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Research Article
Range extension and expanded description of Micryletta hekouensis Liu, Hou, Mo & Rao, 2021 (Amphibia, Anura, Microhylidae), with comments on Micryletta of Northern Vietnam
expand article infoTan Van Nguyen‡, Shuo Liu§, Vy The Tran|, Thinh Gia Tran, Alexei V. Trofimets#, Vinh Quang Dau¤, Nikolay A. Poyarkov#«
‡ Duy Tan University, Da Nang, Vietnam
§ Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| Institute of Tropical Biology, Vietnam Academy of Science and Technology, Ho Chi Minh City, Vietnam
¶ University of Science, Ho Chi Minh City, Ho Chi Minh City, Vietnam
# Lomonosov Moscow State University, Moscow, Russia
¤ Hong Duc University, Thanh Hoa, Vietnam
« Joint Vietnam - Russia Tropical Science and Technology Research Centre, Hanoi, Vietnam

Corresponding author: Vinh Quang Dau ( dauquangvinhna@hdu.edu.vn )

Corresponding author: Nikolay A. Poyarkov ( n.poyarkov@gmail.com )

Academic editor: Günter Gollmann
© 2024 Tan Van Nguyen, Shuo Liu, Vy The Tran, Thinh Gia Tran, Alexei V. Trofimets, Vinh Quang Dau, Nikolay A. Poyarkov.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Nguyen TV, Liu S, Tran VT, Tran TG, Trofimets AV, Dau VQ, Poyarkov NA (2024) Range extension and expanded description of Micryletta hekouensis Liu, Hou, Mo & Rao, 2021 (Amphibia, Anura, Microhylidae), with comments on Micryletta of Northern Vietnam. Herpetozoa 37: 111-121. https://doi.org/10.3897/herpetozoa.37.e120524
ZooBank: urn:lsid:zoobank.org:pub:6AE8549D-C842-40C6-B420-8CA185169682
Open Access

Abstract

The Paddy frog species Micryletta hekouensis was described based on only two specimens from Nanxi Village, Nanxi Town, Hekou County, Honghe Prefecture, Yunnan Province, China. Herein, we report on new findings and a range extension of this species based on a re-examination of preserved specimens deposited in Duy Tan University (DTU) and Zoological Museum of Lomonosov Moscow State University (ZMMU) collected from Vietnam. All new specimens were previously identified as Micryletta cf. inornata or M. cf. steinegeri. Molecular analyses based on mitochondrial DNA supported the morphological findings. The newly identified specimens have a pairwise divergence of only 0.7% from those of the type series of M. hekouensis, based on the 16s rRNA mtDNA gene. Based on the new information, we confirm the presence of M. hekouensis in Vietnam and update the diagnostic characters of this species and its distribution. We suggest the species should be considered as Near Threatened (NT) following the IUCN’s Red List categories. Further studies reassessing the populations of the Micryletta inornata complex in the Indochinese Region (including Vietnam, Laos, Cambodia, and Thailand) are required.

Key Words

Cat Ba National Park, Cuc Phuong National Park, Micryletta inornata, Micryletta steinegeri, morphology, mtDNA, new record, phylogeny, redescription

Introduction

The Paddy frogs of the genus Micryletta Dubois, 1987 are a little-known group of microhylids, with 13 nominal species currently recognized, namely: M. aishani Das, Garg, Hamidy, Smith & Biju, 2019; M. dissimulans Suwannapoom, Nguyen, Pawangkhanant, Gorin, Chomdej, Che & Poyarkov, 2020; M. erythropoda (Tarkhnishvili, 1994); M. hekouensis Liu, Hou, Mo & Rao, 2021; M. immaculata Yang & Poyarkov, 2021; M. inornata (Boulenger, 1890); M. lineata (Taylor, 1962); M. melanops Poyarkov, Nguyen, Yang & Gorin, 2021; M. menglienica (Yang & Su, 1980); M. nigromaculata Poyarkov, Nguyen, Duong, Gorin & Yang, 2018; M. steinegeri (Boulenger, 1909); M. subaraji Sankar, Law, Law, Shivaram, Abraham & Chan, 2022; and M. sumatrana Munir, Hamidy, Matsui, Kusrini & Nishikawa, 2020 (Sankar et al. 2022; Frost 2024). However, the small body size, elusive habits, as well as the remarkable morphological similarity of some of the Micryletta species complicates taxonomic studies of this group. Therefore, the taxonomic diversity of the genus Micryletta is not yet fully realized and requires additional studies. Presently, four nominal Micryletta species are recorded from Vietnam, including Micryletta erythropoda, M. melanops, M. menglienica, and M. nigromaculata. Two other species, namely Micryletta inornata (restricted to Sumatra Island and Southern Myanmar) and M. steinegeri (restricted to the Taiwan Island of China), have been reported from Vietnam in previous works (Nguyen et al. 2009; Poyarkov et al. 2018, 2021b), but recent phylogenetic studies suggest that these records were likely based on misidentifications with either Micryletta cf. immaculata or M. menglienica or M. hekouensis (Miller et al. 2021; Poyarkov et al. 2021b; Sankar et al. 2022; see Discussion).

The Hekou Paddy Frog, Micryletta hekouensis was described based on one male and one female specimen, both originating from Nanxi Village, Nanxi Town, Hekou County, Honghe Prefecture, Yunnan Province, China (Liu et al. 2021a). To date, this species was known only from its type locality in China. The species is characterized by: comparatively small body size (SVL 20.5 mm in male, 20.8 mm in female); areas above the canthus rostralis, upper eyelids, areas posterior to eyelids, and dorsum of upper arms golden, other parts of the dorsum are almost solid black or yellowish grey with brownish black stripes; lateral sides of head and body black or yellowish grey, a white stripe from lower front of eye along upper lip back to anterior forelimb insertion; ventral side of body and limbs is pink brown, chin region in adult males brownish black, small and irregular white marbling patterns on chest and lateral belly; supratympanic fold indistinct; outer metatarsal tubercle absent; webbing between toes absent; tibiotarsal articulation adpressed limb reaching level of front of eye (Liu et al. 2021a).

The recent molecular results of Miller et al. (2021) and Sankar et al. (2022) revealed that populations previously identified as Micryletta cf. inornata or M. cf. steinegeri in the Ninh Binh and Hai Phong in Northern Vietnam reported by Poyarkov et al. (2018) were nested within the same lineage as the holotype and paratype of Micryletta hekouensis, implying that this species has a more extensive distribution than currently recognized. To address this question, we re-examined specimens previously identified as Micryletta cf. inornata or M. cf. steinegeri from Ninh Binh and Hai Phong Provinces deposited in the zoological collections of the Duy Tan University (DTU, Vietnam) and Zoological Museum of Lomonosov Moscow State University (ZMMU, Russia), respectively. Our results confirm that the specimens from Ninh Binh Province as well as Hai Phong Province belong to Micryletta hekouensis. We herein formally confirm the occurrence of Micryletta hekouensis in Vietnam, update the distribution of this species, provide additional data on its natural history and revise its diagnostic characters.

