Rhacophorus napoensis Li, Liu, Yu & Sun, 2022

Nguyen, Tan Van, Liu, Shuo, Wilkinson, Jeffery A., Tran, Thinh Gia, Tran, Phuc Nguyen, Trofimets, Alexey V., Dau, Vinh Quang & Poyarkov, Nikolay A., 2024, Redescription and a significant range extension of Rhacophorus napoensis Li, Liu, Yu & Sun, 2022 (Amphibia, Anura, Rhacophorinae) with the first record from Vietnam, Herpetozoa 37, pp. 123-136 : 123

Rhacophorus napoensis Li, Liu, Yu & Sun, 2022

, Figs 3 , 4

Holotype.

GXNU YU000172, adult male collected by Shuo Liu on 25 March 2019.

Type locality.

Napo County, Baise City, Guangxi Autonomous Region, China (23°1'20"N, 105°50'58" E; elevation 1032 m a.s.l.).

Chresonymy.

Rhacophorus rhodopus (non Rhacophorus rhodopus Liu & Hu, 1969) - Nguyen et al. (2008: 364, in part); Nguyen et al. (2009: 181, in part); Hecht et al. (2013: 526-527, in part); Nguyen et al. (2014: 276-277, in part); Pham et al. (2016: 37-38, in part); Poyarkov et al. (2021: 61-62, in part).

Rhacophorus napoensis Li, Liu, Yu & Sun (2022: 130).

Suggested name in Vietnamese.

Ếch cây Na pha

Specimens examined

(n= 11). Two adult males HDU 1179-80 from Pu Hoat NR, Que Phong Dist. , Nghe An Province, Vietnam (ca. 19.66313°N, 104.78185°E; elevation 1360 m a.s.l) collected by V.Q. Dau et al. on 12 April 2011 . One adult female HDU 1130 from Khe Co area in Pu Huong NR, Chau Cuong Dist., Nghe An Province, Vietnam (19.33155°N, 105.0016°E, elevation 645 m a.s.l.) collected by V.Q. Dau on 22 July 2013 . One adult male ZMMU NAP-07414 from Khe Cam I area within Tay Yen Tu NR, Son Dong Dist., Bac Giang Province, Vietnam (21.18058°N, 106.72683°E, elevation 181 m a.s.l.) collected by N.A. Poyarkov on 07 July 2017 . Four adult males DTU 84-85, 87-88 and one adult female DTU 86 from Khe Moi area within Pu Mat NP, Con Cuong Dist., Nghe An Province, Vietnam (ca. 18.917446°N, 104.773233°E; elevation 900 m a.s.l) collected by T.V. Nguyen on 27 August 2018 . Two adult males DTU 89-90 from Khe Bu area within Pu Mat NP, Tam Quang Dist., Nghe An Province, Vietnam (ca. 19.037120°N, 104.605944°E; elevation 760 m a.s.l) collected by T.V. Nguyen on 12 February 2019 .

Revised diagnosis.

Medium-sized within genus Rhacophorus (SVL 38.6-43.2 mm in males, 54.9-55.8 mm in females); snout pointed, projecting beyond margin of lower jaw in ventral view, and the tip has a distinct bulge; tympanum distinct, rounded; maxillary teeth distinct; tongue cordiform, notably notched posteriorly; external single subgular vocal sac; the tibiotarsal articulation reaches the snout; entire web between fingers and toes; single inner metatarsal tubercle, flat; banding exists in dorsal surface of limbs posterior part of dorsum; two to three black spots at axillary region; webbing not black; and dorsum reddish brown with or without small black spots (dorsum hoary in color with numerous black spots after preservation per original diagnosis); ventral yellowish white (data from Li et al. (2022) and this study).

Comparisons.

