A New Legless Loam-swimming Lizard (Reptilia: Squamata: Scincidae:

Genus Brachymeles) from the Bicol Peninsula, Luzon Island, Philippines

Cameron D. Siler1, Danny S. Balete2, Arvin C. Diesmos3, and Rafe M. Brown1

A new limbless species of scincid lizard of the genus Brachymeles is described from Mt. Labo, Bicol Peninsula, LuzonIsland, Philippines. The species was encountered only on this isolated volcanic peak and is conspicuously absent fromsurrounding, well-surveyed regions of the Bicol Peninsula. The new species is the fourth known limbless species ofBrachymeles 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 bothcolor and scalation. The discovery brings the total number of known Brachymeles species in the Luzon Faunal Region toeleven, including two limbless forms.

Isang panibagong uri ng mga bubuling Brachymeles na walang mga paa ang isinalarawan mula sa bundok ng Labo, satimog-hilagang Luzon, sa Pilipinas. Ang Brachymeles na ito ay matatagpuan lamang sa isang liblib na kabundukan saCamarines Norte ng Kabikolan. Ito ay pang-apat lamang sa mga walang paang uri ng Brachymeles sa buong mundo atpangatlong natuklasan sa Pilipinas. Ito rin ang pumapangalawa sa haba ng katawan sa mga kauri nitong walang mgapaa. Maliban sa sukat ng pangatawan, ito ay makikilala rin mula sa mga kauri nito sa taglay nitong mga katangian saanyong panglabas, kulay, at pangaliskis. Sa pagkatuklas ng Brachymeles na ito, umabot na sa labing isa ang mgaBrachymeles 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 thePhilippines. 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 fourgenera that possess both fully limbed and limbless species(Brachymeles, Chalcides, Lerista, and Scelotes; Lande, 1978;Wiens and Slingluff, 2001; Brandley et al., 2008). Within thegenus, 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 withreduced 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 threespecies are limbless (B. apus, B. vermis, and B. minimus).Among the seven non-pentadactyl species, there exists a fullspectrum of limb and digit reduced states, from moderatelydeveloped 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 andexternal morphology, which has made diagnosing speciesboundaries on the basis of morphology difficult (Brown,1956; Brown and Rabor, 1967; Brown and Alcala, 1980; Sileret al., 2009, 2010). Among the 17 known species, threepolytypic 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. boulengericontains four subspecies. Several species are known to occuracross broad geographic distributions, but many of the limb-reduced and limbless species are known from single islandsor 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 at1115 m elevation. The species possessed a combination ofmorphological characters that fell within the range of thoseknown for other species of Brachymeles, including thepresence of a supranasal scale, brown body coloration, 21–23 midbody scale rows, and the general similarity in headscale patterns. In 2008, 13 additional specimens of the samespecies were collected from 200–1000 m elevation (Fig. 1).The new species is semi-fossorial and was found within rottenlogs and in the loose soil and leaf litter around them. Hereinwe describe the species, diagnose it from all congeners, andreport on its natural history, ecology, and habitat.

MATERIALS AND METHODS

We recorded morphometric data from alcohol-preservedspecimens that were fixed in 10% formalin. Sex wasdetermined by gonadal inspection, and measurements weretaken with digital calipers to the nearest 0.1 mm. Allmeasurements were scored by the first author. Colordescriptions are based on preserved specimens, field notes,and color digital images in life.

Meristic and mensural characters are chosen based onBrown 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 edgeof forelimb insertion and anterior edge of hind limbinsertion), total length (TotL: distance from tip of snout totip of tail), midbody width (MBW: measured from lateralsurface to opposing lateral edge at midpoint of axilla–groinregion), midbody depth (MBD: measured from ventralsurface to dorsal surface at midpoint of axilla–groin region),tail length (TL: measured from posterior margin of vent totip of tail), tail width (TW: measured at widest section of tailposterior 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 66045-7561; E-mail: (CDS) camsiler@ku.edu. Send reprint requests to CDS.

2 Laksambuhay Conservation Foundation, Los Banos, Laguna Province, Philippines.3 Herpetology Section, Zoology Division, Philippine National Museum, Rizal Park, Burgos St., Manila, Philippines.Submitted: 4 December 2008. Accepted: 26 August 2009. Associate Editor: T. W. Reeder.F 2010 by the American Society of Ichthyologists and Herpetologists DOI: 10.1643/CH-08-231

Copeia 2010, No. 1, 114–122

ventral to dorsal surface of tail at the same point as TW),head length (HL: from tip of snout to posterior margin ofjaw articulation), head width (HW: widest measure of headwidth at jaw articulations), head depth (HD: measured fromventral to dorsal surface of head at jaw articulations), snout–forearm length (SnFa: measured from tip of snout to anteriormargin of forelimb insertion), eye diameter (ED: at widestpoint), eye–narial distance (END: from anterior margin ofeye to posterior margin of nares), snout length (SNL: fromanterior margin of eye to tip of snout), internarial distance(IND: from dorsal aspect between most laterally distal edgesof nares), forelimb length (FLL: measured from forelimbinsertion to tip of Finger III or longest digit), hind limblength (HLL: measured from hind limb insertion to tip ofToe IV or longest digit), midbody scale-row count (MBSR:number of longitudinal scale rows measured around widestpoint of midbody), paravertebral scale-row count (PVSR:number of scale rows measured between parietals and thebase of the tail opposite the vent), axilla–groin scale-rowcount (AGSR: number of scale rows measured betweenposterior edge of forelimb insertion and anterior edge of

hindlimb insertion), Finger III lamellae count (FinIIIlam: allenlarged, undivided lamellae beneath Finger III), Toe IVlamellae count (ToeIVlam: all enlarged, undivided lamellaebeneath Toe IV), supralabial count (SL), infralabial count(IFL), supraciliary count (SC), and supraocular count (SO). Inthe description, ranges are followed by mean 6 standarddeviation in parentheses.

