Draco palawanensis

Excerpt from:

Phylogenetic Systematics, Scaling Relationships, and the Evolution of Gliding Performance in Flying Lizards (Genus Draco)
Copyright by Jimmy Adair McGuire 1998

Draco palawanensis sp. nov.
Draco volans Mocquard, 1890:128.
Draco volans volans Hennig, 1936a:176.
Draco volans sumatranus Musters, 1983:87.

Holotype.—PNM 5770, an adult male, from Barangay Alfonzo 13, Quezon, Palawan Island, Palawan Province, Republic of the Philippines, less than 25 m elevation; collected on 12 June, 1994 by Rafe M. Brown.

Paratypes.—All specimens from Palawan Island, Palawan Province: CAS 28612, 28614 no additional locality data; CAS 28615 about 13 km SW of Iwahig, site 511, about 300 ft. elevation; CAS 28616 about 5 km S Iwahig, site 421b, 100 ft. elevation; CAS 28649 about 7 km WNW Iwahig, site 440, 1000 ft. elevation; CAS 157297–98, 96 km NE Puerto Princesa; CAS 157328 99 km NE Puerto Princesa, Tinitian River, 1–2 km upstream from mouth; CAS 157350 94.5–95.5 km NE Puerto Princesa, E side of coast road in coconut grove; Cincinnati Museum of Natural History (CMNH) 5636-42, PNM 5769–75 Barangay Alfonzo 13, Quezon; TNHC 56707–25 immediate vicinity of the National Museum, Quezon.

Diagnosis.—Draco palawanensis can be distinguished from all other species of Draco in the Philippines by the following combination of characteristics:
(1) medium in size (maximum snout-vent length [SVL] of males = 82 mm [n=22], females = 84 mm [n=12];
(2) nostrils oriented laterally on the snout;
(3) enlarged,thornlike superciliary scale absent;
(4) dorsal scales variable in size, often keeled or rugose;
(5) tympana unscaled;
(6) six or rarely five ribs supporting patagium;
(7) lacrimal bone absent;
(8) large black postrictal ocellus surrounding an enlarged white tubercle present;
(9) in males, dorsal surface of patagium dull orange, with rectangular black blotches covering entire dorsal patagium; black blotches very small (1 mm in diameter) proximally, to large (5–9 mm in diameter) near patagial margin;
(10) in females, dorsal surface of patagium dull yellow, with rectangular black blotches covering entire dorsal patagium; black blotches very small (1 mm in diameter) proximally, to large (5–9 mm in diameter) near patagial margin;
(11) ventral patagium of males yellow over proximal one–third, dull orange over distal two–thirds, with several large black marginal blotches;
(12) ventral patagium of females pale yellow over its entire surface, with several large black marginal blotches;
(13) males with triangular, yellow–green dewlap; tissues underlying proximal portion of dewlap bright orange;
(14) pale gray dorsal coloration with brown mottling in both sexes;
(15) orbital region of males suffused with dark gray pigments.

Draco palawanensis can be distinguished from all other species of Draco by its unique patagial color pattern composed of a dull orange (males) or dull yellow (females) dorsal base color, overlain with rectangular black spots that increase in size from 1 mm in diameter proximally to large blotches 5–9 mm in diameter near the patagial margin. Draco palawanensis also can be distinguished from all other species of Draco on the basis of the unique morphology of its maxilla; the portion of the maxilla that forms the ventral edge of the lacrimal foramen forms a low wall where the lacrimal bone would lie. From D. bimaculatus, D. palawanensis can be further diagnosed on the basis of the number of ribs supporting the patagium (six versus five), its triangular greenish–yellow dewlap (versus rounded and off–white in males, black and white in females), by the absence (versus presence) of a large black spot at the corner of the mouth enclosing an enlarged white tubercle, and by its larger size (maximum SVL of 84 mm versus 71 mm). From D. cyanopterus and D. reticulatus, it can be further distinguished by the absence (versus presence) of an enlarged, thornlike superciliary scale, and by its greenish–yellow dewlap (versus reddish–brown with a yellow tip). From D. jareckii, D. quadrasi, and most populations of D. spilopterus, the new species can be further diagnosed by its unscaled (versus scaled over) tympana. From D. mindanensis, it can be distinguished on the basis of its greenish–yellow dewlap (versus tangerine–orange), the number of ribs supporting the patagium (six versus five), the absence (versus presence) of a lacrimal bone, its unscaled (versus scaled over) tympana, and in the position of its nostrils (oriented laterally rather than vertically). From D. ornatus, it can be further distinguished by its greenish–yellow dewlap (versus vivid chartreuse) and by its unscaled (versus scaled over) tympana. From D. guentheri, D. palawanensis can be further distinguished by the absence (versus presence) of an enlarged, thornlike superciliary tubercle, its yellow–green dewlap (versus reddish–brown), and by its pale gray dorsal body coloration in males (versus malachite green).