We summarize the main characters separating Rhacophorus napoensis from the R. bipunctatus and R. rhodopus in Suppl. material 1: table S2. Rhacophorus napoensis differs from R. bipunctatus by having: lower maximum SVL in both sexes (43.2 mm in males, 55.8 mm in females vs. 50.4 mm in males, 59.1 mm in females), absent yellow pigmentation at the upper and lower portions of iris (vs. present, see Suppl. material 1: fig. S1), ventral coloration yellowish white (vs. bright yellow), dorsal coloration brown or reddish brown (vs. green or brown), snout pointed, and the tip has a distinct bulge (vs. broad and pointed), loreal region oblique (vs. concave), tympanum distinct (vs. slight indistinct), tongue cordiform, notably notched posteriorly (vs. round, slight notched posteriorly), two to three black spots at axillary region (vs. one big and one small black spot at axillary region). Rhacophorus napoensis differs from R. rohdopus by having: larger body size in males (SVL 38.6-43.2 mm [avg. 41.41 mm] vs. 31.2-38.0 mm [avg. 35.16 mm]), slightly lower ratio TbL/SVL in both sexes (0.45-0.51 [avg. 0.48] in males, 0.43-0.46 [avg. 0.45] in females vs. 0.47-0.55 [avg. 0.51] in males, 0.44-0.50 [avg. 0.47], ventral coloration yellowish white (vs. bright yellow), tongue cordiform, notably notched posteriorly (vs. narrow and long, deeply notched posteriorly), external single subgular vocal sac (vs. internal single), the tibiotarsal articulation reaches the snout (vs. reaches the eye), two to three black spots at axillary region (vs. one black or dark round spot at axillary region).

Futhemore,

Rhacophorus napoensis can be rapidly distinguished from most of the closely-related species of the R. reinwardtii complex (includes: R. borneensis Matsui, Shimada & Sudin, R. helenae Rowley, Tran, Hoang & Le, R. kio Ohler & Delorme, R. norhayatiae Chan & Grismer, and R. reinwardtii (Schlegel)) by having a distinctly smaller body size in both sexes (SVL 38.6-43.2 mm in males, 54.9-55.8 in females vs. 50.1 mm male, 62 mm in females in R. borneensis (data from Matsui et al. 2013); 72.3-85.5 mm [avg. 77.7 mm] in males, 89.4-90.7 mm [avg. 90.1 mm] in females of the R. helenae (data from Rowley et al. 2014); 66.6-69.5 mm [avg. 68.2 mm] in males, 78.0-88.9 mm [avg. 84.6 mm] in females of R. kio (data from Ohler & Delorme, 2006; Fajri et al. 2023); 60.6-64.7 mm [avg. 61.9 mm] in males, 75.7-83.0 mm [avg. 80.3 mm] in females of the R. norhayatiae (data from Chan and Grismer 2010); and 41.6-52.5 mm [avg. 46.4 mm] in males, 66.6-74.8 mm [avg. 70.7 mm] in females of the R. reinwardtii (data from Fajri et al. 2023); the absence of black spots/pigmentation on webs (vs. present in all five species), brown dorsum coloration in life (vs. green in all five species), and a significantly different color pattern on flanks.

Description based on examined specimens from Vietnam

(n=11). SVL 38.6-43.6 mm in males (n=9), 54.9-55.8 mm in females (n=2); habitus relatively slender; head almost equal or slight width greater than long (HW/HL 1.00-1.05 in males, 1.04-1.05 in females); snout pointed in dorsal view and slightly acuminate in profile, protruding from the margin of the lower jaw; eyes relatively larger, slightly protuberant, pupil horizontal, eye diameter slightly equal to snout length (ED/SL 0.86-1.00 in males, 0.72-0.82 in females), pineal ocellus absent. Top of head flat, canthus rostralis rounded and distinct; loreal region oblique; nostril round, small, closer to eye than to eye tip of snout (NS/EN 0.94-1.32 in males, 1.02-1.07 in females); interorbital distance slightly greater than internarial distance (IOD/IN 1.02-1.24 in males, 1.07-1.10 in females) and upper eyelid width (IOD/UEW 1.00-1.31 in males, 1.18-1.19 in females). Tympanum and supratympanic fold distinct. Vomerine teeth present; tongue cordiform, attached anteriorly, notably notched posteriorly; choanae oval; external single subgular vocal sac, vocal sac openings at bottom of the mouth on both sides.