Fig. 2. Illustration of head of female holotype of Brachymeles lukbani(PNM 9567) in dorsal, lateral, and ventral views. Taxonomically usefulhead 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, withnumbers indicating scales in the supraciliary series.

Fig. 1. Known distribution of Brachymeles lukbani on Mt. Labo, BicolPeninsula, Philippines. The inset shows the location of Luzon Island(colored in dark gray) within the Philippines. The type locality of thenew 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 indicatedby a black square.

Siler et al.—New limbless species of Brachymeles skink 115

Brachymeles lukbani, new speciesFigures 2, 3; Tables 1–3

Holotype.—PNM 9567 (field no. RMB 9664, formerly KU313599; Fig. 2), adult female, Philippines, Mt. Labo, Bar-angay Tulay Na Lupa, Municipality of Labo, CamarinesNorte Province, Luzon Island, 14.039367uN, 122.78655uE(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 313597–99, 313601, 313603–04,313606, 313608, PNM 9589–92 (formerly KU 313605,313600, 313602, and 313596, respectively), including eightadult females, one adult male, and three juveniles ofunknown sex, 21 June–4 July 2008, 200–1000 m elevation;FMNH 270191, adult male, 21 April–11 May 2006, 1115 melevation, same locality, Danny S. Balete.

Diagnosis.—Brachymeles lukbani can be distinguished fromcongeners by the following combination of characters: bodyform long, slender; limbless; midbody scale rows 21–23;paravertebral scale rows 100–106; infralabial scales six;supraciliary scales six; supraocular scales five; pineal eyespot; contact between frontoparietal scales; postmental scalewidth equal to mental scale width; contact between the firstpair of chin shield scales; non-fusion of mental and firstinfralabial scales; enlarged, differentiated nuchal scales;continuous subocular scale row; third pair of enlarged chinshields; and uniform body coloration (Tables 1, 2).

Comparisons.—From all pentadactyl species and subspeciesof Brachymeles (B. bicolor, B. boulengeri boholensis, B. boulen-geri 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 thecomplete absence of external limb elements (vs. presence); asmaller maximum MBW (6.2 mm vs. greater than11.6 mm); absence of auricular openings (vs. presence);absence of a postnasal scale (vs. presence, with the exceptionof B. g. gracilis; presence or absence); presence of enlarged,differentiated nuchal scales (vs. absence, with the exceptionof B. bicolor; presence); presence of 21–23 midbody scalerows (vs. greater than 23); and presence of 100–106paravertebral 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 havinga postmental scale width equal to mental scale width; fromall pentadactyl species except B. talinis, B. g. gracilis, B. g.hilong, and B. b. boholensis by the presence of a third pair ofenlarged 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 maximumTotL (158.8 mm vs. greater than 166.2 mm), and a uniformbody color.

The new species differs from all non-pentadactyl, limbedspecies of Brachymeles (B. bonitae, B. cebuensis, B. elerae, B.pathfineri, B. samarensis, B. sp. undescribed tridactyl [Siler etal., 2009], B. tridactylus, and B. wrighti) by the completeabsence of external limb elements, from all non-pentadactylspecies except B. wrighti by its larger maximum SVL(88.7 mm vs. less than 81.3 mm) and its larger maximumTotL (158.8 mm SVL vs. less than 154.1 mm), and from allnon-pentadactyl species except B. bonitae and B. wrighti by

the presence of 100–106 paravertebral scale rows (vs. 90–109, B. bonitae; 102, B. wrighti [Brown and Alcala, 1980]).

In addition, the new species differs from B. tridactylus bythe presence of six supralabial scales (vs. six or seven), sixinfralabial scales (vs. six or seven), six supraciliary scales (vs.five), five supraocular scales (vs. four), contact betweenfrontoparietal scales (vs. no contact), postmental widthequal to mental width (vs. greater than), contact betweenthe first pair of chin shield scales (vs. contact or no contact),a continuous subocular scale row (vs. absence), and theabsence of dorsal longitudinal rows of dark spots (vs.presence).

From B. elerae, the new species further differs by its smallerMBW (4.5–6.2 [5.3 6 0.5] mm vs. 6.3–6.5 [6.4 6 0.1] mm),no contact between prefrontal scales (vs. contact), contactbetween the first pair of enlarged chin shields (vs. nocontact), the presence of six supralabial scales (vs. five orsix), 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 darkspots (vs. presence).

Brachymeles lukbani further differs from B. wrighti byhaving a smaller maximum SVL (88.7 mm vs. 120 mm[Brown and Alcala, 1980]), the presence of 21–23 midbodyscale rows (vs. 28 [Brown and Alcala, 1980]), six infralabialscales (vs. seven [Brown and Alcala, 1980]), and lack ofcontact between prefrontal scales (vs. contact [Brown andAlcala, 1980]).

