THE genus Brachymeles consists of 17 recognized,

Transcription

1 Copeia 2010, No. 1, A New Legless Loam-swimming Lizard (Reptilia: Squamata: Scincidae: Genus Brachymeles) from the Bicol Peninsula, Luzon Island, Philippines Cameron D. Siler 1, Danny S. Balete 2, Arvin C. Diesmos 3, and Rafe M. Brown 1 A new limbless species of scincid lizard of the genus Brachymeles is described from Mt. Labo, Bicol Peninsula, Luzon Island, Philippines. The species was encountered only on this isolated volcanic peak and is conspicuously absent from surrounding, well-surveyed regions of the Bicol Peninsula. The new species is the fourth known limbless species of Brachymeles and the third to be discovered in the Philippines. It is the second longest limbless species of Brachymeles, and, aside from size, can be distinguished from all congeners by features of its external morphology, including both color and scalation. The discovery brings the total number of known Brachymeles species in the Luzon Faunal Region to eleven, including two limbless forms. Isang panibagong uri ng mga bubuling Brachymeles na walang mga paa ang isinalarawan mula sa bundok ng Labo, sa timog-hilagang Luzon, sa Pilipinas. Ang Brachymeles na ito ay matatagpuan lamang sa isang liblib na kabundukan sa Camarines Norte ng Kabikolan. Ito ay pang-apat lamang sa mga walang paang uri ng Brachymeles sa buong mundo at pangatlong natuklasan sa Pilipinas. Ito rin ang pumapangalawa sa haba ng katawan sa mga kauri nitong walang mga paa. Maliban sa sukat ng pangatawan, ito ay makikilala rin mula sa mga kauri nito sa taglay nitong mga katangian sa anyong panglabas, kulay, at pangaliskis. Sa pagkatuklas ng Brachymeles na ito, umabot na sa labing isa ang mga Brachymeles mula sa Luzon Faunal Region, at sa dalawa ang uring walang mga paa na makikita rito. THE genus Brachymeles consists of 17 recognized, semi-fossorial species. All but one is endemic to the Philippines. The one exception is B. apus from northern Borneo (Brown and Alcala, 1980; Hikida, 1982). This group of skinks is unusual in being one of only four genera that possess both fully limbed and limbless species (Brachymeles, Chalcides, Lerista, and Scelotes; Lande, 1978; Wiens and Slingluff, 2001; Brandley et al., 2008). Within the genus, six species are pentadactyl (B. bicolor, B. boulengeri, B. gracilis, B. schadenbergi, B. talinis, and B. sp. undescribed [Siler et al., 2010]), seven species are non-pentadactyl with reduced limbs and numbers of digits (B. bonitae, B. cebuensis, B. elerae, B. pathfineri, B. samarensis, B. tridactylus, B. wrighti, and B. sp. undescribed tridactyl [Siler et al., 2009]), and three species are limbless (B. apus, B. vermis, and B. minimus). Among the seven non-pentadactyl species, there exists a full spectrum of limb and digit reduced states, from moderately developed limbs with four digits to minute limbs or stumps altogether lacking digits (Taylor, 1917, 1918, 1922; Brown and Alcala, 1980; Hikida, 1982). Members of the genus have similar body plans and external morphology, which has made diagnosing species boundaries on the basis of morphology difficult (Brown, 1956; Brown and Rabor, 1967; Brown and Alcala, 1980; Siler et al., 2009, 2010). Among the 17 known species, three polytypic species are recognized (Brachymeles boulengeri, B. gracilis, and B. schadenbergi; Brown, 1956; Brown and Rabor, 1967; Brown and Alcala, 1980). Both B. gracilis and B. schadenbergi each consist of two subspecies, and B. boulengeri contains four subspecies. Several species are known to occur across broad geographic distributions, but many of the limbreduced and limbless species are known from single islands or isolated mountain peaks (Brown, 1956; Brown and Rabor, 1967; Brown and Alcala, 1980). In 2006 and 2008, expeditions were conducted on Mt. Labo in the Bicol region of the Philippines (Fig. 1). One specimen of a small, limbless skink was collected in 2006 at 1115 m elevation. The species possessed a combination of morphological characters that fell within the range of those known for other species of Brachymeles, including the presence of a supranasal scale, brown body coloration, midbody scale rows, and the general similarity in head scale patterns. In 2008, 13 additional specimens of the same species were collected from m elevation (Fig. 1). The new species is semi-fossorial and was found within rotten logs and in the loose soil and leaf litter around them. Herein we describe the species, diagnose it from all congeners, and report on its natural history, ecology, and habitat. MATERIALS AND METHODS We recorded morphometric data from alcohol-preserved specimens that were fixed in 10% formalin. Sex was determined by gonadal inspection, and measurements were taken with digital calipers to the nearest 0.1 mm. All measurements were scored by the first author. Color descriptions are based on preserved specimens, field notes, and color digital images in life. Meristic and mensural characters are chosen based on Brown and Alcala (1980), Brown et al. (1995a, 1995b, 1999), and Greer et al. (2006). They are defined as follows (Fig. 2): snout vent length (SVL: distance from tip of snout to vent), axilla groin distance (AGD: distance between posterior edge of forelimb insertion and anterior edge of hind limb insertion), total length (TotL: distance from tip of snout to tip of tail), midbody width (MBW: measured from lateral surface to opposing lateral edge at midpoint of axilla groin region), midbody depth (MBD: measured from ventral surface to dorsal surface at midpoint of axilla groin region), tail length (TL: measured from posterior margin of vent to tip of tail), tail width (TW: measured at widest section of tail posterior to hemipene bulge), tail depth (TD: measured from 1 Natural History Museum and Biodiversity Research Center, Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas ; (CDS) camsiler@ku.edu. Send reprint requests to CDS. 2 Laksambuhay Conservation Foundation, Los Baños, Laguna Province, Philippines. 