Zhangixalus yunnanensis, Pan & Hou & Yu & Liu, 2024

Pan, Yuanqiang, Hou, Mian, Yu, Guohua & Liu, Shuo, 2024, A new species of Zhangixalus (Anura, Rhacophoridae) from Yunnan, China, Zoosystematics and Evolution 100 (1), pp. 183-197 : 183

Zhangixalus yunnanensis sp. nov.

Figs 4 , 5 , 6 Yunnan tree Frog/ Yún Nán Shù Wā (云南树蛙)

Type material.

Holotype: GXNU YU20160340, adult male, collected on 20 April 2020 by Guohua Yu from Mopan Mountain, Xinping County, Yunnan Province, China (23°56'06"N, 102°01'18"E, 2443 m a.s.l.).

Paratypes: GXNU YU20160267-20160269, three adult males, collected on 14 July 2019 from the type locality by Guohua Yu; GXNU YU20160336-20160338, three adult males, collected on 20 April 2020 by Guohua Yu from the type locality; and two adult females (GXNU YU20160335 and YU20160355), collected on 20 April 2020 by Guohua Yu from the type locality.

Etymology.

The species epithet is named for Yunnan, China, where the species was collected. We suggest the English common name "Yunnan tree frog" and the Chinese common name “Yún Nán Shù Wā ( 云南树蛙)”.

Diagnosis.

The new treefrog species is assigned to Zhangixalus by the presence of intercalary cartilage between terminal and penultimate phalanges of digits, Y-shaped distal end of terminal phalanx, tips of digits expanded into large discs bearing circum-marginal grooves, and vomerine teeth present, dermal folds along limbs not significant, tarsal projections absent, green dorsa colouration and medium body size ( Jiang et al. 2019). Phylogenetically, the new species is nested within the genus Zhangixalus with strong support (100% for BI and 73% for ML).

Zhangixalus yunnanensis sp. nov. can be distinguished from its congeners by a combination of the following characters: 1) body size medium (SVL 31.3-36.0 mm [34.6 ± 1.6, n = 7] in males and 47.6-48.6 mm [48.1 ± 0.71, n = 2] in females); 2) head wider than long; 3) iris yellowish-brown; 4) tibiotarsal articulation reaching posterior corner of eye; 5) IND/SVL 11.6%-12. 8% (12.1% ± 0.0043, n =7) in males; 6) HL/SVL 31.0%-32.8% (32.3% ± 0.0068, n = 7) in males; 7) UEW/SVL 8.9%-10.00% (9.5% ± 0.0041, n = 7) in males; 8) dorsum uniformly green; 9) black blotches in axilla, groin and posterior part of thigh; 10) vocal sac external, single; 11) throat black; 12) webbing greyish; and 13) fingers webbing formula I2-2II2-3III2-2IV and toes webbing formula I2-2II1.5-2.5III2-3IV3-1.5V.

Description of holotype.

Adult male, body robust, size small (SVL 36.0 mm); HL (11.8 mm) 84.9% of HW (13.9 mm); snout rounded, sloping in profile, protruding beyond margin of lower jaw in ventral view; snout (SL 5.5 mm) longer than eye (ED 4.3 mm); canthus rostralis blunt; lore region oblique, slightly concave; nostril oval, slightly protuberant, located at the middle between snout tip and eye; IND (4.3 mm) equal to IOD and wider than UEW (3.6 mm); pineal spot absent; pupil oval, horizontal; tympanum distinct (TD 2.3 mm), rounded, slightly greater than half of ED, nearly equal to the distance between eye and nostril (DNE 2.2 mm); supratympanic fold distinct, curves from posterior edge of eye to insertion of arm; vomerine teeth in two oblique series touching inner front edge of choanae, separated by space almost equal to length of each series; choanae oval; tongue attached anteriorly and notched posteriorly; single external vocal sac, with a sac slit opening on floor of mouth at each corner.

Relative length of fingers I <II <IV <III; tips of all fingers expanded into discs with circum-marginal grooves; nuptial pad present on first finger; fingers webbed one third, webbing formula I2-2II2-3III2-2IV; lateral fringe on free edge of all fingers; subarticular tubercles prominent and rounded, formula 1, 1, 2, 2; supernumerary tubercles present; inner metacarpal tubercle large, ovoid, outer metacarpal tubercle smaller in size, flattened; white dermal fringe along outer edge of forearm present, not well developed.

