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A New Limb-Reduced, Loam-Swimming Skink (Squamata: Scincidae: Brachymeles) from Central Luzon Island, Philippines

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A New Limb-Reduced, Loam-Swimming Skink (Squamata: Scincidae: Brachymeles) from Central Luzon Island, Philippines
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  A NEW LIMB-REDUCED, LOAM-SWIMMING SKINK(SQUAMATA: SCINCIDAE:  BRACHYMELES ) FROM CENTRALLUZON ISLAND, PHILIPPINES C AMERON  D. S ILER 1,4 , E DMOND  L. R ICO 2 , M ARIANO  R. D UYA 3 ,  AND  R AFE  M. B ROWN 1 1 Natural History Museum and Biodiversity Research Center, Department of Ecology and Evolutionary Biology,University of Kansas, Lawrence, KS 66045-7561, USA 2 Conservation International, 6 Maalalahanin St., Teachers Village, Quezon City, Manila, Philippines 3 Sierra Madre Biodiversity Corridor Program, Conservation International Philippines, Door 5 De Peralta Building,Bagay Road, Caritan Centro, Tuguegarao City, Cagayan Province, Philippines A BSTRACT : We describe a new species of scincid lizard of the genus  Brachymeles  from montane forests(1400–1450 m) of Mt. Palali, Caraballo Mountain Range, in central Luzon Island, Philippines. The new species is the second known species of   Brachymeles  that has only three digits on both the forelimb andhindlimbs. Additional morphological characters include unique scale pigmentation and absence of a pinealeyespot and an auricular opening. The new species is the eighth known  Brachymeles  from Luzon Island andthe twelfth non-pentadactyl species. With this new discovery, the Luzon Faunal Region holds the greatestdiversity of species of the genus  Brachymeles  in the world. Key words:  Biodiversity; Endemism; Faunal region; Fossoriality; Limb reduction; Philippines S CINCID  lizards of the genus  Brachymeles are known from 17 recognized species; all areendemic to the Philippines, except  B. apus from northern Borneo (Brown and Alcala,1980; Hikida, 1982). The genus  Brachymeles is one of only four scincid genera to possessboth fully limbed and limbless species ( Bra-chymeles ,  Chalcides ,  Lerista , and  Scelotes ;Brandley et al., 2008; Lande, 1978; Wiensand Slingluff, 2001). Six species of   Brachy- meles  are pentadactyl ( B. bicolor  ,  B. boulen- geri ,  B. gracilis ,  B. schadenbergi ,  B. talinis ,and  B.  sp. nov.; Siler et al., in press  a ); sevenare non-pentadactyl with reduced limbs andnumbers of digits ( B. bonitae ,  B. cebuensis ,  B.elerae ,  B. pathfineri ,  B. samarensis ,  B. tridac- tylus , and  B. wrighti ); and four are limbless( B. apus ,  B. minimus ,  B. vermis , and  B.  sp.nov.; Siler et al., in press  b ). Among the sevennon-pentadactyl species, some have minutelimbs lacking digits, whereas others havemoderately developed limbs with nearly alldigits present (Brown and Alcala, 1980;Hikida, 1982; Taylor, 1917, 1918, 1922 a ).The conservative body plans and externalmorphology within  Brachymeles  have made itdifficult to assess species diversity on the basisof morphology alone (Brown, 1956; Brownand Rabor, 1967). Previous studies haveidentified three widespread polytypic species(Brown, 1956; Brown and Alcala, 1980; Brownand Rabor, 1967). Both  Brachymeles gracilis and  B. schadenbergi  contain two subspecies,and  B. boulengeri  contains four subspecies.All species are semi-fossorial, inhabitingrotting logs, loose soil, and