Ii: Taxonomic Revision of Brachymeles Samarensis and Description of Five New Species
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Herpetological Monographs, 25, 2011, 76–112 E 2011 by The Herpetologists’ League, Inc. PHYLOGENY-BASED SPECIES DELIMITATION IN PHILIPPINE SLENDER SKINKS (REPTILIA: SQUAMATA: SCINCIDAE) II: TAXONOMIC REVISION OF BRACHYMELES SAMARENSIS AND DESCRIPTION OF FIVE NEW SPECIES 1,3 1 1 2 CAMERON D. SILER ,ALLISON M. FUITEN ,ROBIN M. JONES ,ANGEL C. ALCALA , 1 AND RAFE M. BROWN 1Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, 1345 Jayhawk Boulevard, Lawrence, KS 66045-7593, USA 2SUAKCREM Marine Laboratory, Silliman University, Bantayan, Dumaguete City, Philippines 6200 ABSTRACT: With robust new datasets from morphology and DNA sequences, we review the limbed, nonpentadactyl species of the Brachymeles samarensis complex (now known to include B. cebuensis, B. minimus, and B. lukbani), and describe five new species in this highly limb-reduced, endemic Philippine clade of scincid lizards. For more than four decades, B. samarensis has been recognized as a single ‘‘widespread’’ species. This perception of the species’ peculiar geographic range has persisted as a result of weak sampling and similar gross morphology (body sizes, scale pigmentation) among populations. However, previous authors have noted morphological variation between different island populations, and our new data build on these observations and extend them to delimit new proposed species boundaries. Our data indicate that the ‘‘widespread’’ species B. samarensis is actually a complex of six distinct lineages, some of which are not each others’ closest relatives, and each of which is genetically unique. The taxa we define possess allopatric geographic ranges and differ from their congeners by numerous diagnostic characters of external morphology, and therefore should be recognized as full species in accordance with any lineage-based species concept. Species diversity in the genus has doubled in the last 3 yr, with these six taxa increasing the total known number of species of Brachymeles to 30. Key words: Biodiversity; Endemism; Faunal region; Fossorial lizards; Limb reduction; Species delimitation; Taxonomy FEW GENERA of scincid lizards are known to B. tridactylus, and B. wrighti), and five are possess species representing a full spectrum of entirely limbless (B. apus, B. minimus, B. body forms, from fully limbed, pentadactyl miriamae, B. lukbani, and B. vermis). species to limbless species (see Siler et al., Among the nonpentadactyl species, numer- 2011b; Siler and Brown, 2011). In the genus ous studies have documented a wide range of Brachymeles, all but two of the 26 recognized limb- and digit-reduced states, from minute species are endemic to the Philippines, with limbs with 0–3 digits (B. bonitae, B. cebuensis, the exceptions being a single species (B. apus) B. muntingkamay, B. samarensis, B. tridacty- from northern Borneo and another (B. lus), to moderately developed limbs with miriamae) from Thailand (Brown and Alcala, four to five digits on the hands and feet (B. 1980; Hikida, 1982; Siler, 2010; Siler et al., elerae, B. pathfinderi, B. wright;Dume´ril and 2009, 2010a,b, 2011a,b,c; Siler and Brown, Bibron, 1839; Brown, 1956; Brown and Rabor, 2010, 2011). Thirteen species are pentadactyl 1967; Brown and Alcala, 1980; Taylor, 1917, (B. bicolor, B. boholensis, B. boulengeri, B. 1918, 1925; Siler, 2010; Siler et al., 2009, gracilis, B. kadwa, B. makusog, B. mind- 2010a, 2011a,b,c; Siler and Brown, 2011). All orensis, B. orientalis, B. schadenbergi, B. species are semifossorial and typically found talinis, B. taylori, B. tungaoi, and B. vindumi), in dry, rotting material inside or underneath eight are nonpentadactyl with incompletely decaying logs or in loose soil, forest floor developed limbs and reduced numbers of detritus, and leaf litter. digits (B. bonitae, B. cebuensis, B. elerae, B. Although the genus was named well over muntingkamay, B. pathfinderi, B. samarensis, 150 yr ago (Dume´ril and Bibron, 1839), the rate of Brachymeles species descriptions 3 CORRESPONDENCE: e-mail, [email protected] reached an apparent asymptotic maximum in 76 2011] HERPETOLOGICAL MONOGRAPHS 77 1980 (Brown and Alcala, 1980). The one diversity in the genus for 30 yr, until Taylor exception is B. minimus, a legless species published a series of herpetofaunal descriptions described in 1995 (Brown and Alcala, 1995). in the early 1900s (Taylor, 1917, 1918, 1922, For more than a century, limited numbers of 1925). It would be 50 yr before Brown (1956) specimens in museum collections, combined described B. samarensis from a single juvenile with the similar body plans and external specimen (FMNH 44472) collected in Guiuan, morphological features among species of Samar Island, Philippines in 