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| Leptobrachium tenasserimense
Pawangkhanant, Poyarkov, Duong, Naiduangchan & Suwannapoom, 2018
DOI: 10.7717/peerj.5584
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Abstract
We describe a new species of the genus Leptobrachium from the Khao Laem Mountain, Suan Phung District, Ratchaburi Province, Tenasserim Region, western Thailand, based on molecular and morphological evidences. The new species, Leptobrachium tenasserimense sp. nov., can be distinguished from all other congeners by the following combination of characters: (1) adult SVL of 41.4–58.8 mm in males and 54.7–58.6 mm in females; (2) rounded finger and toe tips; (3) relative finger lengths: II<IV<I<III; relative toe lengths: I<II<V<III<IV; (4) toe webbing thick and well developed; (5) inner metatarsal tubercle small; (6) iris bicolored, black ventrally and turquoise dorsally, with light blue sclera; (7) dorsum brown to grey with distinct darker markings edged with brown; (8) belly and limbs ventrally whitish with contrasting confluent black reticulations; (9) tympanum mostly free of dark marking; (10) narrow dark canthal stripe present; (11) lateral row of dark spots absent; (12) limbs dorsally with distinct dark bars; tibia with four to five dark transverse bars; (13) dense dark reticulation or large dark blotch at groin continuing to ventral and posterior sides of thighs; (14) femoral gland in shape of large white blotch; (15) males with single vocal sac, mature males lack lip spinules. Our study provides further evidence for a hidden biodiversity of montane areas of Tenasserim Region on the border of Thailand and Myanmar.
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| Figure 5: Color variation of Leptobrachium tenasserimense sp. nov. in life. (A) Natural habitat at the type locality in Khao Laem Mountain, Suan Phung District, Ratchaburi Province; (B) and (C) dorsolateral views of adult male (not collected) in situ; (D) ventral view of adult male (not collected) in situ.
Photos (A–D) by Parinya Pawangkhanant.
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| Figure 1: Map of Thailand and adjacent parts of Indochina, showing distribution of Leptobrachium smithi species group members (clade L1). Yellow, L. smithi; red, L. rakhinense; blue, Leptobrachium tenasserimense sp. nov. Star denotes type locality of the respective species.
Locality information abbreviations: Distr., District; Div., Division; F.P., Forest Park; Isl., Island; N.P., National Park; Prov., Province; Res., Reserve; St., State; Twn., Township; W.F., waterfall; W.S., Wildlife Sanctuary.
Leptobrachium rakhinensis Wogan, 2012: 1-Nyaung Gwo, Padaung Twn., Pyi Distr., Bago Div., Myanmar (Wogan, 2012); 2-Rakhine Yoma W.S., Gwa Twn., Rakhine St., Myanmar (type locality) (Wogan, 2012); 3-Khoko Gwe, Rakhine Yoma W.S., Gwa Twn., Rakhine St., Myanmar (type locality) (Wogan, 2012). Leptobrachium smithi Matsui, Nabhitabhata & Panha, 1999: 4-Ma Gawe Res., Kalaw Twn., Taunggyi Dist., Shan St., Myanmar (Wogan, 2012); 5-Phasua W.F., Mae Hong Son Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999); 6-Doi Chiang Dao Mt., Chiang Mai Prov., Thailand; 7-Doi Suthep Mt., Chiang Mai Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999) ; 8-Doi Inthanon Mt., Chiang Mai Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999); 9-Mae Yom N.P., Phrae Prov., Thailand (C Suwannapoom, 2018, unpublished data); 10-Tambol Auan, Amphoe Pua, Nan Prov., Thailand (FMNH 270740); 11-Houay Deng, Xaignabouli, Sayaboury Prov., Laos (Brown et al., 2009); 12-Houey Thao, Luang Prabang, Luang Prabang Prov., Laos (Ohler et al., 2011); 13-Ban Sop Khao, Ban Keng Koung, Ban Van Thong, Luang Prabang Prov., Laos (Ohler et al., 2011); 14-Kyaik Hti Yo W.S., Kyaihto Twn., Mon St., Myanmar (Wogan, 2012; Matsui et al., 2010); 15-Taksinmaharat N.P., Tak Prov., Thailand (P Pawangkhanant, 2018, unpublished data); 16-Thung Salaeng Luang N.P., Phetchabun Prov., Thailand (Grosjean et al., 2015); 17-Phu Luang N.P., Loei Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999; Matsui et al., 2010); 18-Nam Nao N.P., Chaiyaphum Prov., Thailand (P Pawangkhanant, 2018, unpublished data); 19-Huai Kha Khaeng W.S., Uthai Thani Prov., Thailand (Niyomwan, Srisom & Pawangkhanant, 2016); 20-Sangkhla Buri Distr., Kanchanaburi Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999); 21-Erawan and