3 Herpetology Section, Zoology Division, Philippine National Museum, Rizal Park, Burgos St., Manila, Philippines. Submitted: 4 December Accepted: 26 August Associate Editor: T. W. Reeder. F 2010 by the American Society of Ichthyologists and Herpetologists DOI: /CH

2 Siler et al. New limbless species of Brachymeles skink 115 Fig. 1. Known distribution of Brachymeles lukbani on Mt. Labo, Bicol Peninsula, Philippines. The inset shows the location of Luzon Island (colored in dark gray) within the Philippines. The type locality of the new species (Mt. Labo, Barangay Tulay Na Lupa, Municipality of Labo, Camarines Norte Province, Luzon Island) is indicated by a black circle, and the type locality of B. minimus on Catanduanes Island is indicated by a black square. ventral to dorsal surface of tail at the same point as TW), head length (HL: from tip of snout to posterior margin of jaw articulation), head width (HW: widest measure of head width at jaw articulations), head depth (HD: measured from ventral to dorsal surface of head at jaw articulations), snout forearm length (SnFa: measured from tip of snout to anterior margin of forelimb insertion), eye diameter (ED: at widest point), eye narial distance (END: from anterior margin of eye to posterior margin of nares), snout length (SNL: from anterior margin of eye to tip of snout), internarial distance (IND: from dorsal aspect between most laterally distal edges of nares), forelimb length (FLL: measured from forelimb insertion to tip of Finger III or longest digit), hind limb length (HLL: measured from hind limb insertion to tip of Toe IV or longest digit), midbody scale-row count (MBSR: number of longitudinal scale rows measured around widest point of midbody), paravertebral scale-row count (PVSR: number of scale rows measured between parietals and the base of the tail opposite the vent), axilla groin scale-row count (AGSR: number of scale rows measured between posterior edge of forelimb insertion and anterior edge of Fig. 2. Illustration of head of female holotype of Brachymeles lukbani (PNM 9567) in dorsal, lateral, and ventral views. Taxonomically useful head scales within Brachymeles are labeled as follows: C, chin shield; F, frontal; FN, frontonasal; FP, frontoparietal; IL, infralabial; IP, interparietal; L, loreal; M, mental; N, nasal; P, parietal; PF, prefrontal; PM, postmental; PN, postnasal; PO, preocular; PSO, presubocular; R, rostral; SC, supraciliary; SL, supralabial; SN, supranasal; and SO, supraocular. Roman numerals indicate scales in the supraocular series, with numbers indicating scales in the supraciliary series. hindlimb insertion), Finger III lamellae count (FinIIIlam: all enlarged, undivided lamellae beneath Finger III), Toe IV lamellae count (ToeIVlam: all enlarged, undivided lamellae beneath Toe IV), supralabial count (SL), infralabial count (IFL), supraciliary count (SC), and supraocular count (SO). In the description, ranges are followed by mean 6 standard deviation in parentheses.

3 116 Copeia 2010, No. 1 Brachymeles lukbani, new species Figures 2, 3; Tables 1 3 Holotype. PNM 9567 (field no. RMB 9664, formerly KU ; Fig. 2), adult female, Philippines, Mt. Labo, Barangay Tulay Na Lupa, Municipality of Labo, Camarines Norte Province, Luzon Island, uN, uE (WGS-84), 660 m above sea level, 1800 hr, 22 June 2008, C. D. Siler, R. M. Brown, J. Phenix, L. Welton, J. B. Fernandez, V. Yngente, and M. Yngente. Paratopotypes. KU , , , , , PNM (formerly KU , , , and , respectively), including eight adult females, one adult male, and three juveniles of unknown sex, 21 June 4 July 2008, m elevation; FMNH , adult male, 21 April 11 May 2006, 1115 m elevation, same locality, Danny S. Balete. Diagnosis. Brachymeles lukbani can be distinguished from congeners by the following combination of characters: body form long, slender; limbless; midbody scale rows 21 23; paravertebral scale rows ; infralabial scales six; supraciliary scales six; supraocular scales five; pineal eye spot; contact between frontoparietal scales; postmental scale width equal to mental scale width; contact between the first pair of chin shield scales; non-fusion of mental and first infralabial scales; enlarged, differentiated nuchal scales; continuous subocular scale row; third pair of enlarged chin shields; and uniform body coloration (Tables 1, 2). Comparisons. From all pentadactyl species and subspecies of Brachymeles (B. bicolor, B. boulengeri boholensis, B. boulengeri boulengeri, B. boulengeri mindorensis, B. boulengeri taylori, B. gracilis gracilis, B. gracilis hilong, B. schadenbergi orientalis, B. schadenbergi schadenbergi, B. sp. undescribed [Siler et al., 2010], and B. talinis), B. lukbani is