Materials and methods

Material examined

We examined twelve specimens that were previously registered as M. cf. inornata or M. cf. steinegeri from Cuc Phuong National Park (hereafter NP), Ninh Binh Province and Cat Ba NP, Hai Phong Province, Northern Vietnam (Poyarkov et al. 2018) (see Table 1). Morphological comparisons were based on literature data from: Boulenger (1890); Das et al. (2019); Liu et al. (2021a,b); Miller et al. (2021); Munir et al. (2020); Poyarkov et al. (2018, 2021b); Sankar et al. (2022); Suwannapoom et al. (2020); Tarkhnishvili (1994); Taylor (1962); Yang and Poyarkov (2021) (see Suppl. material 1).

Table 1.
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Sequences (16S rRNA) used in molecular analyses of this study.

No. Previously taxon Proposed taxon Voucher Locality Accession Reference
1 M. aishani M. aishani SDBDU 3920 India: Assam, Cachar, Subhong MK889218 Das et al. (2019)
2 M. aishani M. aishani CAS 231526 Myanmar: Kachin, Indawgyi WS MW035599 Miller et al. (2021)
3 M. dissimulans M. dissimulans AUP 01690 Thailand: Songkla, Saba Yoi MT573414 Suwannapoon et al. (2020)
4 M. dissimulans M. dissimulans AUP 01691 Thailand: Songkla, Saba Yoi MT573415 Suwannapoon et al. (2020)
5 M. dissimulans M. dissimulans AUP 01696 Thailand: Songkla, Saba Yoi MT573416 Suwannapoon et al. (2020)
6 M. dissimulans M. dissimulans AUP 01698 Thailand: Songkla, Saba Yoi MT573413 Suwannapoon et al. (2020)
7 M. erythropoda M. erythropoda ZMMU A4721-1533 Vietnam: Dong Nai, Ma Da N.R. MH756146 Poyarkov et al. (2018)
8 M. erythropoda M. erythropoda ZMMU A4721-1542 Vietnam: Dong Nai, Ma Da N.R. MH756147 Poyarkov et al. (2018)
9 M. hekouensis M. hekouensis KIZ 20210510 China: Yunnan, Honghe, Hekou MZ536627 Liu et al. (2021a)
10 M. hekouensis M. hekouensis KIZ 20210511 China: Yunnan, Honghe, Hekou MZ536628 Liu et al. (2021a)
11 M. cf. inornata M. hekouensis DTU 310 Vietnam: Ninh Binh, Cuc Phuong N.P. PP264232 This study
12 M. cf. inornata M. hekouensis DTU 311 Vietnam: Ninh Binh, Cuc Phuong N.P. PP264231 This study
13 M. cf. inornata M. hekouensis DTU 312 Vietnam: Ninh Binh, Cuc Phuong N.P. PP264230 This study
14 M. cf. inornata M. hekouensis ZMMU NAP-3352-1 Vietnam: Hai Phong, Cat Ba N.P. MH879843 Poyarkov et al. (2018)
15 M. cf. inornata M. hekouensis ZMMU NAP-3352-2 Vietnam: Hai Phong, Cat Ba N.P. MH879844 Poyarkov et al. (2018)
16 M. cf. inornata M. hekouensis ZMMU NAP-3580 Vietnam: Hai Phong, Cat Ba N.P. MH879845 Poyarkov et al. (2018)
17 M. immaculata M. immaculata KFBG 14270 China: Hainan, Exian MW376736 Yang and Poyarkov (2021)
18 M. immaculata M. immaculata KFBG 14271 China: Hainan, Exian MW376737 Yang and Poyarkov (2021)
19 M. inornata M. immaculata FMNH 255121 Laos: Khammouan, Boualapha KC179997 de Sa et al. (2012)
20 M. inornata M. immaculata TZ9892 Vietnam: Ha Tinh, Ke Go AF285206 Ziegler (2002)
21 M. inornata M. inornata MZB 23949 Indonesia: Sumatra, Deli Serdang LC208135 Alhadi et al. (2019)
22 M. inornata M. inornata MZB 23947 Indonesia: Sumatra, Deli Serdang LC208136 Alhadi et al. (2019)
23 M. inornata M. inornata MZB 23948 Indonesia: Sumatra, Deli Serdang LC208137 Alhadi et al. (2019)
24 M. inornata M. inornata MZB 27242 Indonesia: Sumatra, Aceh LC208138 Alhadi et al. (2019)
25 M. inornata M. inornata USNM 587625 Myanmar: Tanintharyi MT609033 Miller et al. (2021)
26 M. inornata M. inornata USNM 587901 Myanmar: Tanintharyi MT609034 Miller et al. (2021)
27 M. inornata M. lineata KUHE 23858 Thailand: Ranong AB634695 Matsui et al. (2011)
28 M. inornata M. lineata CAS 247206 Myanmar: Tanintharyi, Kawthaung KM509167 Peloso et al. (2015)
29 M. melanops M. melanops ZMMU NAP-00449 Vietnam: Lam Dong, Biduop-Nui Ba N.P. MZ474684 Poyarkov et al. (2021b)
30 M. melanops M. melanops ZMMU NAP-01381 Vietnam: Lam Dong, Biduop-Nui Ba N.P. MZ474685 Poyarkov et al. (2021b)
31 M. menglienica M. menglienica KIZ 20210708 China: Yunnan, Pu’er, Menglian OK335183 Liu et al. (2021b)
32 M. menglienica M. menglienica KIZ 20210709 China: Yunnan, Pu’er, Menglian OK335184 Liu et al. (2021b)
33 M. menglienica M. menglienica KFBGF 14653 China: Yunnan, Xishuangbanna, Mengla OR053962 Yeung et al. (2023)
34 M. inornata M. menglienica KUHE 20497 Thailand: Phrae, Mae Yom AB598341 Matsui et al. (2011)
35 M. inornata M. menglienica K 3068 Thailand: Chiang Mai, Doi Chiang Dao KR827953 Grosjean et al. (2015)
36 M. inornata M. menglienica K 3246 Laos: Luangprabang, Ban Sop Chuna KC180027 Grosjean et al. (2015)
37 M. nigromaculata M. nigromaculata ZMMU A5947 Vietnam: Hai Phong, Cat Ba N.P. MH756148 Poyarkov et al. (2018)
38 M. nigromaculata M. nigromaculata ZMMU A5937 Vietnam: Hai Phong, Cat Ba N.P. MH756149 Poyarkov et al. (2018)
39 M. nigromaculata M. nigromaculata ZMMU A5946 Vietnam: Hai Phong, Cat Ba N.P. MH756151 Poyarkov et al. (2018)
40 M. nigromaculata M. nigromaculata DTU 301 Vietnam: Ninh Binh, Cuc Phuong N.P. MH756154 Poyarkov et al. (2018)
41 M. steinegeri M. steinegeri KUHE 35937 China: Taiwan, Yunlin AB634696 Matsui et al. (2011)
42 M. steinegeri M. steinegeri ZMMU A5336-1 China: Taiwan, Kaohsiung MW376732 Poyarkov et al. (2018)
43 M. steinegeri M. steinegeri ZMMU A5336-2 China: Taiwan, Kaohsiung MW376733 Poyarkov et al. (2018)
44 M. steinegeri M. steinegeri ZMMU A5336-3 China: Taiwan, Kaohsiung MW376734 Poyarkov et al. (2018)
45 M. subaraji M. subaraji ZRC1.13370 Singapore: Kranji Marshes ON026065 Sankar et al. (2022)
46 M. subaraji M. subaraji ZRC 1.13369 Singapore: Kranji Marshes ON026064 Sankar et al. (2022)
47 M. subaraji M. subaraji ZRC 1.13389 Singapore: Kranji Marshes ON026066 Sankar et al. (2022)
48 M. subaraji M. subaraji ZRC 1.13323 Singapore: Kranji Marshes ON026063 Sankar et al. (2022)
49 M. sumatrana M. sumatrana MZB 30594 Indonesia: Sumatra Selatan MN727065 Munir et al. (2020)
Our group
50 Kaloula pulchra Kaloula pulchra NMNS 3208 China KC822614 Blackburn et al. (2013)
51 Kaloula pulchra Mysticellus franki ZSI/WGRC/V/A/967 India: Kerala, Wayand MK285340 Garg and Biju (2019)
52 Kaloula pulchra Uperodon systoma SDBDU 2005.4723 India: Tamil Nadu: Kunnapattu MG557949 Garg and Biju (2019)