Because D. palawanensis has been treated by previous authors as conspecific with D. volans sumatranus and D. cornutus of the Greater Sunda Shelf (all three were recognized as D. volans by Inger, 1983), a proper diagnosis of D. palawanensis also requires comparison with these species. Draco palawanensis is easily distinguished from D. cornutus on the basis of its pale gray dorsal coloration in males (versus malachite green), the absence (versus presence) of an enlarged, thornlike superciliary scale, the absence (versus presence) of an ultramarine wash over the pectoral and ventral abdominal regions in both sexes, its ventral patagial coloration of pale yellow over the proximal one–third, dull orange over the distal two–thirds in males (versus blue–gray), and by its dorsal patagial color pattern; the dorsal patagium in D. cornutus males is malachite green over its proximal third, brick red over most of the distal two–thirds, with an ash–gray patch at the anterolateral edge, and an elongate black marginal patch. Draco palawanensis can be diagnosed from D. volans sumatranus on the basis of its patagial color pattern (the dorsal patagium of D. volans sumatranus is covered with round white, pale orange, or pale yellow spots over most of its surface, and over the distal half of patagium, there are extensive black pigments such that the base coloration is black over this portion of the wing). The ventral patagium of D. volans sumatranus males is blue–gray with large melanic blotches covering the entire ventral surface, whereas the ventral patagium of D. palawanensis males is pale yellow over its proximal one–third and dull orange over its distal two–thirds, with several large black marginal blotches. Furthermore, the morphology of the maxillary bone in D. palawanensis is distinctive (see above) and the frontal bone of D. volans sumatranus has a crenulated margin that is not present in D. palawanensis.

Description of holotype.—Dorsal head scales small to medium–sized, heterogeneous, keeled or rugose; rostral two times wider than high, bordered by six postrostrals; internasals, frontonasals, and prefrontals small except for a series of enlarged, strongly keeled scales arranged in shape of inverted "Y"; the base originating a few scales posterior to rostral, arms contacting supraorbitals; supraoculars granular laterally, grading to much larger size medially; medialmost supraoculars larger than all surrounding cephalic scales except parietals; frontoparietals and parietals slightly larger than scales of snout; interparietal much smaller than surrounding parietals, with opalescent lens; nasals turret–like, pierced centrally by external nares, nares point laterally and slightly dorsally; 3–3 canthals, strongly keeled; anterior superciliaries elongate, keeled; posterior superciliaries granular, except for two enlarged, keeled scales, similar in structure to anterior superciliaries, wider than high, not laterally compressed and thornlike; loreals and lorilabials immediately superior to supralabials relatively large, remaining loreals and lorilabials much smaller, but larger than adjacent palpebrals; an enlarged scale, wider than high, present immediately superior and slightly posterior to posteriormost supralabial; several pre–, sub–, and postoculars enlarged forming continuous subocular series; a series of three large keeled scales extending posteriorly from posterior border of orbit; supralabials 11–11, pentagonal, 1–3 times longer than high, posteriormost supralabial longest; infralabials 10–10, pentagonal or rectangular; tympanum not scaled over; tympanum surrounded by granular scales, a slightly enlarged tubercle present a few scales anterior to tympanum; scales surrounding corner of mouth granular; remaining temporals, occipitals, and nuchals granular except for a tubercle superior to tympanum midway between tympanum and nuchal crest and a larger tubercle posterior and slightly superior to tympanum immediately posterior to underlying quadrate bone; mental bordered by four postmentals; gular scales and scales of dewlap and ventral surfaces of throat lappets granular, scales of dorsal surfaces of throat lappets enlarged distally; dewlap scales of males slightly enlarged at distal extremity.

