Zhangixalus franki, Ninh & Nguyen & Orlov & Nguyen & Ziegler, 2020

Ninh, Hoa Thi, Nguyen, Tao Thien, Orlov, Nikolai, Nguyen, Truong Quang & Ziegler, Thomas, 2020, A New Species of the Genus Zhangixalus (Amphibia: Rhacophoridae) from Vietnam, European Journal of Taxonomy 688, pp. 1-18 : 7-12

Zhangixalus franki sp. nov.

urn:lsid:zoobank.org:act:346FA039-3D9A-4F41-A4F2-57F5E7ABA793

Fig. 2

Diagnosis

The new species can be assigned to the genus Zhangixalus based on the following morphological characters: snout pointed; presence of intercalary cartilage between terminal and penultimate phalanges of digits, distal end of terminal phalanx in Y-shape; tips of digits expanded into large disks, bearing circum-marginal grooves; fingers webbed; presence of supra-cloacal dermal ridge; and pupil horizontal ( Jiang et al. 2019). In addition, the new species is unambiguously nested in the genus Zhangixalus by molecular phylogenetic evidence. It is closely related to Z. duboisi and Z. omeimontis and nested in the same clade with Zhangixalus dugritei (David, 1872) , the type species of this genus.

The new species is distinguished from its congeners by a combination of the following morphological characters: 1) size large (SVL 77.9–85.8 mm for the males); 2) head slightly wider than long; 3) snout pointed; 4) dorsal skin smooth; 5) finger webbing formula I1-1II0-1III½-0IV; 6) dorsal surface of head and body green with dark brown spots; 7) lower jaw region greyish, throat, chest and belly white; 8) white stripe along edge of jaw, insertion of limbs, and along lateral ridges of fore limbs, hind limbs and flank, separating upper green part from lower grey part.

Etymology

We name this new species in honor of Dr Frank Mutschmann, late amphibian veterinarian and conservationist from Berlin, Germany, in recognition of his support of our amphibian research and conservation projects in Vietnam. As common names we suggest Frank’s Tree Frog (English), Ếch cây frank (Vietnamese) and Franks Ruderfrosch (German).

Material examined

Holotype

VIETNAM • adult ♂; northern Vietnam, Ha Giang Province, Quan Ba District, in the forest of Tung Vai Commune ; 23002′45″ N, 104050′59″ E; elevation 1360 m a.s.l.; 11 Jun. 2019; collected by T.T. Nguyen; VNMN 011682 .

Paratypes

VIETNAM • 4 adult ♂♂; same data as for holotype; 13 Jun. 2019; collected by T.T. Nguyen; VNMN 011683 , VNMN 011684 , IEBR A.2019.7-A.2019.8 ( VNMN 011685 , VNMN 011686 ) and one sub-adult VNMN 011687 .

Description of holotype

SIZE. Large, body robust (SVL 82.8 mm).

HEAD. Slightly compressed, wider than long (HW 26.5 mm, HL 25.7 mm), convex above; snout pointed, slightly protruding beyond lower jaw in lateral view, and longer than horizontal diameter of eye (SNL 11.6 mm, ED 8.2 mm).

CANTHUS ROSTRALIS. Rounded, loreal region oblique, concave; interorbital distance greater than internarial distance and upper eyelid width (IOD 9.2 mm, IN 8.1 mm, UEW 6.2 mm); distance between anterior corners of eyes approximately 69% of distance between posterior corners of eyes.

NOSTRILS. Round, without lateral flap of skin, closer to tip of snout than to eye.

PUPIL. Oval, horizontal.

TYMPANUM. Distinct, round, about half of eye diameter, and two times greater than distance between tympanum and eye.

PINEAL OCELLUS. Absent; spinules on upper eyelid absent; vomerine teeth well developed, in two oblique ridges.

CHOANAE. Round.

TONGUE. Deeply notched posteriorly; supratympanic fold distinct, extending from behind eye to beyond level of axilla.

FORELIMBS. Upper arm short, about one third of forearm length (FLL 14.7 mm, HAL 41.7 mm), dermal fringe present along outer edge of forearm; not well developed; relative finger lengths I<II<V<III; tips of fingers with enlarged discs with distinct circum-marginal grooves, disc of finger III approximately 1.5 times width of finger III (fd3/fw3 1.5), greater than tympanum diameter (fd3/TYD 1.27); webbing formula I1-1II0-1III½-0IV; subarticular tubercles distinct, blunt, round, formula 1, 1, 2, 2.

