Megophrys caobangensis, Nguyen & Pham & Nguyen & Luong & Ziegler, 2020

Nguyen, Truong Quang, Pham, Cuong The, Nguyen, Tao Thien, Luong, Anh Mai & Ziegler, Thomas, 2020, A new species of Megophrys (Amphibia: Anura: Megophryidae) from Vietnam, Zootaxa 4722 (5), pp. 401-422 : 403-416

Megophrys caobangensis sp. nov.

( Figs. 2 , 3 )

Holotype. IEBR 4384 (Field number CB 2015.68 ), adult male, collected by C. T. Pham & T. V. Nguyen on 13 October 2015 in the evergreen forest (22 o 36.675’N, 105 o 53.039’E, at an elevation of 1,252 m asl.) within Phia Oac-Phia Den National Park , Nguyen Binh District, Cao Bang Province, northeastern Vietnam.

Paratypes (n = 10). Specimens collected from the forest of Phia Oac-Phia Den National Park , Nguyen Binh District , Cao Bang Province, Vietnam: two adult males IEBR 4385 , 4386 (Field numbers CB 2015.60 , 61 ), collected by C. T. Pham and T. V. Nguyen on 12 October 2015 (21 o 36.151’N, 107 o 52.495’E, at an elevation of 1518 m asl.) ; eight adult males IEBR 4387–4391 (Field numbers CB 2015 . 69–73), and VNMN 2019.04 – 2019.06 (Field numbers CB 2015.94 – 96 ), collected by C. T. Pham and T. V. Nguyen on 13 October 2015 (22 o 36.147’N, 105 o 52.726’E, at an elevation of 1461 m asl.)

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Diagnosis. The new species was strongly supported as a member of Megophrys based on molecular analyses ( Fig. 1 ) and is distinguishable from its congeners by a combination of the following morphological characters (n = 11, adult males): 1) size small (SVL 34.9–38.9 mm in males); 2) tympanum visible (TD/ED 0.40–0.50); 3) vomerine teeth absent; 4) tongue not notched posteriorly; 5) vocal sac present; 6) toes with rudimentary webbing; 7) subarticular tubercles and lateral fringes absent on all digits; 8) nuptial pads with spicules on fingers I and II in males; 9) dorsal skin with scattered granules and tubercles; 10) flank with tubercles; 11) dorsum with a X-shaped dorsal ridge; 12) dorsolateral folds prominent; 13) a horn-like small tubercle present at the outer edge of the eyelid; and 14) dorsal surface yellowish brown with a dark brown triangle between the eyes and a dark brown marking along the X-shaped ridge on the back.

Description of holotype. Adult male; SVL 35.9 mm; head as long as wide (HL 12.4 mm, HW 12.4 mm); snout round anteriorly in dorsal view, projecting beyond lower jaw; nostril lateral, oval, closer to the eye than to the tip of snout (NS 2.7 mm, EN 1.7 mm); canthus rostralis distinct; pupil horizontally oval; loreal region slightly concave and oblique; eye diameter greater than snout length (SL 4.5 mm, ED 4.9 mm); internarial distance wider than interorbital distance and upper eyelid (IND 4.7 mm, IOD 3.5 mm, UEW 3.8 mm); tympanum visible, oval, 43% of eye diameter (TD 2.1 mm); vomerine teeth absent, maxillary teeth present; tongue cordiform, not notched posteriorly; vocal sac single.

Forelimbs: Upper arm length (UAL) 6.7 mm, forearm length (FAL) 7.3 mm; relative finger lengths IV<I<II<III; fingers free of webbing; tips of fingers blunt; subarticular tubercles absent; palmar tubercles indistinct; inner metatarsal tubercle oval, elongate; outer metatarsal tubercle small; fingers I and II with elongate nuptial pads(1.82 mm on fingers I), covered by spicules.

Hindlimbs: Tibia longer than thigh (FeL 16.3 mm, TbL 17.3 mm), approximately four times longer than wide (TbW 3.9 mm); tips of toes blunt; relative length of toes I<II<V<III<IV; toes with rudimentary webbing; subarticular tubercles absent; lateral fringes absent; tarsal fold absent; inner metatarsal tubercle elongate; outer metatarsal tubercle absent; tibio-tarsal articulation reaching to the middle of eye.