Dorsal body scales small, slightly imbricate, variably keeled; a midvertebral nuchal crest composed of laterally compressed dorsal scales present, comprised of 18 scales in males; lateral nuchal crests composed of 3–4 scales; middorsals approximately two times larger than scales of lower flanks, a discontinuous series of enlarged keeled scales extending from lateral nuchal crests, along base of patagium, to sacral region; caudals strongly keeled; paired, enlarged middorsal caudals extending length of tail; paired, enlarged, subcaudals extending length of tail; over proximal approximately 10% of tail, lateral caudals strongly keeled forming weak fringe; dorsal patagium with juxtaposed scales, variably keeled, keels arranged into linear series extending parallel to axis of body; ventral patagium with flat, delicate scales, variably keeled; ventral body scales strongly keeled, approximately equal in size as largest dorsals; brachials imbricate, variable in size and degree of keeling; prebrachials about equal to largest dorsals in size, strongly keeled, grading smoothly into smaller keeled suprabrachials; postbrachials much smaller than other brachials, weakly keeled or unkeeled; infrabrachials weakly keeled, approximately equal to postbrachials in size, smaller than suprabrachials; antebrachials slightly larger than brachials, variably keeled, imbricate; infra–antebrachials smaller than other antebrachials; infracarpals granular, keeled or mucronate, proximal subdigital lamellae with 2–4 keels, distal subdigital lamellae with 1–2 keels; femorals highly variable in size and degree of keeling; prefemorals, anterior suprafemorals larger than dorsals, strongly keeled; posterior suprafemorals granular, unkeeled; postfemorals granular, variably keeled, keels directed posteriorly rather than distally; infrafemorals much smaller than ventrals, keeled; a series of enlarged, flaplike posterior infrafemorals forming conspicuous fringe along posterior edge of upper hind limb, continuing along posterior edge of lower hind limb; tibials keeled, small proximally and distally, equal to or slightly larger than dorsals in size elsewhere, pretibials largest; infratarsals strongly keeled or mucronate, much smaller than supratarsals, proximal subdigital lamellae with 2–6 keels, distal subdigital lamellae with 1–2 keels, 24–28 fourth toe subdigital lamellae. Patagia supported by 6 ribs; pleurodont teeth 7; lacrimal bone absent.

Coloration of holotype in preservative.—In preservative, dorsal coloration pale gray with dark brown and black mottling; head with extensive dark brown and black pigments on pale gray base, dorsal head with such extensive dark pigments that head appears dark brown with scattered pale gray flecks; a prominent transverse melanic bar crosses anterior orbital region, a melanic interorbital spot present within the transverse bar; orbital region suffused with dark brown pigments, ciliaries pale gray; the subocular region pale gray, bordered ventrally by horizontally–oriented melanic bar that lies just superior to supralabials; lateral surfaces of neck and dorsal surfaces of throat lappets pale gray, with brown reticulum; dorsal body pale gray with several diffuse, asymmetrical, brown blotches; tail banded with dark brown on pale gray; upper arm gray with dark brown mottling; forearm from elbow to tips of digits gray with dark brown banding; hind limbs gray with dark brown mottling over femoral and proximal portion of shank, from mid–shank to tips of digits banded; dorsal patagium orange–brown with several pale tan or gray longitudinal striations proximally, the entire dorsal surface covered with rectangular, block–like, black spots that are very small proximally (1 mm in diameter), but grade into larger blotches distally, the largest blotch near the patagial margin 9 mm in diameter, the dark blotches tending to follow the pale striations; ventral gular coloration white with fine, pale gray mottling anteriorly, nearly uniform gray posteriorly, entire dewlap appearing gray; ventral throat lappets gray–brown with diffuse white speckling; ventral surface of body and limbs pale gray–white, scattered brown flecks present over lateral pectoral region; ventral surface of tail with brown and pale gray bands over proximal half, with brown and tan bands over distal half; ventral patagium pale gray with 3–2 irregular black marginal blotches.

Variation.—A medium–sized species, maximum observed SVL in males = 82 mm, females = 84 mm; rostral 1–2 times wider than high, bordered by 4–8 postrostrals; internasals, frontonasals, and prefrontals small excepting a series of enlarged, strongly keeled scales arranged in shape of inverted "Y", sometimes scales that form "arms" of "Y" not enlarged leaving an "I" on snout; 2–3 canthals; an enlarged scale, wider than tall sometimes present immediately superior to posteriormost supralabial; one to several pre–, sub–, and postoculars may be enlarged forming continuous or discontinuous subocular series, remaining postoculars small; supralabials 8–14, rectangular, pentagonal, or with anterior border convex and posterior border concave, 1–3 times longer than tall, anteriormost supralabial usually smaller than others, posteriormost supralabial usually longest; infralabials 8–13, pentagonal or occasionally rectangular; 1–2 tubercles superior to tympanum midway between tympanum and nuchal crest and 1–2 larger tubercles posterior and slightly superior to tympanum immediately posterior to underlying quadrate bone; mental bordered by 3–6 postmentals; dewlap scales of males slightly enlarged at distal extremity.

