Dibamus dalaiensis, Neang, Thy, Holden, Jeremy, Eastoe, Toby, Seng, Rathea, Ith, Saveng & Grismer, Lee, 2011

Neang, Thy, Holden, Jeremy, Eastoe, Toby, Seng, Rathea, Ith, Saveng & Grismer, Lee, 2011, A new species of Dibamus (Squamata: Dibamidae) from Phnom Samkos Wildlife Sanctuary, southwestern Cardamom Mountains, Cambodia, Zootaxa 2828, pp. 58-68 : 59-65

Dibamus dalaiensis sp. nov.

Figure 1 .

Holotype: LSUHC 0 9777, adult male, collected by Thy Neang, Jeremy Holden, Toby Eastoe, Rathea Seng and Saveng Ith, 20 November 2009, from the primary hill evergreen forest of Phnom Dalai in Phnom Samkos Wildlife Sanctuary, southwestern Cardamom Mountains, Pursat province, Cambodia at (12° 26' 26.091" N, 103° 4' 39.708" E), 1009 metres above sea level.

Paratypes: Three adult females, LSUHC 0 9778 and CBC 0 0 559, CBC 0 0 560, collected from the same locality, by the same researchers on the same date as the holotype.

Diagnosis: Dibamus dalaiensis is differentiated from all other congeners by having the following combination of characters: maximum SVL of 127.6 mm; tail length 18–22% of SVL; labial and nasal sutures complete; rostral suture present but incomplete; rostral pad divided into two equal parts; a single postocular; three scales bordering the posterior edge of first infralabial; an enlarged, medial, sublabial scale; 20 midbody scale rows; 22 transverse scale rows just posterior to head; 20 transverse scale rows just anterior to vent; 185–209 ventral scales; 48–52 subcaudal scales; relative size of frontal to frontanasal 1.4; and relative size of interparietal to surrounding scales 1.5. These characters are scored across all nominal species of Dibamus in Table 2.

Description of holotype: SVL 123.8 mm; tail 24.8 mm (20% of SVL); head slightly longer (HL 3.5 mm) than wide (3.1 mm); snout bluntly rounded, projecting beyond jaw; teeth small, acute; E-S 2.1 mm; E-N 1.4 mm; IN 1.1 mm; IO 2.2 mm; labial suture and nasal sutures complete; rostral suture present but incomplete; rostral pad with numerous, evenly distributed papillae; single postocular scale; single upper anterior labial bordered posteriorly by single supralabial and ocular scale; eyes dimly visible below ocular scale; frontal relatively large, 1.4 times of frontonasal; frontonasal 1.8 times wider than long; interparietal bordered posteriorly by four smaller nuchal scales; relative size of interparietal to nuchal scale 1.8; mental trapezoidal, bordered by first two infralabials; three scales on posterior edge of first infralabial, the medial scale largest ( Fig. 2 ).

Body wormlike, almost cylindrical: midbody diameter 3.8 mm; TW 3.7 mm (ratio: 0.9); body scales smooth, subcycloid; 20 midbody scale rows; 50 subcaudals; 22 transverse scale rows just posterior to head; 20 scale rows anterior to vent; scales near vent thick; 185 ventrals; vestigial hind limbs present, flap-like, flattened, curved inward, lacking toe pad, covered by imbricating scales; two large scales between base of hind limbs, largest scale at tip of hind limbs; the length of right and left hind limbs 3.7; tail tip blunt, covered by a single rounded scale, not terminating in a spine.

Coloration in life: Labial and nasal scales beige to opaque; anal region dull-white; nuchal region dark brown; dorsum and flanks light brown; ventral surface lighter; tail darker brown; subcaudal region lighter. In preservative, labial, nasal, infralabial, and mental slightly darker, opaque or blue; dorsum and flanks pale brown; ventral surface lighter brown; tail darker brown; subcaudal region lighter brown. Body scales brownish, dark centrally and transparent on their posterior edges; nuchal and body scales bearing a cream colored band and small cream colored markings ( Fig. 1 ).

Variation: All three female paratypes are very similar to the holotype in morphology (Table 1). The major variation is the possession of two, short, flap-like hind limbs in the male which are absent in females. Paratype LSUHC 0 9778 has a cream colored band behind the neck encircling the body, a cream colored ventral band approximately one third of the way down the body that does not encircle the body, a cream-colored spot behind the right eye, and three smaller nuchal scales contacting the posterior border of interparietal as opposed to the other paratypes and holotype which have four scales. CBC 0 0 559 has a large cream colored band encircling the body near midbody, cream colored dots encircling the midportion of the tail and a few small scattered cream colored spots on body.