Morphological analyses

Measurements were taken using a digital caliper under a light dissecting microscope to the nearest 0.01 mm, subsequently rounded to 0.1 mm. The morphometrics of adults and character terminology followed Nguyen et al. (2020), including SVL: snout-vent length, HL: head length (from the back of mandible to tip of snout), HW: maximum head width (across angles of jaws), SL: snout length (from anterior corner of eye to tip of snout), NSD: distance from nostril to the tip of snout, END: distance from anterior corner of eye to the nostril, IND: internarial distance, IOD: interorbital distance, ED: eye diameter, UEW: maximum width of upper eyelid, TD: tympanum diameter, TYED: distance from anterior margin of tympanum to posterior corner of the eye, FLL: forearm length (from axilla to elbow), HAL: hand length (from elbow to the tip of third finger), FL1–4: finger length I–IV, OPTL: outer palmar tubercle length, IPTL: inner palmar tubercle length, NPL: nuptial pad length, FeL: femur length (from vent to knee), TbL: tibia length (from knee to tarsus), TbW: maximum tibia width, FoL: foot length (from tarsus to the tip of fourth toe), TL 1–5: toe length I–V, IMTL: inner metatarsal tubercle length, FD3D: maximal diameter of disk of finger III, and TD4D: maximal diameter of disk toe IV. Terminology for describing eye colouration in living individuals followed Glaw and Vences (1997); subarticular tubercle formulas and webbing formula followed those of Savage (1975). All measurements were taken on the right side of the examined specimen. Sex was determined by gonadal inspection following dissection.

Molecular phylogeny

We synthesized previously published sequences of the Micryletta steinegeri members from GenBank to estimate the phylogenetic relationships of the genus Micryletta and genetically identity samples referable to M. hekouensis. We focused on sequences for the mitochondrial 16S rRNA gene as it is phylogenetically informative for most Paddy frogs and has the largest availability of any gene for Micryletta. As the sequences of the three specimens (DTU 310-12) provided by Poyarkov et al. (2018) are too short to obtain a stable phylogenetic position, we obtained longer sequences of these three specimens and uploaded them to GenBank. We aligned the 16S sequences of 13 species of Micryletta; we used the sequences of Kaloula pulchra Gray, 1831; Mysticellus franki Garg & Biju, 2019; and Uperodon systoma (Schneider, 1799) to root the tree (GenBank accession numbers, voucher specimens, locality, and source information are summarized in Table 1).

Sequences were aligned using MUSCLE (Edgar 2004) integrated in MEGA 11 (Tamura et al. 2021) with default parameters. Genetic divergences (uncorrected p-distance) were calculated in MEGA 11. The best substitution models were selected using the Akaike Information Criterion (AIC) in ModelFinder (Kalyaanamoorthy et al. 2017). Maximum likelihood phylogenetic analysis was performed in IQ-TREE 1.6.12 (Nguyen et al. 2015) based on the TIM2+F+I+G4 model, and nodal support was estimated by 1,000 ultrafast bootstrap (UFB) replicates. Nodes with UFB values of 95 and above were considered significantly supported (Minh et al. 2013). Bayesian Inference was performed in MrBayes 3.2.7 (Ronquist et al. 2012) based on the GTR+F+I+G4 model. Two runs were performed simultaneously with four Markov chains starting from a random tree. The chains were run for 5,000,000 generations and sampled every 100 generations. The first 25% of the sampled trees were discarded as burn-in and then the remaining trees were used to estimate Bayesian posterior probabilities (BPPs). Nodes were considered well-supported if they had BPPs of 0.95 or higher (Huelsenbeck et al. 2001; Wilcox et al. 2002).

Results

The ML and BI analyses of 16S rRNA sequences recovered trees with similar topologies (Fig. 1). With respect to the position of M. hekouensis, our phylogenetic results largely conform to those of Poyarkov et al. (2018), Miller et al. (2021), Liu et al. (2021a) and Sankar et al. (2022). The reconstructed phylogenetic relationship indicates that four species, namely M. steinegeri, M. menglienica, M. immaculata, and M. hekouensis are nested within a single monophyletic clade M. steinegeri complex (Fig. 1).

Figure 1. 

Maximum Likelihood (ML) tree of Micryletta derived from the analysis of 16s mitochondrial DNA gene sequences. For voucher specimen information and GenBank accession numbers see Table 1. Numbers at tree nodes correspond to ML UFBS/BI PP support values, respectively. Photos by J.B Zhao, J.H. Yang, C.W. You, and N.A. Poyarkov.

The uncorrected p-distances of the 16s gene fragment among examined members of the M. steinegeri species groups are presented in Table 2. Six sequences of Micryletta spp (PP264232 [DTU 310], PP264231 [DTU 311], PP264230 [DTU 312], respectively, reported from Cuc Phuong NP., Ninh Binh Province as well as MH879843 [ZMMU NAP-3352-1], MH879844 [ZMMU NAP-33521–2], MH879845 [ZMMU NAP-3580], respectively, reported from Cat Ba NP., Hai Phong Province, Vietnam clustered with the type series of M. hekouensis from Nanxi Town, Hekou County, Honghe Prefecture, Yunnan Province, China, and were only 0.7% divergent from the type series of M. hekouensis.