Skin texture in life: Dorsal surface with scattered granules and tubercles; dorsum with a X-shaped ridge; dorsolateral folds prominent; a horn-like tubercle present on the outer edge of the upper eyelid; supratympanic fold dis- tinct; temporal region with small black spines; flanks with some tubercles; dorsal surface of limbs granular; throat, chest, belly and ventral surface of thigh smooth.

Coloration in life: Dorsum yellowish brown with a dark brown triangle between the eyes; a dark brown marking along X-shaped ridge; flanks yellowish brown with some small black spots; tympanum dark brown; pupil black, outlined in copper-gold, iris lemon-yellow with tiny dark reticulations spreading from pupil; dorsal surface of fore and hind limbs yellowish brown with dark crossbars; throat and chest dark brown, pectoral glands white; anterior part of belly white with brown blotches, posterior part of belly white, two broad dark brown stripes on either side of belly; ventral surface of limbs dark brown with white marking, anterior part of thigh, inner metatarsal and outer metatarsal tubercles orange-red; posterior part of thigh dark brown; femoral glands white; toe webbing dark brown.

Coloration in preservative: Dorsum greyish with a dark brown triangle between the eyes; a dark brown marking along X-shaped ridge; flanks greyish with some small dark spots; throat and chest brown; two broad dark brown stripes on either side of belly; dorsal surface of fore and hind limbs greyish with dark brown crossbars; posterior part of thigh dark brown; femoral gland white; toe webbing dark brown.

Variation. Measurements and morphological characters of the type series are given in Table 3 . No female specimens were collected but all male specimens have a single vocal sac and nuptial pads with spicules on fingers I and II.

Comparisons. We compared the new species with other species of Megophrys from Vietnam and neighbouring countries, including Laos, Cambodia, Thailand and southern China. Megophrys caobangensis sp. nov. can be distinguished from its congeners by morphological characters as shown in Table 4 . The new species was compared with the members of the subgenus Panophrys as listed below.

Morphologically, Megophrys caobangensis sp. nov. is most similar to M. tuberogranulata Shen, Mo & Li but they are different from each other in internarial distance in males (IND 4.5–4.9 mm in the new species vs. 4.0– 4.4 mm in M. tuberogranulata), a greater average TbL/SVL ratio in males (0.49 vs 0.46 in M. tuberogranulata), the fourth finger being the shortest on forelimb of the new species (vs. the second finger being the shortest in M. tuberogranulata), and anterior part of thigh orange-red, posterior part of thigh dark brown (vs. sides of thigh scarlet in M. tuberogranulata).