leaf litter. Addi-tionally, all known species exhibit a distinct,serpentine ‘‘swimming’’ mode of locomotionthrough humus and rotting log loam.In March 2007, ELR and colleaguesconducted herpetological surveys at higherelevations on Mt. Palali in the Municipality of Quezon in central Luzon Island (Fig. 1).Seventeen individuals of an undescribedspecies of   Brachymeles  were collected be-tween 1400–1450 m. The new species isfound in terrestrial microhabitats in thehumus of rotting logs and loose soil. Herein, we describe the new species and report on itsnatural history, ecology, and habitat.M ATERIALS AND  M ETHODS  We examined alcohol-preserved specimensthat were fixed in 10% formalin (Appendix 1),and examined sex by gonadal inspection. Wemeasured all specimens with digital calipers tothenearest0.1 mm.Tominimizeinter-observerbias and other sources of potential error (Lee,1990), CDS scored all measurements. Museumabbreviations follow Leviton et al. (1985). 4 C ORRESPONDENCE : e-mail, camsiler@ku.edu Herpetologica,  65(4), 2009, 449–459 E  2009 by The Herpetologists’ League, Inc. 449  Based on Siler et al. (in press  a ,  b ) we chosethe following meristic and mensural charac-ters (Fig. 2): snout–vent length (SVL), axilla–groin distance, total length, midbody width,midbody depth, tail length, tail width, taildepth, head length, head width, head depth,snout–forearm length, eye diameter, eye–narial distance, snout length, internarial dis-tance, forelimb length, hindlimb length, mid-body scale-row count, paravertebral scale-row count, axilla–groin scale-row count, Finger IIIlamellae count, Toe IV lamellae count,supralabial count, infralabial count, supracili-ary count, and supraocular count. In thespecies description below, ranges are followedby mean 6 standard deviation in parentheses.R ESULTS Brachymeles  muntingkamay   sp. nov .(Figs. 2–3) Holotype .—An adult female (PNM 9566;field no. ELR 1388, formerly KU 308923;Figs. 2–4), collected at 10:00 hr on 23 March F IG . 1.—Known distribution of   Brachymeles munting-kamay  on Mt. Palali in central Luzon Island, Philippines.The type locality (Barangay Maddiangat, Municipality of Quezon, Nueva Vizcaya Province) is indicated by ablack dot.F IG . 2.—Head of female holotype of   Brachymeles muntingkamay  (PNM 9566) in dorsal, lateral, and ventral views. Taxonomically relevant head scales within  Brachy- meles  are labeled as follows: C, chin shield; F, frontal; FN,frontonasal; FP, frontoparietal; IL, infralabial; IP, inter-parietal; L, loreal; M, mental; N, nasal; P, parietal; PF,prefrontal; PM, postmental; PO, preocular; PSO, pre-subocular; R, rostral; SC, supraciliary; SL, supralabial; SN,supranasal; and SO, supraocular. Roman numeralsindicate scales in the supraocular series, with numbersindicating scales in the supraciliary series. Scale bar  5 2 mm.450 HERPETOLOGICA [ Vol. 65, No. 4  2007 at 1424 m elevation on Mt. Palali(16 u  26 9  21.9 0  N, 121 u  13 9  24.1 0  E; WGS-84)Barangay Maddiangat, Municipality of Que-zon, Nueva Vizcaya Province, Luzon Island,Philippines, by Edmond L. Rico. Paratopotypes .—KU 308865–66, 308900–06, 308908, 308953, PNM 9578–82, 11 adultfemales and five juveniles of unknown sexcollected between 18 and 25 March 2007. Diagnosis .