Table 2.
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Uncorrected p-distances (%) of 16S rRNA sequences between the species of Micryletta.

Species 1 2 3 4 5 6 7 8 9 10 11 12 13
1 Micryletta aishani
2 Micryletta dissimulans 4.4
3 Micryletta erythropoda 4.8 7.4
4 Micryletta hekouensis (China) 3.6 5.0 6.5
5 Micryletta hekouensis (Vietnam) 3.0 4.7 6.3 0.7
6 Micryletta immaculata 4.3 6.3 6.8 3.9 3.5
7 Micryletta inornata 5.0 5.9 7.6 5.5 5.1 7.0
8 Micryletta lineata 3.4 6.0 3.1 4.6 4.4 5.4 6.3
9 Micryletta melanops 3.0 4.4 7.1 5.9 5.6 5.9 5.6 5.5
10 Micryletta menglienica 3.6 5.4 6.4 3.2 2.8 2.6 6.6 4.8 5.4
11 Micryletta nigromaculata 4.7 5.2 8.3 8.1 7.6 7.5 6.6 7.2 6.8 7.1
12 Micryletta steinegeri 3.6 4.8 6.7 3.1 2.8 3.6 5.5 5.1 6.5 2.8 7.2
13 Micryletta subaraji 4.6 5.2 7.5 6.6 6.3 6.9 2.9 6.4 7.1 6.5 7.9 7.1
14 Micryletta sumatrana 5.9 5.1 9.1 6.7 6.3 7.8 8.1 7.4 6.2 7.1 5.5 6.0 8.9

Furthermore, we also examined the morphology of other Micryletta specimens previously registered as Micryletta cf. inornata or M. cf. steinegeri from Ninh Binh and Hai Phong including five specimens DTU 310–312 as well as ZMMU NAP-3580, ZMMU NAP-3580 and found morphological similarities with M. hekouensis. These results support our hypothesis that previous records of M. inornata (restricted to Sumatra Island in Indonesia, southern Myanmar) and M. steinegeri (restricted to Taiwan Island in China) in Northern Vietnam (Ninh Binh and Hai Phong province), should be referred to as M. hekouensis. Therefore, we extend the distribution of Micryletta hekouensis to Vietnam and provide an expanded diagnosis and description.

Taxonomic account

Micryletta hekouensis

Table 3, Fig. 2

Micryletta cf. inornata – Poyarkov et al. (2018: 1–27, in part); Miller et al. (2021: 248, in part).

Micryletta cf. steinegeri – Poyarkov et al. (2021a: 42–43, in part).

Micryletta hekouensis – Liu, Hou, Mo & Rao (2021: 133).

Micryletta hekouensis – Sankar et al. (2022: 462).

Holotype

KIZ 20210510, adult male collected by Shuo Liu on 15 May 2021. Type locality: Nanxi Village, Nanxi Town, Hekou County, Honghe Prefecture, Yunnan Province, China (22°38'17"N, 103°59'8"E; elevation 350 m a.s.l.).

Figure 2. 

The Micryletta hekouensis alive: from Cuc Phuong NP., Ninh Binh, Vietnam. A, B. DTU 316, adult male; C. DTU 311, adult male; D, E. DTU 317, adult female); from Cat Ba NP, Hai Phong, Vietnam; F, G. ZMMU NAP-3580, adult female); from Hekou, Yunnan, China; H. KIZ 20210510, holotype, adult male; I. KIZ 20210511, paratype, subadult female). Photos by: TV. Nguyen (A–E), NA. Poyarkov (F, G), and L. Shuo (H–K).

Suggested name in Vietnamese

Nhái bầu Hà khẩu.

Specimens examined

(n = 12). Two adult males DTU 310, 316 and four adult females DTU 309, 311–312, 317 from Cuc Phuong NP, Ninh Binh Province, Vietnam (ca. 20.2594°N, 105.6928°E; elevation of 160–215 m a.s.l) collected by Tan Van Nguyen on 3 June 2018. Three adult males ZMMU NAP-2176, ZMMU NAP-3580, ZMMU NAP-5572 and three adult females ZMMU NAP-3352, ZMMU NAP-3574, ZMMU NAP-5574 from Cat Ba NP, Hai Phong Province, Vietnam (ca. 20.8123°N, 106.9988°E; elevation of 90 m a.s.l.) collected by Nikolay A. Poyarkov in October 2013.

Table 3.
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Measurements (in mm) of the specimens of Micryletta hekouensis in Vietnam.

Specimen number Sex SVL HW HL SL ED NSD END UEW IOD IND FLL HAL fd3D FeL TbL FoL TbW td4D IMTL
DTU 310 M 22.2 6.9 6.4 2.5 3.0 1.3 1.6 2.0 2.9 2.3 5.1 11.4 0.7 9.5 9.8 16.3 3.0 0.6 0.9
DTU 316 M 24.1 7.2 7.2 2.9 3.0 1.3 1.9 2.0 3.1 2.3 6.0 14.0 0.5 11.6 12.5 20.3 3.3 0.5 0.9
ZMMU NAP-2176 M 21.6 6.7 7.2 2.8 2.1 1.8 1.6 1.8 2.7 1.6 5.5 10.8 0.5 8.4 10.5 16.2 2.5 0.5 0.7
ZMMU NAP-3580 M 20.0 6.2 6.6 2.7 2.5 1.0 1.4 1.6 3.0 2.2 6.1 9.8 0.5 8.9 9.9 14.9 1.9 0.6 0.6
ZMMU NAP-5572 M 23.1 7.9 7.1 3.7 3.0 0.8 2.2 1.3 4.1 1.9 7.4 12.6 0.5 11.6 13.2 19.6 2.4 0.6 0.5
Min 20.0 6.2 6.4 2.5 2.1 0.8 1.4 1.3 2.7 1.6 5.1 9.8 0.5 8.4 9.8 14.9 1.9 0.5 0.5
Max 22.2 6.9 6.4 2.5 3.0 1.3 1.6 2.0 2.9 2.3 5.1 11.4 0.7 9.5 9.8 16.3 3.0 0.6 0.9
Mean 22.2 7.0 6.9 2.9 2.7 1.2 1.7 1.7 3.1 2.1 6.0 11.7 0.5 10.0 11.2 17.5 2.6 0.6 0.7
SD 1.54 0.63 0.36 0.47 0.40 0.37 0.33 0.33 0.53 0.28 0.85 1.62 0.07 1.49 1.56 2.34 0.52 0.07 0.17
DTU 309 F (gravid) 28.9 7.9 7.7 3.2 3.2 1.3 1.9 2.2 3.6 2.5 6.5 14.6 0.7 12.5 13.0 19.8 3.1 0.5 1.6
DTU 311 F (gravid) 27.1 7.4 7.6 2.7 3.1 1.3 1.7 1.8 3.4 2.3 5.8 13.3 0.7 11.2 11.7 19.7 3.8 0.8 1.1
DTU 312 F (gravid) 29.5 7.6 7.1 2.8 3.3 1.3 1.8 1.8 3.3 2.6 5.3 13.4 0.7 12.4 12.6 19.3 3.6 0.6 1.0
DTU 317 F (gravid) 28.7 9.4 8.8 3.3 3.2 1.6 2.1 2.3 3.0 2.5 6.9 15.0 0.6 13.6 13.3 21.7 3.6 0.7 1.0
ZMMU NAP-3352 F 25.4 8.9 8.0 3.5 2.9 1.5 2.3 1.7 3.5 2.6 6.5 14.0 0.4 11.5 14.0 20.6 2.7 0.4 0.6
ZMMU NAP-3574 F 26.0 9.6 7.9 3.6 3.1 1.4 2.0 2.0 3.9 2.4 7.4 14.0 0.4 12.9 13.0 20.5 2.9 0.4 0.8
ZMMU NAP-5574 F 26.8 9.5 8.5 3.3 3.2 0.9 1.7 1.6 4.1 2.4 7.5 15.7 0.6 11.6 13.1 21.5 2.8 0.5 0.4
Min 25.4 7.4 7.1 2.7 2.9 0.9 1.7 1.6 3.0 2.3 5.3 13.3 0.4 11.2 11.7 19.3 2.7 0.4 0.4
Max 29.5 9.6 8.8 3.6 3.3 1.6 2.3 2.3 4.1 2.6 7.5 15.7 0.7 13.6 14.0 21.7 3.8 0.8 1.6
Mean 27.5 8.6 8.0 3.2 3.1 1.3 1.9 1.9 3.6 2.5 6.6 14.3 0.6 12.3 13.0 20.4 3.2 0.6 0.9
SD 1.55 0.96 0.58 0.34 0.13 0.22 0.23 0.26 0.38 0.11 0.80 0.88 0.14 0.86 0.68 0.92 0.46 0.14 0.37