From B. pathfinderi, the new species is further differenti-ated by the absence of contact between prefrontal scales (vs.contact [Brown and Alcala, 1980]), presence of enlarged,differentiated nuchal scales (vs. absence), absence of auric-ular openings (vs. presence [Brown and Alcala, 1980]),absence of dorsolateral stripes (vs. presence [Brown andAlcala, 1980]), and absence of dorsal longitudinal rows ofdark spots (vs. presence [Brown and Alcala, 1980]).

The new species is further diagnosed from B. bonitae bythe presence of six supralabial scales (vs. six or seven;Table 1), six infralabial scales (vs. five to seven; Table 1), sixsupraciliary scales (vs. five or six; Table 1), five supraocularscales (vs. four; Table 1), contact between frontoparietalscales (vs. no contact; Table 2), postmental width equal tomental (vs. less than; Table 2), contact between the first pairof enlarged chin shields (vs. no contact; Table 2), non-fusionof the mental and first infralabial (vs. fusion or non-fusion;Table 2), and from B. samarensis by the presence of 21–23midbody scale rows (vs. 20; Table 1) and the presence of sixinfralabial scales (vs. seven; Table 1).

The new species differs from all limbless species ofBrachymeles (B. apus, B. minimus, and B. vermis) by thefollowing combinations of morphological characters, withcharacter states of congeners found in Tables 1 and 2. FromB. apus, B. minimus, and B. vermis, the new species differs byits body size (Table 1). From B. apus and B. vermis, the newspecies 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 widthequal to mental (Table 2), and contact between the first pairof enlarged chin shields (Table 2). From B. apus and B.minimus, the new species differs by the presence of 100–106paravertebral scale rows (Table 1). Additionally, the newspecies differs from B. apus by having a smaller relative taillength (Table 1), non-fusion of mental and first infralabial

116 Copeia 2010, No. 1

Fig. 3. Photograph in life of Brachymeles lukbani paratype (PNM 9590 5 RMB 9672), male, SVL 5 80.7 mm. Photographs by R. M. Brown.

Siler et al.—New limbless species of Brachymeles skink 117

(Table 2), and the presence of enlarged, differentiatednuchal scales (Table 2). From B. minimus, the new speciesdiffers by the presence of 21–23 midbody scale rows(Table 1), and from B. vermis by the absence of dorsallongitudinal rows of dark spots (Table 2).

Description of holotype.—A small Brachymeles, SVL 80.0 mm;mature female, gravid, two eggs present in uterus; bodymoderately slender; head not well differentiated from neck,narrower than body, HW 5.9% SVL, 94.0% HL; snoutmoderately long, bluntly rounded in dorsal and lateralprofile, SNL 52.0% HL; auricular opening absent; eyes small,ED 1.5% SVL, 24.0% HL, 63.2% END, pupil horizontallyelliptical; body slightly dorso-ventrally compressed, MBD78.6% MBW; body scales smooth, glossy, imbricate; longi-tudinal scale rows at midbody 22; paravertebral scale rows100; external limb elements absent, depression present inbody scales at point of expected limb insertion, small scalebuds present at depression centers; tail nearly as wide asbody, 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 suturewith 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, moderatelyseparated; postnasals absent; prefrontals moderately sepa-

rated; frontal nearly square in shape, its anterior margin inbroad contact with prefrontal, in contact with first twoanterior supraoculars, anteriormost supraocular one-fourthits width; supraoculars five; frontoparietals large, in broadcontact medially, each frontoparietal in contact withinterior three supraoculars; interparietal large, its lengthslightly greater than midline length of frontoparietal;interparietal longer than wide, diamond-shaped, wideranteriorly, its length equal to three-fourths length of frontal;parietal eyespot present in posterior one third of scale;parietals as broad as frontoparietals laterally, narrowermedially, in narrow contact behind interparietal (rightoverlaps left); enlarged, differentiated nuchals present, twointerior, 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 thanposterior loreal, in contact with frontal, supranasal, first andsecond supralabials, second loreal, and prefrontal; preocu-lars two, dorsal smaller than ventral; supraciliaries six, theanteriormost in contact with frontal and separating poste-rior loreal from first supraocular, posteriormost extending toposterior edge of fifth supraocular; single subocular rowcomplete, in contact with supralabials; supraoculars five;lower eyelid with one row of scales; supralabials six, firsttwice size of other supralabials, fourth supralabial beneathanterior one-half of eye; infralabials six.

