Figure 5–6
Malayan Mountain Horned Agamid
Holotype. Adult male (ZRC 2.6805) from Bishop’s Trail, Fraser’s Hill, Pahang, Peninsular Malaysia (3 º 43.230 'N; 101 º 44.887 'E) collected on 28 June 2008 by Jesse L. Grismer, L. Lee Grismer, Perry L. Wood Jr., at 2330 h 1,112 m a.s.l.
Paratypes. ZRC 2.5994; gravid female from Pahang, Cameron Highlands, Telom Valley, Peninsular Malaysia, collected during March, 1935. LSUHC 9094; juvenile male from Fraser’s Hill collected on Bishop’s Trial, Pahang, Peninsular Malaysia (3 º 43.234 'N; 101 º 44.891 'E) on 27 June 2008 by Perry L. Wood Jr. at 2100 h at 1,130 m a.s.l.
Diagnosis. Maximum SVL of adult males 118.4 mm, maximum SVL of females 112.7 mm; head triangular, snout short (SL/HL 46–52 %); eye moderate (EYE/HL 28–30 %); no enlarged elliptical scales below orbit; scales on the canthus rostralis-supraorbital ridge 14 or 15; large rectangular rostral scale; a short cylindrical spine above posterior margin of eye surrounded by a rosette of four smaller keeled scales at base; spine on occiput between tympanum and nuchal crest present; tympanum naked, oblong, taller than wide; dewlap present in males and females; body triangular in cross section; scales of flanks intermixed with randomly arranged clusters of larger keeled scales; nuchal crest present; 11–13 scales in nape diastema; vertebral crest composed of enlarged, pointed scales beginning at shoulder region and tapering to a series of enlarged keeled scales on anterior portion of tail; crest scales largest at base of nape; tail 140–150 % of SVL; black collar present; posterior 2 / 3 of tail black to dark brown; greenish-yellow to light orange spots encircled by gray on body, gular region orangish yellow; no yellow medial stripe on dewlap (Table 1).
Description of the Holotype. (Fig. 5). Adult male, SVL 118.4 mm, TL 174.0 mm. Head short (HL/SVL 20 %), head narrow (HW/SVL 20 %), head tall (HD/HL 80 %), head triangular in dorsal and lateral profile; moderate snout (SL/HL 50 %); interorbital and frontal regions, and rostrum wide (RW/RH 250 %); steeply sloping anteriorly; canthus rostralis prominent, forming a large projecting shelf extending posteriorly above eye, composed of 15 enlarged scales, shelf terminates with a notch anterior to the postorbital spine surrounded by four smaller keeled scales; rostral large, rectangular, bordered laterally by the first supralabials and posteriorly by nine smaller scales; nasals crater-like, surrounded by two prenasal and four postnasal scales; eight scales between nasal scales; supranasals somewhat elongate; enlarged scales above orbit weakly keeled; an enlarged row of keeled scales below orbit extending from anterior margin of eye to middle of eye; eye large (EYE/HL 30 %); interorbital, frontal, and prefrontal scales keeled and smaller then enlarged row of keeled scales below the orbit; no hair organs on anterior end of keels in lateral frontal scales; three enlarged, keeled, azygous prefrontals forming a Y-shaped pattern; scales of occiput flat to weakly keeled; enlarged parietals, no pineal eyespot; short cylindrical epidermal spine above posterior margin of eye; occipital spine surrounded by four enlarged keeled scales on the left side and five on the right side; suborbital scales enlarged, keeled extending in a single row of six from below posterior margin of eye to anterior margin of tympanum, increasing in size posteriorly, terminal scale spine-like; elongate cylindrical epidermal spine on lateral margin of nape; tympanum exposed, oblong, taller than wide surrounded by small conical scales; supralabials 12, rectangular, not decreasing in size posteriorly; mental somewhat square anteriorly and becoming triangular posteriorly, much larger than adjacent infralabials; two postmentals similar in size, all five scales contacting mental; chinshields enlarged, extending posteriorly past angle of jaw, separated from infralabials by one scale row anteriorly and three at angle of jaw; infralabials 12, rectangular; gulars sharply keeled and spinose with no enlarged midventral row; extensible dewlap present; large gular pouch; nuchal crest with a diastema 10 scales wide at base of nape; nuchal crest composed of eight elongate, lancolate scales bordered on each side by two rows of enlarged, spinose scales; dorsal body crest present, extending from posterior margin of diastema onto base of tail, vertebral crest composed of enlarged epidermal, laterally compressed, spinose scales, bordered by a single row of slightly smaller paravertebral squarish, spinose scales; vertebral crest tapers slightly to base of tail then fades approximately one-third down tail.
