Limnonectes nguyenorum mcleod, kurlbaum & hoang, 2015 (anura: dicroglossidae), a new frog record from yen bai province, northwestern Viet Nam

141 HNUE JOURNAL OF SCIENCE DOI: 10.18173/2354-1059.2019-83 Natural Sciences 2019, Volume 64, Issue 10, pp. 141-147 This paper is available online at Limnonectes nguyenorum MCLEOD, KURLBAUM & HOANG, 2015 (ANURA: DICROGLOSSIDAE), A NEW FROG RECORD FROM YEN BAI PROVINCE, NORTHWESTERN VIETNAM Le Trung Dung and Do Thi Yen Faculty of Biology, Hanoi National University of Education Abstract. We report Nguyen's fanged frog (Limnonectes nguyenorum) for the first time from Yen Bai Province in northwestern Vietnam. Specimens were collected in May 2017 and June 2019 from Mu Cang Chai Species and Habitat Conservation Area, Mu Cang Chai District, Yen Bai Province and identified based on morphological data. Our record extends the known elevation range of the species (up to 1763 m vs. 1000 m in first records) and brings the number of Limnonectes species recorded from Yen Bai Province to two and is the first record of Limnonectes nguyenorum from Mu Cang Chai Species and Habitat Conservation Area. Keywords: Limnonectes nguyenorum, Mu Cang Chai, morphology, new record. 1. Introduction The fanged frog genus Limnonectes Fitzinger is comprised of 74 species which are distributed widely in Asia (Frost, 2019 [1]). Limnonectes is one of the most diverse groups of amphibians with 16 of which have been described in the last ten years (Pham et al. 2017 [2]). To date, 12 species have been reported from Vietnam (Frost 2019 [1]). Nguyen's fanged frog (Limnonectes nguyenorum McLeod, Kurlbaum & Hoang 2015 [3]) has been recorded from three provinces (Ha Giang, Son La, and Vinh Phuc provinces) (McLeod et al. 2015 [3]; Ziegler et al. 2015 [4]; Pham et al. 2016 [5]). This species belongs to the Limnonectes kuhlii group which is known to harbour cryptic species; several new species have been recently described from this group based on a combination of morphological and molecular data (Suwannapoom et al. 2016 [6]; Pham et al. 2017 [2], 2018 [7]). Mu Cang Chai Species and Habitat Conservation Area (SHCA) in northwestern Vietnam is known to support a high diversity of amphibians with 33 species recorded to date, including several species that are currently believed to be endemic to the mountain Received February 17, 2019. Revised October 15, 2019. Accepted October 22, 2019. Contact Le Trung Dung, e-mail address: letrungdung_sp@hnue.edu.vn Le Trung Dung and Do Thi Yen 142 (Le et al. 2018 [8]; Tapley et al. 2018 [9]). However, only one species of Limnonectes has reported from this area, Limnonectes banaensis Ye, Fei, Xie, & Jiang (previously known as L. kuhlii, Ohler et al. 2000). During fieldwork on Mu Cang Chai SHCA in May 2017 and June 2019, we encountered several Limnonectes in small streams near Che Tao and Nam Khat communes, Mu Cang Chai District, Yen Bai Province. Morphological data confirm the identity of the specimens as L. nguyenorum and we herein report the first record of the species Mu Cang Chai SHCA and for Yen Bai Province. 2. Content 2.1. Materials and methodology Field surveys (Fig. 1) were conducted in Mu Cang Chai SHCA, Yen Bai Province, northwestern Vietnam, in May 2017 and June 2019 by Dzung Trung Le, Yen Thi Do, Anh Ngoc Dao, Nam Hai Nguyen, Huy Quoc Nguyen, Hai Nam Tran, Tien Quang Phan (hereafter YTD et al.). Specimens were collected from 19:00 to 24:00. After taking photographs specimens were euthanized in a closed vessel with a piece of cotton wool containing ethyl acetate, fixed in 85% ethanol and subsequently stored in 70% ethanol (Simmons, 2002 [10]). Specimens were deposited in the Museum of Biology, Hanoi National University of Education (HNUE), Hanoi, Vietnam. Figure 1. Distribution of Limnonectes nguyenorum in Vietnam: Red circles – previously recorded sites; Yellow circle – Mu Cang Chai Species and Habitat Conservation Area, Yen Bai Province Measurements were taken with a digital calliper to the nearest 0.1 