Mental wider than long, in contact with first infralabialon both sides; single enlarged postmental, its width equal to

Table 1. Summary of Meristic and Mensural Characters in Brachymeles lukbani and Specimens of All Other Known Limbless Species ofBrachymeles. Brachymeles bonitae and B. samarensis are included based on body size. Sample size, body length, and total length among males andfemales, and general geographical distribution (PAIC 5 Pleistocene Aggregate Island Complexes, sensu Brown and Diesmos, 2002) are included forreference (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 & LuzonPAICs

Samar, Leyte, BicolPeninsula

SVL (f) 69.9–81.1(76.4 6 4.0)

62.93–64.31(63.67 6 0.69)

62.84–74.70(70.67 6 6.78)

106.15 49.74–59.76(56.36 6 3.92)

62.44–66.08(63.40 6 1.53)

SVL (m) 80.7, 88.7 56.96, 61.19 N/A N/A 65.08–79.96(73.51 6 6.38)

N/A

TotL (f) 119.8–143.5(133.5 6 9.6)

107.76–115.14(111.28 6 3.70)

111.49–112.93(112.21 6 1.02)

175.28 93.41–150.36(126.65 6 19.93)

97.72–112.89(107.26 6 8.31)

TotL (m) N/.A, 158.8 103.58, 106.40 N/A N/A 102.60–144.49(121.28 6 15.59)

N/A

TL/SVL 71–86 (79 6 5) 69–82 (76 6 5) 49–52 (50 6 2) 65 35–93 (69 6 18) 57–81 (71 6 13)FLL N/A N/A N/A N/A 1.00–1.52

(1.25 6 0.14)1.12–2.59

(1.71 6 0.54)HLL N/A N/A N/A N/A 1.33–2.01

(1.64 6 0.22)2.54–3.07

(2.84 6 0.21)MBSR 21–23 20 22–24 24 21–23 20AGSR N/A N/A N/A N/A 73–90 67–72PVSR 100–106 91–97 104–107 112 90–109 86–92SL 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)

118 Copeia 2010, No. 1

that of mental; three pairs of enlarged chin shields, scales offirst pair in broad contact, nearly equal in width to thirdpair; second pair slightly wider than first and third pairs,separated by a single row of undifferentiated scales; thirdpair separated by three rows of undifferentiated scales.

Coloration in alcohol.—Body color uniform light chocolatebrown; head scales homogeneous light brown; rostral, nasal,postnasal, supranasal, and first supralabial dark gray, lackingbrown coloration; pineal eyespot light cream.

Coloration in life.—(Differences from preserved specimensobserved in digital photographs and field notes of CDS andRMB.) Anterior portion of body scales with slightly darkerbrown pigmentation; scale edges light brown to creamcolored; snout, labial and ocular scales darker brown tocharcoal colored.

Measurements of holotype (mm).—SVL 80.0; TotL 143.6; MBW5.6; MBD 4.4; TL 63.6; TW 4.1; TD 3.7; HL 5.0; HW 4.7; HD3.7; 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 charactersmeasured in the series are presented in Table 3. The degreeof connection between frontoparietal scales varies in thetype series from broad overlap (KU 313597–98, 313601,313603–04, 313606, 313608, PNM 9567, 9590–92) to pointcontact (FMNH 270191, KU 313607, PNM 9589). Addition-ally, the pineal eyespot varies among the type series fromdistinct and clearly visible (KU 313597–98, 313603, 313606,313608, PNM 9567, 9589) to faint and not clearly defined(FMNH 270191, KU 313601, 313604, 313607, PNM 9590–92).

Ecology and natural history.—Brachymeles lukbani occurs inprimary and secondary forest. Individuals were found in thedry rot loam within decaying logs, loose soil, and leaf litter.The coloration of the new species provided obviouscamouflage within soil and humus. Individuals werediscovered only after rotting logs and soil habitats weredisturbed, and individuals would immediately attemptescape by lateral undulation. The new species is ovovivip-arous, as are the other species of Brachymeles for whichreproductive mode is known (Brown and Alcala, 1980;Hikida, 1982). Two large eggs were observed in the uterus ofgravid females.

Other sympatric lizard species occurring in the BicolPeninsula include Brachymeles samarensis, B. boulengeriboulengeri, B. sp. undescribed (Siler et al., 2010), Bronchocelacristatella, Cyrtodactylus philippinicus, Dasia atrocostata, Dracospilopterus, Eutropis multicarinata borealis, Eutropis multifas-ciata, Gonocephalus sophiae, Gehyra mutilata, Gekko gecko, G.mindorensis, Hemidactylus frenatus, H. platyurus, Hydrosauruspustulatus, Lamprolepis smaragdina, Lipinia pulchella pulchella,Luperosaurus cumingii, Pseudogekko smaragdina, P. compressi-corpus, Sphenomorphus abdictus, S. cumingi, S. decipiens, S.jagori, S. knollmanae, S. laterimaculatus, S. leucospilos, S. steerei,Tropidophorus grayi, Varanus marmoratus, and V. olivaceus.

Table 2. Summary of Qualitative Diagnostic Characters (Present, Absent) in Brachymeles lukbani and Specimens of All Other Known LimblessSpecies of Brachymeles. Brachymeles bonitae and B. samarensis are included based on body size. The pairs of enlarged scales posterior to thepostmental scale are abbreviated as chin shield pairs with reference to the 1st, 2nd, and 3rd 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 + + 2 2 2 +Postmental vs. mental width Equal Equal PMW , MW PMW . MW PMW , MW Equal1st chin shield pair contact + + 2 2 2 +Chin shield pair size 1 5 3 , 2 3 , 1 , 2 1 , 3 , 2 1 5 3 , 2 3 , 2 , 1 1 , 3 , 2Chin shield pair separationa 1(0); 2(1);

3(3)1(0); 2(1);

3(3)1(1); 2(1);

3(3)1(1); 2(2);

3(3)1(1); 2(1);

3(3)1(0); 2(1);

3(3)Mental/1st IFL fusion 2 2 2 + + or 2 2

Differentiated nuchals + + + 2 + +Continuous subocular scale

row+ + 2 2 + +

Dorsal longitudinal rows ofdark spots

2 2 +, reducedventrally

2 2 2

a Parentheses show the number of small ventral scale rows separating each enlarged pair of chin shields.