Megophrys caobangensis sp. nov. differs from M. acuta Wang, Li & Jin by having a smaller TD/ED ratio in males (0.40–0.47 vs. 0.57–0.71 in M. acuta ), a greater TbL/SVL ratio in males (0.45–0.52 vs. 0.38–0.45 in M. acuta ), and the absence of lateral fringes on toes (vs. narrow lateral fringes on toes in M. acuta ); from M. baolongensis Ye, Fei & Xie by having a smaller body size in males (SVL 34.9–38.9 mm vs. 41.8–45 in M. baolongensis), tongue not notched (vs. tongue feebly notched in M. baolongensis), and a greater average FoL/SVL ratio in males (0.69 vs. 0.42 in M. baolongensis); from M. binchuanensis Ye & Fei by having an average ED/SL ratio>1 (vs. <1 in M. binchuanensis), a greater average FoL/SVL ratio in males (0.69 vs. 0.44 in M. binchuanensis), a larger eye in males (ED 4.8–5.3 mm vs 3.4–4.0 mm in M. binchuanensis), and the absence of lateral fringes on toes (vs. present in M. binchuanensis); from M. binlingensis Jiang, Fei & Ye by having a smaller body size in males (SVL 34.9–38.9 mm vs. 45.1–51.0 mm in M. binlingensis), a smaller TD/ED ratio in males (0.40–0.47 vs. 0.47–0.61 in M. binlingensis), tongue not notched (vs. tongue feebly notched in M. binlingensis), and the absence of lateral fringes on toes (vs. present in M. binlingensis); from M. boettgeri (Boulenger) by having a smaller TD/ED ratio in males (0.40–0.47 vs. 0.51–0.53 in M. boettgeri), tongue not notched (vs. tongue feebly notched in M. boettgeri), and the absence of lateral fringes on toes (vs. present in M. boettgeri); from M. brachykolos Inger & Romer by having a smaller TD/ED ratio in males (0.40–0.47 vs. 0.61–0.67 in M. brachykolos), a greater average FoL/SVL ratio in males (0.69 vs. 0.41 in M. brachykolos), and toes with rudiment of webbing (vs. at most one-fourth webbed in M. brachykolos); from M. cheni (Wang & Liu) by having a larger body size in males (SVL 34.9–38.9 mm vs. 26.2–29.5 mm in M. cheni), a smaller average HW/SVL ratio in males (0.34 vs. 0.42 in M. cheni), a smaller average HL/SVL ratio in males (0.35 vs. 0.37 in M. cheni), tongue not notched (vs. tongue notched in M. cheni), and the absence of lateral fringes on toes (vs. present in M. cheni); from M. daweimontis Rao & Yang by having a smaller TD/ED ratio in males (0.40–0.47 vs. 0.53–0.55 in M. daweimontis), the absence of vomerine teeth (vs. present in M. daweimontis) and a larger eye in males (4.8–5.3 mm vs. 4 mm in M. daweimontis); from M. dongguangensis Wang, Lyu, Liu, Liao, Zeng, Zhao, Li & Wang by the absence of vomerine teeth (vs. present in M. dongguangensis), HL/HW>1 (vs. <1 in M. dongguangensis), and a smaller average FoL/SVL ratio in males (0.40–0.50 vs. 0.58–0.70 in M. dongguangensis); from M. fansipanensis Tapley, Cutajar, Mahony, Nguyen, Dau, Luong, Le, Nguyen, Nguyen, Portway, Luong & Rowley by having a smaller TD/ED ratio in males (0.40–0.47 vs 0.53–0.8 in M. fansipanensis), a larger eye in males (4.8–5.3 mm vs. 2.8–4.2 mm in M. fansipanensis), and the absence of vomerine teeth (vs. present in M. fansipanensis); from M. hoanglienensis Tapley, Cutajar, Mahony, Nguyen, Dau, Luong, Le, Nguyen, Nguyen, Portway, Luong & Rowley by having a smaller TD/ED ratio in males (0.40–0.47 vs 0.54–0.75 in M. hoanglienensis), a smaller average HW/ SVL ratio in males (0.32–0.37 mm vs. 0.37–0.42 mm in M. hoanglienensis), and the absence of vomerine teeth (vs. present in M. hoanglienensis); from M. huangshanensis Fei & Ye by having tongue not notched (vs. tongue feebly notched in M. huangshanensis) and the absence of subarticular tubercles on toes (vs. present in M. huangshanensis); from M. jingdongensis by having a smaller body size in males (SVL 41.8–45 mm vs. 53–56.5 mm in M. jingdongensis ), the absence of vomerine teeth (vs. present in M. jingdongensis ), and the absence of lateral fringes on toes (vs. lateral fringes on toes wide in M. jingdongensis ); from M. jinggangenis (Wang) by having a smaller TD/ED ratio in males (0.40–0.47 vs. 0.76–0.88 in M. jinggangenis), the absence of vomerine teeth (vs. present in M. jinggangenis), the absence of lateral fringes on toes (vs. lateral fringes on toes narrow in M. jinggangenis), toes with rudiment of webbing (vs one-fourth webbed in M. jinggangenis), and the absence of subarticular tubercles on toes (vs. present in M. jinggangenis); from M. jiulianensis Wang, Lyu, Liu, Liao, Zeng, Zhao, Li & Wang by the absence of vomerine teeth (vs. present in M. jiulianensis), HL/HW>1 (vs. <1 in M. jiulianensis), and a smaller TD/ED ratio in males (0.40–0.47 vs. 0.76–0.88 in M. jiulianensis); from M. kuatunensis Pope by having tongue not notched (vs. tongue feebly notched in M. kuatunensis) and the absence of lateral fringes on toes (vs. lateral fringes on toes narrow in M. kuatunensis); from M. latidactyla Orlov, Poyarkov & Nguyen by having a smaller TD/ED ratio in males (0.40–0.47 vs. 0.85 in M. latidactyla), the absence of vomerine teeth (vs. present in M. lactidactyla), and the absence of lateral fringes on toes (vs. lateral fringes on toes wide in M. lactidactyla); from M. leishanensis Li, Xu, Liu, Jiang, Wei & Wang by having the ratio HL/HW>1 (vs. <1 in M. leishanensis), a greater average ED/TYD ratio in males (2.0 vs. 1.7 in