Variation based on examined specimens from Vietnam

(n = 12). According to the original description of Liu et al. (2021a) the species M. hekouensis is a small-sized species of Micryletta with SVL 20.5 mm in adult male (Holotype, KIZ 20210510) and SVL 20.8 mm in adult female (Paratype, KIZ 20210511). However, the specimens from Vietnam exhibit generally larger body sizes: SVL 20.0–24.1 mm in males (n = 5), 25.4–29.5 mm in females (n = 7). Therefore, we propose that the paratype specimen should be considered a subadut female, and that M. hekouensis in fact represents a medium-sized species within its genus. Moreover, the TbL/SVL ratio in female specimens from Vietnam (0.43–0.55) was also slightly larger than in the paratype female from China (0.40). Furthermore, Liu et al. (2021a) reported this species to have a small rounded and distinct tympanum; however, the specimens from Vietnam had the tympanum hidden. It is not clear if the observed morphological differences between the type series of M. hekouensis from China and the series from Vietnam represent the actual intraspecific variation, or might result from the different state of specimen preservation, the reproductive condition of the specimens, or the observer effect. However, though we acknowledge the limitations of mtDNA markers for species delimitation in amphibians (e.g., Velo-Antón et al. 2023), the overall similarity of the Chinese and Vietnamese specimens of M. hekouensis in external morphological traits and coloration strongly suggest that they belong to the same species.

Additionally, the Vietnamese specimens examined were characterized by: habitus relatively slender; head small and triangular, width approximately equal to length (HW/HL 0.93–1.11 in males, 0.97–1.22 in females); snout abruptly rounded in dorsal view and slightly acuminate in profile, projecting beyond margin of lower jaw; eyes relatively small, slightly protuberant, pupil oval, transverse, eye diameter slightly equal to snout length (ED/SL 0.75–1.20 in males, 0.83–1.18 in females). Top of the head flat, canthus rostralis rounded and distinct; loreal region weakly concave; nostril round, closer to tip of snout than to eye; interorbital distance greater than internarial distance (IOD/IN 1.26–2.16 in males, 1.20–1.71 in females) and upper eyelid width (IOD/UEW 1.45–1.91 in males, 1.30–1.89 in females). Tympanum and supratympanic fold indistinct. Choanae rounded; vomerine teeth absent; opening of vocal sac long cleft; tongue oval, with no notch at posterior tip.

Forelimbs : Forearm length ca. three times shorter than hand length (FLL/HAL 0.43–0.62 in males, 0.40–0.53 in females). Fingers slender with no webbing, rounded in cross-section, no lateral fringes; relative finger lengths: I<II<IV<III; tips of fingers round and not dilated; subarticular tubercles on fingers distinct, rounded and prominent, formula: 1, 1, 2, 2; supernumerary tubercles on palm present and developed; three metacarpal tubercles, inner one rounded and smallest, median one rounded and almost directly in front of oval outer one; two rounded and one elongated prominent supernumerary palmar tubercles on the base of fingers II–IV, respectively; nuptial pad absent.

Hindlimbs : Tibia slightly longer than thigh (FeL/TbL 0.80–0.97 in males, 0.82–1.02), approximately three times longer than wide (TbL/TbW 3.27–5.50 in males, 3.08–5.19 in females); tibiotarsal articulation of adpressed limb reaching eye; foot longer than tibia (TbL/FoL 0.60–0.67 in males, 0.59–0.68 in females). Relative toe lengths: I<II<V<III<IV; tarsal fold absent; tips of toes round and not dilated, slightly wider than those of fingers; webbing between toes absent; subarticular tubercles on toes oval and prominent, formula: 1, 1, 2, 3, 2; dermal ridges present under 2nd to 4th toes but indistinct; inner metatarsal tubercle rounded, prominent, and small; outer metatarsal tubercle absent.

Dorsal skin scattered with small tubercles on dorsum of body, flanks, and hindlimbs, dorsal skin of forelimbs smooth; subtle longitudinal median ridge present on dorsum; dorsolateral fold absent; lateral sides of head smooth; ventral skin of body and limbs smooth.

Colouration in life

Coloration varies greatly, dorsum of body purple brown, blueish grey, or dark brown with two indistinct parallel longitudinal grey stripes on back. Dorsum of forelimbs light yellow, dorsum of hindlimbs the same color as dorsum of body, no bands on dorsum of limbs. Upper lip white. Ventral side of head, body, and limbs greyish brown, purple grey or pinkish brown. Chin region brownish black, males usually have a darker one than females, white marbling patterns on chest and belly, some white spots on chin region and ventral side of limbs. Iris bicolored, with upper third bronze and lower two-thirds brownish black.