mm. Morphological terminology followed McLeod (2008) [11]: SVL = snout–vent length; HW = head width; HL = head length; MN = mandible–nostril distance; MBE = mandible–behind eye distance; MFE = mandible–front eye distance; IFE = distance between anterior corners of eyes; IPE = distance between posterior corners of eyes; IN Limnonectes nguyenorum mcleod, Kurlbaum & Hoang, 2015 (Anura: Dicroglossidae), a new 143 = internarial distance nostril; EN = eye–nostril distance; ED = eye diameter; NS = nostril–snout distance; SL = Snout lengt; IUE = internarial upper eyelid; UEW = upper eyelid width; FLL = forearm length, from elbow to base of outer palmar tubercle; HAL = hand length, from base of outer palmar tubercle to tip of third finger; TFL = third finger length; FL = thigh length, from vent to knee; TL = shank length; FOL = foot length, from base of inner metatarsal tubercle to tip of fourth toe; FTL = fourth toe leghth; IMT = length of inner metatarsal tubercle; ITL= inner toe length; TW = maximum shank width; a.s.l., above sea level. For webbing formula, we followed Glaw and Vences (2007) [12]. 2.2. Results Specimens examined (n=2). Two adult males (HNUE MCC.2017.108 and HNUE MCC.2019.51): HNUE MCC.2017.108 collected on 3 May 2017, from a small stream Mu Cang Chai SHCA, near Che Tao Commune, Yen Bai Province (21 0 43.281’N 103 0 59.765'E, at an elevation of 1,332 m a.s.l.); HNUE MCC.2019.51 collected on 16 June 2019, from a small stream Mu Cang Chai SHCA, near Che Tao Commune, Yen Bai Province (21⁰39.462’N 104⁰05.604’E, at an elevation of 1,763 m a.s.l.). Figure 2. Limnonectes nguyenorum (HNUE MCC.108, an adult male) from Mu Cang Chai Species and Habitat Conservation Areas in life: A, lateral view; B, ventral view; C, leg view; and D, planar view and E, palmar view. Photos by Y. T. Do. Le Trung Dung and Do Thi Yen 144 Description. Morphological characters of the specimens (Fig. 2) from Mu Cang Chai SHCA, Yen Bai Province agreed with the descriptions of Mcleod et al. (2015) [3] and Pham et al. (2016) [5]: SVL 40.7-41.5 mm in the males; head slightly enlarged (HL/SVL 0.37-0.39); head longer than wide (HL 15.4-15.8 mm, HW 14.4-15.0 mm); canthus rostralis indistinct and rounded, lores flat; distinct supratympanic fold; tympanum not visible; Finger tips rounded, relative length of fingers decreasing III–IV– II–I; no webbing on fingers. Toe tips rounded, relative length of toes decreasing IV–III– V–II–I. Full webbing between toes, inner metatarsal tubercle oval; skin on head and venter smooth; skin on throat, dorsal surfaces of forelimb, thigh, and dorsum feebly crenulate; pericloacal area, dorsal surfaces of shank and foot covered with small heterogeneous sized tubercles tipped with translucent spinules; Coloration in life: dorsum, head and body greyish yellow-brown; dark horizontal stripes between the eyes dorsum and dorsal surfaces of limbs yellow-brown; supratympanic fold dark brown, tips of tubercles white; dorsal surface of thighs and tibias. Based on the current understanding of systematics, taxonomy, and species distributions in Indochina, L. nguyenorum and L. bannaensis are the only sympatric species of the L. kuhlii Complex in Vietnam (McLeod et al. 2015 [3]). The species L. nguyenorum differs L. bannaensis by having a smaller size and heterogeneously sized tubercles on the leg vs. smooth appearance in L. bannaensis (McLeod et al. 2015 [3] and this study). The only other geographically proximate and closely related taxon with which L. nguyenorum could be confused based on size and general appearance is L. taylori, which is known from northwestern Thailand, northwestern Laos, and eastern Myanmar (McLeod 2010 as “Lineage 12”, Matsui 2010b). The species L. nguyenorum differs L. taylori by having smaller size and heterogeneously sized tubercles on the leg and L. taylori has most closely clustered tubercles giving the leg a rough appearance (McLeod et al. 2015 [3]). Natural history. Specimens were collected from 20:00 h to 24:00 h in the middle of smalls, a