HINDLIMBS. Heels overlapping when held at right angles to body; tibia length about five times greater than tibia width (TbL 39.3 mm, TbW 8.5 mm), longer than thigh length (FeL 34.1 mm), shorter than foot length (FoL 53.4 mm); relative toe lengths I<II<III<V<IV; tips of toes with enlarged discs with distinct circum-marginal grooves, discs slightly smaller than those of fingers; webbing formula I0-0II0-½III0- 1IV0-0V; subarticular tubercles distinct, blunt, round, formula 1, 1, 2, 3, 2; inner metatarsal tubercle small (IMT 3.2 mm); dermal ridge present along outer edge of tibia and tarsus; dermal projection present at tibiotarsal articulation.

SKIN TEXTURE. Dorsal surface of head and body smooth, canthal and supratympanic folds on each side developed, throat and chest smooth, belly rough, ventral surface of fore and hind limbs smooth, a short dermal appendage above vent.

COLORATION IN LIFE. Iris bronze, pupil black; dorsal surface of head and body green with some small dark brown spots, various in size and shape; tympanum region green or dark green; a yellowish brown stripe running from tip of snout, along canthus rostralis, bordering upper eyelid, along supratympanic fold to posterior of axilla; dorsal surface of fore and hind limbs green, fingers and toes grey; axilla, lower part of flank and belly grey; white stripe present along edge of upper jaw, limb insertions, and dermal fringes of fore and hind limbs; flank with white stripe, separating upper green part from lower grey part; ventral surface of arm and thigh grey; anterior and posterior parts of thigh and ventral surface of tibia grey; lower jaw and throat region grey; supracloacal area grey; ventral side of webbing greyish brown, nuptial pad grey. Color can change from green to dark green depending on activity and environmental conditions.

COLORATION IN PRESERVATIVE. As in life, but with green dorsal surface fading to blue and cream white ventral surface fading to greyish brown, brown line extending from tip of snout to axilla.

MALE SECONDARY SEXUAL CHARACTERS. Male specimens with smooth oval nuptial pad on prepollex and inner edge of finger I, and a subgular vocal sac.

Variation of paratypes

The ground color of dorsum is dark green or green, ventral surface is grey or greyish brown. The number of dark brown spots on dorsum ranges from 9 to 45, variable in size and shape. For measurements of type series see Table 3 .

Comparisons

In the following, we compared the new species with other members of Zhangixalus distributed in Vietnam and neighboring countries.

Zhangixalus franki sp. nov can be distinguished from the following 29 species in the genus Zhangixalus by having a larger size in males (SVL 77.9-85.8) versus Z. achantharrhena at 36.52–40.56 mm ( Harvey et al. 2002); Z. arboreus at 42–60 mm ( Wilkinson 2003); Z. arvalis at 39–46.4 mm ( Lue et al. 1995); Z. aurantiventris at 48–54 mm ( Lue et al. 1994); Z. chenfui at 33–41 mm ( Fei et al. 2010); Z. dorsoviridis ( Bourret, 1937) at 31.31– 2.43 mm ( Orlov et al. 2001); Z. dugritei at 31.65–47 mm ( Liu 1950; Orlov et al. 2001; Fei et al. 2010); Z. dulitensis at 38.39–39.66 mm ( Harvey et al. 2002); Z. hongchibaensis at 46.5–49.7 mm ( Li et al. 2012a); Z. hungfuensis at 31–37 mm ( Fei et al. 2010) Z. jarujini at 33.7– 40 mm ( Fei et al. 2010); Z. leucofasciatus at 35–48 mm ( Fei et al. 2010); Z. lishuiensis at 34.2–35.8 mm ( Liu et al. 2017); Z. minimus at 21.3–33.0 mm ( Rao et al. 2006); Z. moltrechti at 33–46 mm ( Fei et al. 2010); Z. nigropunctatus at 32–37 mm ( Fei et al. 2010); Z. owstoni at 42–51 mm ( Maeda & Matsui 1990); Z. pinglongensis at 32.0– 38.5 mm ( Mo et al. 2016); Z. prasinatus at 49–56 mm ( Fei et al. 2010); Z. prominanus at 50.46–51.26 mm ( Harvey et al. 2002); Z. puerensis at 35.5–41 mm ( Bain & Nguyen 2004); Z. schlegelii at 49 mm ( Stejneger 1907); Z. suffry at 38.5–52.9 mm ( Bordoloi et al. 2007); Z. taipeianus at 30.7–36.7 mm ( Liang & Wang 1978); Z. viridis at 45–56 mm ( Goris & Maeda 2004); Z. wui at 35.2–38.2 mm ( Li et al. 2012a); Z. yaoshanensis at 31.6–36.4 mm ( Chen et al. 2018); Z. yinggelingensis at 43–43.4 mm ( Chou et al. 2007); Z. zhoukaiyae at 27.9–36.88 mm ( Pan et al. 2017).

