Brachymeles dalawangdaliri, Davis, Drew R., Geheber, Aaron D., Watters, Jessa L., Penrod, Michelle L., Feller, Kathryn D., Ashford, Alissa, Kouri, Josh, Nguyen, Daniel, Shauberger, Kathryn, Sheatsley, Kyra, Winfrey, Claire, Wong, Rachel, Sanguila, Marites B., Brown, Rafe M. & Siler, Cameron D., 2016

Davis, Drew R., Geheber, Aaron D., Watters, Jessa L., Penrod, Michelle L., Feller, Kathryn D., Ashford, Alissa, Kouri, Josh, Nguyen, Daniel, Shauberger, Kathryn, Sheatsley, Kyra, Winfrey, Claire, Wong, Rachel, Sanguila, Marites B., Brown, Rafe M. & Siler, Cameron D., 2016, Additions to Philippine Slender Skinks of the Brachymeles bonitae Complex (Reptilia: Squamata: Scincidae) III: a new species from Tablas Island, Zootaxa 4132 (1) : -

Brachymeles dalawangdaliri sp. nov.

( Figs. 2 , 3 )

Brachymeles bonitae Duméril & Bibron 1839 ; Taylor 1917; Brown 1956:5; Brown & Rabor 1967:526; Brown & Alcala 1970; Brown & Alcala 1980:20; Davis et al. 2014; Geheber et al. 2016; Siler et al. 2016.

Holotype. CAS 137149, adult male, collected among rotting leaves in early secondary growth forest on 24 May 1972, in Barrio Dubduban, Municipality of San Augustin, Romblon Province, Tablas Island, Philippines (12.58333° N, 122.10000° E; WGS 84; 500–800 ft. elev.), by L.C. Alcala.

Paratypes. Five adult females ( CAS 137148, 137150, 137151, 137153, 137154) and one adult male ( CAS 137152) were collected in Barrio Dubduban, Municipality of San Augustin, Romblon Province, Tablas Island, Philippines (12.58333° N, 122.10000° E; WGS 84), by L.C. Alcala. CAS 137148 was collected in a rotting coconut trunk on 23 May 1972 (150–250 ft. elev.), CAS 137150–137152 were collected in humus under a rotting log in original forest on 1 June 1972 (450 ft. elev.), and CAS 137153, 137154 were collected in humus under a rotting log in original forest on 2 June 1972 (550 ft. elev.).

Diagnosis. Following recent taxonomic revisions of Brachymeles (Siler et al. 2011; Davis et al. 2014) the new species is assigned to the B. bonitae Complex based on the following suite of morphological characters: (1) limbs present, (2) non-pentadactyl, (3) fore-limbs with 0–3 fingers. (4) hind limbs with 0–2 toes, (5) paravertebral scale rows ≥ 91, (6) presacral vertebrae 47–53, (7) supraoculars four, (8) enlarged, differentiated nuchals present, (9) longitudinal rows of dark spots around the body absent, and (10) auricular opening absent.

Brachymeles dalawangdaliri sp. nov. can be distinguished from congeners by the following combination of characters: (1) body size small (SVL 66.0– 80.9 mm), (2) fore-limbs bidactyl, (3) hind limbs digitless, unidactyl, or bidactyl, (4) limb length short, (5) supralabials six or seven, (6) infralabials six or seven, (7) supraciliaries five, (8) supraoculars four, (9) midbody scale rows 24 or 25, (10) axilla–groin scale rows 80–83, (11) paravertebral scale rows 97–101, (12) prefrontal contact absent, (13) frontoparietal contact present or absent, (14) enlarged chin shields in two pairs, (15) nuchals enlarged, (16) auricular opening absent, (17) presacral vertebrae 49, and (18) uniform body color (Tables 1, 2).

