the genus have similar body plans and external morphology, which has proven problematic for diagnosing species diversity on the basis of external characters alone (Brown and Alcala, 1980). Among the 17 known species, there are three polytypic species (Brachymeles boulengeri, Brachymeles gracilis, and Brachymeles schadenbergi; Brown, 1956; Brown and Rabor, 1967; Brown and Alcala, 1980). Both B. gracilis and B. schadenbergi contain two recognized subspecies, and B. boulengeri contains four subspecies. Several species are widely distributed across multiple faunal regions of the Philippines. One of these is Brachymeles talinis, which exhibits considerable morphological variation among populations (Brown, 1956; Brown and Rabor, 1967; Brown and Alcala, 1980). As currently recognized, B. talinis occurs across the northern and central faunal regions of the Philippines (Brown and Diesmos, 2002). In 2007 and 2008, we conducted two biotic surveys in the Bicol region of the Philippines. The first targeted Catanduanes Island and the second the Bicol Peninsula of Luzon Island (Fig. 1). Eight specimens of a large, undescribed species of Brachymeles were collected in 2007 from 200–530-m elevation on Catanduanes Island. The following year, 10 more individuals were collected on Mt. Labo on the Bicol Peninsula of Luzon Island from 200–1,000-m elevation (Fig. 1). The new species is semifossorial, was found in the loam of rotting logs and surrounding forest floor humus, and was captured in pitfall traps. In this paper, we describe the species and report on its natural history, ecology, and habitat. MATERIALS AND METHODS We recorded morphometric data from alcohol-preserved specimens (Appendix 1). Sex was determined by gonadal inspection, and measurements were taken with digital calipers to the nearest 0.1 mm. To avoid interobserver bias and other sources of potential error (Lee, 1990), all measurements were scored by CDS. Color descriptions are based on the preserved specimens, field notes, and color digital images in life. Meristic and mensural characters are based on Brown and Alcala (1980), Brown et al. (1995a,b, 1999), and Greer et al. (2006) and 2 Corresponding Author: E-mail: [email protected] Journal of Herpetology, Vol. 44, No. 1, pp. 49–60, 2010 Copyright 2010 Society for the Study of Amphibians and Reptiles