distinguished by the complete absence of external limb elements (vs. presence); a smaller maximum MBW (6.2 mm vs. greater than 11.6 mm); absence of auricular openings (vs. presence); absence of a postnasal scale (vs. presence, with the exception of B. g. gracilis; presence or absence); presence of enlarged, differentiated nuchal scales (vs. absence, with the exception of B. bicolor; presence); presence of midbody scale rows (vs. greater than 23); and presence of paravertebral scale rows (vs. fewer than 92). Additionally, the new species differs from all pentadactyl species except B. s. schadenbergi, B. s. orientalis, and B. b. mindorensis by having a postmental scale width equal to mental scale width; from all pentadactyl species except B. talinis, B. g. gracilis, B. g. hilong, and B. b. boholensis by the presence of a third pair of enlarged chin shields; from all pentadactyl species except B. g. gracilis and B. g. hilong by having a smaller maximum SVL (88.7 mm vs. greater than 92.1 mm), a smaller maximum TotL (158.8 mm vs. greater than mm), and a uniform body color. The new species differs from all non-pentadactyl, limbed species of Brachymeles (B. bonitae, B. cebuensis, B. elerae, B. pathfineri, B. samarensis, B. sp. undescribed tridactyl [Siler et al., 2009], B. tridactylus, and B. wrighti) by the complete absence of external limb elements, from all non-pentadactyl species except B. wrighti by its larger maximum SVL (88.7 mm vs. less than 81.3 mm) and its larger maximum TotL (158.8 mm SVL vs. less than mm), and from all non-pentadactyl species except B. bonitae and B. wrighti by the presence of paravertebral scale rows (vs , B. bonitae; 102, B. wrighti [Brown and Alcala, 1980]). In addition, the new species differs from B. tridactylus by the presence of six supralabial scales (vs. six or seven), six infralabial scales (vs. six or seven), six supraciliary scales (vs. five), five supraocular scales (vs. four), contact between frontoparietal scales (vs. no contact), postmental width equal to mental width (vs. greater than), contact between the first pair of chin shield scales (vs. contact or no contact), a continuous subocular scale row (vs. absence), and the absence of dorsal longitudinal rows of dark spots (vs. presence). From B. elerae, the new species further differs by its smaller MBW ( [ ] mm vs [ ] mm), no contact between prefrontal scales (vs. contact), contact between the first pair of enlarged chin shields (vs. no contact), the presence of six supralabial scales (vs. five or six), six infralabial scales (vs. four or five), a pineal eyespot (vs. absence), enlarged, differentiated nuchal scales (vs. absence), and absence of dorsal longitudinal rows of dark spots (vs. presence). Brachymeles lukbani further differs from B. wrighti by having a smaller maximum SVL (88.7 mm vs. 120 mm [Brown and Alcala, 1980]), the presence of midbody scale rows (vs. 28 [Brown and Alcala, 1980]), six infralabial scales (vs. seven [Brown and Alcala, 1980]), and lack of contact between prefrontal scales (vs. contact [Brown and Alcala, 1980]). From B. pathfinderi, the new species is further differentiated by the absence of contact between prefrontal scales (vs. contact [Brown and Alcala, 1980]), presence of enlarged, differentiated nuchal scales (vs. absence), absence of auricular openings (vs. presence [Brown and Alcala, 1980]), absence of dorsolateral stripes (vs. presence [Brown and Alcala, 1980]), and absence of dorsal longitudinal rows of dark spots (vs. presence [Brown and Alcala, 1980]). The new species is further diagnosed from B. bonitae by the presence of six supralabial scales (vs. six or seven; Table 1), six infralabial scales (vs. five to seven; Table 1), six supraciliary scales (vs. five or six; Table 1), five supraocular scales (vs. four; Table 1), contact between frontoparietal scales (vs. no contact; Table 2), postmental width equal to mental (vs. less than; Table 2), contact between the first pair of enlarged chin shields (vs. no contact; Table 2), non-fusion of the mental and first infralabial (vs. fusion or non-fusion; Table 2), and from B. samarensis by the presence of midbody scale rows (vs. 20; Table 1) and the presence of six infralabial scales (vs. seven; Table 1). The new species differs from all limbless species of Brachymeles (B. apus, B. minimus, and B. vermis) by the following combinations of morphological characters, with character states of congeners found in Tables 1 and 2. From B. apus, B. minimus, and B. vermis, the new species differs by its body size (Table 1). From B. apus and B. vermis, the new species is distinguished by the presence of six infralabials (Table 1), six supraciliaries (Table 1), five supraoculars (Table 1), a continuous subocular scale row (Table 2), contact between frontoparietals (Table 2), postmental width equal to mental (Table 2), and contact between the first pair of enlarged chin shields (Table 2). From B. apus and B. minimus, the new species differs by the presence of paravertebral scale rows (Table 1). Additionally, the new species differs from B. apus by having a smaller relative tail length (Table 1), non-fusion of mental and first infralabial

4 Siler et al. New limbless species of Brachymeles skink 117 Fig. 3. Photograph in life of Brachymeles lukbani paratype (PNM RMB 9672), male, SVL mm. Photographs by R. M. Brown.

