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| Microhyla irrawaddy
Poyarkov, Gorin, Zaw, Kretova, Gogoleva, Pawangkhanant & Che, 2019
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Abstract
We present a morphological and molecular assessment of the Microhyla fauna of Myanmar based on new collections from central (Magway Division) and northern (Kachin State) parts of the country. In total, six species of Microhyla are documented, including M. berdmorei, M. heymonsi, M. butleri, M. mukhlesuri and two new species described from the semi-arid savanna-like plains of the middle part of the Irrawaddy (Ayeyarwady) River Valley. We used a 2 481-bp long 12S rRNA–16S rRNA fragment of mtDNA to hypothesize genealogical relationships within Microhyla. We applied an integrative taxonomic approach combining molecular, morphological, and acoustic lines of evidence to evaluate the taxonomic status of Myanmar Microhyla. We demonstrated that the newly discovered populations of Microhyla sp. from the Magway Division represent two yet undescribed species. These two new sympatric species are assigned to the M. achatina species group, with both adapted to the seasonally dry environments of the Irrawaddy Valley. Microhyla fodiens sp. nov. is a stout-bodied species with a remarkably enlarged shovel-like outer metatarsal tubercle used for burrowing and is highly divergent from other known congeners (P-distance≥8.8%). Microhyla irrawaddy sp. nov. is a small-bodied slender frog reconstructed as a sister species to M. kodial from southern India (P-distance=5.3%); however, it clearly differs from the latter both in external morphology and advertisement call parameters. Microhyla mukhlesuri is reported from Myanmar for the first time. We further discuss the morphological diagnostics and biogeography of Microhyla species recorded in Myanmar.
Key words: Narrow-mouth frogs, Burma, Indochina, Magway, Kachin, Biodiversity, Taxonomy, mtDNA, Morphology, Acoustics, Advertisement call
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Figure 1 Map of Myanmar (A) showing geographic location of survey sites, including the close-up of Irrawaddy River Valley near Pakokku, Magway Division (B) Colors of localities correspond to B those used in Figure 3. Photo shows female Microhyla irrawaddy sp. nov.
Photo by Nikolay A. Poyarkov.
Map data – courtesy of Google Maps (2018).
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Figure 3 Bayesian inference tree of Microhyla derived from analysis of 2 481 bp long alignment of 12S rRNA, tRNAVal, and 16S rRNA gene fragments For voucher specimen information and GenBank accession Nos. see Table 1. Red and blue denote new species of Microhyla from Myanmar (see Figure 1). Numbers at tree nodes correspond to BI PP/ML BS support values, respectively. Outgroup taxa not shown.
Photos showing six species of Microhyla recorded from Myanmar
taken by Nikolay A. Poyarkov.
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| Figure 2 Species of Microhyla encountered during our herpetological surveys in the Magway Division and Kachin State of Myanmar. A: Male Microhyla irrawaddy sp. nov. from Pakokku, Magway (paratype); B: Female Microhyla irrawaddy sp. nov. from Kan Pauk, Magway (paratype); C: Male Microhyla fodiens sp. nov. from Kan Pauk, Magway (holotype); D: Male M. mukhlesuri from Pakokku, Magway; E: Male M. mukhlesuri from Ingyin Taung Mt., Kachin; F: Male M. heymonsi from Ingyin Taung Mt., Kachin; G: Male M. butleri from Ingyin Taung Mt., Kachin.
Photos by Nikolay A. Poyarkov.
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| Figure 7 Natural habitats of Microhyla in Myanmar. A: Natural habitat of Microhyla fodiens sp. nov. at Kan Pauk village, Magway (type locality), green hill in background is Shinma Taung Mountain; B: Breeding habitat of Microhyla irrawaddy sp. nov. from Pakokku, Magway (type locality); C: Natural habitat of M. heymonsi, M. butleri, and M. mukhlesuri in bamboo forest on slopes of Ingyin Taung Mt., Indawgyi Lake region, Kachin.
Photos by Parinya Pawangkhanant.
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Figure 2 Species of Microhyla encountered during our herpetological surveys in the Magway Division and Kachin State of Myanmar.
A: Male Microhyla irrawaddy sp. nov. from Pakokku, Magway (paratype); B: Female Microhyla irrawaddy sp. nov. from Kan Pauk, Magway (paratype); C: Male Microhyla fodiens sp. nov. from Kan Pauk, Magway (holotype); D: Male M. mukhlesuri from Pakokku, Magway; E: Male M. mukhlesuri from Ingyin Taung Mt., Kachin; F: Male M. heymonsi from Ingyin Taung Mt., Kachin; G: Male M. butleri from Ingyin Taung Mt., Kachin.
