Xenophrys truongsonensis, Luong & Hoang & Pham & Nguyen & Orlov & Ziegler & Nguyen, 2022

Luong, Anh Mai, Hoang, Chung Van, Pham, Cuong The, Nguyen, Tao Thien, Orlov, Nikolai, Ziegler, Thomas & Nguyen, Truong Quang, 2022, A new species of Xenophrys (Amphibia: Anura: Megophryidae) from Truong Son Range, Vietnam, Zootaxa 5150 (3), pp. 333-356 : 341-352

Xenophrys truongsonensis sp. nov.

( Figs. 3 , 4 )

Megophrys sp 12., Chen et al. 2017

Megophrys cf. maosoensis 3, Mahony et al. 2018

Holotype. IEBR A.4940, adult male, collected by A.M. Luong, C. V. Hoang, T. V. Nguyen on 24 May 2018 in the evergreen forest (12 o 23’13.8”N, 108 o 20’33.9”E, at an elevation of 1267 m asl.) within Chu Yang Sin National Park , Krong Bong District, Dak Lak Province, Vietnam.

Paratypes (n = 18). Specimens collected from the forest of A Luoi District, Thua Thien Hue Province, Vietnam: two adult males IEBR A.4934–4935 (AL.2017.98, 107) and one adult female IEBR A.4936 (AL.2017.106) collected by T. V. Nguyen, C. T. Pham on 6 April 2017 in the evergreen forest (16 o 08’39.32”N, 107 o 35’47.56”E, at an elevation of 713 m asl.) ; one adult male IEBR A.4937 (AL.2018.1) collected by T.Q. Phan on 16 March 2018 in the evergreen forest (16 o 10’45.43”N, 107 o 29’53.22”E, at an elevation of 798 m asl.) . Specimens collected from the forest of Kon Plong District, Kon Tum Province, Vietnam: two adult males IEBR A.4941–4942 ( NL.116, 161) and adult female IEBR A.4943 collected by A.M. Luong, V. H.D. Nguyen, N. Orlov on 9 November 2018 in the evergreen forest (14 o 40’30.7”N, 108 o 15’35.1”E, at an elevation of 1319 m asl.) . Specimens collected from the forest of Chu Yang Sin National Park, Krong Bong District, Dak Lak Province, Vietnam: one adult male IEBR A.4944 collected by A.M. Luong, C. V. Hoang, T. V. Nguyen on 24 May 2018 in the evergreen forest (12 o 23’13.8”N, 108 o 20’33.9”E, at an elevation of 1267 m asl.) ; one adult male IEBR A.4938 ( CYS.2019.69), collected by A.M. Luong and Q.H. Do on 11 March 2019 (12 o 23’12.7”N, 108 o 20’33.4”E, at an elevation of 1270 m asl.) . Specimens collected from the forest of Nam Ka Nature Reserve, Lak District, Dak Lak Province, Vietnam: one adult male IEBR A.4945 collected by A.M. Luong, C. V. Hoang, T. V. Nguyen on 28 May 2018 in the evergreen forest (12 o 20’11.5”N, 108 o 01’51.4”E, at an elevation of 532 m asl.) . Specimens collected from the forest of Nam Nung Nature Reserve, Dak Glong District, Dak Nong Province, Vietnam: two adult males IEBR A.4946–4947 collected by A.M. Luong on 23 October 2017 in the evergreen forest (12 o 12’24.21”N, 107 o 50’41.23”E, at an elevation of 794 m asl.) . Specimens collected from the forest of Bi Doup-Nui Ba National Park, Lac Duong District, Lam Dong Province, Vietnam: two adult males IEBR A.4948–4949 and two adult females IEBR A.4950–4951 collected by A.M. Luong, C. V. Hoang, Y. T. Nguyen, L. V. Pham, T. D. Pham on 14 May 2018 in the evergreen forest (12 o 05’50.2”N, 108 o 21’25.3”E, at an elevation of 1605 m asl.) . Specimens collected from the forest of Phuoc Binh National Park, Phuoc Binh District, Ninh Thuan Province, Vietnam: one adult male IEBR A.4952 and one adult female IEBR A.4953 collected by A.M. Luong, C. V. Hoang on 26 April 2018 in the evergreen forest (12 o 01’26.0”N, 108 o 44’16.9”E, at an elevation of 823 m asl.) .