Table 3. Summary of Univariate Morphological Variation amongMensural Characters in the Type Series of Brachymeles lukbani.Values are given for both males. For females, ranges are given abovemeans 6 1 standard deviation.

Males n = 2 Females n = 9

SVL 80.7, 88.7 69.9–81.1 (76.3 6 4.0)TotL N/A, 158.8 119.8–143.5 (133.5 6 9.6)MBW 5.4, 5.6 4.5–6.2 (5.3 6 0.6)MBD 4.3, 4.4 3.4–4.8 (4.1 6 0.6)TL 70.1 49.9–63.6 (58.8 6 5.6)TW 4.6, 4.7 3.6–4.5 (4.1 6 0.4)TD 4.0, 4.2 2.8–4.0 (3.6 6 0.3)HL 5.5 4.4–5.3 (5.0 6 0.3)HW 5.2, 5.3 4.2–5.2 (4.7 6 0.3)HD 4.1 3.3–4.1 (3.7 6 0.2)ED 1.0, 1.2 1.0–1.2 (1.1 6 0.1)END 2.0, 2.3 1.7–2.1 (2.0 6 0.1)SNL 2.5, 3.0 2.3–2.9 (2.6 6 0.2)IND 1.2 1.2–1.5 (1.4 6 0.1)

Siler et al.—New limbless species of Brachymeles skink 119

Additionally, Brachymeles minimus is known to occur onCatanduanes Island where Eutropis indeprensa and Spheno-morphus lawtoni additionally have been reported (Ross andGonzales, 1992; Brown and Alcala, 1995).

Distribution.—Brachymeles lukbani is known from Mt. Labo inthe Camarines Norte Province of Luzon Island (Fig. 1). Thenew species has been collected from 200–1115 m above sealevel. It is possible that this species has a wider distributionin the immediate area of the Bicol Peninsula; however,additional survey work in this region is necessary before thisconjecture can be confirmed.

Etymology.—The new species is named in honor of VicenteR. Lukban (11 February 1860–16 November 1916), whoserole in directing military operations for the Philippine armywas instrumental in helping to win Philippine indepen-dence. He would later become a general in charge of thepolitical 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 thenew species. Suggested common name: Lukban’s Loam-swimming Skink.

DISCUSSION

It has been shown that species with limited dispersal abilitycan exhibit high rates of genetic differentiation andspeciation via geographic isolation, with low levels ofintrapopulation polymorphism and heterozygosity (Wright,1931, 1943; Selander et al., 1974; Patton and Yang, 1977;Patton and Feder, 1978; Nevo, 1979). The processes thatproduce this pattern could be enhanced within a geograph-ically complex island like Luzon, where numerous species ofthe genus Brachymeles coexist. Whether decreased vagilityassociated with a semi-fossorial lifestyle has promoteddiversification within Brachymeles has yet to be addressed.It is clear that a comprehensive phylogenetic analysis isneeded to thoroughly assess species-level diversity.

With the discovery of the new species, there are now 18species of Brachymeles, 17 of which are endemic to thePhilippines. The last discovery of a limbless species ofBrachymeles was more than a decade ago, when B. minimuswas 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 withtype localities separated by a narrow, shallow sea channel(Fig. 1). Without a phylogenetic hypothesis for the genus, itis unknown how recently these two limbless species haveevolved from a common ancestor. Additionally, a phylog-eny should yield insights into character evolution andwhether a limbless body plan has evolved more than oncewithin Brachymeles.

The island of Luzon is a complex of large mountainranges, intervening river valleys, and isolated volcanicpeaks. The island’s geological history has likely promoteddiversification of a variety of lineages (e.g., Platymantis forestfrogs; Brown et al., 1997; Alcala et al., 1998; Brown et al.,1999; Brown and Gonzales, 2007). This complex geographicsetting provides fertile ground for the discovery of crypticspecies (Ross and Gonzales, 1992; Brown et al., 1995a,1995b; Siler et al., 2009, 2010). Brachymeles lukbani repre-sents the tenth species of Brachymeles known from LuzonIsland, and the eleventh species within the Luzon Faunal

Region (Brown and Diesmos, 2002; Siler et al., 2009, 2010).With all known limbless Brachymeles species exhibitingrestricted geographic distributions, it is possible that thenew species occurs only on Mt. Labo. However, additionalpopulations of B. lukbani may eventually be discovered inother localities on the Bicol and Caramoan Peninsulas.Collecting efforts focused on rotting log loam and leaf littermicrohabitats must be conducted throughout the regionbefore a complete assessment of the species’ geographicrange and appropriate conservation status can be made. Atpresent, the new species is known from a broad elevationalrange (200–1115 m) on Mt. Labo of the Bicol Peninsula. Weconsider the status of the new species ‘‘data deficient,’’pending the collection of additional information ondistribution, abundance, and habitat requirements.

MATERIAL EXAMINED

All specimens examined are from the Philippines orMalaysia. Numbers in parentheses indicate the number ofspecimens examined for each species. Several sample sizesare greater than those observed in the description due to theexamination of sub-adult specimens which were excluded inmorphometric analyses.