Forelimbs: Forearm length ca. two times shorter than hand length (FLL/HAL 0.40-0.48 in males, 0.40-0.45 in females). Fingers short, tips of all fingers expanded into discs; entire web between fingers; relative finger lengths: I<II<IV<III; subarticular tubercles on fingers distinct, rounded and prominent, formula: 1, 1, 2, 2; supernumerary tubercles below the base of finger absent; single thenar (inner metacarpal) tubercle large, oval, distinct; nuptial pad present on finger I in adult males.

Hindlimbs: thigh slightly longer than tibia (FeL/TbL 1.00-1.06 in males, 1.00-1.01 in females), approximately four to five times longer than wide (TbL/TbW 4.43-6.41 in males, 4.06-5.20 in females); tibiotarsal articulation of adpressed limb reaching snout; foot longer than tibia (TbL/FoL 0.68-0.73 in males, 0.68-0.70 in females). Relative toe lengths: I<II<III<V<IV; tarsal fold present; tips of all toes expanded into discs; entire webbing between toes; subarticular tubercles on toes oval and prominent, formula: 1, 1, 2, 3, 2; supernumerary tubercle below the base of toe absent; inner metatarsal tubercle rounded, prominent, and small; outer metatarsal tubercle absent.

The skin of dorsal throat, ventral part of tibia, foot and tarsus smooth; the skin of chest, venter, vent and thigh rough and granular; some warts are found around the vent and flanks; dermal fringe along joint, vent and the outer sides of limbs. Cloacal dermal fringe present.

Colouration in life

(Figs 3 , 4 ): Dorsum reddish brown or gray brown with small black spots; two or three large black blotches on axilla and flanks present; transverse bands on hind limbs absent or indistinct; ventral yellowish white; webbing of fingers and toes reddish orange without black spotted. Iris copper or pale yellow.

Distribution

(Fig. 1 ). Rhacophorus napoensis was previously known only from Napo County, Baise City, Guangxi Autonomous Region, China ( Li et al. 2022). We here report on the first records for Vietnam including provinces, namely: Bac Giang (Tay Yen Tu NR), Thanh Hoa (Xuan Lien NP), Nghe An (Pu Hoat NR, Pu Huong NR, and Pu Mat NP), and Ha Tinh (Vu Quang NP) previously reported as Rhacophorus rhodopus . The new location in Huong Son area within Vu Quang NP. is ca. 520 airline kilometers south of the type locality. Given its geographic proximity, it likely occurs in several secondary and evergreen forests of Northern and North-Central Vietnam, Central Laos as well as Southern China; in particular, the records previously reported as Rhacophorus rhodopus from Ha Giang (Bac Me Dist.), Ha Noi (Soc Son Dist.), Lai Chau (Sin Ho Dist.), Lao Cai (Van Ban NR), Son La (Copia NR, Sop Cop NR, Xuan Nha NR); Phu Tho (Xuan Son NP); Quang Binh (Phong Nha-Ke Bang NP); Quang Tri (Bac Huong Hoa NR) provinces of Northern and North-Central Vietnam; Khammouan, Bolikhamxay, and Xiangkhoang provinces of Central Laos, as well as from southeastern Yunnan Province (Wenshan Prefecture, and Pingbian and Hekou counties) and other parts of Giangxi Autonomous Region (Jinxiu County) of China are anticipated.

Natural history notes.

