Zhangixalus pachyproctus, Yu & Hui & Hou & Wu & Rao & Yang, 2019

Yu, Guohua, Hui, Hong, Hou, Mian, Wu, Zhengjun, Rao, Dingqi & Yang, Junxing, 2019, A new species of Zhangixalus (Anura: Rhacophoridae), previously confused with Zhangixalus smaragdinus (Blyth, 1852), Zootaxa 4711 (2), pp. 275-292 : 282-288

Zhangixalus pachyproctus sp. nov.

Figs 8–11

urn:lsid:zoobank.org:act:E1AD0416-AAED-4277-AAE3-39D9146AE143

Holotype. KIZ 20160119 , an adult male, collected on 9 June 2016 by Guohua Yu from Bubeng Village (21°36’53.53’’N, 101°35’6.92’’E, 684 m a.s.l.; Fig. 1 ), Mengla Township , Mengla County, Xishuangbanna Autonomous Prefecture, Yunnan Province, China.

Paratypes. KIZ 20160118 , KIZ 20160122 , and KIZ 20160123 , three adult males, collected on 9 June 2016 by Guohua Yu from the type locality . KIZ 090148 and KIZ 090149, two adult males, collected on 15 May 2009 by Guohua Yu from Caiyanghe Nature Reserve (22°35’15.14’’N, 101°4’49.26’’E, 1560 m a.s.l.; site 8 in Fig. 1 ), Puer City, Yunnan Province, China . KIZ 20160126 , a female, collected on 9 June 2016 by Guohua Yu from the type locality . KIZ 20160219–20160221 , three juveniles, collected on 19 June 2017 by Hong Hui from Bulang Mt. (21°34’41.78’’N, 100°20’6.85’’E, 1085 m a.s.l.; site 9 in Fig. 1 ), Menghai County, Xishuangbanna Autonomous Prefecture, Yunnan Province, China .

Etymology. The specific epithet is derived from the Greek “πᾰχύᾰ” for “thick, massif” and the Greek “πρωκτός” for “anus”, referring to the protruding vent of the new species ( Fig. 8 ). It is a word in apposition, so not to be modi- fied.

Diagnosis. The new 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 disks bearing circummarginal grooves, and vomerine teeth present, dermal folds along limbs not significant, tarsal projections absent, green dorsal coloration, and large body size according to Jiang et al. (2019). The new species is distinguished from its congeners by a combination of its large body size (adult males SVL 73.4–78.2 mm; female SVL 102.4 mm), green dorsum, narrow white stripes along edge of lower jaw, body sides, outer side of limbs, and above vent, complete webbing between fingers II–IV and all toes, large grey reticular mottles below the white stripe on flank, and protruding vent.

Description of holotype. Adult male (SVL 78.2 mm); head large, its length (22.5 mm) 77.6% of head width (29.0 mm); snout rounded, sloping in profile, protruding slightly beyond margin of lower jaw in ventral view; canthus rostralis distinct, rounded; loreal region sloping, slightly concave; nostrils oval, slightly protuberant, much closer to snout tip than to eye; internarial distance (8.8 mm) narrower than interorbital distance (9.7 mm) and wider than upper eyelid width (6.8 mm); pineal spot absent; pupil oval, horizontal; tympanum distinct, rounded, tympanic rim elevated relative to skin of temporal region, more than half eye diameter; supratympanic fold distinct, green, curving from posterior edge of eye to insertion of arm; vomerine teeth present in two series, touching inner front edges of choanae, separated by distance less than length of each series; choanae oval; tongue attached anteriorly, deeply notched posteriorly; internal single subgular vocal sac, vocal sac opening on floor of mouth at each corner.

Forelimbs relatively robust; relative length of fingers I <II <IV <III; tips of all fingers expanded into discs with circummarginal and transverse ventral grooves; nuptial pads present on first and second fingers; fingers webbed, webbing formula I 2–2 II 1 –1.5 III 1–1 IV; subarticular tubercles prominent and rounded, formula 1, 1, 2, 2, proximal one smaller than distal one on third and fourth fingers; supranumerary tubercles present on metacarpals; thenar (inner metacarpal) tubercle large, oval; outer metacarpal tubercle, small, rounded; a narrow dermal fringe along outer edge of forearm and forth finger.