5 118 Copeia 2010, No. 1 Table 1. Summary of Meristic and Mensural Characters in Brachymeles lukbani and Specimens of All Other Known Limbless Species of Brachymeles. Brachymeles bonitae and B. samarensis are included based on body size. Sample size, body length, and total length among males and females, and general geographical distribution (PAIC 5 Pleistocene Aggregate Island Complexes, sensu Brown and Diesmos, 2002) are included for reference (SVL and TotL given as range over mean 6 standard deviation; TL/SVL given as percentage over mean 6 standard deviation). B. lukbani (2 m, 9 f) B. minimus (2 m, 3 f) B. vermis (3 f) B. apus (1 f) B. bonitae (6 m, 7 f) B. samarensis (5 f) Range Mt. Labo Catanduanes Island Sulu Archipelago Borneo Mindoro & Luzon PAICs Samar, Leyte, Bicol Peninsula SVL (f) ( ) ( ) ( ) ( ) ( ) SVL (m) 80.7, , N/A N/A N/A ( ) TotL (f) ( ) ( ) ( ) ( ) ( ) TotL (m) N/.A, , N/A N/A N/A ( ) TL/SVL (79 6 5) (76 6 5) (50 6 2) ( ) ( ) FLL N/A N/A N/A N/A ( ) ( ) HLL N/A N/A N/A N/A ( ) ( ) MBSR AGSR N/A N/A N/A N/A PVSR SL 6 (11) 6 (5) 6 (3) 6 6 (12) 6 (5) 7 (1) IFL 6 (11) 6 (5) 5 (3) 5 5 (1) 7 (5) 6 (10) 7 (2) SC 6 (11) 6 (5) 1 (1) 2 5 (12) 6 (5) 2 (2) 6 (1) SO 5 (11) 5 (5) 4 (3) 5 4 (13) 5 (5) (Table 2), and the presence of enlarged, differentiated nuchal scales (Table 2). From B. minimus, the new species differs by the presence of midbody scale rows (Table 1), and from B. vermis by the absence of dorsal longitudinal rows of dark spots (Table 2). Description of holotype. A small Brachymeles, SVL 80.0 mm; mature female, gravid, two eggs present in uterus; body moderately slender; head not well differentiated from neck, narrower than body, HW 5.9% SVL, 94.0% HL; snout moderately long, bluntly rounded in dorsal and lateral profile, SNL 52.0% HL; auricular opening absent; eyes small, ED 1.5% SVL, 24.0% HL, 63.2% END, pupil horizontally elliptical; body slightly dorso-ventrally compressed, MBD 78.6% MBW; body scales smooth, glossy, imbricate; longitudinal scale rows at midbody 22; paravertebral scale rows 100; external limb elements absent, depression present in body scales at point of expected limb insertion, small scale buds present at depression centers; tail nearly as wide as body, gradually tapering to end over distal third, TW 73.2% MBW, TL 79.5% of SVL. Rostral projecting onto dorsal snout to point in line with center of nasal, broader than high, forming short suture with frontonasal; frontonasal wider than long; nostril ovoid, in center of teardrop-shaped nasal, point facing posteriorly, longer axis directed anteroventrally and posterodorsally; nasals well separated; supranasals present, large, moderately separated; postnasals absent; prefrontals moderately separated; frontal nearly square in shape, its anterior margin in broad contact with prefrontal, in contact with first two anterior supraoculars, anteriormost supraocular one-fourth its width; supraoculars five; frontoparietals large, in broad contact medially, each frontoparietal in contact with interior three supraoculars; interparietal large, its length slightly greater than midline length of frontoparietal; interparietal longer than wide, diamond-shaped, wider anteriorly, its length equal to three-fourths length of frontal; parietal eyespot present in posterior one third of scale; parietals as broad as frontoparietals laterally, narrower medially, in narrow contact behind interparietal (right overlaps left); enlarged, differentiated nuchals present, two interior, overlap posterior to parietal scales (right over left); loreals two, decreasing in size from anterior to posterior, anterior loreal twice as long as and slightly higher than posterior loreal, in contact with frontal, supranasal, first and second supralabials, second loreal, and prefrontal; preoculars two, dorsal smaller than ventral; supraciliaries six, the anteriormost in contact with frontal and separating posterior loreal from first supraocular, posteriormost extending to posterior edge of fifth supraocular; single subocular row complete, in contact with supralabials; supraoculars five; lower eyelid with one row of scales; supralabials six, first twice size of other supralabials, fourth supralabial beneath anterior one-half of eye; infralabials six. Mental wider than long, in contact with first infralabial on both sides; single enlarged postmental, its width equal to