Hind limbs relatively short, heels do not meet when legs positioned at right angle to body; tibiotarsal articulation reaching posterior margin of eye; relative length of toes I <II <V <III <IV; tibia (TL 14.3 mm) 39.7% of body size, shorter than foot (FL16.2 mm); tips of toes expanded into discs with circum-marginal grooves, smaller than finger discs; toes webbed, webbing formula I2-2II1.5-2.5III2-3IV3-1.5V; subarticular tubercles prominent and rounded, formula 1, 1, 2, 3, 2; supernumerary tubercles present; inner metatarsal tubercle oval, prominent; outer metatarsal tubercle absent; white dermal fringe along outer edge of tibia, tarsus and fifth toe.

Dorsal surface of body and head smooth; dorsolateral folds absent; throat smooth; chest, belly and ventral surface of thigh granular; a few white warts around vent.

Colouration in life.

Iris yellowish-brown with dark wash; dorsal surface green; side of head and tympanic region green; lower part of flanks cream mottled with greyish-brown; throat black; venter and chest cream-white mottled with yolk yellow; limbs dorsally green and ventrally light yellow; anterior and posterior of thigh light yellow; large black blotches in axilla, groin and posterior part of thigh; white fringes along outer edge from elbow to the fourth finger and from tibiotarsal articulation to the fifth toe; webbing between fingers and toes grey; dorsal surface of discs greyish-brown.

Colouration in preservative.

Dorsal surface violet; lower part of flanks and ventral surface of body and limbs white.

Sexual dimorphism.

The new species is sexually dimorphic with females being distinctly larger than males (Table 2 ) and having no vocal sac and nuptial pad. Males have external single subgular vocal sac and light yellow nuptial pad on base of finger I.

Morphological variation.

The colour pattern varied amongst individuals. The paratype GXNU YU20160267 has no black blotches on both anterior and posterior parts of the thigh (Fig. 6a, b ). The holotype (GXNU YU20160340) and two paratypes (GXNU YU20160267 and GXNU YU20160338) have no black blotches on tibia and tarsal, paratypes GXNU YU20160268 and GXNU YU20160269 have black blotches on tarsal, but have none on tibia and the other four paratypes (GXNU YU20160355, YU20160336, YU20160335 and YU20160337) have black blotches on both tibia and tarsal. The two specimens from Longling have no black blotches on tibia and tarsal. Dorsal surfaces are uniformly green in all types with the exception of GXNU YU20160335, which has small yellow spots scattered on the dorsal surface of the body and limbs (Fig. 6c ). In addition, colouration of the new species in life can vary as day period and microhabitat change; dorsum is lighter nocturnally than during the day, with dorsal surfaces appearing light to dark green.

Distribution and ecology.

The new species is currently known from the type locality (Mt. Mopan, Xinping, Yunnan) and Longling, Yunnan, China. Breeding was observed from April to July at the type locality. In April, adult males assembled and called on ground beside permanent pools (Fig. 7a ) and the eggs were laid in white foam nests deposited in mud near the pool (Fig. 7b ); in mid-July, sparse calls of this species were heard. Zhangixalus puerensis and Hyla anectans (Jerdon, 1870) were found at the same site. The Jinping and Pingbian populations previously recorded as Z. nigropunctatus have been re-assigned into Z. dorsoviridis ( Li et al. 2012a) and we confirmed that the sample KIZ 060821287, which was collected from Jinping and identified as Z. nigropunctatus ( Yu et al., 2008), also belongs to Z. dorsoviridis . Considering that Longchuan and Yingjiang are close to Longling, the populations previously recorded as Z. nigropunctatus from Longchuan and Yingjiang of Yunnan probably belong to the new species pending more data.

Comparison.