— Brachymeles muntingkamay can be distinguished from congeners by thefollowing combination of characters: (1) pres-ence of limbs, (2) three digits on forelimbs andhindlimbs, (3) small body size, SVL less than85 mm, (4) pineal eye spot absent, (5) auricularopenings absent, (6) prefrontals in contact, (7)frontoparietals not in contact, (8) postnasalsabsent, (9) postmental wider than mental, (10)first pair of chin shields not in contact, (11)scale spots covering body, (12) midbody scalerows 22–24, (13) paravertebral scale rows 85–90, (14) six supralabials, and (15) six infralabials(Table 1, 2). Comparisons .—The new species is mor-phologically most similar to  Brachymeles tridactylus , the only other species with threeforelimb and hindlimb digits, and  B. elerae ,the only other non-pentadactyl species topossess dark scale spots on each scale(Table 2). From  Brachymeles tridactylus , thenew species differs by having a shorter meantail length, longer limbs, fewer axilla–groinscale rows, more supraciliaries and supraocu-lars, prefrontals in contact, no contact be-tween the first pair of enlarged chin shields,and the absence of a pineal eyespot andenlarged, differentiated nuchal scales (Ta-ble 1, 2). From  Brachymeles elerae , the new species differs by having shorter forelimbs,frontoparietals not in contact, postmental wider than mental scale, discontinuous subo-cular scale row, and enlarged, differentiatedsubdigital lamellae absent (Table 1, 2). Addi-tional characters distinguishing the new spe-cies from all non-pentadactyl, limbed speciesof   Brachymeles  are summarized in Tables 1and 2. Brachymeles muntingkamay  differs from alllimbless species of   Brachymeles  ( B. apus ,  B. minimus ,  B. vermis , and  B.  sp. nov.; Siler etal., in press  b ) in having limbs, prefrontals incontact, and fewer paravertebral scale rows(85–90 vs. greater than 91), and in lacking apineal eyespot. The new species furtherdiffers from  B. minimus ,  B. vermis , and  B. sp. nov. (Siler et al., in press  b ), in the absenceof enlarged, differentiated nuchal scales andlack of contact between the frontoparietals. Itdiffers from  B. minimus  by having moremidbody scale rows (22–24 vs. 20), a discon-tinuous subocular scale row, and a postmentalthat is wider than the mental. The species canbe distinguished from  B. apus  and  B. vermis by its greater number of infralabial (6 vs. 5)and supraciliary (6–7 vs. fewer than 2) scalesand from  B. apus  by its lack of a mental fusedto first infralabial.From all pentadactyl species of   Brachy- meles  ( B. bicolor  ,  B. boulengeri ,  B. gracilis ,  B. schadenbergi ,  B. talinis , and  B.  sp. nov.; Siler F IG . 3.—Preserved female holotype of   Brachymeles muntingkamay  (PNM 9566), showing dorsal aspect, fore limbs,and hindlimbs. Left 5  anterior; scale bar 5  3 mm. December 2009 ] HERPETOLOGICA 451  T ABLE  1.—Summary of meristic and mensural characters in  Brachymeles muntingkamay  and specimens of all other known limbed, non-pentadactyl species of   Brachymeles .Sample size, body length and total length among males and females, and general geographical distribution (PAIC 5 Pleistocene Aggregate Island Complexes, sensu Brown andDiesmos, 2002) are included for reference (linear measurements given as range over mean 6 standard deviation; ratios given as percentage over mean 6 standard deviation).Dashes denote missing data in cases where specimens were unavailable for examination.  