Prior to this study, the biological data of Rhacophorus napoensis were very limited; for example, it was only reported from an altitude of 1.032 m a.s.l. ( Li et al. 2022). The species appears to be closely associated with secondary and evergreen forests with a wide range of altitudes of 400-430 mm a.s.l. from Bac Giang Province, at 870 m a.s.l. from Thanh Hoa Province, and 654-900 m a.s.l. from Nghe An Province ( Hecht et al. 2013; Pham et al. 2016; this study). In Tay Yen Tu NR, Bac Giang Province, the frogs were found on trees and bushes, ca. 0.5-1.5 m above ground, near ponded water, in secondary forest. Other species of rhacophorids were recorded syntopically and included: Kurixalus cf. hainanus (Zhao, Wang & Shi), Polypedates megacephalus Hallowell, Rohanixalus cf. hansenae (Cochran), Theloderma albopunctatum (Liu & Hu), T. corticale (Boulenger), T. cf. lateriticum Bain, Nguyen & Doan, Zhangixalus pachyproctus Yu, Hui, Hou, Wu, Rao & Yang (Hecth et al. 2013; this study). In Xuan Lien NP., the frogs were found on trees and bushes, ca. 0.5-1.5 m above the ground, near ponded water, between 19:00 and 23:00. The surrounding habitat consisted of secondary forest composed of small to medium and sized hardwoods. Other species of rhacophorid were recorded syntopically and included: Gracixalus quangi Rowley, Dau, Nguyen, Cao & Nguyen, Kurixalus cf. hainanus , Raorchestes cf. malipoensis Huang, Liu, Du, Bernstein, Liu, Yang, Yu & Wu, Polypedates megacephalus , Rhacophorus kio Ohler & Delorme, R. orlovi Ziegler & Kohler, Theloderma albopunctatum , Zhangixalus pachyproctus ( Pham et al. 2016; our data). In Pu Hoat NR, Nghe An Province, the frogs were found in a tree, ca. 0.5-2.0 m above the ground, more than 10 meters from the nearest stream, adjacent to a puddle in the secondary forest. The call of the frogs recorded in August is comprised of two calls types, 1-2 notes; calls types note 1, with 3-29 pulses, and calls types note 2, with 4-26 pulses of a call. The dominant frequency varied from 1,9-2,3 kHz. Other species of rhacophorids recorded syntopically included: Gracixalus quangi , Gracixalus sp., Raorchestes cf. malipoensis , Rhacophorus kio , R. orlovi , Theloderma albopunctatum , T. gordoni Taylor, Zhangixalus feae (Boulenger), Z. pachyproctus (Dau et al. 2012; our data). In Pu Mat NP, Nghe An Province, the frogs were found calling from leaves or branches 1-2.5 m above ground, near a ponded water, between 19:00 and 21:00. The surrounding habitat consisted of secondary forest composed of medium to larger hardwoods. During the breeding season, which lasted from May-August, this species breeds in rain pools and standing water in streams within forests. Foam nests were created on tree branches that overhang shallow, moving water (TV Nguyen pers. obs.). Other species of rhacophorids recorded syntopically included: Kurixalus cf. hainanus , Kurixalus gracilloides Nguyen, Duong, Luu & Poyarkov, Polypedates megacephalus Hallowell, Rohanixalus cf. hansenae , Raorchestes cf. malipoensis , Rhacophorus kio , R. orlovi , Theloderma albopunctatum , T. lateriticum , T. gordoni Taylor, and Zhangixalus dennysi (Blanford) ( Nguyen et al. 2020a; this study)

Figures

Figure 1. Distribution ranges of the species of the Rhacophorus napoensis in southern China and Vietnam. Notes: numbers indicate different localities where the species have been recorded (see Suppl. material 1: table S 3 for the details of localities).

Figure 3. Morphological details of Rhacophorus napoensis from Tay Yen Tu NR, Bac Giang, Vietnam (ZMMU NAP- 07414, adult male) A. Dorsal aspect; B. Ventral aspect; C. Head in lateral aspect; D. Volar view of left hand; E. Plantar view of left foot. Photographs by N. A. Poyarkov.

Figure 4. Alive specimens of Rhacophorus napoensis: from Tay Yen Tu NR, Bac Giang, Vietnam (A. ZMMU NAP- 07414, adult male); from Pu Mat NP, Nghe An, Vietnam (B, C. DTU 89; adult male); from Pu Hoat NR, Nghe An, Vietnam (D, E. HDU 1179 - 1180, two adult males, respectively); from Pu Huong NR, Nghe An, Vietnam (F. HDU 1130, adult female). Photographs by: N. A. Poyarkov (A), T. V. Nguyen (B, C), and V. Q. Dau (D, F).