Body moderately developed, triangular in cross-section; dorsal scales small with medially projecting spines; larger randomly arranged scale clusters among dorsals; scales of pectoral region and abdomen larger than dorsals, keeled, spinose, arranged in semi-transverse rows; no enlarged, keeled scales anterior to vent; limbs relatively long; dorsal and ventral scales of forelimbs keeled, spinose, and nearly the same size; five digits on manus; subdigital scales keeled; scales of hind limbs keeled and spinose; postfemoral scales small, interspersed with larger spinose scales; five digits on appendages; subdigital scales keeled; subdigital lamellae on the fourth finger 21; subdigital lamellae on fourth toe 25; tail 146 % of SVL, covered with keeled spinose scales; keels on subcaudals posteriorly directed, same size as keels of other caudal scales; base of tail in males nearly twice as wide as females.
Coloration in life. (Fig. 5). Dorsal ground color of the head, body, and limbs orangish-yellow; sides and the top of the head immaculate orangish-yellow; eye patch dark and restricted to orbit not extending into the postorbital region; iris brownish-orange; black collar present fading dorsally; gular region same orangishyellow; body covered with medium-sized light orange spots edged in a faded black color and extend onto base of tail; undersides of limbs pale orange; forelimbs nearly uniform in color; smaller spots similar to that of the body on hind limbs; no faint knee patches; posterior 2 / 3 of tail black remainder of tail similar to color of body; abdomen pale orange with irregular darker markings.
Variation. (Fig. 6). The paratypes resemble the holotype in all aspects of morphology except the juvenile male LSUHC 9094 has more but smaller spots on the dorsum. The head is light green and the dorsum is yellowish-green with yellow spots. Adult female ZRC 2.5994 has fewer but larger spots on the dorsum. Scalation and morphological variation is presented in Table 3.
Distribution. Acanthosaura titiwangsaensis is only known from the montane areas of Cameron Highlands and Bukit Fraser in the Banjaran Titi Wangsa, Peninsular Malaysia. Given that this range extends into southern Thailand and other montane endemics restricted to this range extend across the Thai-Malaysian border (Boulenger 1903; Flower 1896, 1899), it is possible that A. titiwangsaensis may also extend further north as well.
Natural history. This species was found at night sleeping head-up on the trunks of small trees, approximately 8 cm in diameter, approximately 2–3 m above the ground. We did not see lizards during the day but presume its diurnal habits resemble those of Acanthosaura bintangensis. Like other species of Acanthosaura, we believe this species forages on the ground for food, digging through the soil (Taylor 1963) based on soil fragments found on the labial scales and within the external nares of specimens from Fraser’s Hill. A gravid female was found during March (ZRC 25994) from Cameron Highlands.
Etymology. This specific epithet titwangsaensis is in reference to the mountain range, Banjaran Titiwangsa, to which we believe this species is likely to be restricted.
Sex ZRC 2.6805 Holotype Male LSUHC 9094 Paratype Juvenile ZRC 2.5994 Paratype Female SVL 118.4 91.8 112.7 TL 174 136 160 HL 24 20 24.3 HW 23.4 17.5 20.7 HD 20.2 15.7 18.6 SL 12.5 9.7 11.4 EYE 7.2 5.6 7.7 TD 3.7 2.7 4
TN 1 1 1
PS 4.4 3.3 3.5 NS 4.4 3.8 2.7 NSL 2.4 1.6 1.9 DS 2.1 2 1.7 DSL 1.9 1.5 2
WN 1.6 1.6 1.4 WDS 2.3 1.6 2.1 DIAS 5.9 5.1 7.6 DIASN 10 13 11
DIAS /SVL 0.05 0.06 0.07 FOREL 47.6 38 51.7 HINDL 65.6 48.5 60.5 SUPRAL 12 13 12
INFRAL 12 11 11
VENT 57 54 47
FI 21 21 20
TO 25 27 23
TL/SVL 1.5 1.5 1.4 OS 2.3 1.8 2.2 NSSOS 4 or 5 5 5
CS 15 15 14
RW 4.5 3.6 5.2 RH 1.8 1.4 2
RS 9 9 9
NS 8 8 8
NCS 11 12 11
NSCSL 7 9 11
NR 2 1 1
NSSLC 11 12 14
MW 1.8 1.4 2
MH 1.8 1.4 2.4
to be continued.