muntingkamay (12 f)  tridactylus (9 m, 11 f)  bonitae (6 m, 7 f)  samarensis (5 f) cebuensis (8 f) elerae (2 m, 1 f)  pathfinderi 1 (1 m, 1 f)  wrighti 1 (1 —) Range Luzon Island Visayan PAIC Mindoro & LuzonPAICsSamar, Leyte, Bicol Cebu Island Luzon Island MindanaoIslandLuzon IslandSVL (f) 61.8–81.3(73.6 6  5.9)45.5–59.1(52.1 6  5.0)49.7–59.8(56.4 6  3.9)62.4–66.1(63.4 6 1.5)51.5–67.9(61.8 6  5.3)68.2, 71.9 60.4 120.0 2 SVL (m) N/A 55.7–78.3(68.5 6  7.4)65.1–80.0(73.5 6  6.4)N/A N/A 71.5 52.4 —Total length (f) 107.4–136.0(124.0 6  8.6)102.6–154.1(132.6 6  14.0)93.4–150.4(126.7 6  19.9)97.7–112.9(107.3  6 8.3)104.3–128.0(119.0 6  8.5)109.9, 131.9 119.0 —Total length (m) N/A 105.3–133.67(115.9 6  15.4)102.6–144.5(121.3 6  15.6)N/A N/A N/A — —Forelimb length 2.4–3.0(2.7 6  0.2)1.5–2.5(2.0 6 0.3)1.0–1.5(1.3 6  0.1)1.1–2.6(1.7 6  0.5)1.1–1.8(1.5 6 0.3)3.3–3.5(3.4 6 0.1)4.0 4.5Hind limb length 5.3–6.0(5.7 6  0.2)2.6–3.6(3.1 6 0.3)1.3–2.0(1.6 6  0.2)2.5–3.1(2.8 6  0.2)2.3–3.0(2.7 6 0.3)4.3–5.4(5.0 6 0.6)8.9, 9.1 12.2Tail length / SVL 50–79(65 6  10)69–112(92 6 12)35–93(69 6  18)57–81(71 6  13)78–115(92 6 13)61–84(72 6 16)— —Head length / SVL 8–10(8 6  1)6–9(8  6 0)6–8(7 6  1)8–9(8  6  1)7–11(8  6 2)7–8(8  6 0)12, — —Axilla–groin distance / SVL 72–77(75 6 2)72–87(76 6  3)72–84(78 6  4)70–76(74 6  3)70–78(75 6  3)71–74(73 6 2)68, — 78Forelimb length / SVL 3–4(4 6  0)2–3(3  6 0)1–2(2 6  0)2–4(3  6  1)2–3(2  6 0)5–5(5  6 0)7, 8 4Hind-limb length / SVL 7–9(8 6  1)3–6(5  6 1)2–3(2 6  0)4–5(5  6  0)3–5(4  6 0)6–8(7  6 1)15, 17 10Forelimb length / Axilla–groin distance4–6(5 6  1)2–5(4  6 1)2–3(2 6  0)2–6(4  6  1)2–4(3  6 1)6–7(7  6 0)— —Hind limb length / Axilla–groin distance8–11(10 6  1)4–8(6  6 1)2–4(3 6  0)5–7(6  6  1)5–7(6  6 1)8–11(10 6 1)22, 25 13Toe IV lamellae 0 0 0 0 0 3 4, 5 3Midbody scale-row count 22–24 22–24 21–23 20 22–24 22–24 22, 24 28Axilla–groin scale-row count 65–70 70–79 73–90 67–72 65–69 63–67 — —Paravertebral scale-row count 85–90 88–98 90–109 86–92 84–88 84–87 63, 66 102Supralabial count 6 (12) 6 (12) 6 (12) 6 (5) 6 (8) 6 (3) 6 (2) 67 (8) 7 (1)  4   5  2   H E R P  E T  O L  O G I   C A   [     V  o l     . 6   5    , N o . 4    et al., in press  a ),  B. muntingkamay  differs inhaving a reduced number of digits onforelimbs and hindlimbs (3 vs. 5; Fig. 3);smaller forelimb lengths (3–4 [4  6  0]% SVL,4–6 [5  6  1]% Axilla–groin distance vs. 7–17[12 6 2]% SVL, 9–29 [18 6 3]% Axilla–groindistance); smaller hindlimb lengths (7–9 [8 6 1]% SVL, 8–11 [10  6  1]% Axilla–groindistance vs. 10–28 [20  6  3]% SVL, 16–53[31  6  5]% Axilla–groin distance); parietalscale in contact with three supraoccular scales(vs. 2); discontinuous subocular scale row (vs.continuous); absence of auricular openings(vs. presence); presence of 22–24 midbody scale rows (vs. 24–26 in  B. gracilis gracilis ,and more than 24 in all other pentadactylspecies and subspecies); and, with the excep-tion of   B. bicolor  , presence of 85–90 paraver-tebral scale rows (vs. less than or equal to 73). With the exception of   B. schadenbergi scha-denbergi  and  B. gracilis gracilis , the new species differs from all pentadactyl species by the absence of a pineal eyespot (vs. presence). Description of holotype .