Middorsals 2–4 times larger than scales of lower flanks; midvertebral nuchal crest composed of 17–23 scales in males, 2–24 scales in females; lateral nuchal crests present in both sexes; a conspicuously enlarged series of keeled paravertebral scales rarely evident (one of 33); ventral body scales strongly keeled, may be slightly larger, equal in size, or smaller than largest dorsals; proximal subdigital lamellae of manus with 2–4 keels, distal subdigital lamellae of manus with 1–2 keels; proximal subdigital lamellae of pes with 2–4 keels, distal subdigital lamellae of pes with 1–2 keels, 24–30 subdigital lamellae on fourth toe. Patagia supported by 6–6 ribs in 32 of 33 specimens, one with 5–6 ribs; pleurodont teeth usually 6 (14 of 32) or 7 (17 of 32), one with 8.

Coloration in life.—The dorsal pattern of Draco palawanensis is composed of brown, black, and tan pigments on a pale gray base. The dark pigments contrast sharply with the pale gray giving a mottled appearance. The tail is banded with dark brown and pale gray. The limbs are mottled proximally, banded distally. Both sexes have a melanic interorbital spot, but only females have a melanic nuchal spot. The orbital region of males is suffused with dark gray pigments, the ciliaries pale yellow. In females, the orbital region has a series of radiating melanic lines on a pale gray base. The ventral body coloration is white, and pale brown spots may be present over the pectoral region. In males, the gular pattern is composed of brown mottling on a pale tan field, which gives a reticulated appearance; the proximal one–third of the dewlap is grayish–brown, but appears orange during display because the tissues underlying the skin are bright orange; the distal two–thirds of the dewlap is uniform greenish–yellow. In females, the gular coloration is pale tan with faint white spots. The dorsal patagial coloration is similar in males and females. In males, the base coloration of the patagium is dull orange. Proximally, there are several pale tan or gray longitudinal striations. The entire dorsal surface of the patagium is covered with rectangular, block–like, black spots that are very small proximally (approximately 1 mm in diameter), but grade into larger blotches distally such that they are approximately 5–7 mm in diameter near the patagial margin. The dorsal patagium of females is similar to that of males, except that the base coloration is drab yellow rather than dull orange. The ventral patagium of males is yellow over the proximal one–third, dull orange over the distal two–thirds, with several large black marginal blotches. The ventral patagium of females is similar, but the base coloration of the entire ventral surface is pale yellow.

Distribution.—Draco palawanensis is known only from Palawan Island (Figure 1.1), but can be expected on larger land bridge islands separated from Palawan by shallow water. Likely candidates include Balabac, Dumaran, Linpacan, Culion, and Busuanga.

Natural History.—Little is known regarding the natural history of Draco palawanensis. The species is common on the trunks of coconut trees and Casurina trees, both of which represent heavily disturbed habitats. In natural dipterocarp rainforest, the species probably occupies forest edge and possibly forest canopy, as in D. spilopterus and D. volans (personal observation). During courtship, males first slowly extend the dewlap until the tip is projecting well forward of the snout, the dewlap is then slowly retracted, and finally 2–4 rapid double flicks of the dewlap are performed. During intensive courtship displays, the male also may open one of the patagia and orient its body perpendicular to that of the female. In addition to the movements of the dewlap and patagia, males also incorporate push–up displays, using the forelimbs only.

Etymology.—The specific epithet palawanensis refers to the island on which this endemic species occurs.

Comments.—As far as we are aware, every worker who has commented on the taxonomic status of the Draco palawanensis populations has considered them conspecific with Bornean Draco volans (Draco volans sumatranus of some authors). In addition to the morphological characters that distinguish D. palawanensis from D. volans, ND2 mitochondrial DNA sequence data (unpublished) also indicate that these are independent lineages. Indeed, the sequence data suggest that D. palawanensis is more closely related to the Philippine species D. spilopterus, D. quadrasi, D. cyanopterus, D. reticulatus, D. ornatus, and D. guentheri, as well as D. cornutus of the Greater Sunda shelf, than it is to D. volans (including Bornean populations). Thus, the phylogenetic relationships of D. palawanensis preclude us from treating the Palawan population as a synonym of D. volans (sensu stricto).

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