Brachymeles apus: (1) Malaysia: Borneo: Sabah: Mt. Kina-balu National Park, Sayap Sub-Station: SP 06915.

Brachymeles bicolor: (11) Luzon Island: Cagayan Province:Municipality of Baggao: Sitio Hot Springs: CAS 186111;Isabela Province, Sierra Madres Mountain Range: PNM9568–77.

Brachymeles bonitae: (13) Masbate Island: Masbate Prov-ince: Municipality of Mobo: Tugbo Barrio: CAS 144223;Mapuyo Barrio: Palangkahoy: CAS 144270; Mindoro Island:Mindoro Oriental Province: Mt. Halcon: SE slope ofBarawanan Peak: CAS-SU 25713, 25793, 25886–88, 25904;Sumagui: CAS 62064 (paratype); Polillo Island: QuezonProvince: Municipality of Polillo: Barangay Pinaglubayan:KU 307747–49, 307755.

Brachymeles boulengeri boholensis: (19) Bohol Island: BoholProvince: 6 km S of Municipality of Sierra Bullones: TeachersPark: CAS-SU (holotype) 24528; 13 km SE of Municipality ofSierra Bullones: Dusita Barrio: CAS-SU (paratypes) 24502–04,24518, 24520–25, 24541, 24543, CAS-SU 25443–44, 25447;1 km E of Dusita Barrio: Abacjanan: CAS-SU 24867;Municipality of Sierra Bullones: Sandayong: CAS-SU 18709,18717.

Brachymeles boulengeri boulengeri: (15) Polillo Island:Quezon Province: Municipality of Polillo: CAS (paratypes)62272–73, 62276–77; Luzon Island: Laguna Province: Mu-nicipality of Los Banos: CAS 61096; Mt. Maquiling: CAS61297; Polillo Island: Quezon Province: Municipality ofPolillo: Barangay Pinaglubayan: KU 307439, 307750–54,307756–58.

Brachymeles boulengeri mindorensis: (18) Mindoro Island:Mindoro Oriental Province: 30 km SE of Municipality ofCalapan: Bank of Tarogin River: CAS-SU (holotype) 24487;SE slope of Mt. Halcon, Tarogin Barrio: CAS-SU (paratypes)24549–54, 24561–62, 24564; 24566, 24568, 24573–74,24577–79; Mt. Halcon, SE slope of Barawanan Peak: CAS-SU (paratype) 24570.

Brachymeles boulengeri taylori: (21) Negros Island: NegrosOriental Province: 3 km W of Municipality of Valencia:Cuernos de Negros Mountain Range: Sitio Lunga: ridge onnorth side of Maiti River: CAS-SU (holotype) 18615, CAS-SU21873; ridge on south side of Maiti River: CAS-SU (paratype)

120 Copeia 2010, No. 1

18641, 18656–57, 18748; Cuernos de Negros MountainRange: CAS-SU (paratype) 18649; top of Dayungan Ridge:CAS-SU 21877, 21880, 21883–84; 24 km NW of Bondo Barrio:Bantolinao: CAS-SU 22355–56; Cebu Island: Cebu Province:10 km from Municipality of Carcar: Tapal Barrio: SitioMantalongon: CAS 154671, 154673, 154678–82, 154686.

Brachymeles cebuensis: (8) Cebu Island: 40 km SW of CebuCity: Tapal Barrio, Sitio Mantalungon: CAS-SU (holotype)24400, (paratypes) 24396–97, 24399, 24401, 24403; 10 kmfrom Municipality of Carcar: Tapal Barrio: CAS 102405(paratype); 3 km NW of Cebu City, Buhisan Barrio, BuhisanReforestation Project: CAS-SU 27537.

Brachymeles elerae: (4) Luzon Island: Kalinga Province:Municipality of Balbalan: CAS 61499–500, PNM 9563–4.

Brachymeles gracilis gracilis: (18) Mindanao Island: Davaodel Sur Province: Municipality of Malalag: Sitio Kibawalan:CAS-SU 24163, 24165, CAS 124811, 139307–09; Davao City:Buhangin, Kabanti-an: CAS 124803–04, 139293–95, 139303–05; Digos City: Tres de Mayo Barrio: CAS 124806–08, 139300.

Brachymeles gracilis hilong: (20) Mindanao Island: Agusandel Norte Province: Municipality of Cabadbaran: DiuataMountain Range: Mt. Hilonghilong: Balangbalang: CAS-SU(holotype) 24407, (paratype) 102406, 133578, CAS-SU24411, 133577, 133581–82, 133609, 133612, 133692–93,133703–06, 133743, 133745–47; Surigao del Sur Province:Municipality of Lanuza: Diuata Mountain Range: SibuhayBarrio: CAS-SU (paratype) 24315.

Brachymeles minimus: (6) Catanduanes Island: Catan-duanes Province: Municipality of Gigmoto: Barangay SanPedro: KU 308129–31, 308210–12.

Brachymeles samarensis: (7) Samar Island: Eastern SamarProvince: Municipality of Taft: Barangay San Rafael: KU310849–50, 310852, 311294–6; Leyte Island: Leyte Province:Municipality of Baybay: Barangay Pilim: Sitio San Vicente:KU 311225.