Zhangixalus franki sp. nov. differs from the following seven species by having dorsum smooth; dorsal surface green with some small dark spots; chest and belly grey; supratympanic fold well developed, brown or gold; white stripe along lateral ridges of fore and hind limbs and flank, separating upper green part from lower grey part; and webbing between fingers incomplete verses dorsum of Z. duboisi green and brown, skin granular with horny spinules, venter fleshy with brown spots ( Ohler et al. 2000); snout of Z. hui yellowish brown ( Li et al. 2012a); dorsum and dorsal aspect of limbs of Z. omeimontis green with large brown markings ( Liu 1950), supratympanic fold of Z. pachyproctus , Z. smaragdinus and Z. dennysi green and weakly developed ( Yu et al. 2019; Fei et al. 2010); lateral ridges of fore and hind limbs and flank of Z. dennysi without white stripe; supratympanic fold yellow and webbing between fingers complete in Z. feae ( Ziegler et al. 2014) .

The new species mostly resembles Z. burmanus , but with clearly distinguishing characters: males of Zhangixalus franki sp. nov. with SVL at 77.9–85.5 mm larger than those of Z. burmanus with SVL at 47–70.5 ( Ohler 2009; Jiang et al. 2016; Wilkinson & Rao 2004); webbing between fingers in males of Zhangixalus franki sp. nov. is more developed than that in males of Z. burmanus (I1-1II0-1III½-0IV vs I1–1¼II1–2½III1–1IV in Z. burmanus Ohler 2009 ); color on upper and, lower parts of flank separated from each other by white line, and dark spots on anterior and posterior sides of thigh are absent in Zhangixalus franki sp. nov. whereas, dark brown spots enclosing cream spots on flanks and thigh present in Z. burmanus ( Wilkinson & Rao 2004) .

Distribution

Zhangixalus franki sp. nov. is currently known only from the type locality in Ha Giang Province, northern Vietnam ( Fig. 3 ). The species was recorded at elevations between 1320 and 1360 m a.s.l.

Natural history

Specimens of the new species were collected from 19:00 to 24:00 on trees, close to small ponds in undisturbed evergreen forest ( Fig. 4 ). Other tree frogs that were found at the same site were Polypedates sp. (of the P. leucomystax species complex), Z. duboisi and Kurixalus sp. Females, larval stages and eggs of the new species are unknown.

Conservation status

The new species is expected to be found in evergreen forests of Guangxi Province, southern China. However, the actual distributional range should be confirmed in further studies. Given the available information, we suggest this species be considered as Data Deficient following IUCN’s Red List categories ( IUCN 2020).

Figures

Fig. 2. A–B. Dorsal and lateral views. C. Drawing of ventral view of left hand and right foot of the adult male holotype (VNMN 011682) of Zhangixalus franki sp. nov. from Quan Ba District, Ha Giang Province, northern Vietnam.

Fig. 3. Map showing the type locality of Zhangixalus franki sp. nov. (●) in Quan Ba District, Ha Giang Province, northern Vietnam and distribution of Z. burmanus (Andersson, 1939) (Ɨ), Z. duboisi (Ohler, Marquis, Swan & Grosjean, 2000) (▲) and Z. omeimontis (Stejneger, 1924) (*orange star).

Fig. 4. Habitat of Zhangixalus franki sp. nov. at the type locality in Quan Ba District, Ha Giang Province, Vietnam.