shallow stream near Che Tao Commune (Fig. 3). The stream was bordered by the secondary forest above. The air temperature was 24 o C and ambient humidity was 80%. Table 1. Measurements (in mm) of Limnonectes nguyenorum from Yen Bai Province, Vietnam Characters HNUE MCC.2017.108 HNUE MCC.2019.51 Min – Max (n = 2) SVL 40.7 41.5 40.7–41.5 HW 15.0 14.4 14.4–15.0 HL 15.8 15.4 15.4–15.8 MN 13.7 14.4 13.7–14.4 MFE 11.0 11.4 11.0–11.4 MBE 7.7 7.6 7.6–7.7 IFE 7.5 6.2 6.2–7.5 IPE 9.4 9.4 9.4 IN 3.0 2.9 2.9–3.0 Limnonectes nguyenorum mcleod, Kurlbaum & Hoang, 2015 (Anura: Dicroglossidae), a new 145 EN 3.9 3.1 3.1–3.9 EL 4.1 4.2 4.1–4.2 TYD - - - TYE - - - NS 2.5 2.7 2.5–2.7 SL 6.4 5.4 5.4–6.4 IUE 3.4 3.5 3.4–3.5 UEW 3.0 2.9 2.9–3.0 FLL 7.5 8.2 7.5–8.2 HAL 9.2 8.6 8.6–9.2 TFL 4.3 4.4 4.3–4.4 FL 18.7 19.3 18.7–19.3 TL 18.6 20.3 18.6–20.3 FOL 17.5 20 17.5–20.0 FTL 10.2 12.6 10.2–12.6 IMT 1.5 1.7 1.5–1.7 ITL 3.8 3.5 3.5–3.8 TW 3.7 4.6 3.7–4.6 Figure 3. Habitat of L. nguyenorum from Mu Cang Chai Species and Habitat Conservation Area, Yen Bai Province: A, Landscape; B, Habitat 2.3. Discussion Specimens from Yen Bai differ from the type specimens of L. nguyenorum from Ha Giang (McLeod et al. 2015 [3]) and specimens from Son La (Pham et al. 2016) [5] in having a smaller size in males: SVL 40.7-41.5mm versus 43.5-43.8 mm (type specimens), versus 46.1-46.5 mm (Son La’s specimens) and tubercles present on the dorsum that were absent in the type specimens (McLeod et al. 2015 [3], Pham et al. 2016 [5]). Our finding increases the number of Limnonectes species known from Mu Cang Chai SHCA and Yen Bai Province to two (Nguyen et al. 2009 [13] and this study). We expect that Mu Cang Chai SHCA and Yen Bai Province contains additional diversity within the genus Limnonectes. Limnonectes nguyenorum was discovered at an Le Trung Dung and Do Thi Yen 146 elevation of 900 m (McLeod et al. 2015 [3]) and the highest elevation record for this species previously was 1300 m (Son La Province, Pham et al. 2016 [5]). Our record extends the known elevational distribution of the species to 1763 m. Several new species of amphibian have been recently described from Mu Cang Chai SHCA and the surrounding area of Hoang Lien NP (Nguyen et al. 2013 [14]; Rowley et al. 2013 [15]; Matsui et al. 2017 [16]; Tapley et al. 2017 [17]; Tapley et al. 2018 [9]) indicating that the diversity of amphibians in this area is underestimated. Further study is necessary to document the true amphibian diversity of Mount Fansipan. 3. Conclusions The species Nguyen's fanged frog (Limnonectes nguyenorum) was recorded for the first time from Yen Bai Province in northwestern Vietnam. Specimens were collected in May 2017 and June 2019 from Mu Cang Chai SHCA, Mu Cang Chai District, Yen Bai Province and identified based on morphological data. Morphologically, L. nguyenorum is very similar to L. bannaensis and L. taylori but it differs from the latter by size and heterogeneously sized tubercles on the leg. Our record extends the known elevation range of the species (up to 1763 m vs. 1000 m in first records) and brings the number of Limnonectes species recorded from Yen Bai Province to two and is the first record of L. nguyenorum from Mu Cang Chai SHCA. Acknowledgements: We are grateful to the directorate of the Mu Cang Chai SHCA for support of our fieldwork. We thank A. N. Dao, N. H. Nguyen, H. Q. Nguyen, H. N. Tran, T. M. Doan and T. Q. Phan (HNUE) for their assistance in the field. We thank E. Sterling (New York) and K. Koy (Berkeley) for providing the map. REFERENCES [1] Frost, D.R.,. 2019. Amphibian Species of the World: an Online Reference. Version 6.0. Electronic Database accessible at amphibia/index.html. American Museum of Natural History. New York, USA. (accessed on 30 May 2019). [2] Pham, T.C., Le, M.D., T.T, N., Ziegler, T., Wu, Z.J. & Nguyen, T.Q., 2017. A new species of Limnonectes (Amphibia: Anura: Dicroglossidae) from Vietnam. Zootaxa, Vol. 4269, No. 4, pp. 545-558. 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