Diagnosis. The new species is distinguishable from its congeners by a combination of the following morphological characters: 1) size medium (SVL 58.8–71.4 mm in males; SVL 65.6–87.3 mm in females); 2) tympanum distinct (TD/ED 0.51–0.67 in males; TD/ED 0.53–0.59 in females); 3) vomerine teeth present; 4) tongue feebly notched posteriorly; 5) external vocal sac absent; 6) toes with rudimentary webbing; 7) subarticular tubercles absent; 8) lateral fringes narrow along toes; 9) dorsal skin of body with weak granules; 10) flank with small tubercles; 11) dorsum with a dorsal ridge, in>-<shape; 12) dorsolateral folds prominent; 13) dorsal surface from reddish brown to grayish brown with a brown triangle between the eyes, and a dark brown marking edged along dorsal ridge on the back; and 14) small white spots present on flank and back of thigh.

Description of holotype. Adult male; SVL 67.2 mm; head as long as wide (HL 26.2 mm, HW 26.2 mm); snout round in dorsal view, obtusely protruding in lateral view; nostril lateral, oval, closer to the tip of snout than to the eye (NS 3.9 mm, EN 4.5 mm); canthus rostralis angular; pupil vertically elliptical; loreal region acute, concave; eye diameter shorter than snout length (SL 8.4 mm, ED 8.0 mm); internarial distance narrower than interorbital distance but wider than upper eyelid (IND 7.2 mm, IOD 7.6 mm, UEW 5.3mm); tympanum distinct, oval, 51% of eye diameter (TD 4.1 mm); vomerine teeth present, maxillary teeth present; tongue round, feebly notched posteriorly; external vocal sac absent.

Forelimbs: Hand length (HAL) 34.1 mm, forearm length (FLL) 16.0 mm; relative finger lengths I<II<IV<III; fingers free of webbing; tips of fingers round, subarticular tubercles and palmar tubercles absent; inner metatarsal tubercle oval, elongate; outer metatarsal tubercle absent.

Hindlimbs: Tibia longer than thigh (FeL 35.9 mm, TbL 38.7 mm), approximately five times longer than wide (TbW 7.7 mm); tips of toes round, relative length of toes I<II<V<III<IV; toes with rudimentary webbing; subarticular tubercles absent; toes with narrow lateral fringes; tarsal fold absent; inner metatarsal tubercle elongate; outer metatarsal tubercle absent; tibio-tarsal articulation reaching to the middle of nostril when adpressed along body.

Skin texture in life: Dorsal surface with small granules; back with a dorsal ridge, in>-<shape; dorsolateral folds prominent; supratympanic fold distinct; flank with small tubercles; dorsal surface of limbs granular with short transverse ridges; throat, chest, belly and ventral surface of thigh smooth.

Coloration in life: Dorsum reddish brown with a dark brown triangle between the eyes; a dark brown marking edged along dorsal ridge; flanks yellowish brown with some small black spots; tympanum dark brown; pupil black, outlined in reddish brown, iris copper-brown with tiny dark reticulations spreading from pupil; upper lip with a continuous white stripe, running from the nostril to shoulder; small white spots on flank and back of thigh; dorsal surface of fore and hind limbs reddish brown with dark crossbars; throat and chest dark brown, pectoral glands white; anterior part of belly white with brown pattern, posterior part of belly white; ventral surface of limbs dark brown with white marking, anterior part of thigh, posterior part of thigh dark brown; femoral glands white; toe webbing dark brown.

Coloration in preservative: Dorsum greyish with a dark brown triangle marking between the eyes; a dark brown marking edged along dorsal ridge; flanks greyish with some small dark spots; throat and chest brown; belly cream with brown pattern; 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 . Adult males are smaller than adult females. Dorsum is reddish brown or grayish brown.

Comparisons. We compared the new species with other species of Xenophrys from Vietnam and neighboring countries, including Laos, Cambodia, Thailand, and China. Xenophrys truongsonensis sp. nov. can be distinguished from its congeners by morphological characters as shown in Table 4 .