Revised diagnosis

Medium-sized within genus Micryletta (SVL 20.0–24.1 mm in males, 25.4–29.5 mm in females); areas above canthus rostralis, upper eyelids, areas posterior to eyelids, and dorsum of upper arms golden, other parts of dorsum almost solid black or yellowish grey with brownish black stripes; lateral sides of the head and body black or yellowish grey, a white stripe from lower front of eye along upper lip back to anterior forelimb insertion; ventral side of body and limbs pink brown, chin region in adult males brownish black, small and irregular white marbling patterns on chest and lateral belly; tympanum indistinct; supratympanic fold indistinct; outer metatarsal tubercle absent; webbing between toes absent; tibiotarsal articulation adpressed limb reaching level of eye (data from Liu et al. (2021) and this study).

Comparisons

We summarize the main characters separating Micryletta hekouensis from the other twelve species of the genus Micryletta in Suppl. material 1. In Vietnam, previously this species was often recorded under the names M. steinegeri or M. inornata, therefore we focused on comparing the morphological characteristics of Micryletta hekouensis with these two species. Micryletta hekouensis differs from M. steinegeri by having:venter without dark patterns (vs. with greyish white and brown spots); webbing between toes absent (vs. rudimentary webbing); tibiotarsal articulation adpressed limb reaching level of eye (vs. reaching to tympanum). Micryletta hekouensis differs from M. inornata sensu stricto by having: lager body size in females (SVL 25.4–29.5 mm vs. 19.5 mm); ventral side of body and limbs pinkish brown or pinkish grey with small and irregular white marbling patterns on chest and lateral belly (vs. reddish grey without mottling, nearly immaculate, or chin, chest, and lateral belly with a few dark marbling patterns).

Distribution

Micryletta hekouensis was previously known only from Nanxi Town, Hekou County, Honghe Prefecture, Yunnan Province, China (Liu et al. 2021). We here add further records of this species in Vietnam (Ninh Binh and Hai Phong provinces). The new location in Cat Ba NP is situated ca. 335 airline kilometers southeast of the type locality. Given the geographic proximity and distribution patterns of limestone-associated herpetofauna in Vietnam (see Poyarkov et al. 2021a, 2023), M. hekouensis likely occurs in several limestone karst massifs of Northern Vietnam; in particular, records from Quang Ninh, Lang Son and Bac Giang provinces of Northeastern Vietnam, as well as from Hoa Binh, Ha Nam, and Thanh Hoa provinces of Northwestern Vietnam are anticipated.

Natural history notes

Prior to this study, biological data of Micryletta hekouensis were very limited; it was only reported from an altitude of 350 m a.s.l. (Liu et al. 2021). The species appears to be closely associated with karstic habitats (Poyarkov et al. 2018; Liu et al. 2021). In Cuc Phuong NP, the frogs were observed from 16:00 to 20:00 h under the dead leaves on the ground. Other species of microhylids recorded syntopically with Micryletta hekouensis in Cuc Phuong NP included Kalophrynus interlineatus (Blyth, 1855), Glyphoglossus cf. yunnanensis (Boulenger, 1919), Kaloula pulchra Gray, 1831, Microhyla berdmorei (Blyth, 1856), M. butleri Boulenger, 1900, M. cf. heymonsi Vogt, 1911, M. mukhlesuri Hasan, Islam, Kuramoto, Kurabayashi & Sumida, 2014, M. pulchra (Hallowell, 1861), Micryletta nigromaculata Poyakov, Nguyen, Duong, Gorin & Yang, 2017, and Vietnamophryne cf. orlovi Poyarkov, Suwannapoom, Pawangkhanant, Aksornneam, Duong, Korost & Che, 2018. In Cat Ba NP, the frogs were observed from 16:00 to 20:00 h hiding between small pieces of limestone rocks. Other species of microhylids recorded syntopically with Micryletta hekouensis in Cat Ba NP included Kaloula pulchra, Microhyla butleri, M. fissipes Boulenger 1884, M. cf. heymonsi, M. pulchra, Micryletta nigromaculata. We also recorded gravid females of M. hekouensis in June in Cuc Phuong, but other reproduction biology data, such as advertisement call, tadpole morphology, as well as diet of the species remains unknown. It is remarkable that in both localities of Micryletta hekouensis in Vietnam, this species was recorded in syntopy with M. nigromaculata, another species of the genus Micryletta strongly associated with limestone karst formations of northern Vietnam.

Discussion

In this study we re-examined specimens reported by Poyakov et al. (2018, 2021) from karstic habitats in northern Vietnam (Ninh Binh and Hai Phong Provinces) that had previously been assigned to Micryletta cf. inornata or M. cf. steinegeri and found that all of these should be assigned to the recently described Micryletta hekouensis, representing the first record of this species in Vietnam. The discovery of Micryletta hekouensis in this study raises the known number of Micryletta species in Vietnam to five, with two species endemic to this country, namely M. melanops and M. nigromaculata. Consequently, we suggest to remove Micryletta steinegeri from the fauna of Vietnam.

Future studies reassessing the taxonomy and distribution of populations of Micryletta inornata sensu lato in Vietnam as well as other countries of the Indochinese Region (Laos, Cambodia, Thailand) are required for clarification. Until this work, two species of Micryletta, previously confused with M. inornata were considered to be endemic to China: M. menglienica (until now known only from two locations in Menglian and Mengla counties, Yunnan Province, China) and Micryletta immaculata (presently considered to be endemic to Hainan Island, China) (Liu et al. 2021; Poyarkov et al. 2021b; Yang and Poyarkov 2021; Yeung et al. 2023). In our molecular study, we found that populations of M. cf. inornata reported from Ha Tinh Province, Vietnam and Khammouan Province, Laos, were clustered with M. immaculata with minimal genetic distance among them (p = 0.9–2.3%). Meanwhile, populations of M. cf. inornata from Phrae and Chiang Mai provinces, Thailand and Luangprabang Province, Laos were grouped with M. menglienica and were also found to be genetically very closely related to it (p = 0.2–1.5%). Our results suggest that these two species may have a wider distribution than currently recorded. Micryletta immaculata is likely distributed in southern China, in northern and central Vietnam, central Laos, while M. menglienica likely inhabits southern Yunnan, northern Vietnam, northern Laos, northern Thailand, and possibly also can be found in eastern Myanmar (see Fig. 3). Therefore, re-examination of specimens previously reported as M. inornata as well as additional specimens from other locations within the Indochinese Region are required. As noted above, mtDNA markers alone cannot serve as a solid basis for species identification (Solovyeva et al. 2023; Velo-Antón et al. 2023); therefore a thorough examination of phenotypic and multilocus nuclear data is required to obtain a more comprehensive understanding of Micryletta diversity and distribution in Indochina.

Figure 3. 