Hindlimbs relatively robust, heels slightly overlapping when legs at right angle to body; thigh (35.9 mm) short- er than tibia (36.8 mm) and foot (36.4 mm); relative length of toes I <II <III <V <IV; tips of toes expanded into discs with circummarginal and transverse ventral grooves; toe discs smaller than finger discs; toes webbed, webbing formula I 1–1 II 1–1 III 1–1 IV 1–1 V; subarticular tubercles distinct, rounded, formula 1, 1, 2, 3, 2; supernumerary tubercles present, indistinct; inner metatarsal tubercle distinct, oval; outer metatarsal tubercle absent; a narrow dermal fringe along outer edge of tarsus and fifth toe.

Dorsal skin smooth; flanks, throat, chest, belly, and ventral surface of thighs granular; dorsolateral folds absent; vent protruding, forming an arc-shaped swelling.

Coloration of holotype in life. Iris bronze; dorsal surface almost uniformly green, mottled with few small light yellow blotches ( Fig. 3a ); light yellow stripe starting from margin of lower jaw along flank to groin, separating green dorsum from greyish white venter; white stripes along outer side of limbs and above vent; dorsal surfaces of two outer fingers and toes pale green, mixed with pale violet; discs and dorsal surfaces of other fingers and toes cream-colored; webbing pale blue-black; ventral surface of body and limbs grey white; lower part of flanks, abdomen, and ventral surfaces of hindlimbs scattered with clouded light brown spots.

Coloration of holotype in preservative. In preservative, green turned to violet; lower part of flanks and ventral surface of body and limbs grey white, scattered with clouded light brown spots.

Variation. The new species is sexually dimorphic with the only known female being larger than males ( Table 2 ). Compared with the males, the female has more yellow marks on the dorsal surface of body and limbs and lateral sides of head ( Fig. 10a ), and its vent does not protrude obviously ( Fig. 10b ). Ventral surface of body and limbs of the holotype and three paratypes (KIZ 20160122, KIZ 20160123, and KIZ 091049) is scattered with clouded light brown spots, but ventral surface of body and limbs of KIZ 20160118, KIZ 20160126, and KIZ 090148 is almost immaculate. TL is longer than FL in most specimens with the exception of KIZ 090148. TD is slightly shorter than DNE in most specimens, but TD is slightly longer than DNE in KIZ 20160126, KIZ 20160219, and KIZ 20160221. Additionally, the three juveniles (KIZ 20160219–20160221) differed from adults in life by having red coloration on hands and feet and yellow coloration on ventral surface of body ( Fig. 11 ).

Distribution and ecology. The new species is known from southern Yunnan, China (Jinghong, Mengla, Menghai, and Puer), Vietnam (Bac Giang and Nghe An), and Thailand (Prachuap Khiri Khan). Additionally, previous records of Z. smaragdinus (as R. maximus ) from places in northern and central Vietnam (Dien Bien, Thanh Hoa, Cao Bang, Quang Binh, and Son La Province; Nguyen et al. 2015; Pham et al. 2016; Pham et al. 2017a; Pham et al. 2017b), central Laos (Khammouane Province; Luu et al. 2014), and upper northeastern and western Thailand (Loei, Kanchanaburi, Phetchaburi, and Ratchaburi Province; Youjaroen et al. 2018) likely also refer to the new species.

To our knowledge, the species inhabits forests at 500–1560 m elevation. Specimens from southern Yunnan were collected in May or June. At the type locality, adult males assembled and called on leaf or in grass beside temporary puddles after raining ( Fig. 12 ). A breeding pair was observed in amplexus on the ground beside a puddle. Rhacophorus rhodopus Liu & Hu, 1960 , Rhacophorus kio Ohler & Delorme, 2006 , and Polypedates megacephalus Hallowell, 1861 were also encountered at the type locality.

Comparisons. The new species can be distinguished from its sister-species Z. smaragdinus , with which the new species has previously been confused, by the protruding posterior end of the body in males that forms an arcshaped swelling (versus vent not protruding in Z. smaragdinus ), large thick grey reticular mottles below the white stripe on flank (versus fine), narrower interspace between vomerine ridges, and more sloped snout in profile. Moreover, the PCA analysis suggested that the new species also differs from Z. smaragdinus by a series of morphometric characters associated with head and hindlimb such as wider head, longer internarial distance, larger tympanum, and longer hindlimb. In addition, head longer (HL 31.5 mm) than wide (HW 30.8 mm) in the female lectotype of Polypedates smaragdinus according to Ohler & Deuti (2018), but head wider (HW 38.8) than long (HL 31.1 mm) in the female specimen of the new species (KIZ 20160126; Table 2 ).