Figure 7 Natural habitats of Microhyla in Myanmar.
B: Breeding habitat of Microhyla irrawaddy sp. nov. from Pakokku, Magway (type locality);
A: Natural habitat of Microhyla fodiens sp. nov. at Kan Pauk village, Magway (type locality), green hill in background is Shinma Taung Mountain;
C: Natural habitat of M. heymonsi, M. butleri, and M. mukhlesuri in bamboo forest on slopes of Ingyin Taung Mt., Indawgyi Lake region, Kachin.
Photos by Nikolay A. Poyarkov & Parinya Pawangkhanant.
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| Figure 6 Holotype of Microhyla fodiens sp. nov. (ZMMU A5960), male, in life. A: Dorsolateral view in situ; B: Lateral view of head; C: Posterior view of thighs and inguinal region showing regular black markings. Photos by Nikolay A. Poyarkov (A) and Parinya Pawangkhanant (B, C). |
Microhyla fodiens sp. nov.
Chresonymy:
Microhyla rubra – (?) Parker, 1934, p. 145 (B. M. 87.2.26.24,
coll. from“Moulmein, Burma”by W. Theobald).
Microhyla rubra – Wogan et al., 2008, p. 84–86; Peloso et
al., 2016, p. 5, 23.
Microhyla sp. B – Mulcahy et al., 2018, p. 99, 116–117.
Diagnosis: Microhyla fodiens sp. nov. is characterized by a
combination of the following morphological attributes: (1)
males with medium body size, SVL 20.8 – 29.12 mm in two
adult individuals, body habitus stout; (2) head flattened,
triangular, much wider than long, snout rounded in dorsal and
bluntly rounded in lateral views, notably protruding above
lower jaw in ventral aspect; canthus rostralis rounded,
indistinct; (3) skin on dorsum and flanks feebly granular with
numerous small round tubercles, ventral surfaces smooth;
(4) dorsolateral skinfold presents as row of large tubercles
ventrally underlined with black stripe; (5) mid-vertebral skin
ridge and dorsomedial stripe absent; (6) supratympanic fold
almost indistinct; (7) finger I well developed, notably less than
one-half length of finger II; (8) finger and toe tips lacking disks
and median longitudinal grooves; (9) two large palmar
tubercles (inner palmar tubercle ovoid, slightly elongated;
outer palmar tubercle almost rounded); (10) two very prominent
metatarsal tubercles (inner metatarsal tubercle large, beanshaped, outer metatarsal tubercle greatly enlarged, shovelshaped); (11) limbs short, tibiotarsal articulation of adpressed
limb not reaching eye level; (12) toe webbing basal, reaching
proximal tubercles; webbing formula: I 1–2 II 1¾–3 III 2¾–3¾
IV 4 – 2¾ V; (13) superciliary tubercles absent; (14) dorsum
beige-brown with“teddy-bear-shaped”dark-brown marking
running from interorbital to sacral region; two large dark-black
inguinal spots continuing on dorsal surfaces of thighs;
posterior surfaces of thighs and cloacal region with regular
black stripes; chin and throat marbled with gray, chest and
belly whitish, limbs ventrally pink. Interspecific genetic Pdistances in 16S rRNA gene fragment between new species
and congeners vary from 9.1% to 12.4%.
....
Distribution: Microhyla fodiens sp. nov. is currently known
only from the type locality in Kan Pauk, Yesagyo Township,
Magway Division, Myanmar (Figure 1). The species was
recorded at an elevation of 230 m a.s.l. The actual distribution
of the new species is unknown, but it is likely to be found in
other arid areas of the Irrawaddy River Valley in the region of
the Irrawaddy and Chindwin interfluve; discovery of new
localities in Magway, Sagaing, and Mandalay divisions is
anticipated. The record of“Microhyla rubra”from“Moulmein,
Burma”(now Mawlamyine) by Parker (1934) based on W.
Theobald’s collection comes from Mon State in southern
Myanmar—a region with a much milder tropical monsoon
climate—might refer to a different species. The taxonomic
status of this record requires clarification by further studies.
Etymology: The specific name“fodiens”is a Latin adjective
in the nominative singular derived from“fodio”— Latin verb
meaning“to dig”or“to burrow”referring to the distinctive
enlarged shovel-shaped outer metatarsal tubercle of the new
species, suggesting that it is a good burrower, which may
serve as an adaptation to the dry climate of the Irrawaddy
River Valley in central Myanmar. The recommended common
name in English is “Burrowing narrow-mouth frog”. The
recommended common name in Burmese is“Twin Aoung
Thaephar”.