Distribution ranges of the species of the Micryletta steinegeri complex. Notes: numbers indicate different localities where the species have been recorded (see Suppl. material 2 for the details of localities)

Micryletta hekouensis is to date known only from two national parks in Northern Vietnam and one region in southern Yunnan; in all three localities these frogs were recorded from a very specific limestone-associated habitat. It is important to notice that karst massifs in Vietnam, as well as in other parts of Southeast Asia, are facing ongoing severe threats from progressing deforestation and destruction for cement manufacturing purposes; their continued exploitation for limestone cannot be stopped (Clements et al. 2006; Poyarkov et al. 2021a, 2023). Uncontrolled destruction of limestone massifs may represent the major threatening factor for the species. Although the actual distribution and population status of Micryletta hekouensis remains unknown, it is obvious that the species is restricted to isolated highly endangered limestone karst massifs of northern Vietnam and southern Yunnan. Additional surveys in other limestone areas of Northern Vietnam as well as southern Yunnan are essential for elucidating the biology of the species. Our new findings of additional populations of M. hekouensis in Vietnam expanded its extent of occurrence (EOO) to 23374 km2. Given the available information, we suggest Micryletta hekouensis to be considered Near Threatened (NT) following IUCN’s Red List categories (IUCN 2019).

We also take this opportunity to comment on a recent paper by Pham et al. (2023), who reported on range extension and dietary ecology of Micryletta nigromaculata from Son La Province of Northwestern Vietnam. Though the authors claim that the morphological characteristics of the specimens from Son La Province they examined “match well with the diagnosis of Micryletta nigromaculata” (Pham et al. 2023: p. 134) this statement is largely misleading, as the photos presented in their paper allow to unambiguously identify this population as M. menglienica. For example, in two specimens depicted in Fig. 1 of Pham et al. (2023) white markings are distinctly visible on their upper lips (a feature never observed in M. nigromaculata), a light hour-glass shaped pattern on dorsum is absent (always present in M. nigromaculata), and body flanks have wide continuous dark bands (vs. black blotches of irregular shape in M. nigromaculata) (see Poyarkov et al. 2018). Therefore, even by judging the published photos of both species, the Son La population can hardly be identified as M. nigromaculata. Herein, we would like to report that the Son La population described as “M. nigromaculata” by Pham et al. (2023) was misidentified and further stress the necessity of accurate comparison of specimens and diagnostic characters with museum vouchers and published information. Furthermore, as Micryletta species are often hard to identify by morphological data alone (though not in the case of M. nigromaculata), the authors should verify their identification by the means of DNA barcoding, especially in cases when they are not sure about the species identification.

Acknowledgements

We are deeply grateful to Jiangbo Zhao, Jian-Huan Yang (China) and Chung-Wei You (Taiwan) for providing photos of Micryletta spp. We also warmly thank Ngoc Quynh Nguyen (SIFASV, Vietnam) for help in the preparation of the figures. We are grateful to Christopher Oldnall for English proofreading and linguistic help. We thank Günter Gollmann and three anonymous reviewers for kindly reviewing a previous version of the manuscript. NAP and AVT are grateful to Andrei N. Kuznetsov, Svetlana P. Kuznetsova (JVRT STRC), Hoi Dang Nguyen (JVRT STRC), and Leonid P. Korzoun (MSU) for support and organization of fieldwork. This research is supported in part by the Rufford Foundation (Grant No. 39897-1) and the Russian Science Foundation (RSF grant No. 22-14-00037, molecular analyses).