6 Siler et al. New limbless species of Brachymeles skink 119 Table 2. Summary of Qualitative Diagnostic Characters (Present, Absent) in Brachymeles lukbani and Specimens of All Other Known Limbless Species of Brachymeles. Brachymeles bonitae and B. samarensis are included based on body size. The pairs of enlarged scales posterior to the postmental scale are abbreviated as chin shield pairs with reference to the 1 st,2 nd, and 3 rd pairs (when present). B. lukbani (2 m, 9 f) B. minimus (2 m, 3 f) B. vermis (3 f) B. apus (1 f) B. bonitae (6 m, 7 f) B. samarensis (5 f) Number of digits (fore-/hind) Limbless Limbless Limbless Limbless 0 2 claws/ 0 2 claws 1 3 claws/ 1 3 claws Frontoparietal contact Postmental vs. mental width Equal Equal PMW, MW PMW. MW PMW, MW Equal 1 st chin shield pair contact Chin shield pair size 1 5 3, 2 3, 1, 2 1, 3, , 2 3, 2, 1 1, 3, 2 Chin shield pair separation a 1(0); 2(1); 1(0); 2(1); 1(1); 2(1); 1(1); 2(2); 1(1); 2(1); 1(0); 2(1); Mental/1 st IFL fusion or 2 2 Differentiated nuchals Continuous subocular scale row Dorsal longitudinal rows of dark spots 2 2 +, reduced ventrally a Parentheses show the number of small ventral scale rows separating each enlarged pair of chin shields that of mental; three pairs of enlarged chin shields, scales of first pair in broad contact, nearly equal in width to third pair; second pair slightly wider than first and third pairs, separated by a single row of undifferentiated scales; third pair separated by three rows of undifferentiated scales. Coloration in alcohol. Body color uniform light chocolate brown; head scales homogeneous light brown; rostral, nasal, postnasal, supranasal, and first supralabial dark gray, lacking brown coloration; pineal eyespot light cream. Coloration in life. (Differences from preserved specimens observed in digital photographs and field notes of CDS and RMB.) Anterior portion of body scales with slightly darker brown pigmentation; scale edges light brown to cream colored; snout, labial and ocular scales darker brown to charcoal colored. Table 3. Summary of Univariate Morphological Variation among Mensural Characters in the Type Series of Brachymeles lukbani. Values are given for both males. For females, ranges are given above means 6 1 standard deviation. Males n = 2 Females n = 9 SVL 80.7, ( ) TotL N/A, ( ) MBW 5.4, ( ) MBD 4.3, ( ) TL ( ) TW 4.6, ( ) TD 4.0, ( ) HL ( ) HW 5.2, ( ) HD ( ) ED 1.0, ( ) END 2.0, ( ) SNL 2.5, ( ) IND ( ) Measurements of holotype (mm). SVL 80.0; TotL 143.6; MBW 5.6; MBD 4.4; TL 63.6; TW 4.1; TD 3.7; HL 5.0; HW 4.7; HD 3.7; ED 1.2; END 1.9; SNL 2.6; IND 1.4; MBSR 22; PVSR 100; SL 6; IFL 6; SC 6; SO 5. Variation. Summaries of variation in mensural characters measured in the series are presented in Table 3. The degree of connection between frontoparietal scales varies in the type series from broad overlap (KU , , , , , PNM 9567, ) to point contact (FMNH , KU , PNM 9589). Additionally, the pineal eyespot varies among the type series from distinct and clearly visible (KU , , , , PNM 9567, 9589) to faint and not clearly defined (FMNH , KU , , , PNM ). Ecology and natural history. Brachymeles lukbani occurs in primary and secondary forest. Individuals were found in the dry rot loam within decaying logs, loose soil, and leaf litter. The coloration of the new species provided obvious camouflage within soil and humus. Individuals were discovered only after rotting logs and soil habitats were disturbed, and individuals would immediately attempt escape by lateral undulation. The new species is ovoviviparous, as are the other species of Brachymeles for which reproductive mode is known (Brown and Alcala, 1980; Hikida, 1982). Two large eggs were observed in the uterus of gravid females. Other sympatric lizard species occurring in the Bicol Peninsula include Brachymeles samarensis, B. boulengeri boulengeri, B. sp. undescribed (Siler et al., 2010), Bronchocela cristatella, Cyrtodactylus philippinicus, Dasia atrocostata, Draco spilopterus, Eutropis multicarinata borealis, Eutropis multifasciata, Gonocephalus sophiae, Gehyra mutilata, Gekko gecko, G. mindorensis, Hemidactylus frenatus, H. platyurus, Hydrosaurus pustulatus, Lamprolepis smaragdina, Lipinia pulchella pulchella, Luperosaurus cumingii, Pseudogekko smaragdina, P. compressicorpus, Sphenomorphus abdictus, S. cumingi, S. decipiens, S. jagori, S. knollmanae, S. laterimaculatus, S. leucospilos, S. steerei, Tropidophorus grayi, Varanus marmoratus, and V. olivaceus.