Pilok Distr., Kanchanaburi Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999); 22-Kaeng Krachan, Phetchaburi Prov., Thailand (Matsui et al., 2010); 23-Pa Lao U, Phetchaburi Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999); 24-Tanintharyi N.R., Yebyu Twn., Dawei Distr., Tanintharyi Div., Myanmar (Wogan, 2012); 25-Khlong Saen, Surat Thani Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999); 26-Namtok Raman F.P.; Phang Nga Prov., Thailand (Ohler et al., 2011; Grosjean et al., 2015); 27-Phuket Isl., Phang Nga Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999); 28-Khao Luang N.P., Nakhon Si Thammarat Prov., Thailand (Matsui, Nabhitabhata & Panha, 1999); 29-Kaochong, Trang Prov., Thailand (type locality) (Matsui, Nabhitabhata & Panha, 1999; Matsui et al., 2010); 30-Tha Le Ban National Park, Satun Prov., Thailand (P Pawangkhanant, 2018, unpublished data); 31-Langkawi Isl., Perlis, Malaysia (Matsui, Nabhitabhata & Panha, 1999; Matsui et al., 2010; Grismer et al., 2006). Leptobrachium tenasserimense sp. nov.:32-Pilok Distr., Kanchanaburi Prov., Thailand (Matsui et al., 2010); 33-Khao Laem, Suan Phung Distr., Ratchaburi Prov., Thailand (type locality; sympatric with L. smithi) (this work). |
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| Figure 2: Phylogenetic BI tree of Leptobrachium reconstructed on the base of 2,494 bp (partial 12S rRNA- tRNAval-16S rRNA sequences). Values on the branches correspond to BI PP/ML BS, respectively; black, grey and white circles correspond to well-supported, moderately supported and non-supported nodes, respectively. Color marking of species in L. smithi species group corresponds to Fig. 1. For specimen and locality information see Table 1. Photo by Nikolay A. Poyarkov. |
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| Figure 3: Male holotype of Leptobrachium tenasserimense sp. nov. (AUP-00362) after preservation. (A) Ventral view; (B) dorsal view; (C) volar view of left hand; (D) palmar view of right foot.
Photos by Parinya Pawangkhanant.
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| Figure 4: Female paratype of Leptobrachium tenasserimense sp. nov. (ZMMU A-5918) in life. (A) Ventral view; (B) dorsal view; (C) lateral view of head; (D) volar view of left hand; (E) palmar view of left foot.
Photos by Nikolay A. Poyarkov.
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Leptobrachium tenasserimense sp. nov.
Chresonymy: “Leptobrachium sp. 4”—Matsui et al., 2010: 263.
Etymology. The specific name is a Latinized toponymic adjective in neutral gender derived from “Tenasserim”—a historical name of the region in the northern part of the Malayan Peninsula in southern Indochina, and for the mountain chain known as “Tenasserim Hills”, where the new species occurs.
Diagnosis. A member of the genus Leptobrachium on the basis of head width being larger than tibia length; skin dorsally with a network of ridges; oval and large axillary glands present; extremities of digits rounded; breeding males lacking spines on fingers and breast; and bicolored iris (Yang, Wang & Chan, 2016). The new species can be distinguished from other congeners by the following combination of morphological characteristics: (1) medium-sized species, with adult SVL of 41.4–58.8 mm in males and 54.7–58.6 mm in females; (2) rounded finger and toe tips; (3) relative finger lengths: II<IV<I<III; relative toe lengths: I<II<V<III<IV; (4) toe webbing thick and well developed; (5) inner metatarsal tubercle comparatively small; (6) iris bicolored, black ventrally and turquoise dorsally, with light blue sclera; (7) dorsum brown to grey with distinct darker markings edged with dark-brown, dark head markings usually distinct; (8) belly and limbs ventrally whitish with dense contrasting confluent black blotches and reticulations; (9) tympanum free of dark marking or dark coloration covering only the uppermost one-third of tympanum; (10) dark canthal stripe present, narrow, not covering loreal region; (11) ventro-lateral row of dark spots or blotches absent; (12) limbs, including fingers and toes, dorsally with distinct dark bars; tibia with four to five dark transverse bars; (13) dense dark reticulations or large dark blotches at groin continuing to ventral and posterior sides of thighs; (14) femoral gland in shape of large white rounded blotch; (15) males with single vocal sac, mature males lack lip spinules.
