Alpine gecko (Gekko alpinus), the highest species at elevation 2400-2542 meters in Jinsha River Basin

NEWS - Alpine gecko (Gekko alpinus sp. nov.), subgenus Japonigekko (Gekkonidae), is described from the Jinsha River Basin in Sichuan Province, southwest China, based on integrative taxonomy combining molecular data and morphological characters obtained from a type series of 11 specimens.

G. alpinus has SVL 56.44-74.16 mm in adults; narrow head, HW/HL 0.51-0.79; midbody scale rows 92-114, 98-114 in males and 92-106 in females; interorbital scales between anterior angles of eyes 22-28; ventral scale rows 32-39; tubercles present on dorsal body, forelimbs, hindlimbs and tail; precloacal pores 4-7 in males and absent in females.

Subdigital lamellae of first finger 8-11, fourth finger 12-14, first toe 8-11, fourth toe 12-15, no webbing between fingers and toes; ventral scales between mental cleft and cloaca 158-189; nostrils in contact with rostral; postcloacal tubercles one or two; dorsal surface of body with 6-7 large dark gray bands between nape and sacrum.

Currently known only from the Jinsha River Basin between the border of Mangkang County, Xizang Autonomous Region and Batang County, Sichuan Province, China, at an elevation of 2400-2542 meters. Active at night and inhabits scrub or dry rocky cliffs in arid river valleys and building walls. Ants were found in the gut of one specimen.

The specific epithet alpinus is from Latin meaning from Alpēs ("Alps") + -īnus, of or pertaining to the Alps, alpine. This refers not only to the distribution range in the high Hengduan Mountains, but also the highest distribution elevation for all Japonigekko species. The Chinese name is "高山壁虎" (Gāo Shān Bì Hŭ).

The discovery of G. alpinus increased the total number to 89 species, the subgenus Japonigekko to 34 species and the subgenus in China to 21 species, including 6 species distributed in Sichuan Province (G. alpinus, G. chinensis, G. cib, G. japonicus, G. jinjiangensis and G. scabridus).

The elevation range of G. jinjiangensis is 2000-2476 m. However, the type series of G. jinjiangensis was only found at 2045-2114 m. The record of G. jinjiangensis with a length of 2476 m was originally a Gekko population in Batang District which was actually G. alpinus.

Therefore, this study revised the range of G. jinjiangensis to 2045-2114 m, while G. alpinus was distributed 2400-2542 m. The discovery of this new species marks the highest range recorded for the subgenus Japonigekko and is also a new provincial record for the genus in Xizang Autonomous Region.

The hot-dry valley of the Jinsha River in Hengduan Mountain has diverse habitat heterogeneity and topographic complexity that supports a variety of reptile species and promotes rapid evolutionary changes of species. The discovery of G. alpinus also highlights the previously underestimated reptile diversity in this area.

G. alpinus population on each side of the Jinsha River showed no genetic differentiation (16S/ND2: 0-0.2%/0-0.2%), similar to Diploderma batangense (ND2: 0-0.4%), which implies that the Jinsha River in Hengduan Mountain in Batang and Mangkang did not pose a significant geographical isolation barrier for local reptiles.

G. alpinus forms a well-supported sister lineage (SH 100/UFB 100/BI 100) with G. jinjiangensis (SH 98/UFB 100/BI 100) with great evolutionary differentiation. Uncorrected pairwise divergence of mitochondrial 16S/ND2 genes ranged from 2.2% (G. chinensis vs G. similignum), 5.4% (G. chinensis vs G. similignum), 18.4% (G. chinensis vs G. swinhonis and G. similignum vs G. swinhonis), 26.5% (G. melli vs G. similignum).

While genetic distances between G. alpinus and its relatives ranged from 3.6% (vs G. jinjiangensis) to 14.0% (vs G. swinhonis) for 16S and 7.1% (vs G. jinjiangensis) to 24.1% (vs G. similignum) for ND2 indicating genetic differentiation between species and supporting the representation of a new taxon.

Original research

Ma S, Shi S-C, Shen C, Chang L-M, Jiang J-P (2024). Discovery of a new species of the subgenus Japonigekko (Squamata, Gekkonidae, Gekko) from the Hengduan Mountains, southwestern China: the best Japonigekko mountaineer. ZooKeys 1215: 289-309, DOI:10.3897/zookeys.1215.125043

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