Comparisons. Brachymeles dalawangdaliri sp. nov. can be distinguished from B. ilocandia , B. isangdaliri , B. mapalonggaon , and B. tridactylus by having bidactyl fore-limbs and 0–2 digits on the hind limbs (versus being digitless [ B. ilocandia , B. mapalanggaon ], unidactyl [ B. isangdaliri ], or tridactyl [ B. tridactylus ]); from B. bonitae by having fewer number of presacral vertebrae (49 versus 53), fewer number of axilla–groin scale rows (80–83 versus 83–90), fewer number of paravertebral scale rows (97–101 versus 103–110), a greater number of infralabials (6, 7 versus 5), and by the absence (versus presence) of a 3rd chin shield and fused mental; from B. ilocandia by having a longer fore-limb (1.4–2.2 mm versus 1.1–1.4) and hind limb length (1.9–2.2 mm versus 1.6– 1.9), fewer number of presacral vertebrae (49 versus 50–53), and by the absence (versus presence) of a 3rd chin shield pair; from B. isangdaliri by having a longer snout–vent length (66.0– 80.9 mm versus 59.5), a longer forelimb length (1.4–2.2 mm versus 1.3), a greater number of presacral vertebrae (49 versus 47), greater number of midbody scale rows (24, 25 versus 22), a greater number of axilla–groin scale rows (80–83 versus 73), and fewer number of supraciliaries (5 versus 6); from B. ligtas by having a longer fore-limb length (1.4–2.2 mm versus 1.2– 1.4), fewer number of presacral vertebrae (49 versus 50), a greater number of midbody scale rows (24, 25 versus 22), a greater number of axilla–groin scale rows (80–83 versus 74–76), a greater number of paravertebral scale rows (97–101 versus 91–93), and by the absence (versus presence) of a 3rd chin shield pair; from B. mapalanggaon by having a longer fore-limb (1.4–2.2 mm versus 0.8–1.0) and hind limb length (1.9–2.2 mm versus 1.2–1.6), fewer number of presacral vertebrae (49 versus 51), and a greater number of midbody scale rows (24, 25 versus 22, 23); from B. tridactylus by having a shorter hind limb length (1.9–2.2 mm versus 2.6–3.6), a greater number of presacral vertebrae (49 versus 47), a greater number of axilla–groin scale rows (80–83 versus 72–79), and by the absence (versus presence) of a 3rd chin shield pair.

Brachymeles dalawangdaliri sp. nov. can be distinguished from all limbless species of Brachymeles by having limbs, and from all pentadactyl species of Brachymeles by having bidactyl fore-limbs and digitless, unidactyl, or bidactyl hind limbs.

Description of holotype. Details of the head scalation are shown in Figure 2 . Adult, male, body small, slender, SVL 74.9 mm; head weakly differentiated from neck, nearly as wide as body, HW 7.9% SVL, 107.3% HL; HL 37.1% SnFa; SnFa 19.7% SVL; snout narrow, sharply rounded in dorsal and lateral profile, SNL 60.2% HL; ear completely hidden by scales; eyes small, ED 17.9% HL, 40.5% END, pupil subcircular; body slightly depressed, nearly uniform in thickness, MBW 100.0% MBH; scales smooth, glossy, imbricate; longitudinal scale rows at midbody 24; paravertebral scale rows 97; axilla–groin scale rows 80; limbs short, diminutive, bluntly rounded, with digits reduced to two small digit growths on fore-limbs, single digit growth on hind limb; finger and toe lamellae absent; FLL 3.6% AGD, 2.8% SVL; HLL 3.9% AGD, 3.0% SVL; tail not as wide as body, TW 72.6% MBW, autotomized posterior to cloaca, length unavailable.

Rostral projecting onto dorsal snout to level in line with posterior edge of nasal, roughly equal in width and height, in contact with frontonasal; frontonasal wider than long; nostril small, ovoid, in center of single trapezoidal nasal, longer axis directed posterodorsally and anteroventrally; supranasals present; postnasals absent; prefrontals moderately separated; frontal roughly hexagonal-shaped, its anterior margin in moderate contact with frontonasal, in contact with first two anterior supraoculars, 4× wider than anterior supraocular; supraoculars four; frontoparietals moderate in size, in moderate medial contact, frontoparietals in contact with supraoculars two and three; interparietal moderate in size, its length roughly equal to 2× midline length of frontoparietal, longer than wide, diamond-shaped, wider anteriorly, pineal eyespot not visible; parietals wider than frontoparietals, in moderate contact behind interparietal; head scales damaged in nuchal region; enlarged nuchals present; loreals two, anterior loreal about as long as and slightly higher than posterior loreal; preoculars two; presubocular one; supraciliaries five, the anteriormost contacting prefrontal and separating posterior loreal from first supraocular, posteriormost extending to midline edge of fourth supraocular; subocular scale row single, incomplete, in contact with supralabials; lower eyelid with one row of scales; supralabials seven, first twice the width of others, third, fourth and fifth subocular; infralabials seven ( Figs. 2 , 3 ).

Mental wider than long, in contact with first infralabial on left side of head, fused with first infralabial on right side of head; postmental single, enlarged, its width equal to width of mental; followed by two pairs of enlarged chin shields, first pair moderately separated, second pair slightly smaller than first, broadly separated by three medial scales ( Figs. 2 , 3 ). Scales on limbs smaller than body scales.