TABLE 1. Measurements of holotype and paratypes of Dibamus dalaiensis sp. nov.

Holotype Paratypes

Dibamus dalaiensis sp. nov. from Cambodia Male Female Female Female LSUHC 9777 LSUHC 9778 CBC 0 0 559 CBC 0 0 560

Number of postoculars 1 1 1 1 Number of scales on posterior edge of infralabial 3 3 3 3 Number of midbody scales 20 20 20 20 Midbody diameter 3.8 3.8 3.8 3.7 Number of subcaudal scales 50 48 52 48 Relative size of frontal (see methods) 1.4 1.4 1.5 1.4 Relative size of interparietal (see methods) 1.8 1.4 1.4 1.3 SVL (mm) 123.8 124.6 116.8 127.6 Tail length (% of SVL) 20 18 22 19 Tail length (mm) 24.8 22.7 25.2 23.7 Hind limb length (mm) 3.7 - - - Enlarge median sublabial + + + + Presence of band: present (+), absent (-) - + + - Labial suture (LS): complete (+), incomplete (-) + + + + Nasal suture (NS): complete (+), incomplete (-) + + + + Rostral suture (RS): present + + + + complete or incomplete (+), absent (-)

Comparisons: Dibamus dalaiensis differs from all other species of Dibamus by possessing an enlarged, central, sublabial scale as opposed to relatively similar size of those scales in all dibamids. A single postocular scale in Dibamus dalaiensis differentiates it from D. alfredi ( Taylor 1962) , D. celebensis ( Schlegel 1858) , D. dezwaani ( Das & Lim 2005) , D. ingeri ( Das & Lim 2003) , D. kondaoensis ( Honda et al. 2001) , D. novaeguineae (Dum ril & Bibron 1839), D. seramensis ( Greer 1985) , D. taylori ( Greer 1985) , D. tebal ( Das & Lim 2009) and D. vorisi ( Das & Lim 2003) which have two or more postoculars (D. s eramensis has four and D. taylori has three). Dibamus dalaiensis is further separated from D. bogadeki ( Daresky 1992) , D. booliati ( Das & Yaakob 2003) , D. bourreti ( Angel 1935) , D. deharvengi ( Ineich 1999) , D. montanus ( Smith 1921) , D. nicobaricum (Steindachner 1867) , D. seramensis , D. smithi ( Greer 1985) , D. somsaki ( Honda et al. 1997) and D. tiomanensis (Das et al. 2004) , in having three scales on posterior edge of infralabial as opposed to two scales. Other differences are presented in Table 2.

In having one postocular scale, three scales on posterior edge of the infralabial, and 20 midbody scale rows, Dibamus dalaiensis most closely resembles D. greeri ( Daresky 1992) and D. leucurus ( Bleeker 1860) . However, D. dalaiensis can be separated from D. greeri in having one supralabial as opposed to two; maximum SVL of 127.6 mm (n=4) as opposed to 86 mm (n=3); tail length of 18–22 as opposed to 23–28 % of SVL; one infralabial as opposed to two; 50 subcaudal scales in the male and 48–52 in females as opposed to 53 in males and 54 in females. Dibamus dalaiensis can be distinguished from D. leucurus in having 48–52 subcaudal scales as opposed to 41–47; maximum SVL of 127.6 mm as opposed to 136 mm; and the presence of an incomplete rostral suture as opposed to its absence.

Etymology: The specific epithet dalaiensis refers to the type locality of Phnom Dalai in Phnom Samkos Wildlife Sanctuary, southwestern Cardamom Mountains, Cambodia.

Natural history: The holotype was found during midday on the soil surface beneath a rotten log in primary evergreen forest. The specimen was observed with only the posterior half of its body above ground. Two females were found beneath decayed, fallen logs of 20–40 cm diameter in close proximity to the holotype. Another female was found beneath a log in loose soil approximately 50 m from the rest of the type series but in the same habitat. Lizards were not found in other nearby areas and seemed to be locally concentrated.

