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

Abstract

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.

A new species of Gracixalus (Anura, Rhacophoridae) from northwestern Vietnam

“… MP analysis of the dataset recovered the 263 most parsimonious trees with 525 steps (Consistency index = 0.51; Retention index = 0.72). Similar to Yu et al (2019) and Le et al (2021) , our study supported the division of the genus into three distinct lineages, Clades I, II, and III, with strong nodal support from the Bayesian analysis. While Clade II was also well corroborated by ML and MP analyses, BP and UFB values for Clade I and UFB value for Clade III were insignificant.…”

“…The new species is assigned to the genus Gracixalus based on molecular phylogenetic analyses and the following morphological characters: the presence of intercalary cartilage between terminal and penultimate phalanges of digits, tips of digits expanded into large discs bearing circum-marginal grooves, the vomerine teeth being absent, horizontal pupil, tibia ~ 4–5× longer than wide, translucent skin, inner (first and second) and outer (third and fourth) fingers not opposable, and dorsum with an inversed Y-shaped dark brown marking ( Fei et al 2009 ; Rowley et al 2011 , 2020 ; Chen et al 2018 ; Yu et al 2019 ; Le et al 2021 ).…”

“…We compared the new species with other members of the genus Gracixalus and data obtained from the literature ( Boulenger 1893 ; Bourret 1937 ; Hu et al 1978 ; Ye and Hu 1984 ; Matsui and Orlov 2004 ; Nguyen et al 2008 ; Rowley et al 2011 , 2014 , 2020 ; Mo et al 2013 ; Nguyen et al 2013 ; Matsui et al 2015 ; Matsui et al 2017 ; Zeng et al 2017 ; Chen et al 2018 ; Wang et al 2018 ; Yu et al 2019 ; Le et al 2021 ) (Table 3 ).…”

“…During our recent field work in northwestern Vietnam, specimens of a small treefrog species were collected in the karst forest of Dien Bien and Son La provinces. This treefrog taxon appears to be a member of the genus Gracixalus due to its small size ( SVL < 40 mm), the presence of intercalary cartilage between terminal and penultimate phalanges of digits, tips of digits expanded into large discs bearing circum-marginal grooves, the vomerine teeth being absent, horizontal pupil, tibia ~ 4–5× longer than wide, translucent skin, inner (first and second) and outer (third and fourth) fingers not opposable, and dorsum with an inversed Y-shaped dark brown marking on dorsum ( Fei et al 2009 ; Rowley et al 2011 , 2020 ; Chen et al 2018 ; Yu et al 2019 ; Le et al 2021 ). Closer examination showed that this taxon could be clearly distinguished from other known members of the genus by a combination of several morphological features in adults.…”

“…In Vietnam, five species were recently discovered, namely G. lumarius Rowley, Le, Dau, Hoang & Cao, 2014; G. sapaensis Matsui, Ohler, Eto & Nguyen, 2017;G. trieng Rowley, Le, Hoang, Cao & Dau, 2020; G. ziegleri Le, Do, Tran, Nguyen, Orlov, Ninh & Nguyen, 2021;and G. yunnanensis Yu, Li, Wang, Rao, Wu & Yang, 2019. Recent phylogenetic analyses showed that there are still several unnamed distinct lineages in the G. jinxiuensis species group, indicating that species richness of Gracixalus remains underestimated (e.g., Matsui et al 2017;Chen et al 2018).…”