Variation. Differences in digit number and scalation patterns were observed between the holotype and paratype series. The holotype (CAS 137149) and three paratypes (CAS 137148, 137153, 137154) possessed seven supralabials and seven infralabials, with three other paratypes (CAS 137150–137152) having six supralabials and six infralabials. Unlike the holotype and majority of paratypes, the frontoparietal scales were observed to contact medially in two specimens (CAS 137153, 137154). Observed digit number variation included body plans with two fingers and one toe (CAS 137149 [holotype], 137151, 137153, 137154), two fingers and two toes (CAS 137148, 137150), and two fingers and no toes (CAS 137152).

Coloration of holotype in life. Coloration in life is unrecorded; however, because Brachymeles specimens do not change significantly during preservation (Siler & Brown 2010; Siler et al. 2011a, 2012a; Davis et al. 2014), we suspect that the preserved coloration and patterns are much like those in life.

Coloration of holotype in preservative. The background color on the dorsal, lateral and ventral sides of the body and tail is a solid Prout’s Brown (Color 47; Köhler 2012). The ventral side of the head is the same solid color as the ventral side of the body ( Fig. 3 ; Prout’s Brown; Color 47; Köhler 2012). On the dorsal and lateral sides of the head, a single Fuscous splotch can be seen just above each orbit ( Fig. 3 ; Color 283; Köhler 2012).

Etymology. The name of the new species presented in this paper is derived from the Tagalog (Filipino) terms ‘dalawa,’ meaning two, and ‘daliri,’ meaning finger, referencing one of the defining characteristics of the new species, the two digits on the fore-limbs. Suggested common name: Tablas Slender Skink.

Distribution. Brachymeles dalawangdaliri sp. nov. is known only from Tablas Island, Romblon Island Group, Philippines ( Fig. 1 ).

TABLE ·. Summary of meristic anđ mensural characters among species of the Brachymeles bonitae Complex. Sample size, bođy length anđ total length among males anđ females, anđ general geographical đistribution (PAIC = Pleistocene Aggregate Islanđ Complexes, sensu Brown & Diesmos [2002]) are incluđeđ for reference (SVL, TotL, FLL, HLL given as range over mean ± stanđarđ đeviation; all bođy proportions given as percentage over mean ± stanđarđ đeviation).

bonitae dalawangdaliri sp. nov. ilocandia isangdaliri ligtas mapalanggaon tridactylus (3 m, 1 f) (2 m, 5 f) (9 f) (1 f) (3 m, 2 f) (3 m, 6 f) (12 m, 9 f)

Range Luzon & Polillo Tablas Islanđ Luzon & Luzon Islanđ Lubang Islanđ Masbate Islanđ West Visayan islanđs Camiguin Norte PAIC

islanđs

SVL (f) 69.4 69.8=80.9 65.7=77.6 59.5 60.7=69.2 61.7=75.8 59.9=82.3 (73.6 ± 4.4) (73.7 ± 3.7) (65.0 ± 6.0) (67.2 ± 5.4) (71.4 ± 6.9)

SVL (m) 69.7=78.4 66.0= 74.9 N /A N/A 69.4=79.6 65.1=72.7 60.7=77.6 (72.8 ± 4.8) (70.4 ± 6.3) (74.5 ± 5.1) (68.4 ± 3.9) (69.0 ± 6.0)

TotL (f) N/A N/A 122.3=146.0 106.1 119.4 120.2 133.6 1

(134.1 ± 8.0)

TotL (m) 122.0 N /A N/A N/A 160.6 112.6=118.6 120.9=154.1 (115.6 ± 4.3) (136.0 ± 9.8)

/SVL 73 N/A 81=90 78 97=102 67=84 85=112 (85 ± 3) (99 ± 4) (78 ± 9) (95 ± 10)

FLL 1.0=1.7 1.4=2.2 1.1=1.4 1.3 1.2=1.4 0.8=1.0 1.5=2.5 (1.3 ± 0.3) (1.9 ± 0.3) (1.3 ± 0.1) (1.3 ± 0.1) (0.9 ± 0.1) (2.0 ± 0.3)

FLL/SVL 1=2 2=3 1=2 2 2=2 1=2 2=4 (2 ± 0) (3 ± 0) (2 ± 0) (2 ± 0) (1 ± 0) (3 ± 0)

HLL 1.5=2.3 1.9=2.2 1.6=1.9 2.2 1.6=2.0 1.2=1.6 2.6=3.6 (1.9 ± 0.3) (2.1 ± 0.1) (1.8 ± 0.1) (1.8 ± 0.1) (1.4 ± 0.1) (3.1 ± 0.3)