References

  • Alhadi F, Hamidy A, Farajallah A, Munir M, Atmaja VY, Garg S, Biju SD, Smith EN (2019) Rediscovery of Micryletta inornata (Boulenger, 1890) from Sumatra: redescription, molecular identity and taxonomic implications. Zootaxa 4613(1): 111–126. https://doi.org/10.11646/zootaxa.4613.1.5
  • Blackburn DC, Siler CD, Diesmos AC, McGuire JA, Cannatella DC, Brown RM (2013) An adaptive radiation of frogs in a Southeast Asian island archipelago. Evolution 67(9): 2631–2646. https://doi.org/10.1111/evo.12145
  • Boulenger GA (1890) List of the reptiles, batrachians, and freshwater fishes collected by Professor Moesch and Mr. Iversen in the district of Deli, Sumatra. Proceedings of the Zoological Society of London 1890: 30–39.
  • Das A, Garg S, Hamidy A, Smith EN, Biju SD (2019) A new species of Micryletta frog (Microhylidae) from Northeast India. PeerJ 7: e7012. https://doi.org/10.7717/peerj.7012
  • De Sá RO, Streicher JW, Sekonyela R, Forlani MC, Loader SP, Greenbaum E, Richards S, Haddad CFB (2012) Molecular phylogeny of microhylid frogs (Anura: Microhylidae) with emphasis on relationships among New World genera. BMC Evolutionary Biology 12: е241. https://doi.org/10.1186/1471-2148-12-241
  • Edgar RC (2004) MUSCLE: multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Research 32(5): 179–1797. https://doi.org/10.1093/nar/gkh340
  • Frost DR (2024) Amphibian Species of the World: an Online Reference. Version 6.0 (last accessed 1 January 2024). Electronic Database accessible at http://research.amnh.org/herpetology/amphibia/index. html. American Museum of Natural History, New York, USA.
  • Glaw F, Vences M (1997) Anuran eye colouration: definitions, variation, taxonomic implications and possible functions. In: Böhme W, Bischoff W, Ziegler T (Eds) Herpetologia Bonnensis. SEH Proceedings, Bonn, 125–138.
  • Hedges SB (1994) Molecular evidence for the origin of birds. Proceedings of the National Academy of Sciences of the United States of America 91(7): 2621–2624. https://doi.org/10.1073/pnas.91.7.2621
  • Huelsenbeck JP, Ronquist F, Nielsen R, Bollback JP (2001) Bayesian inference of phylogeny and its impact on evolutionary biology. Science 294(5550): 2310–2314. https://doi.org/10.1126/science.1065889
  • Kalyaanamoorthy S, Minh BQ, Wong TKF, von Haeseler A, Jermiin LS (2017) ModelFinder: fast model selection for accurate phylogenetic estimates. Nature Methods 14: 587–589. https://doi.org/10.1038/nmeth.4285
  • Kurabayashi A, Matsui M, Belabut DM, Yong H, Ahmad N, Sudin A, Kuramoto M, Hamidy H, Sumida M (2011) From Antarctica or Asia? New colonization scenario for Australian-New Guinean narrow mouth toads suggested from the findings on a mysterious genus Gastrophrynoides. BMC Evolutionary Biology 11(1): е175. https://doi.org/10.1186/1471-2148-11-175
  • Matsui M, Hamidy A, Belabut DM, Ahmad N, Panha S, Sudin A, Khonsue W, Oh HS, Yong HS, Jiang J, Nishikawa K (2011) Systematic relationships of Oriental tiny frogs of the family Microhylidae (Amphibia, Anura) as revealed by mtDNA genealogy. Molecular Phylogenetics and Evolution 61(1): 167–176. https://doi.org/10.1016/j.ympev.2011.05.015
  • Matsui M, Shimada T, Liu WZ, Maryati M, Khonsue W, Orlov N (2006) Phylogenetic relationships of Oriental torrent frogs in the genus Amolops and its allies (Amphibia, Anura, Ranidae). Molecular Phylogenetics and Evolution 38(3): 659–666. https://doi.org/10.1016/j.ympev.2005.11.019
  • Miller AH, Zug GR, Wogan GOU, Lee JL, Mulcahy DG (2021) Phylogeny, diversity, and distribution of Micryletta (Anura: Microhylidae) in Myanmar. Ichthyology & Herpetology 109(1): 245–257. https://doi.org/10.1643/h2020100
  • Minh BQ, Nguyen MAT, von Haeseler A (2013) Ultrafast approximation for phylogenetic bootstrap. Molecular Biology and Evolution 30(5): 1188–1195. https://doi.org/10.1093/molbev/mst024
  • Munir M, Hamidy A, Matsui M, Kusrini MD, Nishikawa K (2020) A new species of Micryletta (Amphibia: Anura) from Sumatra, Indonesia. Zoological Science 37(3): 295–301. https://doi.org/10.2108/zs200006
  • Nguyen LT, Schmidt HA, von Haeseler A, Minh BQ (2015) IQ-TREE: a fast and effective stochastic algorithm for estimating maximum-likelihood phylogenies. Molecular Biology and Evolution 32: 268–274. https://doi.org/10.1093/molbev/msu300
  • Nguyen TV, Duong TV, Luu KT, Poyarkov NA (2020) A new species of Kurixalus (Anura: Rhacophoridae) from northern Vietnam with comments on the biogeography of the genus. Journal of Natural History 54(1–4): 195–223. https://doi.org/10.1080/00222933.2020.1728411
  • Peloso PLV, Frost DR, Richards SJ, Rodrigues MT, Donnellan S, Matsui M, Raxworthy CJ, Biju SD, Lemmon EM, Lemmon AR (2016) The impact of anchored phylogenomics and taxon sampling on phylogenetic inference in narrow-mouthed frogs (Anura, Microhylidae). Cladistics 32(2): 113–140. https://doi.org/10.1111/cla.12118
  • Pham AV, Nguyen TQ, Sung NB, Tran TV, Le MD, Ngo HN (2023) New record and dietary ecology of an endangered amphibian species, Micryletta nigromaculata Poyarkov, Nguyen, Duong, Gorin & Yang, 2018, from Vietnam. Acta Herpetologica 18(2): 131–138. https://doi.org/10.36253/a_h-14516
  • Poyarkov NA, Nguyen TV, Duong TV, Gorin VA, Yang JH (2018) A new limestone-dwelling species of Micryletta (Amphibia, Anura, Microhylidae) from northern Vietnam. PeerJ 6: e5771. https://doi.org/10.7717/peerj.5771
  • Poyarkov NA, Nguyen TV, Popov ES, Geissler P, Pawangkhanant P, Neang T, Suwannapoom C, Orlov NL (2021a) Recent progress in taxonomic studies, biogeographic analysis and revised checklist of Amphibians in Indochina. Russian Journal of Herpetology 28(3A): 1–110. https://doi.org/10.30906/1026-2296-2021-28-3A-1-110
  • Poyarkov NA, Nguyen TV, Popov ES, Geissler P, Pawangkhanant P, Neang T, Suwannapoom C, Ananjeva NB, Orlov NL (2023) Recent progress in taxonomic studies, biogeographic analysis and revised checklist of Reptilians in Indochina. Russian Journal of Herpetology 30(5): 255–476. https://doi.org/10.30906/1026-2296-2023-30-5-255-476
  • Ronquist F, Teslenko M, Mark PVD, Ayres DL, Darling A, Hohna S, Larget B, Liu L, Suchard MA, Huelsenbeck JP (2012) MrBayes 3.2: Efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic Biology 61(3): 539–542. https://doi.org/10.1093/sysbio/sys029
  • Savage JM (1975) Systematics and distribution of the Mexican and Central American stream frogs related to Eleutherodactylus rugulosus. Copeia 1975(2): 254–306. https://doi.org/10.2307/1442883
  • Solovyeva EN, Dunayev EA, Nazarov RA, Bondarenko DA, Poyarkov NA (2023) COI-barcoding and species delimitation assessment of toad-headed agamas of the genus Phrynocephalus (Agamidae, Squamata) reveal unrecognized diversity in Central Eurasia. Diversity 15: 149. https://doi.org/10.3390/d15020149
  • Suwannapoom C, Nguyen TV, Pawangkhanant P, Gorin VA, Chomdej S, Che J, Poyarkov NA (2020) A new species of Micryletta (Amphibia: Microhylidae) from southern Thailand. Zoological Research, 41: 581–588. https://doi.org/10.24272/j.issn.2095-8137.2020.139
  • Tarkhnishvili DN (1994) Amphibian communities of the southern Viet Nam: preliminary data. Journal of the Bengal Natural History Society 13(1): 3–62.
  • Velo-Antón G, Chambers EA, Poyarkov NA, Canestrelli D, Bisconti R, Naumov B, Fernández Benéitez MJ, Borisenko A, Martínez-Solano I (2023) COI barcoding provides reliable species identification and pinpoints cryptic diversity in Western Palearctic amphibians. Amphibia-Reptilia 44(4): 399–413. https://doi.org/10.1163/15685381-bja10148
  • Wilcox TP, Zwickl DJ, Heath TA, Hillis DM (2002) Phylogenetic relationships of the Dwarf Boas and a comparison of Bayesian and bootstrap measures of phylogenetic support. Molecular Phylogenetics and Evolution 25: 361–371. https://doi.org/10.1016/S1055-7903(02)00244-0
  • Yeung HY, Zhao YB, Yang JH (2023) Confirmation on the occurrence of Micryletta menglienica (Yang & Su, 1980) (Anura: Microhylidae) in Mengla County, Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China. Sauria 45(2): 69–75.

Supplementary materials

Supplementary material 1 

Morphological comparison of Micryletta hekouensis with 13 currently recognized species of the genus Micryletta

Tan Van Nguyen, Shuo Liu, Vy The Tran, Thinh Gia Tran, Alexei V. Trofimets, Vinh Quang Dau, Nikolay A. Poyarkov

Data type: docx

Explanation note: Symbols: (1): SVL (Males, mm); (2) SVL (Females, mm); (3) Iris color; (4) Snout in dorsal view; (5) Foot webbing; (6) Outer metatarsal tubercle; (7) Tibiotarsal articulation of adpressed limb reaching up to; (8) Supratympanic fold; (9) Dorsal skin texture; (10) Dorsal coloration; (11) Dorsal color pattern; (12) Coloration of lateral sides of the head; (13) Coloration of flanks; (14) Ventral coloration.

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.
Download file (20.41 kb)
Supplementary material 2 

List of localities of the Micryletta steinegeri group complex appearing on Fig. 3

Tan Van Nguyen, Shuo Liu, Vy The Tran, Thinh Gia Tran, Alexei V. Trofimets, Vinh Quang Dau, Nikolay A. Poyarkov

Data type: docx

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.
Download file (15.38 kb)
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