Zhangixalus pachyproctus sp. nov. can be distinguished from other medium to large (SVL of adult males> 60 mm) species of Zhangixalus with an immaculately or predominantly green dorsum ( Zhangixalus burmanus [ Andersson, 1939], Zhangixalus dennysi [ Blanford, 1881], Zhangixalus duboisi [Ohler, Marquis, Swan, & Grosjean, 2000], and Zhangixalus feae [ Boulenger, 1893]) by the narrow white stripes passing along the edge of lower jaw, body sides, outer side of limbs, and above vent.

The new species further differs from Z. burmanus by bronze iris (versus yellowish green iris), complete webbing between fingers II–IV (versus fingers II–IV half-webbed), internal single subgular vocal sac (versus paired internal subgular vocal sacs), and absence of brown band on canthus rostralis, upper eyelid, and supratympanic fold (versus present); from Z. dennysi by dorsal surface of discs light brown (versus green) and complete webbing between fingers II–IV (versus fingers II–IV half-webbed); from Z. duboisi by smooth and near immaculate green dorsum (versus many small warts and numerous large reddish brown spots on dorsum), complete webbing between fingers II–IV and between toes (versus fingers and toes half-webbed), and absence of brown band on canthus rostralis, upper eyelid, and supratympanic fold (versus present); and from Z. feae by pale blue-black webbing (versus brown to yellow webbing), dorsal surface of discs light brown (versus green), internal single subgular vocal sac (versus a pair of internal subgular vocal sacs), and absence of pale brown band on canthus rostralis, upper eyelid, and supratympanic fold (versus present).

The new species obviously differs from other Zhangixalus species with green dorsum by having larger body size ( Table 4 ).

The genus Rhacophorus also contains some species with green dorsum and large body size, including Rhacophorus georgii Roux, 1904 , Rhacophorus helenae Rowley, Tran, Hoang, & Le, 2012 , Rhacophorus kio Ohler & Delorme, 2006 , Rhacophorus malabaricus Jerdon, 1870 , Rhacophorus nigropalmatus Boulenger, 1895 , and Rhacophorus norhayatii Chan & Grismer, 2010 . The new species also can be distinguished from these species by the narrow white stripes passing along the edge of lower jaw, body sides, outer side of limbs, and above vent.

Figures

FIGURE 1. Map showing the collection sites of samples used in this study. Sites are labeled as in Table 1 and are highlighted by red (clade A) and green (clade B). Star indicates the type locality of Zhangixalus pachyproctus sp. nov. The triangle and square indicate the approximate type localities of R. gigas and Z. smaragdinus at the Khasi Hills, Meghalaya and the Naga Hills, Nagaland, respectively. The type locality of the nomen R. maximus probably is also at the Khasi Hills.

FIGURE 3. Lateral views of specimens assigned to Zhangixalus pachyproctus sp. nov. (A, KIZ 20160119, collected from Mengla, southern Yunnan; B, KIZ 20160219, collected from Menghai, southern Yunnan; C, KIZ 090124, collected from Puer, southern Yunnan) and Z. smaragdinus (D, KIZ 20160299, collected from Yingjiang, western Yunnan; E, Muotuo, southern Tibet, reproduced from AmphibiaChina 2019; F, MZMU 600, collected from Mizoram, India, reproduced from Lalramdinfeli & Lalremsanga 2017; G, Namdapha Tiger Reserve, northeastern India, reproduced from Deepak et al. 2019; H, BMNH 1940.6.3.14, collected from Kachin, Myanmar, Photo by Jeff Streicher; I, CAS 224706, collected from Kachin, Myanmar, Photo by Eric Ely).

FIGURE 8. Frontolateral view of the holotype of Zhangixalus pachyproctus sp. nov. (KIZ 20160119) in life (a) and dorsal (b) and ventral (c) views of the holotype of the species in preservative. The protruding vent is highlighted using arrow.

FIGURE 9. Ventral view of hand (a) and foot (b) of the holotype of Zhangixalus pachyproctus sp. nov. (KIZ 20160119) in preservative.

FIGURE 10. A female (KIZ 20160126) of Zhangixalus pachyproctus sp. nov. in amplexus (a) and its ventral view in preservative (b).

FIGURE 11. Lateral (a) and ventral (b) views of the subadult of Zhangixalus pachyproctus sp. nov. (KIZ 20160219) in life.

FIGURE 12. Habitat of Zhangixalus pachyproctus sp. nov. at the type locality.