HLL/SVL 2=3 2=3 2=3 4 2=3 2=2 3=6 (3 ± 0) (3 ± 0) (2 ± 0) (3 ± 0) (2 ± 0) (5 ± 1) TABLE 2. Summary of meristic anđ qualitative điagnostic characters (present, absent) among species of the Brachymeles bonitae Complex. The pairs of enlargeđ scales posterior to the postmental scale are abbreviateđ as chin shielđ pairs with reference to the 1st, 2nđ, anđ 3rđ pairs (when present). In cases of scale count variation within species, numbers of inđiviđuals showing specific counts are given in parentheses.

bonitae dalawangdaliri sp. nov. ilocandia isangdaliri ligtas mapalanggaon tridactylus (3 m, 1 f) (2 m, 5 f) (9 f) (1 f) (3 m, 2 f) (3 m, 6 f) (12 m, 9 f)

Number of đigits (fingers/toes) 0/0 1 2/0=2 0/0 1/1 2/0 0/0 3/3 2/1 1

PSV 53 49 50=53 47 50 51 47

MBSR 21=24 24, 25 22=24 22 22 22, 23 22=24

AGSR 83=90 80=83 80=82 73 74=76 80=84 72=79

PVSR 103=110 97=101 97=100 97 91=93 99=102 90= 98 6 6 (3) 6 6 6 6 6 (13) 7 (4) 7 (8) 5 6 (3) 5 (3) 6 6 5 (8) 6 (13) 7 (4) 6 (6) 6 (1) 7 (8) 5 5 5 6 5 5 5 4 4 4 4 4 4 4

Prefrontal contact Absent Absent Absent or Point Absent Absent Absent Absent contact

Frontoparietal contact Absent Present or Absent Absent Absent Present Point contact or Absent Absent

chin shielđ pair contact Absent Absent Absent Absent Present or Absent Absent Present or Absent

chin shielđ pair Present Absent Present Absent Present Present or Absent Present

Mental/1st IFL fusion Present Absent Present or Absent Absent Absent Present or Absent Absent

Enlargeđ nuchals Present Present Present Present Present Present Present

Longituđinal rows of đark Absent Absent Absent Absent Absent Absent Absent

spots

Observeđ for two inđiviđuals.

Natural history. Presumably, Brachymeles dalawangdaliri sp. nov. once occurred in primary growth forest; however, little to no primary forest remains on Tablas Island. This species has never been observed in high densities, a pattern consistent with many members of the B. bonitae Complex. Furthermore, no recent collections of this species have been made, with the last documented observation of B. dalawangdaliri sp. nov. in the wild occurring more than four decades ago. Brachymeles dalawangdaliri sp. nov. may be found in sympatry with B. talinis (Siler & Brown 2010) .

Little is known about the ecology and distribution of Brachymeles dalawangdaliri sp. nov. on Tablas Island. However, this species is endemic to an island with complete or near complete deforestation and no recent observations of wild populations. Therefore, in evaluating B. dalawangdaliri sp. nov. against the IUCN criteria for classification, we find that it qualifies for the status of Vulnerable (VU) based on the following criteria: VU B2ab(iii,iv); D2 (IUCN 2015).

Figures

FIGURE 1. (Left) Map of the Philippine islands, with labels provided for islands with representative samples used for this study. The five recognized major faunal regions (PAICs), major island groups, and additional deep-water islands are labeled for reference. Current islands in the Philippines are shown in medium grey to black; light gray areas enclosed in black 120 m bathymetric contours indicate the hypothesized maximum extent of land during the mid- to late Pleistocene. Location of the Romblon Island Group outlined by a square; Tablas Island highlighted in black. (Right) Map of Romblon Province in relation to the remainder of the Philippines. Known distribution of Brachymeles dalawangdaliri sp. nov. on Tablas Island is indicated with a star.

FIGURE 2. Illustration of the head of Brachymeles dalawangdaliri sp. nov. (CAS 137149, holotype) in dorsal, lateral, and ventral views. Taxonomically diagnostic head scales are labeled as follows: C, chin shield; F, frontal; FN, frontonasal; FP, frontoparietal; IL, infralabial; IP, interparietal; L, loreal; M, mental; N, nasal; Nu, nuchal; P, parietal; PF, prefrontal; PM, postmental; PO, preocular; PSO, presubocular; R, rostral; SC, supraciliary; SL, supralabial; SN, supranasal; and SO, supraocular. Roman numerals indicate scales in the supraocular series, with Arabic numbers indicating scales in the supraciliary series. Illustrations by MLP and CDS.

FIGURE 3. Photograph of lateral and ventral views of head of preserved holotype of Brachymeles dalawangdaliri sp. nov. (CAS 137149). Photographs taken by JLW and MLP.