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| Figure 10 Microhyla irrawaddy sp. nov. type series in situ. A: Dorsolateral view of holotype (ZMMU A5965); B, C: Paratype males (ZMMU A5966 and A5967) in calling position in hollows and buffalo footprints in dirt at type locality. Photos by Parinya Pawangkhanant. |
Microhyla irrawaddy sp. nov.
Chresonymy
Microhyla sp. A – (?) Mulcahy et al., 2018, p. 99, 116–117.
Diagnosis: Microhyla irrawaddy sp. nov. is distinguished by
the following combination of morphological characters:
(1) small adult body size: males SVL 12.3–17.1 mm, females
SVL 16.7 – 20.9 mm, body habitus very slender; (2) head
small, triangular, wider than long, snout acuminate with
rounded tip in dorsal view and rounded in lateral view, slightly
protruding above lower jaw in ventral aspect; canthus rostralis
indistinct; (3) skin on dorsum and flanks granular with
irregularly scattered numerous large and small round
tubercles, ventral surfaces completely smooth; (4) dorsolateral
skinfold and dark lateral band absent; (5) mid-vertebral skin
ridge and dorsomedial stripe absent; (6) supratympanic fold
distinct; (7) finger I well developed, slightly longer than onehalf length of finger II; (8) tips of fingers II–IV and toes II–V
weakly dilated, not forming conspicuous disks; peripheral
grooves ventrally present on tips of fingers II–IV and toes II–
IV; fingers and toes lacking dorsal median grooves or distal
notches; (9) two small palmar tubercles (inner palmar tubercle
rounded, prominent; outer palmar tubercle smaller and less
distinct than inner, rounded, flattened); (10) two small
metatarsal tubercles (inner metatarsal tubercle elongated,
ovoid, flattened; outer metatarsal tubercle small, rounded,
prominent); (11) limbs comparatively short, tibiotarsal
articulation of adpressed limb reaching eye level; (12) toe
webbing completely reduced; webbing formula: I 2–3 II 2–3 III
3 – 4½ IV 4½ – 2¾ V; (13) superciliary tubercles absent; (14)
dorsum yellowish-brown with dark-brown contrasting“teddybear”- shaped marking running from interorbital to sacral
region; larger tubercles on dorsum orange to red; body flanks
grayish with darker mottling not clearly separated from dorsum
coloration; dorsal surfaces of thighs and shanks with two to
three dark crossbars; chin and throat with grayish mottling
(blackish in males), body and limbs ventrally cream to whitish
at belly. Interspecific genetic P-distances in the 16S rRNA
gene fragment between the new species and other currently
recognized species of Microhyla vary from 5.7% to 12.9%.
...
Distribution: Microhyla irrawaddy sp. nov. is at present
known from two closely located areas in Pakokku District of
Magway Division, central Myanmar: i.e., suburbs of Pakokku
city on the bank of the Irrawaddy River (the type locality) and
in the vicinity of Kan Pauk village, Yesagyo Township (ca. 30
km north of type locality) (Figure 1). The species was
recorded from elevations of 60 to 220 m a.s.l.. A genealogically
closely related population of Microhyla (herein indicated as
Microhyla sp. 2, see Table 1) was recorded from the vicinity of
Chatthin in Sagaing Division of northern Myanmar by Mulcahy
et al. (2018). Considering the notable genetic divergence
between Sagaing and Magway populations (P=2.0%), further
research is needed to clarify whether Microhyla sp. 2 is
conspecific with Microhyla irrawaddy sp. nov. The actual
distribution of the new species is unknown and discoveries of
new localities within the middle part of the Irrawaddy River
Valley are anticipated.
Etymology: The new species name“irrawaddy”is given as a
noun in apposition in reference to the Irrawaddy (or, officially,
Ayeyarwady) River – the greatest water basin in Myanmar and
western Indochina, and the cradle of Burmese civilization. The
new species is known to occur in dry areas of the central part
of the Irrawaddy Valley in the Magway Division, but likely has
a wider distribution in the dry zone of central Myanmar. The
recommended common name in English is“Irrawaddy narrow-mouth frog”. The recommended common name in Burmese is
“Myanmar Thaephar”.
Nikolay A. Poyarkov, Jr., Vladislav A. Gorin, Than Zaw, Valentina D. Kretova, Svetlana S. Gogoleva, Parinya Pawangkhanant and Jing Che. 2019. On the Road to Mandalay: Contribution to the Microhyla Tschudi, 1838 (Amphibia: Anura: Microhylidae) Fauna of Myanmar with Description of Two New Species. Zoological Research. DOI: 10.24272/j.issn.2095-8137.2019.044
