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| Acanthosaura syrax P. Trivalairat, K. Trivalairat, Moungkhaek, Caponov & Lorsunyaluck. 2026. Syrax mountain horned dragon | กิ้งก่าเขาหนามเล็กไซแรกซ์ |
Abstract
A new species of mountain horned dragon, Acanthosaura syrax sp. nov., is described from the high–elevation evergreen forests of Mae Wong National Park in western Thailand. Morphological comparisons distinguish the new taxon from its congeners by its smaller body size and the fact that it possesses the smallest nuchal and dorsal scales recorded within the genus. Phylogenetic analysis of mitochondrial ND2 and COI gene sequences further supports this distinction, identifying the new species as a reciprocal monophyletic lineage with 76% and 99% nodal support in maximum–likelihood analyses and 0.78 and 1.00 nodal support in Bayesian Inference analyses based on ND2 and COI genes, respectively. Interspecific pairwise genetic distances between A. syrax sp. nov. and other congeners range from 14.1–15.9% in ND2 gene and 14.96–28.13% in COI gene, while intraspecific variation remains low at 0–0.01% and 0–0.34% in ND2 and COI, respectively. This discovery brings the number of Acanthosaura species to 23 and highlights the significant and unique biodiversity found within the high–altitude evergreen ecosystems of western Thailand.
Key words: COI, Mae Wong National Park, morphology, ND2, reptile, Tak–Kamphaeng Phet Province, taxonomy, tropical rainforest
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| Adult male holotype (THNHM31129) of Acanthosaura syrax sp. nov. from Mae Wong District, Kampheang Phet Province, Thailand, at 1,340 m a.s.l. A. Left lateral view; B. Right lateral view; C. Dorsal view. |
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| Acanthosaura syrax sp. nov. Adult female paratype (THNHM31130 for (A–C), THNHM31131 for (D–F)) A, B. Right lateral view; C, F. Dorsal view. D, E. Left lateral view. |
Acanthosaura syrax sp. nov.
Diagnosis. A small-sized species (maximum SVL 101.2 mm for females and 69.6 mm for males) with a single tiny conical spine above the posterior margin of the eye (maximum PS 2.7 mm for females and 2.0 mm for males); small spine on the occiput between the tympanum and the nuchal crest (maximum OS 4.1 mm for females and 2.4 mm for males); tympanum scaleless, small, roundish; less developed gular pouch; present small scales intermixed with three set of medium keeled scales line transversely from dorsal to ...
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| Acanthosaura syrax sp. nov. Adult female paratype (THNHM31130 for (A–C), THNHM31131 for (D–F)) o A, B. Right lateral view; C, F. Dorsal view. D, E. Left lateral view. |
Etymology. The specific epithet syrax is a noun in apposition, named in reference to the dragon “Syrax”, the mount of Queen Rhaenyra Targaryen [from George R.R. Martin’s A Song of Ice and Fire universe]. This name is inspired by the species’ distinctive yellow-hued coloration, its relatively diminutive size compared to its congeners, and its significant reproductive output, reflected in its high clutch size. We suggest the following common names, “Syrax mountain horned dragon” (English) and “King Ka Khaow Naam Lek Syrax” (กิ้งก่าเขาหนามเล็กไซแรกซ์) (Thai).
Poramad Trivalairat, Krittiya Trivalairat, Nawee Moungkhaek, Simon Caponov and Benchapol Lorsunyaluck. 2026. Acanthosaura syrax sp. nov., A New Species of mountain horned dragon from high-elevation habitats of western Thailand (Squamata, Agamidae). ZooKeys. 1287: 47-76. DOI: doi.org/10.3897/zookeys.1287.186636