7 120 Copeia 2010, No. 1 Additionally, Brachymeles minimus is known to occur on Catanduanes Island where Eutropis indeprensa and Sphenomorphus lawtoni additionally have been reported (Ross and Gonzales, 1992; Brown and Alcala, 1995). Distribution. Brachymeles lukbani is known from Mt. Labo in the Camarines Norte Province of Luzon Island (Fig. 1). The new species has been collected from m above sea level. It is possible that this species has a wider distribution in the immediate area of the Bicol Peninsula; however, additional survey work in this region is necessary before this conjecture can be confirmed. Etymology. The new species is named in honor of Vicente R. Lukban (11 February November 1916), whose role in directing military operations for the Philippine army was instrumental in helping to win Philippine independence. He would later become a general in charge of the political and military operations in Samar and Leyte Island. General Lukban was born in the Municiapality of Labo, Camarines Norte Province, close to the type locality of the new species. Suggested common name: Lukban s Loamswimming Skink. DISCUSSION It has been shown that species with limited dispersal ability can exhibit high rates of genetic differentiation and speciation via geographic isolation, with low levels of intrapopulation polymorphism and heterozygosity (Wright, 1931, 1943; Selander et al., 1974; Patton and Yang, 1977; Patton and Feder, 1978; Nevo, 1979). The processes that produce this pattern could be enhanced within a geographically complex island like Luzon, where numerous species of the genus Brachymeles coexist. Whether decreased vagility associated with a semi-fossorial lifestyle has promoted diversification within Brachymeles has yet to be addressed. It is clear that a comprehensive phylogenetic analysis is needed to thoroughly assess species-level diversity. With the discovery of the new species, there are now 18 species of Brachymeles, 17 of which are endemic to the Philippines. The last discovery of a limbless species of Brachymeles was more than a decade ago, when B. minimus was discovered from Catanduanes Island (Brown and Alcala, 1995). Among the three previously known limbless species, B. lukbani is morphologically most similar to B. minimus. Both species are known from the Luzon Faunal Region with type localities separated by a narrow, shallow sea channel (Fig. 1). Without a phylogenetic hypothesis for the genus, it is unknown how recently these two limbless species have evolved from a common ancestor. Additionally, a phylogeny should yield insights into character evolution and whether a limbless body plan has evolved more than once within Brachymeles. The island of Luzon is a complex of large mountain ranges, intervening river valleys, and isolated volcanic peaks. The island s geological history has likely promoted diversification of a variety of lineages (e.g., Platymantis forest frogs; Brown et al., 1997; Alcala et al., 1998; Brown et al., 1999; Brown and Gonzales, 2007). This complex geographic setting provides fertile ground for the discovery of cryptic species (Ross and Gonzales, 1992; Brown et al., 1995a, 1995b; Siler et al., 2009, 2010). Brachymeles lukbani represents the tenth species of Brachymeles known from Luzon Island, and the eleventh species within the Luzon Faunal Region (Brown and Diesmos, 2002; Siler et al., 2009, 2010). With all known limbless Brachymeles species exhibiting restricted geographic distributions, it is possible that the new species occurs only on Mt. Labo. However, additional populations of B. lukbani may eventually be discovered in other localities on the Bicol and Caramoan Peninsulas. Collecting efforts focused on rotting log loam and leaf litter microhabitats must be conducted throughout the region before a complete assessment of the species geographic range and appropriate conservation status can be made. At present, the new species is known from a broad elevational range ( m) on Mt. Labo of the Bicol Peninsula. We consider the status of the new species data deficient, pending the collection of additional information on distribution, abundance, and habitat requirements. MATERIAL EXAMINED All specimens examined are from the Philippines or Malaysia. Numbers in parentheses indicate the number of specimens examined for each species. Several sample sizes are greater than those observed in the description due to the examination of sub-adult specimens which were excluded in morphometric analyses. Brachymeles apus: (1) Malaysia: Borneo: Sabah: Mt. Kinabalu National Park, Sayap Sub-Station: SP Brachymeles bicolor: (11) Luzon Island: Cagayan Province: Municipality of Baggao: Sitio Hot Springs: CAS ; Isabela Province, Sierra Madres Mountain Range: PNM Brachymeles bonitae: (13) Masbate Island: Masbate Province: Municipality of Mobo: Tugbo Barrio: CAS ; Mapuyo Barrio: Palangkahoy: CAS ; Mindoro Island: Mindoro Oriental Province: Mt. Halcon: SE slope of Barawanan Peak: CAS-SU 25713, 25793, , 25904; Sumagui: CAS (paratype); Polillo Island: Quezon Province: Municipality of Polillo: Barangay Pinaglubayan: KU , Brachymeles boulengeri boholensis: (19) Bohol Island: Bohol Province: 6 km S of Municipality of Sierra Bullones: Teachers Park: CAS-SU (holotype) 24528; 13 km SE of Municipality of Sierra Bullones: Dusita Barrio: CAS-SU (paratypes) , 24518, , 24541, 24543, CAS-SU , 25447; 1 km E