Comparisons to other species. Acanthosaura bintangensis can be differentiated from all other species of Acanthosaura by having elliptical keeled scales below the orbit of the eye and by having more subdigital lamellae on the fourth finger (23 vs. 16–18 for A. armata, 16–17 for A. capra, 19–22 for A. coronata, 14–18 for A. crucigera, 16–21 for A. nataliae, and 17–19 for A. lepidogaster). Acanthosaura bintangensis differs from A. capra and A. nataliae by having a spine on the occiput between tympanum and nuchal crest (vs. lacking), from A. coronata, A. crucigera, and A. lepidogaster by having more subdigital lamellae on the fourth toe (26–28 vs. 22–24 for A. capra, 15–22 for A. coronata, 19–24 for A. crucigera, and 23 for A. lepidogaster). Acanthosaura bintangensis can be differentiated from all other species of Acanthosaura except for A. titiwangsaensis sp. nov. by having more canthus rostralis-supracilliary scales (14–15 vs. 11–13 for A. armata, 13 for A. coronata, 12–13 for A. crucigera, 13 for A. nataliae, and 10–12 for A. lepidogaster). Acanthosaura bintangensis differs from A. armata, A. coronata, A. crucigera, and A. lepidogaster by lacking a light patch on the knee. It can be differentiated from A. coronata and A. nataliae by having a black nuchal collar. Acanthosaura bintangensis differs from A. armata, and A. nataliae, by having a higher number of scales between the diastema (11–15 vs. 1–8 for A. armata and 10 for A. nataliae). Acanthosaura bintangensis can be separated from A. armata, and A. nataliae by having fewer ventral scales (47–57 vs. 59–68 for A. armata, and 64–71 for A. nataliae). Acanthosaura bintangensis differs from A. nataliae by having a lower number of scales between the seventh supralabial and the sixth canthal (9–14 vs. 16 for A. nataliae). Acanthosaura bintangensis differs from A. lepidogaster by having a smaller diastema length divided by snout vent length (4.3–6.7 % vs. 7.8–8.2 % for A. lepidogaster; Table 1).
Acanthosaura titiwangsaensis can be differentiated from all other species of Acanthosaura except for A. bintangensis by having a higher number of canthus rostralis-supracilliary scales (14–15 vs. 11–13 for A. armata, 13 for A. coronata, 12–13 for A. crucigera, 13 A. nataliae, and 10–12 for A. lepidogaster). Acanthosaura titiwangsaensis differs from A. nataliae and A. capra by having an occipital spine. It can be differentiated from A. armata, A. coronata, A. crucigera, and A. lepidogaster by lacking a light patch on the knee. Acanthosaura titiwangsaensis differs from A. armata, A. capra, A. crucigera and A. lepidogaster by having a higher number of subdigital lamellae on the fourth finger (20–21 vs. 16–18 for A. armata, 16–17 for A. capra, 14–18 A. crucigera, and 17–19 for A. lepidogaster). Acanthosaura titiwangsaensis differs from A. armata, A. coronata, A. crucigera, A. nataliae, and A. lepidogaster in having a higher number of scales bordering the rostral (9 vs. 5–7 for A. armata, 8 for A. coronata, 6–7 for A. crucigera) and by having a lower number of scales bordering the nostrils, (9 vs. 13 for A. nataliae, and 10–12 for A. lepidogaster). It can be differentiated from A. armata and A. nataliae on having a lower number of ventral scales (47–57 vs. 59–68 for A. armata, and 64–71 for A. nataliae). It can be differentiated from A. coronata by having a higher number of subdigital lamellae on the fourth toe (23–27 vs. 15–22 for A. coronata It can be differentiated from A. coronata, A, nataliae, and A. lepidogaster in having a higher number of scales from the fifth canthal to the fifth supra labial (9–11 vs. 6–7 for A. coronata, 8 for A. nataliae, and 8 for A. lepidogaster). Acanthosaura titiwangsaensis differs from A. coronata, A. crucigera, and A. nataliae by having a higher number of scales bordering the mental (5 vs. 4 for A. coronata, 4 for A. crucigera, and 4 for A. nataliae). Acanthosaura titiwangsaensis differs from A. lepidogaster by having a smaller diastema length divided by snout vent length (4.9–6.7 % vs. 7.8–8.2 % for A. lepidogaster). This species differs from A. coronata and A. nataliae by having a nuchal diamond present on the nape. Acanthosaura titiwangsaensis differs from A. armata by having a higher number of scales between the diastema (10–13 vs. 1–8 for A. armata). It differs from A. lepidogaster by having a larger gular pouch (Table 1).
Acanthosaura bintangensis and A. titiwangsaensis most closely resemble each other but can be differentiated by their number of subdigital lamellae under the fourth finger (23 in A. bintangensis vs. 20–21 for A. titiwangsaensis); number of scales surrounding the occipital spine (A. bintangensis 6–7 vs. 4–5 for A. titiwangsaensis); number of scales between the fifth canthal to the fifth supralabial (A. bintangensis 7–8 vs. 9–11 for A. titiwangsaensis); by the presence of two elliptical keeled scales below the orbit in A. bintangensis and their absence in A. titiwangsaensis (Fig. 7); by the yellow medial gular stripe in A. bintangensis and its absence in A. titiwangsaensis; and A. bintangensis having more spots on the dorsum than the latter (Table 1; Fig. 2, 5).