1945. At the time of Brachymeles, limited assessments of species- description, Brown (1956) hypothesized the level diversity (Brown, 1956; Brown and species was most closely related to B. elerae Alcala, 1980; Brown and Rabor, 1967; Taylor, due to similarities in the number of paraverte- 1917). Recent studies have revealed the bral scale rows. This single juvenile would species-level diversity within Brachymeles to remain the only vouchered specimen of this be drastically underestimated, and have iden- unique bidactyl species from Samar Island (Siler tified numerous nonmonophyletic species and Brown, 2010). complexes within the Philippines (Siler and By the time Brown and Rabor (1967) Brown, 2010, 2011; Siler et al., 2011a). revised the genus Brachymeles, samples of Additionally, several rare, mid-to-high eleva- specimens morphologically similar to B. sa- tion species long represented by only a few marensis had been collected from the islands specimens (e.g., B. bicolor, B. elerae, B. of Luzon and Leyte. Additionally, Brown and wrighti, B. pathfinderi) have recently been Rabor (1967) reported on a second specimen rediscovered (Siler, 2010) and redescribed as from Samar Island; however, no information valid taxa (Siler et al., 2011a,c). Together, on where the specimen was deposited, or its these studies coupled with increased sampling museum catalog number, was provided. Al- throughout the Philippines and a new, robust though Brown and Rabor (1967) treated B. molecular dataset, allow us to begin evaluating samarensis as a single widespread species, variation across the isolated populations of they referred to the species as a ‘‘complex,’’ widespread species in the Philippines. suggesting that they suspected it contained In a recent study, Siler and Brown (2010) multiple species. They also noted several revised two polytypic species (B. boulengeri distinct morphological differences between and B. schadenbergi) and one widespread island populations, including differences in species (B. talinis), and inferred the presence fore- and hind-limb digit number and head of 10 genetically and morphologically distinct scale patterns. allopatric evolutionary lineages (species). Sev- Additional island populations of B. samar- eral other species are still recognized as ensis were subsequently sampled by the time having widespread distributions that span Brown and Alcala (1980) revised the genus, historical faunal demarcations in the Philip- including populations from the Lapinig Group pines (Brown and Diesmos, 2002, 2009; islands off the northeast coast of Bohol Island Brown and Guttman, 2002; Heaney, 1985), (Fig. 1). Ross and Gonzales (1992) would later including B. samarensis and B. bonitae report on observations of B. samarensis from (Brown, 1956; Brown and Rabor, 1967; Brown Catanduan˜ es Island off the northeast coast of and Alcala, 1980). One of these species (B. the Bicol Peninsula (Fig. 1) and in 2001, RMB samarensis) is the focus of this study. (unpublished data) recorded B. samarensis on the southern tip of the Bicol Peninsula in the TAXONOMIC HISTORY foothills of Mt. Bulusan. The genus Brachymeles was first described by To date, Brachymeles samarensis remains a Dumeril and Bibron (1839) for the small, limb- widespread species spanning islands of the reduced species B. bonitae. Three additional Luzon and Mindanao Pleistocene Aggregate species (Senira bicolor Gray, 1845; Eumeces Island Complexes (PAICs; Brown and Dies- (Riopa) gracilis Fischer, 1885; E. (R.) schaden- mos, 2002; Brown and Guttman, 2002; bergi Fischer, 1885) were transferred to the Fig. 1). Widespread distributions such as this genus by Boettger (1886) and Boulenger (1887). have been the focus of many recent studies These four species represented the known (Brown et al., 2000; Siler and Brown, 2010; 78 HERPETOLOGICAL MONOGRAPHS [No. 25 distinct evolutionary lineages (species). In this paper we provide a phylogenetic analysis of all of these taxa, fully describe each species, clarify taxonomic boundaries, and provide the first illustrations of all included species. We also provide information on each species’ natural history, ecology, and geographic distribution. MATERIALS AND METHODS Field Work, Sample Collection, and Specimen Preservation Fieldwork was conducted on Catanduan˜ es, Lapinig Grande, Leyte, Luzon, and Samar islands, all in the Philippines (Fig. 1) between 2001 and 2009. Specimens were collected between 900 and 1600 h, euthanized in aqueous chloretone, dissected for tissue sam- ples (liver preserved in 95% ethanol or flash frozen in liquid nitrogen), fixed in 10% formalin, and eventually (,2 mo) transferred to 70% ethanol. Newly sequenced specimens are deposited in US and Philippine museum collections (see Acknowledgments and Ap- pendix I, Additional Specimens Examined); voucher information