M. leishanensis), and a longer foot in males (FoL 23.2–26.6 mm vs. 14.9–17.3 mm in M. leishanensis); from M. lini (Wang & Yang) by the absence of lateral fringes on toes (vs. lateral fringes on toes distinct in M. lini ), toes with rudiment of webbing (vs. one-fourth webbed in M. lini ), and the absence of subarticular tubercles on toes (vs. distinct in M. lini ); from M. lishuiensis (Wang, Liu & Jiang) by having a larger body size in males (SVL 34.9–38.9 mm vs. 30.7–34.7 mm in M. lishuiensis), a greater average FoL/SVL ratio in males (0.69 vs. 0.41 in M. lishuiensis), and the presence of horn-like tubercle on outer edge of upper eyelid (vs. absent in M. lishuiensis); from M. minor Stejneger by having a smaller TD/ED ratio in males (0.40–0.47 vs. 0.67–0.74 in M. minor), a broader upper eyelid in males (3.5–4.4 mm vs. 3.0– 3.9 mm in M. minor), a smaller tympanum diameter in males (2.0– 2.4 mm vs. 2.5–3.6 mm in M. minor), and tongue not notched (vs. tongue feebly notched in M. minor); from M. mufumontana Wang, Lyu, Liu, Liao, Zeng, Zhao, Li & Wang by having a larger body size in males (SVL 34.9–38.9 mm vs. 30.1–30.8 in M. mufumontana), a smaller average TYE/TD ratio in males (0.50–0.60 vs. 0.85–1.10 in M. mufumontana), and a smaller TD/ED ratio in males (0.40–0.47 vs. 0.51–0.58 in M. mufumontana); from M. nakunensis Wang, Lyu, Liu, Liao, Zeng, Zhao, Li & Wang by the absence of vomerine teeth (vs. present in M. nakunensis), a larger body size in males (SVL 34.9–38.9 mm vs. 29.9–34.9 mm in M. nakunensis), and a greater TbL/SVL ratio in males (0.45–0.52 vs. 0.35–0.42 in M. nakunensis); from M. nanlingensis Wang, Lyu, Liu, Liao, Zeng, Zhao, Li & Wang by the absence of vomerine teeth (vs. present in M. nanlingensis), a smaller average FoL/SVL ratio in males (0.40–0.50 vs. 0.61–0.73 in M. nanlingensis), and smaller average TYE/TD ratio in males (0.50–0.60 vs. 0.67–0.97 in M. nanlingensis); from M. obesa Wang, Li & Zhao by having an average HL/HW ratio>1 (vs. <1 in M. obesa), a smaller TD/ED ratio in males (0.40–0.47 vs. 0.66 in M. obesa), an average HL/HW ratio>1 (vs. HL/HW<1 in M. obesa), and a larger eye diameter in males (4.8–5.3 mm vs. 4.1 mm in M. obesa); from M. ombrophila Messenger, Dahn, Liang, Xie, Wang & Lu having a larger body size in males (SVL 34.9–38.9 mm vs. 27.4–34.5 mm in M. ombrophila), a smaller TD/ED ratio in males (0.40–0.47 vs. 0.53–0.61 M. ombrophila), and a greater TbL/SVL ratio in males (0.45–0.52 vs. 0.33–0.41 in M. ombrophila); from M. omeimontis Liu by having a smaller body size in males (SVL 34.9–38.9 mm vs. 56–59.5 mm in M. omeimontis , the absence of vomerine teeth (vs. present in M. omeimontis ), the absence of lateral fringes on toes (vs. lateral fringes on toes narrow in M. omeimontis ), and the absence of subarticular tubercles on toes (vs. present in M. omeimontis ); from M. palpebralespinosa Bourret by having a smaller TD/ED ratio in males (0.40–0.47 vs. 0.50–0.57 in M. palpebralespinosa), the absence of vomerine teeth (vs. present in M. palpebralespinosa), the absence of lateral fringes on toes (vs. lateral fringes on toes narrow in M. palpebralespinosa), toes with rudiment of webbing (vs. at least one-fourth webbed in M. palpebralespinosa), and the absence of subarticular tubercles on toes (vs. present in M. palpebralespinosa); from M. parva (Boulenger) by having absence of vomerine teeth (vs. present in M. parva), a smaller average HW/SVL ratio in males (0.34 vs. 0.36 in M. parva), and a larger FoL/SVL ratio in males (0.69 vs. 0.47 in M. parva); from M. rubrimera Tapley, Cutajar, Mahony, Chung, Dau, Nguyen, Luong & Rowley by having a larger body size in males (34.9–38.9 mm vs. 26.7–30.4 mm in M. rubrimera), a smaller TD/ED ratio in males (0.40–0.47 vs. 0.58–0.76 in M. rubrimera), and the absence of vomerine teeth (vs. present in M. rubimera); from M. spinata Liu & Hu by having a smaller body size in males (34.9–38.9 mm vs. 47.2–54.4 mm in M. spinata), tongue not notched (vs. feebly notched in M. spinata), the absence of lateral fringes on toes (vs. present in M. spinata), toes with rudiment of webbing (vs. at least one-fourth webbed in M. spinata), and the absence of subarticular tubercles on toes (vs. present in M. spinata); from M. wugongensis Wang, Lyu, Liu, Liao, Zeng, Zhao, Li & Wang by having a greater TbL/SVL ratio in males (0.45–0.52 vs. 0.37–0.44 in M. wugongensis), HL/HW>1 (vs. <1 in M. wugongensis), and a smaller TD/ED ratio in males (0.40–0.47 vs. 0.51–0.58 in M. wugongensis); from M. wuliangshanensis Ye & Fei by having a larger body size in males (34.9–38.9 mm vs. 27.3–31.6 mm in M. wuliangshanensis), the presence of horn-like tubercle on outer edge of upper eyelid (vs. absence in M. wuliangshanensis), a smaller average HW/SVL ratio in males (0.34 vs. 0.36 in M. wuliangshanensis) and a greater average FoL/SVL ratio in males (0.69 vs. 0.48 in M. wuliangshanensis); and from M. wushanensis Ye & Fei by the presence of horn-like tubercle at edge of upper eyelid (vs. absence in M. wushanensis), the absence of lateral fringes on toes (vs. lateral fringes on toes wide in M. wushanensis), and the absence of subarticular tubercles on toes (vs. present in M wushanensis).

