Fansipan ground skink (Scincella fansipanensis) from northwestern Vietnam at elevations of 2282-2366 meters

NEWS - Fansipan ground skink (Scincella fansipanensis sp. nov.) from northwestern Vietnam, as a new terrestrial skink to science based on an uncorrected genetic distance of 14.60–21.41% (COI gene). This new species is known only from the highland area of Fansipan Mountain in the Hoang Lien Son Mountains of Lao Cai Province.

Scincella Mittleman 1950 included 39 species. Currently, 13 species are known from the Indochina region and 4 of them are widespread species: S. doriae Boulenger (China, Myanmar, Vietnam and possibly Thailand), S. melanosticta Boulenger (Myanmar, Thailand, Cambodia and Vietnam), S. monticola Schmidt (China and Vietnam) and S. reevesii Gray (India, Nepal, China, Myanmar, Thailand, Cambodia, Malaysia and Vietnam).

S. rufocaudata Darevsky & Nguyen is known from the Central Highlands of Vietnam, Cambodia and Laos. S. rupicola Smith has been reported from Thailand, Laos, Cambodia and Vietnam. S. nigrofasciata Neang, Chan & Poyarkov is endemic to Cambodia and S. ochracea Bourret is distributed in Laos and Vietnam.

Five species are endemic to Vietnam: S. apraefrontalis Nguyen, Nguyen, Böhme & Ziegler; S. badenensis Nguyen, Nguyen, Nguyen & Murphy from Tay Ninh; S. baraensis Nguyen, Nguyen, Nguyen & Murphy; S. darevskii Nguyen, Ananjeva, Orlov, Rybaltovsky & Böhme; and S. devorator (Darevsky, Orlov & Ho).

During fieldwork in northwestern Vietnam, researchers collected 10 terrestrial lizards on Fansipan Mountain in the Hoang Lien Son Mountains of Lao Cai Province. Morphological analysis revealed these lizards to belong to an undescribed taxon.

S. fansipanensis adult males have a SVL of 51.7 mm; TaL 88.3 mm, tail regenerated; head longer than wide (STL 8.9 mm, HW 6.9 mm); snout round; lower eyelid with an undivided opaque window; slimmer body; tympanum round, deeply sunk with an oblique edge dorsally; ear opening without lobules.

Head scales smooth; rostral visible from above, in contact with frontonasal; frontonasal wider than long; prefrontals separated from each other; no supranasal; no postnasal; four supraoculars; frontal large, narrowing posteriorly, longer than wide, length approximately 1.11 times its distance from tip of snout, bordered anteriorly by frontonasal and prefrontals, laterally by first two supraoculars, and posteriorly by frontoparietals.

A pair of frontoparietals in contact with the second to fourth supraoculars; interparietal narrow posteriorly, longer than wide; parietals in contact posteriorly, behind the interparietal; one pair of prenuchals; three nuchals in left side and four in right.

Nostril in center of nasal; nasal in contact with the first supralabials, rostral, frontonasal, and anterior loreal; two loreals; six supraciliaries; two preoculars, lower one contacting first presubocular; two presuboculars, lower one in contact with fourth and fifth supralabials; two postsuboculars; one primary temporal, contact with sixth and seventh supralabials.

Two secondary temporals, lower secondary temporal overlapping the upper one, contacting seventh supralabials; seven supralabials, fifth below center of the eye; six infralabials; mentally wider than long, in contact with the first infralabials; postmental undivided, in contact with first two infralabials; three pairs of chin shields, first pair medially in contact with each other.

Dorsal scales smooth, slightly wider than ventral and lateral ones; 22 midbody scale rows; 1/2+4+1/2 scale rows between dark dorsolateral stripes; 68 paravertebral scale rows; 63 ventral scale rows; two enlarged precloacals, outer scales overlapped median ones; tail thick, widened to the tip, small scales around tail base.

Limbs relatively short, pentadactyl; toe separated from finger when limbs adpressed along body; eight smooth subdigital lamellae under finger IV, ten under toe IV.

The dorsal surface of head and body brown with irregularly shaped dark spots; dorsolateral stripe narrow, 1+1/2 scales wide, dark, and without pale spots; the upper part of flank dark brown with paler spots, faint in lower edge; the lower part of flank with a mosaic of black and paler spots; the venter yellowish cream.

Intraspecific variations of Scincella fansipanensis were as follows: none or one pair of prenuchals; two to six nuchals; five or six supraciliaries; six or seven supralabials; 22 or 24 midbody scale rows; 60–68 paravertebral scale rows; 58–64 ventral scales; seven to nine subdigital lamellae on finger IV and 10–12 on toe IV.

For the morphological characteristics of the type series, see Table 2–3. The body color before preservation showed little variation, except in the arrangement of the irregularly shaped dark spots, which differed among individuals. One individual (IEBR R.5190) exhibited very few spots.

Currently known only from Fansipan Mountain, Hoang Lien Son Mountains in Lao Cai Province, west Vietnam sea, at elevation 2282-2366 m. The specimen was found under a fallen tree in an open area or grassland during the day in May.

The lizard appeared to be in brumation, as it did not move or try to escape when the fallen tree was removed. The air temperature was usually around 10–12C from November to April and the minimum temperature is -3C in Hoang Lien National Park. “Fansipanensis” is from Mount Fansipan. Researchers suggest Fansipan ground skink (English) and Thằn lằn cổ fansipan (Vietnamese).

S. fansipanensis is closely related to S. modesta and S. potanini. It can be distinguished by SVL up to 59.0 mm, AG to 36.5 mm; 22 (rarely 24) rows of midbody scales, smooth; 60-68 rows of paravertebral scales; 58-64 rows of ventral scales.

Prefrontals separated from each other; 5 (rarely 6) supraciliaries; 2 to 6 nuchal; there are ear holes, tympanum is deeply concave, without lobules; legs are short, toes are separated from fingers when legs are pressed; toe IV with 10-12 subdigital lamellae, smooth; dorsal surface of body with irregular dark spots.

Original research

Shinya Okabe, Masaharu Motokawa, Yuki Koizumi, Truong Quang Nguyen & Tao Thien Nguyen & Hai Tuan Bui (2024). A new species of the genus Scincella (Squamata: Scincidae) from Mount Fansipan, Hoang Lien Son Range, northwestern Vietnam, Zootaxa 5537 (3): 407–423, DOI:10.11646/zootaxa.5537.3.7

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