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| Sphenomorphus tophus Grismer, Pawangkhanant, Naiduangchan, Grismer, Dugdale, Pierce, Quah, Suwannapoom & Poyarkov. 2026 |
Abstract
A new Forest Skink, belonging to the Sphenomorphus stellatus complex, was discovered in the unique forested sandstone ecosystem of the Khorat Plateau in northeastern Thailand. This new skink was recovered as the sister species to the other Indochinese skinks, S. phuquocensis + S. annamiticus, based on a phylogeny using 1,184 base pairs of 12S and 16S. A multiple factor analysis (MFA) based on a concatenated dataset comprised of size-corrected morphometric, meristic, and color pattern characters revealed this species’ isolated position in morphospace with respect to all other species in the S. stellatus complex. This is the fourth endemic lizard species reported from the Khorat Plateau and adds to a growing list of endemic species across a broad range of taxa. As such, this region desperately needs legal protection and increased field-based systematic research to uncover more unrealized species on this plateau in need of description and protection.
Keywords: Indochina, integrative taxonomy, lizard, Reptilia, Sphenomorphinae, systematics
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| Sphenomorphus tophus sp. nov. holotype (ZMMU Re-18274): (A) ventral view of the full body in life; (B) dorsal, (C) ventral, and (D) lateral (right) view of the head; (E) ventral view of the right foot; (F) ventral view of the left hand; © Photo: N. Poyarkov. |
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| Sphenomorphus tophus sp. nov. holotype (ZMMU Re-18274): (A) dorsal and (B) ventral views of the full body ( Photo: N. Poyarkov); (C) Left dorsolateral view in life (© Photo: P. Pawangkhanant) |
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| Uncatalogued specimens of Sphenomorphus tophus sp. nov. in their microhabitats in ..., Khon Kaen District, Khon Kaen Province, Thailand: (A) an adult emerging from a hole in the sandstone; (B) a juvenile on a sandstone ridge (© Photo: I. Dugdale); (C) an adult crawling down the vertical sandstone surface (Photo: A. Pierce); (D) an adult on the side of a tree (Photo I. Dugdale) |
Sphenomorphus tophus sp. nov.
Diagnosis. At this juncture, Sphenomorphus tophus sp. nov. is separated from all other species of the S. stellatus complex by having the unique combination of a maximum adult SVL of 75.4 mm; head, body, and supracaudal scales smooth; frontal scale not divided; prefrontals not in contact; parietals in contact posterior to interparietal; parietals not divided; six scales bordering the parietals; four nuchals; four supraoculars; two loreals; anterior loreal not divided; loreals in contact with supralabials; no postnasal groove; eight superciliaries; superciliary row not interrupted by fourth supraocular; lower eyelid scales large; seven supralabials; seven infralabials; three pairs of chinshields; one primary temporal scale; two secondary temporals; upper secondary temporal large; no subtemporals; 25 midbody scale rows; 63 paravertebrals; paravertebrals slightly wider than other dorsals; 68 ventrals; two enlarged ...
Suggested common names: Khorat Plateau Forest Skink (in English), จิ้งเหลนภูเขาหินทราย (Jing lhen phu khao hin saii, in Thai), and Коратский древесный сцинк (Koratskiy drevesnyi stsink, in Russian).
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L. Lee Grismer, Parinya Pawangkhanant, Mali Naiduangchan, Jesse L. Grismer, Ian Dugdale, Andrew Pierce, Evan S.H. Quah, Chatmongkon Suwannapoom and Nikolay A. Poyarkov. 2026. A New endemic Forest Skink (Squamata; Scincidae; Sphenomorphus) from the sandstone ecosystem of the Khorat Plateau, Thailand. TAPROBANICA: The Journal of Asian Biodiversity 15(01):1-11. DOI: 10.47605/tapro.v14i1.396 [16 February 2026]