Etymology. The specific epithet “ caobangensis ” refers to the type locality of the new species, Cao Bang Province in northeastern Vietnam. For the common names, we suggest “ Cao Bang Spadefoot Toad” (English), and “Cóc mắt cao bằng” (Vietnamese).

Ecological notes. Specimens were found between 19:00 and 23:00 h in rocky streams of Phia Oac-Phia Den National Park, Nguyen Binh District, Cao Bang Province, Vietnam ( Fig. 5 , 6 ). Most specimens were found on leaves of trees, ca. 0.2–0.5 m above the ground. No calls or tadpoles of this species were recorded or collected. The surrounding habitat was secondary evergreen forest of medium and small hardwoods mixed with bamboo, shrubs and vines. Air temperature at the site was 18.1–25.0 oC and relative humidity was 65–88%. Other amphibian species found at the site were Amolops ricketii (Boulenger) , Quasipaa boulengeri (Günther) , Odorrana geminata Bain, Stuart, Nguyen, Che and Rao , O. nasica (Boulenger) , Rana johnsi (Smith) , and Raorchestes parvulus (Boulenger) .

Distribution. Megophrys caobangensis sp. nov. is currently known only from the type locality in Cao Bang Province, northeastern Vietnam ( Fig. 6 ). It is expected that this species may occur in the nearby evergreen forest in northeastern Vietnam and potentially in neighboring Guangxi Province, China.

Figures

FIGURE 1. Phylogram based on the Maximum likelihood (ML) analysis (16S rRNA gene). ML inferences (ML-BS)/Bayesian posterior probabilities (BPP) are shown near the node. For GenBank accession numbers, refer to Table 2.