Phylogenetically, the new species is closely related to Zhangixalus nigropunctatus and Z. melanoleucus . Zhangixalus yunnanensis sp. nov. can be distinguished from Z. nigropunctatus , with which the new species has previously been confused, by yellowish-brown iris (vs. yellowish-gold; Fig. 8 and Table 6 ), head obviously wider than long (vs. head width nearly equal to head length), tibiotarsal articulation reaching posterior corner of eye (vs. reaching posterior edge of tympanum), wider internarial space (mean IND/SVL in males 12.1% ± 0.0043 [11.6%-12.8%, n = 7] vs. 10.2% ± 0.0047 [9.51%-10.85%, n = 6]), longer hind-limb (mean TFL/SVL in males 65.7% ± 0.0223 [62.92%-69.65%, n = 7] vs. 62.9% ± 0.0167 [60.8%-65.0%, n = 6]), shorter head (mean HL/SVL in males 32.3% ± 0.0068 [31.0%-32.8%, n = 7] vs. 34.6% ± 0.0082 [33.6%-35.5%, n = 6]), wider upper eyelid (mean UEW/SVL in males 9.5% ± 0.0041 [8.9%-10.0%, n = 7] vs. 7.9% ± 0.0034 [7.5%-8.4%, n = 6]), wider head (mean HW/SVL 37.1% ± 0.0122 [35.3%-38.6%, n = 7] vs. 35.2% ± 0.0092 [34.0%-36.0%, n = 6]), smaller tympanum (mean TD/SVL 6.2% ± 0.0021 [5.9%-6.5%, n = 7] vs. 6.9% ± 0.0026 [6.6%-7.3%, n = 6]) and smaller DNE (mean DNE/SVL 6.4% ± 0.0038 [5.9%-7.0%, n = 7] vs. 6.9% ± 0.0025 [6.7%-7.3%, n = 6]) (Tables 1 , 4 ; Fig. 3 ); and from Z. melanoleucus by yellowish-brown iris (vs. reddish-orange; Fig. 8 ), shorter head (mean HL/SVL in males 32.3% ± 0.0068 [1.0%-32.8%, n = 7] vs. 36.8% ± 0.0163 [34.9%-38.9%, n = 4]), shorter snout (mean SL/SVL in males 15.4% ± 0.0026 [14. 9%-15.7%, n = 7] vs. 16.7% ± 0.0072 [15.7%-17.4%, n = 4]), wider upper eyelid (mean UEW/SVL in males 9.5% ± 0.0041 [8.9%-10.0%, n = 7] vs. 8.9% ± 0.0027 [8.5%-9.1%, n = 4]) and smaller eye (mean ED/SVL 11.8% ± 0.0034 [11.2%-12.2%, n = 7] vs. 12.6% ± 0.0058 [11.9%-13.1%, n = 4]) (Fig. 3 ; Table 5 ).

In body size, besides Zhangixalus nigropunctatus and Z. melanoleucus , the new species is relatively similar to Z. achantharrhena (Harvey, Pemberton & Smith, 2002), Z. chenfui , Z. dorsoviridis , Z. dulitensis (Boulenger, 1892), Z. hungfuensis (Liu & Hu, 1961), Z. jarujini (Matsui & Panha, 2006), Z. jodiae (Nguyen, Ninh, Orlov, Nguyen & Ziegler, 2020), Z. leucofasciatus (Liu & Hu, 1962), Z. lishuiensis (Liu, Wang & Jiang, 2017), Z. minimus (Rao, Wilkinsonand & Liu, 2006), Z. moltrechti (Boulenger, 1908), Z. pinglongensis , Z. puerensis , Z. schlegelii ( Günther, 1858), Z. suffry (Bordoloi, Bortamuli & Ohler, 2007), Z. taipeianus (Liang & Wang, 1978), Z. wui (Li, Liu, Chen, Wu, Murphy, Zhao, Wang & Zhang, 2012), Z. yaoshanensis and Z. zhoukaiyae (Table 4 ). The new species can be easily distinguished from Z. achantharrhena , Z. dulitensis , Z. jarujini , Z. puerensis and Z. wui by dorsum uniformly green (vs. green with black and white spots in Z. achantharrhena , yellowish-green with a few purplish dots on head and back and a purplish line round snout in Z. dulitensis , brownish with dark marking in Z. jarujini , green with many reddish-brown blotches edged with dark brown in Z. puerensis and dark yellowish-brown to light green with numerous light-brown spots in Z. wui ); from Z. achantharrhena , Z. chenfui , Z. dulitensis , Z. hungfuensis , Z. jarujini , Z. leucofasciatus , Z. lishuiensis , Z. minimus , Z. suffry , Z. taipeianus and Z. yaoshanensis by having black blotches in axilla, groin and posterior part of thigh (vs. absent); from Z. dorsoviridis , Z. jarujini , Z. lishuiensis , Z. schlegelii and Z. wui by vocal sac external (vs. internal); from Z. achantharrhena , Z. chenfui , Z. dorsoviridis , Z. dulitensis , Z. hungfuensis , Z. jarujini , Z. jodiae , Z. leucofasciatus , Z. lishuiensis , Z. moltrechti , Z. pinglongensis , Z. schlegelii , Z. suffry , Z. taipeianus , Z. wui , Z. yaoshanensis and Z. zhoukaiyae by throat black (vs. bright yellow in Z. achantharrhena , purplish flesh in Z. chenfui , yellow in Z. dorsoviridis and Z. taipeianus , cream in Z. hungfuensis and Z. jarujini , greyish in Z. jodiae and Z. yaoshanensis , white in Z. dulitensis , Z. leucofasciatus , Z. lishuiensis , Z. moltrechti and Z. zhoukaiyae , white with slightly grey background in Z. pinglongensis , cream-white in Z. schlegelii and Z. suffry and creamy-white with greyish-brown blotches in Z. wui ); from Z. achantharrhena , Z. chenfui , Z. dulitensis , Z. jarujini , Z. jodiae , Z. lishuiensis , Z. minimus , Z. moltrechti , Z. pinglongensis , Z. puerensis , Z. schlegelii , Z. suffry and Z. taipeianus by webbing greyish (vs. having red colour in Z. achantharrhena , Z. dulitensis , Z. jarujini , Z. moltrechti , Z. pinglongensis and Z. suffry , pale brownish-yellow in Z. Zhangixalus chenfui , mottled with black blotches in Z. jodiae , Z. minimus and Z. puerensis , purple in Z. schlegelii and yellow in Z. lishuiensis and Z. taipeianus ); from Z. achantharrhena , Z. dulitensis , Z. leucofasciatus , Z. moltrechti , Z. suffry , Z. taipeianus and Z. zhoukaiyae by fingers webbed one third and toes webbed half (vs. fingers webbed half in Z. achantharrhena , Z. leucofasciatus and Z. zhoukaiyae , fingers entirely webbed in Z. dulitensis , fingers webbed half and toes webbed entirely in Z. moltrechti , fingers webbed entirely and toes webbed fully in Z. suffry and toes webbed entirely in Z. taipeianus ); and from Z. achantharrhena , Z. chenfui , Z. dorsoviridis , Z. dulitensis , Z. jodiae , Z. moltrechti and Z. pinglongensis by iris yellowish-brown (vs. dull red, edged with silvery-white in Z. achantharrhena , orange-red in Z. chenfui and Z. dorsoviridis , reddish in Z. dulitensis , silver in Z. jodiae and Z. pinglongensis and red or reddish-brown in Z. moltrechti ). The new species further differs from Z. hungfuensis and Z. wui by nuptial pad present on first finger (vs. present on fingers I and II), from Z. jodiae by lacking orange blotches in the groin, thigh and ventral side of the tibia (vs. present) and from Z. pinglongensis by black blotches on flank and hind-limb being fewer in number and discontinuous (vs. a number of black blotches united to be reticular).