Dibamus Number Number of Number of Mid- Number of Relative Relative Maximum Tail B LS NS RS EMS

of post- scales on scales body subcaudal scales size of size of recorded length

oculars edge of posterior scale frontal interpari SVL (% of

infralabial interparietal rows Male Female etal SVL)

dalaiensis 1(4) 3(4) 4(3) 20 50 48-52 1.4-1.5 1.3-1.8 127.6 18-22 (+,-) + + + +

3(1) 20 50 49.3 1.4 1.5

4 1 3

alfredi 2(4) 3(3)? 20-21 46-47 41-47 1.4-2.0 1.7-2.2 135 17-18 - - - - -

4(1) 20.3 46.5 43.5

3 2 2

bogadeki 1(1) 2(1)? 23 51??? 177 22.5 + + + -?

23 51

1 1

booliati 1(2) 4(2) 4 (2) 20 24-39?? 102.7 9.4-13.0 + - - - -

20 31.5

1 1

bourreti 1(1) 2(1)? 24? 52+ 2.3 4.5 151 23+??? + -

24 52+

1 1

celebensis 2(10) 3(6) 3 26-30 38 -40 35-40 1.2-2.3 1.0-2.9 188 10-13??? - -

3(3) 4(7) 27.4 39.3 38

13 3 4

deharvengi 1(1) 2(1)? 16 57 1.3 1.4 92 22.4? + + + -

16 57

1 1

continuednextpage Dibamus Number Number Number of Mid- Number of Relative Relative Maximum Tail B LS NS RS EMS

of post- of scales body subcaudal scales size of size of recorded length

oculars scales on posterior scale Male Female frontal interpari SVL (% of edge of interparietal rows etal SVL) infralabial

dezwaani 2 4? 22 37?? 123.1 12.75 - + + + -

- - -

greeri 1(3) 1&3(2)? 20 53 54?? 86 23-28 +? - + -

20 53 54

1 1

ingeri 2(3) 3(1)? 20 36 1.5 1 96 14.8 + + +? -

20 36

1 1

kondaoensis 2(1) 3(1) 3 23 59 1.03 1 112.4 19.4 - + + + -

23 59

1 1

leucurus 1(23) 3(21)? 20-23 48-52 41-47 1.2-4.2 1.0-3.1 136 16-20 -?? - -

4(2) 21 49.5 43.5

23 2 4

montanus 1(2) 2(2)? 22 49 43 2 2.2 130 15-18 -?? + -

22 49 43

2 1 1

nicobaricum 1(6) 4(6)? 23-25 34-38 31-36?? 134.7 8.7-18.3 + + + + -

24.6 35.6 34.3

6 3 3

novaeguineae 2(92) 3(53) 3 22-26 42 -45 37-42 1.0-3.0 0.7-2.4 158 10-19 - +? - -

3(2) 4(41) 24.5 43 39.6

5(1) 107 6 9

continuednextpage Dibamus Number Number Number of Mid- Number of Relative Relative Maximum Tail B LS NS RS EMS

of post- of scales body subcaudal scales size of size of recorded length

oculars scales on posterior scale Male Female frontal interpari SVL (% of edge of interparietal rows etal SVL) infralabial

seramensis 4(1) 4(1)? 33 40 0.7 1.2 203 11??? - -

33 40

1 1

smithi 1(1) 2(5)? 18-19 59 59-61 1.5-2.3 1.3-2.0 108 21-24?? - - -

2(4) 18.8 59 60

5 1 3

somsaki 1(4) 2(4) 4 18-19 44 -58 27-57 1.1-1.27 1.0-2.16 106 18-24? + + + -

18.5 51 42

4 2 2

taylori 3(13) 2(2)? 22-28 41-55 41-52 0.2-1.3 1.0-1.2 169 14-19??? - -

4(6) 3(14) 23.4 48.4 48

4(4) 22 5 7

2 4 3 24 42 14 0.1 133.5 18.65 - + + + -

- - -

- - -

tiomanensis 1(3) 4(3) 4 25-26 50 45-48 1.2 1.8 123 15-16 - + + - -

25.3 50 46.5

3 1 2

Vorisi 2(2) 3(2)? 20 33 11 1.2 1 90.1 6.1-16.8 - - - + -

20 33 11

2 1 1

Figures

FIGURE 1. Photograph of female paratype LSUHC 0 9778 with nuchal band and cream spots.

FIGURE 2. A. dorsal; B. ventral; C. lateral views of Dibamus dalaiensis; D. hind limbs of male Dibamus dalaiensis (holotype) from Phnom Dalai, Cardamom Mountains, Cambodia.