FIGURE 2. Dorsolateral view (A) and ventral view (B) of the holotype (IEBR 4384, male) of Megophrys caobangensis sp. nov. in life.

FIGURE 3. Dorsolateral view (A) and ventral view (B) of the holotype (IEBR 4384) of Megophrys caobangensis sp. nov. in preservative.

FIGURE 5. Habitat of Megophrys caobangensis sp. nov. in Phia Oac-Phia Den National Park, Nguyen Binh District, Cao Bang Province, Vietnam: A) forest type and B) microhabitat.

FIGURE 6. Map showing the type locality of Megophrys caobangensis sp. nov. in Cao Bang Province (1), northern Vietnam.

Tables

TABLE 3. Measurements (in mm) and proportions of the type series of Megophrys caobangensis sp. nov. (H = holotype, P = paratype, for other abbreviations see Material and methods).

Specimen ID	IEBR 4384	IEBR 4385	IEBR 4386	IEBR 4387	IEBR 4388	IEBR 4389	IEBR 4390	IEBR 4391	VNMN 2019.04	VNMN 2019 05	VNMN 2019.06
Sex	M	M	M	M	M	M	M	M	M	M	M	Min-Max	Mean±SD
Type status	H	P	P	P	P	P	P	P	P	P	P	(n=11)	(n=11)
SVL	35.9	35.0	34.9	35.5	36.0	36.5	38.0	37.5	38.9	38.3	38.3	34.9–38.9	36.9±1.5
HL	12.4	12.3	12.2	12.5	12.9	13.1	12.7	12.6	12.9	13.4	12.8	12.2–13.4	12.37±0.36
HW	12.4	12.2	12.0	12.4	12.3	12.6	12.8	12.4	12.9	12.9	12.8	12.0–12.9	12.52±0.31
MN	9.0	8.1	8.5	8.5	9.0	8.9	8.3	8.0	9.0	9.4	8.7	8.0–9.4	8.63±0.44
MFE	8.1	7.2	7.7	7.2	8.1	7.4	7.1	6.9	8.1	8.5	7.2	6.9–8.5	7.52±0.52
MBE	3.5	3.3	3.5	3.3	3.9	3.1	3.7	3.5	4.0	3.7	3.6	3.1–4.0	3.55±0.27
SL	4.5	4.1	4.4	4.3	4.4	4.5	4.8	4.4	4.6	4.6	4.5	4.1–4.8	4.47±0.17
ED	4.9	4.9	5.2	4.8	4.9	5.2	5.1	5.2	5.0	5.3	4.9	4.8–5.3	5.05±0.18
UEW	3.8	4.1	3.5	3.7	3.7	4.4	4.2	3.9	3.9	4.1	4.1	3.5–4.4	3.96±0.27
IND	4.7	4.6	4.5	4.5	4.7	4.5	4.8	4.7	4.9	4.8	4.8	4.5–4.9	4.68±0.14
IOD	3.5	3.4	3.1	3.5	3.4	4.2	3.7	3.5	3.3	3.7	3.5	3.1–4.2	3.51±0.3
DAE	6.8	6.9	6.9	7.1	7.2	7.2	7.1	7.0	7.7	7.4	7.3	6.9–7.7	7.17±0.26
DPE	9.8	10.3	10.1	10.4	10.6	11.0	10.1	10.4	10.8	11.0	11.1	10.1–11.1	10.59±0.37
NS	2.7	2.5	2.8	2.6	2.7	2.7	2.7	2.8	2.9	2.9	2.8	2.5–2.9	2.73±0.13
EN	1.7	1.7	1.8	1.5	1.6	2.0	1.7	1.6	1.8	1.6	1.8	1.5–2.0	1.7±0.14
TD	2.1	2.0	2.3	2.2	2.3	2.2	2.4	2.3	2.0	2.4	2.2	2.0–2.4	2.23±0.14
TYE	1.1	1.0	1.1	1.1	1.3	1.1	1.1	1.0	1.2	1.2	1.4	1.0–1.4	1.16±0.14
UAL	6.7	6.3	6.9	6.5	6.3	8.1	7.2	6.3	6.6	7.1	7.0	6.3–8.1	6.83±0.55
FAL	7.3	7.1	6.8	6.8	7.3	7.6	7.1	6.8	7.6	7.0	6.9	6.8–7.6	7.12±0.53

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