Brachymeles schadenbergi orientalis: (21) Bohol Island:Bohol Province: Municipality of Sierra Bullones: DusitaBarrio: CAS-SU (holotype) 24436, CAS-SU (paratypes)24428, 24434, 24437, CAS (paratype) 102404, CAS-SU25452; Dusita Barrio: Abacjanan: CAS-SU (paratypes)24446–51, CAS-SU 25460; Cantaub Barrio: CAS-SU (para-types) 18702, 24442, 24458; Mindanao Island: Agusan delNorte Province: Municipality of Cabadbaran: Diuata Moun-tain Range: Mt. Hilonghilong: Kasinganan: CAS-SU 133301,133616, 133749, 133752, 133754.

Brachymeles schadenbergi schadenbergi: (20) MindanaoIsland: Misamis Occidental Province: 2 km NW of Masawan:CAS 23468–69; 4 km NW of Masawan: CAS 23471; 3 km NWof Masawan: south bank of Dapitan River: CAS 23479–81,23484–85; Zamboanga del Norte Province: Dapitan River:CAS-SU 23494–96; Basilan Island: Basilan Province: PortHolland: Sawmill: CAS 60493; Camiguin Sur Island: Cami-guin Province: Municipality of Catarman: Mt. Mambajao:Sitio Sangsangan: CAS 110976–83.

Brachymeles sp. undescribed limbless: (17) CatanduanesIsland: Catanduanes Province: Municipality of Gigmoto:Barangay San Pedro, Sitio Tungaw: PNM (holotype) 9565,(paratopotypes) 9583–9584, KU (paratopotypes) 308126,308128, 308136, 308208; Luzon Island: Camarines NorteProvince: Municipality of Labo, Barangay Tulay Na Lupa,Mt. Labo: KU (paratypes) 313612–313614, 313616, 313617,PNM (paratypes) 9585–9588, FMNH (paratype) 270200.

Brachymeles sp. undescribed tridactyl: (17) Luzon Island:Nueva Vizcaya Province: Municipality of Quezon: Barangay

Maddiangat: (holotype) PNM 9566, (paratypes) PNM 9578–82, KU 308865–66, 308900–06, 308908, 308953.

Brachymeles talinis: (21) Negros Island: Negros OrientalProvince: 6 km west of Municipality of Valencia: Cuernos deNegros Mountain Range: ridge on north side of Maite River:CAS-SU (holotype) 18358, (paratype) 89813; Cuernos deNegros Mountain Range: Dayungan Ridge: CAS 133871;Dumaguete City: CAS-SU (paratype) 12225; Municipality ofSiaton: 20 km north of Bondo Barrio: CAS-SU 22311–12,22317, 22323; Inampulagan Island: Guimaras Province:Municipality of Sibunag: 8 km west of Pulupandan Town:CAS-SU 27972, 27996–97; Panay Island: Antique Province:Municipality of San Remigio: KU 306651, 306756, 306758,306760, 306765–66, 306772–74, 306786.

Brachymeles tridactylus: (20) Negros Island: Negros Occi-dental Province: 16 km east of Municipality of La Castel-lana: Barrio Cabagna-an: southern slope of Mt. Canlaon:CAS-SU 19424, 19426–27, 19429, 19452, 19458; 20 km eastof Municipality of La Castellana: Sitio Kalapnagan: CAS-SU27082–83; Negros Oriental Province: hills north andnorthwest of Mayaposi: CAS-SU (holotype) 18354; PanayIsland: Antique Province: Municipality of Culasi: BarangayAlojipan: KU 307726–36.

Brachymeles vermis: (5) Jolo Island: Sulu Province: CAS-SU(paratype) 62489, CAS-SU 60720–22, 60857.

ACKNOWLEDGMENTS

We thank the Protected Areas and Wildlife Bureau (PAWB)of the Philippine Department of Environment and NaturalResources (DENR) for facilitating collecting and exportpermits necessary for this and related studies, wherein weare particularly grateful to M. Lim, C. Custodio, and A.Tagtag. Financial support for fieldwork for CDS wasprovided by a Panorama Fund grant from The Universityof Kansas Natural History Museum and Biodiversity Insti-tute, a Madison and Lila Self Fellowship from the Universityof Kansas, as well as an NSF DEB 0804115 to CDS and NSF EF0334952 and DEB 0743491 funds to RMB. For the loans ofspecimens (museum abbreviations follow Leviton et al.,1985), we thank J. Vindum and A. Leviton (CAS), R. Sisonand 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 FellowshipProgram of the University of Kansas, the Philippine-American Education Foundation (administrators of Ful-bright funding), A. Alcala and family, and the Diesmosfamily for their continued support, as well as CAS’s StearnsFellowship for funding a recent visit to examine compara-tive material. Critical reviews of the manuscript wereprovided by L. Trueb and J. Esselstyn.

LITERATURE CITED

Alcala, A. C., W. C. Brown, and A. C. Diesmos. 1998. Twonew species of the genus Platymantis (Amphibia: Ranidae)from Luzon Island, Philippines. Proceedings of theCalifornia Academy of Sciences 50:381–388.

Brandley, M. C., J. P. Huelsenbeck, and J. J. Wiens. 2008.Rates and patterns in the evolution of snake-like bodyform in squamate reptiles: evidence for repeated re-evolution of lost digits and long-term persistence ofintermediate body forms. Evolution 62:2042–2064.