Morphologically, Xenophrys truongsonensis sp. nov. is most similar to X. maosonensis Bourret but they are different from each other by having flank with small tubercles (vs. flank with large tubercles in X. maosonensis ), and toes with narrow lateral fringes (vs. absent in X. maosonensis ), and white spots on flank and back of thigh smaller than those in X. maosonensis .

Xenophrys truongsonensis sp. nov. differs from X. aceras Boulenger by having a greater TbL/SVL ratio in males (0.55–0.64 vs. 0.42–0.46 in X. aceras ), and a greater ratio HL/HW>1 (vs. <1 in M. aceras ); from X. ancrae Mahony, Teeling & Biju by having a larger body size (SVL 58.8–71.4 mm in males, 65.6–87.3 mm in females vs. 39.1–45.0 in males, 48.9 mm in female in X. ancrae ), a greater ratio of TbL/SVL in males (0.55–0.64 vs. 0.48 in X. ancrae ), toes with narrow lateral fringes (vs. absent in X. ancrae ), and the absence of nuptial pads on finger I (vs. present in X. ancrae ); from X. auralensis Ohler, Swan & Daltry by having a greater ratio of TbL/SVL in males (0.55–0.64 vs. 0.51 in X. auralensis ), the presence of vomerine teeth (vs. absent in X. auralensis ), the absence of external vocal sac (vs. present in X. auralensis ), the first finger being shortest (vs. the second finger or fourth finger being shortest in X. auralensis ), and tongue feebly notched (vs. tongue not notched in X. auralensis ); from X. damrei Mahony by having a greater ratio of TbL/SVL in males (0.55–0.64 vs. 0.51 in X. damrei ), the absence of external vocal sac (vs. present in X. damrei ), and the first finger being shortest (vs. the fourth finger being shortest in X. damrei ); from X. glandulosa Fei, Ye, & Huang by the absence of external vocal sac (vs. present in X. glandulosa ), toes with narrow lateral fringes (vs. well developed fringes in X. glandulosa ), and the first finger being the shortest (vs. the second finger or fourth finger being shortest in X. glandulosa ); from X. lekaguli Stuart, Chuaynkern, Chanard, & Inger by having a greater ratio of TbL/SVL (0.55–0.64 in males and 0.54–0.58 mm in females vs. 0.47–0.52 in males and 0.44–0.52 in females in X. lekaguli ), tongue feebly notched (vs. tongue not notched in X. lekaguli ), toes with narrow lateral fringes (vs. absent in X. lekaguli ), and the first finger being shortest (vs. the fourth finger being shortest in X. lekaguli ); from X. longipes Boulenger by having a larger body size in males (SVL 58.8–71.4 mm vs. 47 mm in the male X. longipes ), the absence of external vocal sac (vs. present in X. longipes ), and the first finger being shortest (vs. the second finger being shortest in X. longipes ); from X. mangshanensis Fei & Ye by the absence of external vocal sac (vs. present in X. mangshanensis ), toes with narrow lateral fringes (vs. absent in X. mangshanensis ), toes with rudiment of webbing (vs. without webbing in X. mangshanensis ), and the fisrt finger being shortest (vs. the second finger being shortest in X. mangshanensis ); from X. medogensis Fei, Ye, & Huang by the absence of external vocal sac (vs. present in X. medogensis ), and toes with narrow lateral fringes (vs. absent in X. medogensis ); from X. pachyproctus Huang by having a larger body size (SVL 58.8–71.4 mm in males and 65.6–87.3 mm in females vs. 35.3–36.2 mm in males and 35.8 mm in the female in X. pachyproctus ), a greater ratio of TD/ED (0.51–0.67 in males and 0.53–0.59 in females vs. 0.35 in the male and 0.36 in the female in X. pachyproctus ), a greater ratio of TbL/SVL (0.55–0.6 in males and 0.54–0.58 mm in females vs. 0.48–0.49 in males and 0.5 in the female in X. pachyproctus ), the presence of vomerine teeth (vs. absent in X. pachyproctus ), toes with narrow lateral fringes (vs. absent in X. pachyproctus ), the absence of subarticular tubercles on toes (vs. present in X. pachyproctus ), and the absence of nuptial pads on finger I (vs. present in X. pachyproctus ); from X. takensis Mahony by having a larger body size in males (58.8–71.4 mm vs. 47.3–53.0 mm in X. takensis ), a greater ratio of TD/ED in males (0.51– 0.67 vs 0.42–0.48 in X. takensis ), a greater ratio of TbL/SVL (0.55–0.64 in males and 0.54–0.58 mm in females vs. 0.41–0.49 in males and 0.45 in female in X. takensis ), the absence of external vocal sac (vs. present in X. takensis ), tongue feebly notched (vs. tongue not notched in X. takensis ), toes with narrow lateral fringes (vs. absent in X. takensis ), the first finger being shortest (vs. the fourth finger being shortest in X. takensis ), and the absence of nuptial pads on finger I (vs. present in X. takensis ); from X. yeae by having a larger body size (58.8–71.4 mm in males and 65.6–87.3 mm in females vs. 23.0– 29.1 mm in males and 27.9–31.1 mm in the females in X. yeae ), a greater ratio of TD/ED (0.55–0.64 in males and and 0.53–0.59 in females vs. 0.38–0.47 in males and 0.39–0.50 in females in X. yeae ), and the presence of vomerine teeth (vs. absent in X. yeae ); from X. zhangi Ye & Fei by having a larger body size in males (58.8–71.4 mm vs. 32.5–37.2 mm in X. zhangi ), a greater ratio of TD/ED in males (0.51–0.67 vs 0.5 in X. zhangi ), a greater ratio of TbL/SVL in males (0.55–0.64 vs. 0.49 in X. zhangi ), the absence of external vocal sac (vs. present in X. zhangi ), and the absence of nuptial pads on finger I (vs. present in X. zhangi ); and from X. zhoui by having a larger body size (58.8–71.4 mm in males and 65.6–87.3 mm in females vs. 23 mm in male and 23.5–23.9 mm in the females in X. zhoui ), a greater ratio of TD/ED in males (0.55–0.64 vs. 0.48 in X. zhoui ), the presence of vomerine teeth (vs. absent in X. yeae ), and toes with narrow lateral fringes (vs. absent in X. zhoui ).