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| Figure 5: Color variation of Leptobrachium tenasserimense sp. nov. in life. (A) Natural habitat at the type locality in Khao Laem Mountain, Suan Phung District, Ratchaburi Province; (B) and (C) dorsolateral views of adult male (not collected) in situ; (D) ventral view of adult male (not collected) in situ; (E) male paratype ZMMU A-5919; (F) female paratype ZMMU A-5918; (G) amplexus in situ.
Photos (A–D) by Parinya Pawangkhanant; (E–G) by Nikolay A. Poyarkov.
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| Figure 5: Color variation of Leptobrachium tenasserimense sp. nov. in life. (E) male paratype ZMMU A-5919; (F) female paratype ZMMU A-5918; (G) amplexus in situ.
Photos (E–G) by Nikolay A. Poyarkov.
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Distribution. Currently known only from two localities in the northern part of Tenasserim: from the type locality in Suan Phung District, Ratchaburi Province (this work), and from Pilok District in Kanchanaburi Province (Matsui et al., 2010) (see Fig. 1). Occurrence in Phetchaburi Province of Thailand and in the adjacent parts of Tanintharyi Division of Myanmar is strongly anticipated.
Ecology and Natural history. Specimens of the new species were recorded along a slow-flowing stream in a montane tropical forest on Khao Laem Mountain at elevations from 700 to 1000 m a.s.l. (see Fig. 5A). The multi-species codominant (polydominant) tropical forest at the type locality had dense vegetation with tangles of the giant bamboo (Dendrocalamus asper (Schult.) Backer). Frogs were observed in leaf litter or under tree roots; males were calling during our field observations in August, September and November 2017. Amplexus was recorded in November 2017 (see Fig. 5G).
Herpetofauna species recorded sympatrically with the new species at the type locality include: Leptobrachium smithi, Xenophrys cf. major (Boulenger), Leptobrachella melanoleuca (Matsui), Leptobrachella fuliginosa (Matsui), Amolops panhai Matsui & Nabhitabhata, Alcalus tasanae (Smith), Limnonectes jarujini Matsui, Panha, Khonsue & Kuraishi, Limnonectes doriae (Boulenger), Limnonectes macrognathus (Boulenger), Microhyla berdmorei (Blyth), Acanthosaura crucigera Boulenger, Pseudoxenodon macrops (Blyth), Trimeresurus popeiorum Smith, and Rhabdophis chrysargos (Schlegel). At the type locality of the new species in Khao Laem Mountain L. smithi was recorded in the same biotopes as Leptobrachium tenasserimense sp. nov. at elevations around 800 to 1,200 m a.s.l. and the two species shared same streams for reproduction and the breeding season of two species seem to overlap. Additional studies are required to elucidate reproductive biology and ecology of two sympatric Leptobrachium species of Khao Laem Mountain.
Conclusions:
Our new discovery of Leptobrachium tenasserimense sp. nov. indicates that the montane forests of northern Tenasserim Region on the border of Thailand and Myanmar contain herpetofaunal diversity that is still unrecognized. This comparatively narrow area is known for an exceptionally high number of endemic species of amphibians and reptiles discovered by recent herpetofaunal surveys (Mulcahy et al., 2018), including a new genus and species of microhylid frogs (Suwannapoom et al., 2018), two new species of megophryid frogs (Matsui, 2006), two new species of bufonid frogs (Wilkinson, Sellas & Vindum, 2012; Matsui, Khonsue & Panha, 2018), five endemic gecko species and two endemic species of snakes (see Sumontha et al., 2017). Possible reasons behind such exceptional herpetofaunal endemism are yet unclear; recent studies indicate that the northern part of Tenasserim Region played a key role in the faunal exchange between Sundaland and the mainland Indochina during the Cenozoic (see Chen et al., 2018 for discussion). Our study provides further evidence for the hidden biodiversity of the Tenasserim Region, and suggests that its herpetofauna is still clearly underestimated. Further field surveys are required for facilitating herpetological exploration and elaboration of measured conservation of this hidden diversity.
Parinya Pawangkhanant, Nikolay A. Poyarkov, Tang Van Duong, Mali Naiduangchan and Chatmongkon Suwannapoom. 2018. A New Species of Leptobrachium (Anura, Megophryidae) from western Thailand. PeerJ. 6:e5584. DOI: 10.7717/peerj.5584
