Friday, May 15, 2020

[Herpetology • 2020] Acanthosaura aurantiacrista กิ้งก่าเขาหนามสีส้ม • A New Long Horn Lizard (Squamata: Agamidae) from northern Thailand

Acanthosaura aurantiacrista 
Trivalairat, Kunya, Chanhome, Sumontha, Vasaruchapong, Chomngam & Chiangkul, 2020

“กิ้งก่าเขาหนามสีส้ม” | Orange Crested Horned Lizard || DOI: 10.3897/BDJ.8.e48587 

In Thailand, five species of Acanthosaura have been recorded so far, including Acanthosaura armata from the southern region, A. cardamomensis from the eastern region, A. crucigera from the western region, A. lepidogaster from the northern region and A. phuketensis from the Phuket Island and south-western region. However, comprehensive studies of diversity patterns and distribution of Acanthosaura are still lacking in some areas and need further information for designating areas of special conservation importance and nature protection planning in Thailand.

New information
Acanthosaura aurantiacrista is a new species of long-horned lizard of the genus Acanthosaura from northern Thailand. It is distinguished from all other species of Acanthosaura by a dagger-like nuchal spine with yellowish-orange colouration in females, bright yellow colouration in males and a combination of other morphological characters: a greater tail length to snout-vent length ratio; a larger postorbital spine, nuchal spine, dorsal spine and occipital spine compared to its head length; a smaller diastema to snout-vent length ratio; a greater number of subdigital lamellae on the fourth finger and fourth toe; and a larger gular pouch than other Acanthosaura species. Analysis of mitochondrial ND2 gene sequences revealed a sister clade between the A. aurantiacrista lineage and the A. crucigera lineage with a 100% probability of divergence, according to Bayesian analysis and strong support value for Maximum Likelihood analysis. The pairwise distance ranged from 13.8-15.0% between A. aurantiacrista and A. cardamomensis, 10.9-14.5% between A. aurantiacrista and A. crucigera and 0-1.2% amongst A. aurantiacrista populations. The discovery of this lizard increases the known endemic herpetological diversity and underscores the importance of conservation in the mountain rainforest region of northern Thailand.

Keywords: rainforest, Thanon Thong Chai Mountain Range, northern region, ND2


Figure 2. Holotype THNHM28064 of Acanthosaura aurantiacrista sp. n., adult female from Mae Sariang District, Mae Hong Son Province, Thailand.
A. Dorsal and B. Ventral views of the body; C. Lateral and D. Dorsal view of the head; E. In life.

Acanthosaura aurantiacrista, sp. n.

Diagnosis: Acanthosaura aurantiacrista sp. n. is differentiated from all other congeners by this combination of characters: A large size (maximum SVL 130.1 mm for males and 119.3 mm for females) and a single long conical spine above the posterior margin of the eye; a large spine on the occiput between the tympanum and nuchal crest; tympanum naked, large, roundish; large developed gular pouch; scales on flanks randomly intermixed with small keeled and small tubercle scales; large nuchal crest with 8 large dagger-like and pointed spines; narrow diastema with 8-9 scales between the nuchal and vertebral crests; vertebral crest composed of large dagger-like, pointed spines beginning at the shoulder region and decreasing in size until the base of the tail; nuchal and dorsal crests are orange in females and yellow in males; tail 1.40-1.70 times the SVL; and black collar and black eye patch present, extending posteriorly until reaching the nuchal crest.

Figure 4. Morphology of Acanthosaura aurantiacrista sp. n. from Sop Khong Subdistrict, Omkoi District, Chiang Mai Province, Thailand.
A. Adult male paratype QSMI1448; B. Adult female paratype THNHM28522; C. Subadult male paratype THNHM28523.


Etymology: The specific epithet aurantiacrista came from a combination of the Latin words aurantiaco (orange) and crista (crest). The name refers to a distinctive characteristic of the first discovered female specimen, which exhibited nuchal and dorsal crests with an orange colour. 
We suggest the following common names: “กิ้งก่าเขาหนามสีส้ม” kingkakhaownaam seesom (Thai), Orange Crested Horned Lizard (English), orange-verzierter gehörnter Nackenstachler (German) and Acanthosaurus à crête orange (French).

Figure 5. Distribution of Acanthosaura species in Thailand.  

Figure 6. Ecological area of  Acanthosaura aurantiacrista sp. n. from Sop Khong Subdistrict, Omkoi District, Chiang Mai Province, Thailand.

Distribution: Acanthosaura aurantiacrista sp. n. occurs in the Thanon Thong Chai Mountain Range in northern Thailand: Mae Sariang District, Mae Hong Son Province at 728 m a.s.l.; Sop Khong Subdistrict, Omkoi District, Chiang Mai Province at 935 m a.s.l.; and Nang Lae Subdistrict, Mueang District, Chiang Rai Province at 636 m a.s.l. This species usually lives in rainforests on mountains at elevations over 600 m a.s.l. (Fig. 5).

Ecology: Acanthosaura aurantiacrista sp. n. has been found in evergreen forests on hills up to at least 600 m elevation (Fig. 6). It is active during the day on the ground, logs or rocks or 1-2 m above the ground on trees. During night, it is inactive and sleeps on twigs or trees 1-2 m above the ground. This species displays a defence mechanism against approach or provocation consisting of falling to the ground and running away to find refuge under rocks, log hollows or shrubs.

Poramad Trivalairat, Kirati Kunya, Lawan Chanhome, Montri Sumontha, Taksa Vasaruchapong, Nirut Chomngam and Krittiya Chiangkul. 2020. Acanthosaura aurantiacrista (Squamata: Agamidae), A New Long Horn Lizard from northern Thailand. Biodiversity Data Journal. 8: e48587. DOI: 10.3897/BDJ.8.e48587

กิ้งก่าเขาหนามสีส้ม ชนิดนี้ มีการเเพร่กระจายอยู่ในเขตภาคตะวันตกเฉียงเหนือเเละภาคเหนือของประเทศไทย ซึ่งชื่อของมันถูกตั้งมาจากหนามสีส้มบนหลังของตัวเมียตัวเเรกที่พบ (Holotype) เพื่อเป็นสัญลักษณ์ที่สื่อถึง "ไฟป่า" ในภาคเหนือ ที่มักจะเกิดจากการเผาป่าเพื่อการเกษตร การนำไม้ไปแปรรูป และอื่นๆ จนทำให้เกิดไฟไหม้ลุกลามไปในหลายพื้นที่ และยังเป็นต้นเหตุของปัญหาฝุ่น PM2.5 
ดังนั้นคณะผู้วิจัยจึงอยากให้กิ้งก่าเขาหนามชนิดนี้ เป็นตัวแทนของเหล่าสัตว์ป่าทั้งหลาย ที่ต้องเผชิญผลกระทบจาก “ไฟป่า” เพื่อให้ทุก ๆ คน โดยเฉพาะภาครัฐ ตระหนักถึงปัญหาไฟป่าที่เกิดขึ้นจากฝีมือของมนุษย์อย่างจริงจัง เพื่อที่สัตว์ป่า ทรัพยากรธรรมชาติ และอากาศบริสุทธิ์ จะได้อยู่คู่กับเมืองไทยตลอดไป 
#กิ้งก่าเขาหนามสีส้ม #ไฟป่า #อมก๋อย #ประเทศไทย #Acanthosaura #aurantiacrista