Etymology. Specific epithet is in reference to the type locality of the Truong Son Mountain Range. We recommend “Truongson Horned Toad” as the common English name and “Cóc mắt trường sƠn” as the Vietnamese name.

Ecological notes. Specimens were collected at night between 19:00 and 23:00 on tree leaves, ca 0.2–0.6 m above the ground, or on ground in rocky streams. The surrounding habitat was secondary evergreen forest consisting of medium and small hardwoods mixed with shrubs or secondary evergreen forest consisting of small hardwoods mixed with shrubs ( Fig. 5 ).

Distribution. Xenophrys truongsonensis sp. nov. is currently known from Thua Thien Hue Province southwards to Lam Dong Province, Central Vietnam ( Fig. 6 ). It is expected that this species can be found in the evergreen forests on western side of Truong Son Range in Laos and Cambodia as well.

Figures

FIGURE 3. Dorsolateral and ventral views of the specimens in life: comparative specimen of Xenophrys maosonensis from Cao Bang Province (IEBR A.4970) (A, B), the holotype of Xenophrys truongsonensis sp. nov. (IEBR A.4940) (C, D) Photos by C.V. Hoang and C.T. Pham

FIGURE 4. Lateral view of the head (A), right food (B), right hand (C), back of thigh (D) and flank (E) of the holotype (IEBR A.4940) of Xenophrys truongsonensis sp. nov.; comparative specimen of X. maosonensis (IEBR A.4970) (F, G, H, I, K). White spots on back of thigh (a), white spots on flank (b). Photos by A.M. Luong

FIGURE 5. Habitat of Xenophrys truongsonensis sp. nov. in Vietnam:A) forest in Bi Doup-Nui Ba NP, Lam Dong Province; B) forest in Chu Yang Sin NP, Dak Lak Province; C) forest in Phuoc Binh NP, Ninh Thuan Province; and D) forest in Kon Plong, Kon Tum Province. Photos by A.M. Luong and C.T. Pham

FIGURE 6. Map showing the distribution of Xenophrys truongsonensis sp. nov. in Vietnam: 1) Dak Lak Province (type locality), 2) Thua Thien Hue Province, 3) Quang Nam Province, 4) Kon Tum Province, 5) Dak Nong Province, 6) Lam Dong Province, and 7) Ninh Thuan Province.