Siler et al.—New limbless species of Brachymeles skink 121

Brown, R. M., and A. C. Diesmos. 2002. Application oflineage-based species concepts to oceanic island frogpopulations: the effects of differing taxonomic philoso-phies on the estimation of Philippine biodiversity. Silli-man Journal 42:133–162.

Brown, R. M., J. W. Ferner, and L. A. Ruedas. 1995a. A newspecies of lygosomine lizard (Reptilia: Lacertilia: Scinci-dae; Sphenomorphus) from Mt. Isarog, Luzon Island,Philippines. Proceedings of the Biological Society ofWashington 108:18–28.

Brown, R. M., J. W. Ferner, and R. V. Sison. 1995b.Rediscovery and redescription of Sphenomorphus beyeriTaylor (Reptilia: Lacertilia: Scincidae) from the Zambalesmountains of Luzon, Philippines. Proceedings of theBiological Society of Washington 108:6–17.

Brown, R. M., and J. C. Gonzales. 2007. A new forest frog ofthe genus Platymantis (Amphibia; Anura; Ranidae) fromthe Bicol Peninsula of Luzon Island, Philippines. Copeia2007:251–266.

Brown, R. M., J. A. McGuire, J. W. Ferner, and A. C. Alcala.1999. A new diminutive species of skink (Squamata;Scincidae; Lygosominae: Sphenomorphus) from LuzonIsland, Republic of the Philippines. Copeia 1999:362–370.

Brown, W. C. 1956. A revision of the genus Brachymeles(Scincidae), with descriptions of new species and subspe-cies. Breviora 54:1–19.

Brown, W. C., and A. C. Alcala. 1980. Subfamily Scincinae,p. 13–57. In: Philippine Lizards of the Family Scincidae. D.Law (ed.). Silliman University Press, Dumaguete City,Philippines.

Brown, W. C., and E. L. Alcala. 1995. A new species ofBrachymeles (Reptilia: Scincidae) from Catanduanes Island,Philippines. Proceedings of the Biological Society ofWashington 108:392–394.

Brown, W. C., A. C. Alcala, and A. C. Diesmos. 1997. A newspecies of the genus Platymantis (Amphibia: Ranidae) fromLuzon Island, Philippines. Proceedings of the BiologicalSociety of Washington 110:18–23.

Brown, W. C., and D. S. Rabor. 1967. Review of the genusBrachymeles (Scincidae), with descriptions of new speciesand subspecies. Proceedings of the California Academy ofSciences 15:525–548.

Greer, A. E., P. David, and A. Teynie. 2006. The SoutheastAsian Scincid lizard Siaphos tridigitus Bourret, 1939

(Reptilia, Scincidae): a second specimen. Zoosystema28:785–790.

Hikida, T. 1982. A new limbless Brachymeles (Sauria:Scincidae) from Mt. Kinabalu, North Borneo. Copeia1982:840–844.

Lande, R. 1978. Evolutionary mechanisms of limb loss intetrapods. Evolution 32:73–92.

Nevo, E. 1979. Adaptive convergence and divergence ofsubterranean mammals. Annual Reviews 10:269–308.

Patton, J. L., and J. H. Feder. 1978. Genetic divergencebetween populations of the pocket gopher, Thomomysumbrinus (Richardson). Saugetierkunde 43:12–30.

Patton, J. L., and S. Y. Yang. 1977. Genetic variation inThomomys bottae pocket gophers: macrogeographic pat-terns. Evolution 31:697–720.

Ross, C. A., and P. C. Gonzales. 1992. Amphibians andreptiles of Catanduanes Island, Philippines. NationalMuseum Papers (Manila) 2:50–76.

Selander, R. K., D. W. Kaufman, R. J. Baker, and S. L.Williams. 1974. Genic and chromosomal differentiationin pocket gophers of the Geomys bursarius group. Evolu-tion 28:557–564.

Siler, C. D., A. C. Diesmos, and R. M. Brown. 2010. A newloam-swimming skink, genus Brachymeles (Reptilia: Squa-mata: Scincidae) from the Bicol faunal region, Luzon andCatanduanes islands, Philippines. Journal of Herpetology44:49–60.

Siler, C. D., E. L. Rico, M. R. Duya, and R. M. Brown. 2009.A new limb-reduced, loam-swimming skink (Reptilia:Squamata: Scincidae: genus Brachymeles) from centralLuzon Island, Philippines. Herpetologica 65:449–459.

Taylor, E. H. 1917. Brachymeles, a genus of Philippinelizards. Philippine Journal of Science 12:267–279.

Taylor, E. H. 1918. Reptiles of Sulu archipelago. PhilippineJournal of Science 13:233–267.

Taylor, E. H. 1922. Additions to the herpetological fauna ofthe Philippine Islands, I. Philippine Journal of Science21:161–206.

Wiens, J. J., and J. L. Slingluff. 2001. How lizards turn intosnakes: a phylogenetic analysis of body-form evolution inanguid lizards. Evolution 55:2303–2318.

Wright, S. 1931. Evolution in Mendelian populations.Genetics 16:97–159.

Wright, S. 1943. Isolation by distance. Genetics 28:114–138.

122 Copeia 2010, No. 1