of Dusita Barrio: Abacjanan: CAS-SU 24867; Municipality of Sierra Bullones: Sandayong: CAS-SU 18709, Brachymeles boulengeri boulengeri: (15) Polillo Island: Quezon Province: Municipality of Polillo: CAS (paratypes) , ; Luzon Island: Laguna Province: Municipality of Los Banos: CAS 61096; Mt. Maquiling: CAS 61297; Polillo Island: Quezon Province: Municipality of Polillo: Barangay Pinaglubayan: KU , , Brachymeles boulengeri mindorensis: (18) Mindoro Island: Mindoro Oriental Province: 30 km SE of Municipality of Calapan: Bank of Tarogin River: CAS-SU (holotype) 24487; SE slope of Mt. Halcon, Tarogin Barrio: CAS-SU (paratypes) , , 24564; 24566, 24568, , ; Mt. Halcon, SE slope of Barawanan Peak: CAS- SU (paratype) Brachymeles boulengeri taylori: (21) Negros Island: Negros Oriental Province: 3 km W of Municipality of Valencia: Cuernos de Negros Mountain Range: Sitio Lunga: ridge on north side of Maiti River: CAS-SU (holotype) 18615, CAS-SU 21873; ridge on south side of Maiti River: CAS-SU (paratype)

8 Siler et al. New limbless species of Brachymeles skink , , 18748; Cuernos de Negros Mountain Range: CAS-SU (paratype) 18649; top of Dayungan Ridge: CAS-SU 21877, 21880, ; 24 km NW of Bondo Barrio: Bantolinao: CAS-SU ; Cebu Island: Cebu Province: 10 km from Municipality of Carcar: Tapal Barrio: Sitio Mantalongon: CAS , , , Brachymeles cebuensis: (8) Cebu Island: 40 km SW of Cebu City: Tapal Barrio, Sitio Mantalungon: CAS-SU (holotype) 24400, (paratypes) , 24399, 24401, 24403; 10 km from Municipality of Carcar: Tapal Barrio: CAS (paratype); 3 km NW of Cebu City, Buhisan Barrio, Buhisan Reforestation Project: CAS-SU Brachymeles elerae: (4) Luzon Island: Kalinga Province: Municipality of Balbalan: CAS , PNM Brachymeles gracilis gracilis: (18) Mindanao Island: Davao del Sur Province: Municipality of Malalag: Sitio Kibawalan: CAS-SU 24163, 24165, CAS , ; Davao City: Buhangin, Kabanti-an: CAS , , ; Digos City: Tres de Mayo Barrio: CAS , Brachymeles gracilis hilong: (20) Mindanao Island: Agusan del Norte Province: Municipality of Cabadbaran: Diuata Mountain Range: Mt. Hilonghilong: Balangbalang: CAS-SU (holotype) 24407, (paratype) , , CAS-SU 24411, , , , , , , , ; Surigao del Sur Province: Municipality of Lanuza: Diuata Mountain Range: Sibuhay Barrio: CAS-SU (paratype) Brachymeles minimus: (6) Catanduanes Island: Catanduanes Province: Municipality of Gigmoto: Barangay San Pedro: KU , Brachymeles samarensis: (7) Samar Island: Eastern Samar Province: Municipality of Taft: Barangay San Rafael: KU , , ; Leyte Island: Leyte Province: Municipality of Baybay: Barangay Pilim: Sitio San Vicente: KU Brachymeles schadenbergi orientalis: (21) Bohol Island: Bohol Province: Municipality of Sierra Bullones: Dusita Barrio: CAS-SU (holotype) 24436, CAS-SU (paratypes) 24428, 24434, 24437, CAS (paratype) , CAS-SU 25452; Dusita Barrio: Abacjanan: CAS-SU (paratypes) , CAS-SU 25460; Cantaub Barrio: CAS-SU (paratypes) 18702, 24442, 24458; Mindanao Island: Agusan del Norte Province: Municipality of Cabadbaran: Diuata Mountain Range: Mt. Hilonghilong: Kasinganan: CAS-SU , , , , Brachymeles schadenbergi schadenbergi: (20) Mindanao Island: Misamis Occidental Province: 2 km NW of Masawan: CAS ; 4 km NW of Masawan: CAS 23471; 3 km NW of Masawan: south bank of Dapitan River: CAS , ; Zamboanga del Norte Province: Dapitan River: CAS-SU ; Basilan Island: Basilan Province: Port Holland: Sawmill: CAS 60493; Camiguin Sur Island: Camiguin Province: Municipality of Catarman: Mt. Mambajao: Sitio Sangsangan: CAS Brachymeles sp. undescribed limbless: (17) Catanduanes Island: Catanduanes Province: Municipality of Gigmoto: Barangay San Pedro, Sitio Tungaw: PNM (holotype) 9565, (paratopotypes) , KU (paratopotypes) , , , ; Luzon Island: Camarines Norte Province: Municipality of Labo, Barangay Tulay Na Lupa, Mt. Labo: KU (paratypes) , , , PNM (paratypes) , FMNH (paratype) Brachymeles sp. undescribed tridactyl: (17) Luzon Island: Nueva Vizcaya Province: Municipality of Quezon: Barangay Maddiangat: (holotype) PNM 9566, (paratypes) PNM , KU , , , Brachymeles talinis: (21) Negros Island: Negros Oriental Province: 6 km west of Municipality of Valencia: Cuernos de Negros Mountain Range: ridge on north side of Maite River: CAS-SU (holotype) 18358, (paratype) 89813; Cuernos de Negros Mountain Range: Dayungan Ridge: CAS ; Dumaguete City: CAS-SU (paratype) 12225; Municipality of Siaton: 20 km north of Bondo Barrio: CAS-SU , 22317, 22323; Inampulagan Island: Guimaras Province: Municipality of Sibunag: 8 km west of Pulupandan Town: CAS-SU 27972, ; Panay Island: Antique Province: Municipality of San Remigio: KU , , , , , , Brachymeles tridactylus: (20) Negros Island: Negros Occidental Province: 16 km east of Municipality of La Castellana: Barrio Cabagna-an: southern slope of Mt. Canlaon: CAS-SU 19424, , 19429, 19452, 19458; 20 km east of Municipality of La Castellana: Sitio Kalapnagan: CAS-SU ; Negros Oriental Province: hills north and northwest of Mayaposi: CAS-SU (holotype) 18354; Panay Island: Antique Province: Municipality of Culasi: Barangay Alojipan: KU Brachymeles vermis: (5) Jolo Island: Sulu Province: CAS-SU (paratype) 62489, CAS-SU , ACKNOWLEDGMENTS We thank the Protected Areas and Wildlife Bureau (PAWB) of the Philippine Department of Environment and Natural Resources (DENR) for facilitating collecting and export permits necessary for this and related studies, wherein