The new species is distinguishable from Zhangixalus amamiensis (Inger, 1947), Z. arboreus (Okada & Kawano, 1924), Z. arvalis (Lue, Lai & Chen, 1995), Z. aurantiventris (Lue, Lai & Chen, 1994), Z. burmanus , Z. dennysi (Blanford, 1881), Z. duboisi , Z. dugritei (David, 1872), Z. feae , Z. franki , Z. hongchibaensis (Li, Liu Chen, Wu, Murphy, Zhao, Wang & Zhang, 2012), Z. hui (Liu, 1945), Z. omeimontis , Z. owstoni (Stejneger, 1907), Z. pachyproctus , Z. prasinatus (Mou, Risch & Lue, 1983), Z. prominanus (Smith, 1924), Z. smaragdinus , Z. viridis (Hallowell, 1861) and Z. yinggelingensis (Chou, Lau & Chan, 2007) by smaller body size (Table 4 ). Moreover, the new species can be easily distinguished from Z. burmanus , Z. duboisi , Z. dugritei , Z. hongchibaensis , Z. hui , Z. omeimontis and Z. prasinatus by dorsal surface uniformly green and no brown stripe along canthus rostralis and supratympanic fold (vs. dorsal surface green with brown blotches and a brown stripe along canthus rostralis and supratympanic fold or dorsum green with brown stripe along canthus rostralis and supratympanic fold); from Z. amamiensis , Z. arboreus , Z. aurantiventris , Z. burmanus , Z. dennysi , Z. feae , Z. hongchibaensis , Z. omeimontis , Z. owstoni , Z. pachyproctus , Z. smaragdinus , Z. viridis and Z. yinggelingensis by external vocal sac (vs. internal vocal sac); and from Z. arvalis , Z. aurantiventris , Z. dennysi , Z. feae , Z. franki , Z. pachyproctus , Z. prominanus and Z. smaragdinus by having black blotches in axilla, groin and anterior and posterior part of thighs (vs. absent).

Figures

Figure 3. Scatterplot of principal components 1 and 2 of size-adjusted male morphometric data of Z. yunnanensis sp. nov., Z. nigropunctatus and Z. melanoleucus.

Figure 4. Views of the holotype (GXNU YU 20160340) in life and in preservative. Photos by Guohua Yu.

Figure 5. Views of vomerine teeth, hand and foot of the holotype. Photos by Guohua Yu.

Figure 6. Views of the paratype GXNU YU 20160267 in preservative (a, b) and the paratype GXNU YU 20160335 in life. Photos by Guohua Yu.

Figure 7. Habitat of the new species at the type locality (a) and foam nests of the new species (b). Photos by Guohua Yu.

Figure 8. Irises of the new species (a. Photo by Guohua Yu), Z. nigropunctatus (b. Photo by Guohua Yu) and Z. melanoleucus (c. reproduced from Brakels et al. (2023)).