—A mature female,gravid, two eggs present in uterus; moderately small  Brachymeles , SVL 75.8 mm; body mod-erately slender; head weakly differentiatedfrom neck, nearly as wide as body (Fig. 3);head width 7.6% SVL, 93.5% head length;head length 39.5% snout–forearm length;snout–forearm length 20.5% SVL; snout short,bluntly rounded, snout length 51.0% headlength (Fig. 2); ear completely hidden by scales; eyes small; eye diameter 1.2% SVL,14.8% head length, 43.5% eye–narial distance;pupil horizontally elliptical; body slightly depressed, midbody depth 84.3% midbody  width, uniform in thickness; body scalessmooth, glossy, imbricate; dorsal scales each with three or four slight longitudinal indenta-tions giving appearance of keels; 22 longitu-dinal scale rows at midbody; 85 paravertebralscale rows; 65 axilla–groin scale rows; limbsshort, with digits reduced to three clawedstumps on both forelimbs and hindlimbs,finger and toe lamellae absent (Fig. 3);forelimb length 4.2% axilla–groin distanceand 3.2% SVL, hindlimb length 10.4% axil-la–groin distance and 7.8% SVL; order of digits from shortest to longest for hand: I  , III , II, for foot: I , II 5 III; tail not as wideas body (Fig. 3), tapered toward end, tail    m   u   n    t    i   n   g    k   a   m   a   y     (    1    2    f    )     t   r    i    d   a   c    t   y    l   u   s     (    9   m ,    1    1    f    )     b   o   n    i    t   a   e     (    6   m ,    7    f    )    s   a   m   a   r   e   n   s    i   s     (    5    f    )    c   e    b   u   e   n   s    i   s     (    8    f    )    e    l   e   r   a   e     (    2   m ,    1    f    )    p   a    t    h    f    i   n    d   e   r    i        1     (    1   m ,    1    f    )    w   r    i   g    h    t    i        1     (    1  —    )     I   n    f   r   a    l   a    b    i   a    l   c   o   u   n   t    6    (    1    2    )    6    (    1    2    )    5    (    1    )    7    (    5    )    6    (    5    )    6    (    3    )    6    (    2    )    7    7    (    8    )    6    (    1    0    )    7    (    3    )    7    (    2    )    S   u   p   r   a   c    i    l    i   a   r   y   c   o   u   n   t    6    (    1    0    )    5    (    2    0    )    5    (    1    2    )    6    (    5    )    6    (    8    )    5    (    2    )  —  —    7    (    2    )    6    (    1    )    6    (    1    )    S   u   p   r   o   c   u    l   a   r   c   o   u   n   t    5    (    1    1    )    4    (    2    0    )    4    (    1    3    )    5    (    5    )    5    (    8    )    4    (    2    )    5    (    2    )    5    6    (    1    )    5    (    1    )        1     M   e   a   s   u   r   e   m   e   n   t   s   a   n    d   c   o   u   n   t   s    f   o   r     B   r   a   c    h   y   m   e    l   e   s   p   a    t    h    f    i   n    d   e   r    i    a   n    d     B .   w   r    i   g    h    t    i    w   e   r   e   t   a    k   e   n    f   r   o   m    T   a   y    l   o   r    (    1    9    2    5    )   a   n    d    B   r   o   w   n   a   n    d    A    l   c   a    l   a    (    1    9    8    0    ) .        2     T    h   e   s   e   x   o    f   t    h   e   s    i   n   g    l   e   s   p   e   c    i   m   e   n   o    f     B .   w   r    i   g    h    t    i     i   s   n   o   t    f   o   u   n    d    i   n   t    h   e    l    i   t   e   r   a   t   u   r   e ,   a   n    d   s   o    i   t    i   s   u   n    k   n   o   w   n   w    h   e   t    h   e   r   t    h   e    S    V    L   s    h   o   w   n    i   s   t    h   a   t   o    f   a   m   a    l   e   o   r    f   e   m   a    l   e .     T     A    B    L    E     1 .  —    C   o   n   t    i   n   u   e    d . December 2009 ] HERPETOLOGICA 453
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