A New Species of <i>Gracixalus</i> (Anura: Rhacophoridae) from Northern Vietnam

A new species of Gracixalus is described from northwestern Vietnam based on morphological differences and molecular divergence. Morphologically, the new species, Gracixalus ziegleri sp. nov., is distinguishable from its congeners on the basis of a combination of the following diagnostic characters: (1) size small (SVL 28.1 – 30.5 mm); (2) head slightly wider than long; (3) vomerine teeth absent; (4) upper eyelid and dorsum without spine; (5) supratympanic fold distinct; (6) skin of dorsal and lateral surface of head, body and limbs rough, sparsely scattered with tubercles; (7) ventral skin granular; (8) tibiotarsal projection absent; (9) toes with moderately developed webbing, formula I1 – 11/2 II1 – 2III1 – 2IV2 – 1V; (10) dorsal surface of head and body brown to beige above, with an inverse Y-shaped dark brown marking, extending from interorbital region to central region of dorsum; (11) external vocal sac absent in males; (12) males with a nuptial pad on finger I. Phylogeneticially, the new species is a sister taxon of Gracixalus sapaensis and G. tianlinensis with well-supported values. Currently, the new species is known only from the evergreen montane tropical forest of Yen Bai Province at an elevation of ca. 2200 m a.s.l.