we are particularly grateful to M. Lim, C. Custodio, and A. Tagtag. Financial support for fieldwork for CDS was provided by a Panorama Fund grant from The University of Kansas Natural History Museum and Biodiversity Institute, a Madison and Lila Self Fellowship from the University of Kansas, as well as an NSF DEB to CDS and NSF EF and DEB funds to RMB. For the loans of specimens (museum abbreviations follow Leviton et al., 1985), we thank J. Vindum and A. Leviton (CAS), R. Sison and A. Diesmos (PNM), J. Ferner (CMNH), A. Resetar and H. Voris (FMNH), R. Crombie (USNM), and T. LaDuc (TNHC). CDS thanks the Madison and Lila Self Graduate Fellowship Program of the University of Kansas, the Philippine- American Education Foundation (administrators of Fulbright funding), A. Alcala and family, and the Diesmos family for their continued support, as well as CAS s Stearns Fellowship for funding a recent visit to examine comparative material. Critical reviews of the manuscript were provided by L. Trueb and J. Esselstyn. LITERATURE CITED Alcala, A. C., W. C. Brown, and A. C. Diesmos Two new species of the genus Platymantis (Amphibia: Ranidae) from Luzon Island, Philippines. Proceedings of the California Academy of Sciences 50: Brandley, M. C., J. P. Huelsenbeck, and J. J. Wiens Rates and patterns in the evolution of snake-like body form in squamate reptiles: evidence for repeated reevolution of lost digits and long-term persistence of intermediate body forms. Evolution 62:

9 122 Copeia 2010, No. 1 Brown, R. M., and A. C. Diesmos Application of lineage-based species concepts to oceanic island frog populations: the effects of differing taxonomic philosophies on the estimation of Philippine biodiversity. Silliman Journal 42: Brown, R. M., J. W. Ferner, and L. A. Ruedas. 1995a. A new species of lygosomine lizard (Reptilia: Lacertilia: Scincidae; Sphenomorphus) from Mt. Isarog, Luzon Island, Philippines. Proceedings of the Biological Society of Washington 108: Brown, R. M., J. W. Ferner, and R. V. Sison. 1995b. Rediscovery and redescription of Sphenomorphus beyeri Taylor (Reptilia: Lacertilia: Scincidae) from the Zambales mountains of Luzon, Philippines. Proceedings of the Biological Society of Washington 108:6 17. Brown, R. M., and J. C. Gonzales A new forest frog of the genus Platymantis (Amphibia; Anura; Ranidae) from the Bicol Peninsula of Luzon Island, Philippines. Copeia 2007: Brown, R. M., J. A. McGuire, J. W. Ferner, and A. C. Alcala A new diminutive species of skink (Squamata; Scincidae; Lygosominae: Sphenomorphus) from Luzon Island, Republic of the Philippines. Copeia 1999: Brown, W. C A revision of the genus Brachymeles (Scincidae), with descriptions of new species and subspecies. Breviora 54:1 19. Brown, W. C., and A. C. Alcala Subfamily Scincinae, p In: Philippine Lizards of the Family Scincidae. D. Law (ed.). Silliman University Press, Dumaguete City, Philippines. Brown, W. C., and E. L. Alcala A new species of Brachymeles (Reptilia: Scincidae) from Catanduanes Island, Philippines. Proceedings of the Biological Society of Washington 108: Brown, W. C., A. C. Alcala, and A. C. Diesmos A new species of the genus Platymantis (Amphibia: Ranidae) from Luzon Island, Philippines. Proceedings of the Biological Society of Washington 110: Brown, W. C., and D. S. Rabor Review of the genus Brachymeles (Scincidae), with descriptions of new species and subspecies. Proceedings of the California Academy of Sciences 15: Greer, A. E., P. David, and A. Teynie The Southeast Asian Scincid lizard Siaphos tridigitus Bourret, 1939 (Reptilia, Scincidae): a second specimen. Zoosystema 28: Hikida, T A new limbless Brachymeles (Sauria: Scincidae) from Mt. Kinabalu, North Borneo. Copeia 1982: Lande, R Evolutionary mechanisms of limb loss in tetrapods. Evolution 32: Nevo, E Adaptive convergence and divergence of subterranean mammals. Annual Reviews 10: Patton, J. L., and J. H. Feder Genetic divergence between populations of the pocket gopher, Thomomys umbrinus (Richardson). Saugetierkunde 43: Patton, J. L., and S. Y. Yang Genetic variation in Thomomys bottae pocket gophers: macrogeographic patterns. Evolution 31: Ross, C. A., and P. C. Gonzales Amphibians and reptiles of Catanduanes Island, Philippines. National Museum Papers (Manila) 2: Selander, R. K., D. W. Kaufman, R. J. Baker, and S. L. Williams Genic and chromosomal differentiation in pocket gophers of the Geomys bursarius group. Evolution 28: Siler, C. D., A. C. Diesmos, and R. M. Brown A new loam-swimming skink, genus Brachymeles (Reptilia: Squamata: Scincidae) from the Bicol faunal region, Luzon and Catanduanes islands, Philippines. Journal of Herpetology 44: Siler, C. D., E. L. Rico, M. R. Duya, and R. M. Brown A new limb-reduced, loam-swimming skink (Reptilia: Squamata: Scincidae: genus Brachymeles) from central Luzon Island, Philippines. Herpetologica 65: Taylor, E. H Brachymeles, a genus of Philippine lizards. Philippine Journal of Science 12: Taylor, E. H Reptiles of Sulu archipelago. Philippine Journal of Science 13: Taylor, E. H Additions to the herpetological fauna of the Philippine Islands, I. Philippine Journal of Science 21: Wiens, J. J., and J. L. Slingluff How lizards turn into snakes: a phylogenetic analysis of body-form evolution in anguid lizards. Evolution 55: Wright, S Evolution in Mendelian populations. Genetics 16: Wright, S Isolation by distance. Genetics 28: