A new species of Micryletta (Amphibia: Microhylidae) from southern Thailand

Abstract

We report on a new species, Micryletta dissimulans sp. nov., from the lowland forests of southern Thailand, which is described based on molecular and morphological evidence. The new species is characterized by a combination of the following characters: small body size (20.3–22.4 mm in males, 24.4–26.7 mm in females); slender body habitus; head longer than wide; snout rounded in dorsal and lateral view; eye length equal to snout length; tibiotarsal articulation reaching to tympanum; dorsal surface slightly granulated to shagreened; supratympanic fold indistinct, ventrally edged in black with large black spot behind eye; outer metatarsal tubercle absent; dorsum reddish-brown with merging irregular-shaped brown blotches edged in beige, no black spots on dorsum; body flanks brown with large black spots edged in whitish mottling, two large black blotches in axillary and inguinal areas on each side; lateral sides of head black, with white patches on lips absent, whitish mottling on tympanum and axillary region; ventral surface pinkish to bluish-gray, translucent, laterally with dark-brown marbled pattern, medially immaculate; throat in males dark-gray with sparse white mottling laterally; iris copper-orange. The new species is divergent from all other congeners in 16S rRNA gene sequences (5.0%–7.4%). To date, Micryletta dissimulans sp. nov. is only known from a single locality in Saba Yoi District, Songkhla Province, Thailand, at an elevation of 120 m a.s.l., but is also expected to occur in neighboring parts of Malaysia. We suggest Micryletta dissimulans sp. nov. be considered as a Data Deficient (DD) species following the IUCN’s Red List categories (IUCN Standards and Petitions Committee, 2019).

Full text


AnewspeciesofMicryletta(Amphibia:Microhylidae)
fromsouthernThailand

DEAR EDITOR,
Wereport ona newspecies, Micryletta dissimulanssp. nov.,
from the lowland forests of southern Thailand, which is
described based on molecular and morphological evidence.
The new species is characterized by a combination of the
followingcharacters:smallbodysize(20.3–22.4mminmales,
24.4–26.7mm infemales);slenderbodyhabitus;headlonger
thanwide;snoutroundedindorsalandlateralview;eyelength
equal to snout length; tibiotarsal articulation reaching to
tympanum; dorsal surface slightly granulated to shagreened;
supratympanic fold indistinct, ventrally edged in black with
largeblackspot behindeye;outer metatarsaltubercleabsent;
dorsum reddish-brown with merging irregular-shaped brown
blotches edged in beige, no black spots on dorsum; body
flanksbrown withlargeblack spotsedged inwhitishmottling,
twolargeblackblotchesinaxillaryandinguinalareasoneach
side; lateral sides of head black, with white patches on lips
absent, whitish mottling on tympanum and axillary region;
ventral surface pinkish to bluish-gray, translucent, laterally
withdark-brownmarbled pattern, mediallyimmaculate;throat
in males dark-gray with sparse white mottling laterally; iris
copper-orange. The new species is divergent from all other
congeners in 16S rRNA gene sequences (5.0%–7.4%). To
date, Micryletta dissimulanssp. nov. is only known from a
single locality in Saba Yoi District, Songkhla Province,
Thailand,at anelevationof120m a.s.l.,but isalso expected
to occur in neighboring parts of Malaysia. We suggest
Micryletta dissimulanssp. nov. be considered as a Data
Deficient (DD) species following the IUCN’s Red List
categories(IUCNStandardsandPetitionsCommittee,2019).
Paddy frogs of the genus Micryletta Dubois, 1987 are a
little-knowngroupofmicrohylidfrogsfoundin southernChina,
includingthe HainanandTaiwanislandsinthenorth, through
Indochina, the northeast portion of India and Myanmar to
Nicobar and the Andaman Islands, and through the Malayan
Peninsula to Sumatra in the south (Frost, 2020) (Figure 1A).
Todate,six speciesare recognized withinthe genus:i.e.,M.
aishani Das, Garg, Hamidy, Smith & Biju; M. erythropoda
(Tarkhnishvili); M. nigromaculata Poyarkov, Nguyen, Duong,
Gorin & Yang; M. inornata (Boulenger), M. steinegeri
(Boulenger);andM. sumatranaMunir,Hamidy,Matsui,Kusrini
& Nishikawa (Frost, 2020; Munir et al., 2020). The status of
the subspecies M. inornata lineata (Taylor) remains
controversial,withsome studiesregardingit asafull species
(i.e., M. lineata) (e.g., Zug & Mulcahy, 2020). In addition,
severalpreliminaryphylogenies ofMicryletta haverevealeda
numberofdeeplineages(Alhadietal.,2019;Dasetal.,2019;
Muniret al.,2020;Matsuietal.,2011;Poyarkov etal., 2018),
suggestingthattaxonomyofthegenusisfarfromcomplete.
In August 2018, during fieldwork in the lowland forests of
Songkhla Province in southern Thailand (Figure 1A, locality
16), we collected a series of specimens of an unusual
microhylid species, which was tentatively identified as
Micryletta sp. Consequent phylogenetic analysis of the 16S
rRNAmtDNAgeneconfirmedtheplacementofthispopulation
within Micryletta and the formation of a lineage deeply
divergent from all other recognized species of the genus.
Closer morphological examination showed that this species
could be clearly distinguished from all other congeners by a
combinationofdiagnosticmorphologicalfeatures.Thus,inthe
present paper, we describe the Micryletta population from
SongkhlaProvinceasanewspecies.


Received:09 June 2020; Accepted: 15 July 2020; Online: 11 August
2020
Foundationitems:This studywassupported bytheUnitofExcellence
2020onBiodiversity and NaturalResourcesManagement, University
of Phayao (UoE63005); Thailand Research Fund (TRF:
DBG6180001); and Plant Genetic Conservation Project under the
Royal Initiative of Her Royal Highness Princess Maha Chakri
Sirindhorn, University of Phayao (RD61017) to C.S.; partially
supportedbyChiang MaiUniversity to S.C.;International Partnership
Program of the Chinese Academy of Sciences (CAS)
(152453KYSB20170033), and Southeast Asia Biodiversity Research
Institute, CAS (Y4ZK111B01: 2017CASSEABRIQG002) to J.C.; and
RussianScienceFoundation (19-14-00050; sampling,molecular,and
phylogeneticanalyses)toN.A.P.
DOI:10.24272/j.issn.2095-8137.2020.139
Open Access
This is an open-access article distributed under the terms of the
Creative Commons Attribution Non-Commercial License (http://
creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted
non-commercial use, distribution, and reproduction in any medium,
providedtheoriginalworkisproperlycited.
Copyright ©2020 Editorial Office of Zoological Research, Kunming
InstituteofZoology,ChineseAcademyofSciences


Received:09 June 2020; Accepted: 15 July 2020; Online: 11 August
2020
Foundationitems:This studywassupported bytheUnitofExcellence
2020onBiodiversity and NaturalResourcesManagement, University
of Phayao (UoE63005); Thailand Research Fund (TRF:
DBG6180001); and Plant Genetic Conservation Project under the
Royal Initiative of Her Royal Highness Princess Maha Chakri
Sirindhorn, University of Phayao (RD61017) to C.S.; partially
supportedbyChiang MaiUniversity to S.C.;International Partnership
Program of the Chinese Academy of Sciences (CAS)
(152453KYSB20170033), and Southeast Asia Biodiversity Research
Institute, CAS (Y4ZK111B01: 2017CASSEABRIQG002) to J.C.; and
RussianScienceFoundation (19-14-00050; sampling,molecular,and
phylogeneticanalyses)toN.A.P.
DOI:10.24272/j.issn.2095-8137.2020.139
Open Access
This is an open-access article distributed under the terms of the
Creative Commons Attribution Non-Commercial License (http://
creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted
non-commercial use, distribution, and reproduction in any medium,
providedtheoriginalworkisproperlycited.
Copyright ©2020 Editorial Office of Zoological Research, Kunming
InstituteofZoology,ChineseAcademyofSciences
ZOOLOGICAL RESEARCH
SciencePress Zoological Research41(X):1−8,2020 1


Figure 1 Phylogenetic relationships and distribution of the genus
Micryletta
and the holotype of
Micryletta dissimulans
sp. nov.
(AUP01690) in life
A:Distributionof thegenusMicryletta(greyshading)andlocation ofexaminedpopulations. Forlocalityinfosee SupplementaryTableS1. Adotin
the center of icon denotes the type locality of a species; empty circle denotes locality not included in molecular analysis; star denotes the type
locality of Micryletta dissimulanssp. nov. in Saba Yoi District, Songkhla Province, southern Thailand. B: Phylogenetic BI tree of Micryletta
reconstructedonthebaseof569 bpofpartial 16SrRNAsequences. Valuesonthe branchescorrespondto BIPP/MLBS,respectively;blackand
white circles correspond to well-supported and moderately supported nodes, respectively. C: Holotype of Micryletta dissimulanssp. nov.
(AUP01690),adult male,inlife indorsolateral view.D: Samespecimen inventral view.Photosby N.A.Poyarkov, P.Pawangkhanant, J.H.Yang
andEkiApriliaResdiyantiDevung.

2www.zoores.ac.cn

Atotalofninespecimens werecollected andphotographed
in life before being euthanized using a 20% solution of
benzocaine prior to fixation and storage in 75% ethanol.
Tissue samples for genetic analysis were taken prior to
preservation and stored in 95% ethanol. Specimens and
tissues were subsequently deposited in the herpetological
collections of the School of Agriculture and Natural
Resources, University of Phayao (AUP, Phayao, Thailand)
and the Zoological Museum of Lomonosov Moscow State
University (ZMMU, Moscow, Russia). 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 Poyarkov et al. (2018) (see
Supplementary Methods). Comparative data on the
morphology and taxonomy of Micryletta were obtained from
previous publications on the genus (see Supplementary
Methodsfordetails).
TotalgenomicDNAwasextracted,andapartialfragmentof
the mitochondrial 16S rRNA gene was amplified and
sequenced. DNA extraction, primers, and polymerase chain
reaction(PCR)protocols followedPoyarkovet al. (2018)and
are detailed in the Supplementary Methods. To assess the
genealogical relationships among Micryletta species,
Bayesian inference (BI) and maximum-likelihood (ML)
phylogenetic trees were reconstructed based on analysis of
the 16S rRNA gene fragment (for details of phylogenetic
analyses see Supplementary Methods). Homologous
sequences of all currently recognized Micryletta species and
representative outgroups (Mysticellus franki, Uperodon
systoma, Kaloula pulchra) were downloaded from GenBank
(see Supplementary Table S1). We also calculated pairwise
sequence divergence using uncorrected P-distances
implementedinMEGAv6.0.6(Tamuraetal.,2013).
ThetopologiesrecoveredbybothBIandMLanalyseswere
essentially identical, with relatively robust support for most
terminalnodes(Figure 1B).Thenew microhylidspecies from
SongkhlaProvince nestedinthe genusMicrylettawith strong
support(1.0/97;hereafternodesupportvaluesaregivenforBI
posterior probability/ML bootstrap support, respectively) and
formed a distinct lineage (Figure 1B) with notable genetic
divergence (P-distance≥5.0%) from all other recognized
species within the genus (Supplementary Table S2). Our
phylogenetictreeagreedwithearliertopologiesofPoyarkovet
al.(2018) andDaset al.(2019)but differedsignificantly from
the topology presented in Munir et al. (2020). The Songkhla
Micrylettasp.formedaclade(1.0/100)thatwasclearlydistinct
from all other congeners, with a possible sister species
relationship shown for the recently described species M.
sumatrana from southern Sumatra, Indonesia, although this
grouping received no BI support and only weak ML support
(0.66/75; Figure 1B). All remaining species of Micryletta
formed a well-supported monophylum (0.97/79), with seven
majorsubcladesrecovered within it. Micryletta nigromaculata
from northern Vietnam grouped with Micryletta sp. 1 from
northernLaos(0.97/87)andformedasistercladewithrespect
to all other species of Micryletta (1.0/67). The following
subclades were recovered within the latter group: M. aishani
from northeast India; M. inornata from northern Sumatra,
Indonesia; M. erythropoda from southern Vietnam; M. cf.
lineata from Peninsular Thailand; and populations from
northern Indochina and southern China, including the
mainland and Taiwan. The latter group included the M.
steinegeri sensu stricto lineage from Taiwan, China (lineage
D; Figure 1B), and mainland populations formerly referred to
as“M.cf.inornata” (lineagesA–Cand E; Figure1B) (Das et
al.,2019;Muniretal., 2020;Poyarkovet al.,2018).However,
as the true M. inornata sensu stricto from Sumatra is
phylogenetically distinct from the mainland populations of
Micryletta (Alhadi et al., 2019; Das et al., 2019; Munir et al.,
2020),wehereinreferto themainlandlineages A–CandEof
theM. steinegericomplexasM.cf.steinegeri(Figure1A,B).
The genetic distance between the Micryletta sp. from
Songkhla and other described species of the genus ranged
from P=5.0% (with M. nigromaculata) to P=7.4% (with M.
erythropoda) (Supplementary Table S2). These values of
divergencein the16SrRNAgenearenotablyhigher thanthe
formal P=3% threshold widely applied as an indicator of
species-level differentiation in frogs (Vieites et al., 2009).
Thus, due to congruent morphological (see below) and
moleculardifferencesfromallcurrentlyrecognizedcongeners,
the newly discovered Micryletta population from Songkhla
Provinceisdescribedasanewspeciesbelow.
Taxonomic account
Micryletta dissimulanssp. nov. (Figure 1C, D;
SupplementaryFiguresS1–4;Table1)
Holotype: AUP01690, adult male from a secondary lowland
bamboo forest in Saba Yoi District, Songkhla Province,
southern Thailand (coordinates N6.369°, E100.873°; 120 m
a.s.l.), collected on 22 August 2018 at 2 200 h by P.
PawangkhanantandN.A.Poyarkov.
Paratypes: AUP01691–01694 and AUP01698 (five adult
males), AUP01696–01697 (two adult females), and ZMMU
A7262(adultmale), collected at thesametime and place as
theholotype.
Diagnosis: The new species is assigned to the genus
MicrylettaDubois, 1987based onthe followingmorphological
attributes:body sizesmall; vomerineteethabsent;tympanum
small, rounded, externally visible; subarticular tubercles on
fingers and toes very prominent; three well-developed
metacarpal tubercles; distinct supernumerary palmar and
metatarsaltubercles posteriorto baseof digits;first fingernot
reduced; and webbing on fingers and toes absent (Alhadi et
al., 2019; Das et al., 2019; Dubois, 1987; Munir et al., 2020;
Poyarkov et al., 2018). Micryletta dissimulanssp. nov. is
distinguished from all congeners by a combination of the
following morphological characters: body size small
(20.3–22.4 mm in seven males, 24.4–26.7 mm in two
females);body habitusslender;head longerthan wide;snout
roundedindorsalandlateralviews;eyelength equaltosnout
length; tibiotarsal articulation reaching tympanum; dorsal
Zoological Research41(X):1−8,2020 3

surfaceslightly granulatedto shagreened;supratympanicfold
indistinct, ventrally edged in black; large black spot behind
eye;outermetatarsal tubercle absent; dorsumreddish-brown
withmergingirregular-shapedbrownblotchesedgedinbeige,
noblackspotsondorsum;bodyflanksbrown withlargeblack
spots edged in whitish mottling, two large black blotches in
axillaryand inguinalareas oneach side;lateral sidesofhead
black, with white patches on lips absent, whitish mottling on
tympanum and axillary region; ventral surface pinkish to
bluish-gray, translucent, laterally with dark-brown marbled
pattern, medially immaculate; throat in males dark-gray with
sparsewhitemottlinglaterally;andiriscopper-orange.
Description of holotype:Adultmale,small-sizedspecimenin
good state of preservation; body habitus slender, body
elongated and oval-shaped (Figure 1C); head longer than
wide (HL/HW 1.07); snout short (SL/SVL 0.12), rounded in
dorsal view and bluntly rounded in profile, slightly projecting
beyond lower jaw (Supplementary Figure S1C); eyes
comparatively large (EL/SVL 0.12), slightly protuberant in
dorsal and lateral views, subequal to snout length (EL/SL
1.02)andinterorbitaldistance(EL/IOD0.96).Topofheadflat;
canthus rostralis distinct, rounded; loreal region almost
vertical, concave; nostril oval, lateral, located closer to tip of
snout than to eye (N-EL/SVL 0.07); interorbital distance
noticeably wider than internarial distance (IND/IOD 0.70),
about 1.5 times wider than upper eyelid (UEW/IOD 0.70).
Pineal spot absent; tympanum small (TYD/SVL 0.06), round,
poorlydistinct withtympanic rimnotelevatedabovetympanal
area; supratympanic fold thin and flat, gently curving from
posteriorcornerofeyetowardsaxilla.Choanaeelongatedand
oval-shaped, widely spaced; upper jaw edentate; vomerine
teeth absent; tongue without papillae, roundly spatulate,
lackingposteriornotchandfreebehindforthree-quartersofits
length.
Table 1 Selected measurements (in mm) of
Micryletta dissimulans
sp. nov. type series

SpecimenID AUP01690 AUP01698 AUP01691 AUP01692 AUP01693 AUP01694 ZMMUA7262 AUP01696 AUP01697
Typestatus Holotype Paratype Paratype Paratype Paratype Paratype Paratype Paratype Paratype
Sex MM M M M M M F F
SVL 21.2 21.9 20.9 20.3 21.2 20.3 22.4 26.7 24.4
HL 7.8 7.6 7.2 6.9 6.9 7.1 7.4 7.4 7.3
SL 2.5 2.6 2.4 2.5 2.5 2.2 2.9 3.1 3.1
EL 2.6 2.4 2.5 2.4 2.6 2.4 2.8 3.4 3.3
N-EL 1.4 1.4 1.4 1.5 1.4 1.4 1.6 1.5 1.5
HW 7.3 7.2 7.2 6.8 7.5 7.1 8.5 10.3 8.1
IND 1.9 2.0 1.8 1.9 1.9 2.0 2.3 2.6 2.5
IOD 2.7 2.3 2.2 2.2 2.7 2.5 2.3 2.5 2.5
UEW 1.9 1.5 1.9 1.6 1.9 1.4 1.6 2.7 2.7
FLL 12.7 14.6 13.0 14.0 12.5 14.3 16.0 18.3 17.7
LAL 8.3 9.9 8.2 9.9 8.3 9.6 11.2 13.0 11.8
HAL 5.5 5.4 5.4 5.4 5.8 6.0 6.4 8.0 6.8
IPTL 0.6 0.5 0.5 0.5 0.6 0.6 0.6 0.6 0.5
OPTL 0.9 0.8 0.9 0.8 0.9 0.9 1.0 1.2 1.1
3FDD 0.4 0.5 0.4 0.4 0.3 0.4 0.5 0.9 0.8
HLL 34.4 33.0 33.4 34.6 32.8 33.7 36.9 43.9 41.3
TL 10.8 10.0 10.3 10.3 8.9 10.6 11.1 12.8 12.2
FL 13.8 13.5 13.9 14.3 14.4 13.6 15.4 18.5 17.4
IMTL 0.9 0.8 0.9 0.9 0.9 0.9 0.9 1.1 1.0
4TDD 0.7 0.7 0.7 0.6 0.6 0.6 0.7 0.8 0.8
TD 1.2 1.2 1.1 1.0 1.2 1.2 1.3 1.3 1.2
1FL 2.2 2.4 1.7 2.2 2.1 1.8 2.5 3.9 3.3
2FL 3.2 3.4 3.0 3.0 3.0 2.3 4.0 4.1 4.1
3FL 5.1 5.2 4.7 4.9 3.3 4.0 5.9 6.9 6.8
4FL 3.3 4.4 3.0 4.1 3.6 3.0 4.4 5.0 4.9
1TOEL 2.6 2.4 2.5 2.3 2.6 2.7 2.8 3.1 2.2
2TOEL 43 4.0 3.5 3.4 4.2 4.3 4.4 5.7 5.0
3TOEL 6.7 6.6 6.8 6.0 7.0 7.3 8.0 9.2 8.5
4TOEL 10.4 9.6 9.9 9.0 10.3 9.4 11.3 12.1 11.4
5TOEL 6.5 5.5 6.0 5.3 6.4 5.7 6.5 8.0 7.7
Holotypemeasurementsaregiveninbold.ForcharacterabbreviationsseeSupplementaryMethodssection.M:Male;F:Female.
4www.zoores.ac.cn

Forelimbsshortandslender(FLL/SVL0.60);lowerarmlong
and slender (LAL/SVL 0.39), hand constituting less than half
length of forelimb (HAL/FLL 0.43). Fingers slender, free of
webbing, round in cross-section, lacking lateral skin fringes;
first finger well-developed, slightly shorter than second finger
(1FL/2FL 0.68); relative finger lengths: I<II<IV<III; tips of all
fingersrounded,notexpandedtodisks;subarticular tubercles
on fingers rounded and very prominent, subarticular tubercle
formula: 1, 1, 2, 2; nuptial pads absent; three metacarpal
tubercles:innermetacarpaltubercledistinct,roundedandflat;
outer metacarpal tubercle elongated, larger than inner
metacarpal tubercle (IPTL/OPTL 0.64), reniform, located on
outer proximal edge of palm; medial metacarpal tubercle
large, rounded and prominent, twice diameter of inner
metacarpaltubercle; threeprominentrounded supernumerary
tubercles, each at base of fingers II–IV about same size as
inner metacarpal tubercle, a small rounded supernumerary
tubercle between medial metacarpal tubercle and tubercle at
base of finger III, much smaller than metacarpal tubercles
(SupplementaryFigureS1D).
Hindlimbsslender andlong (HLL/SVL1.63), morethan two
timeslengthofforelimb(FLL/HLL0.37);tibialongandslender
(TL/SVL 0.51), around one-third of hindlimb length (TL/HLL
0.31);heelsmeetwhenhindlimbspositionedatright anglesto
body, tibiotarsal articulation of adpressed limb reaching to
tympanum;footslightlylongerthantibia(FL/TL1.28).Relative
toe lengths: I<II<V<III<IV; tarsus smooth, inner tarsal fold
absent; tips of all toes rounded, weakly dilated into small
disks, two times wider than those of fingers (3FDD/4TDD
0.52); toes free of webbing; subarticular tubercles on toes
roundand prominent,subarticulartubercleformula:1,1,2, 3,
2; inner metatarsal tubercle oval-shaped, prominent, much
shorter than half length of first toe (IMTL/1TOEL 0.34); outer
metatarsal and supernumerary metatarsal tubercles absent
(SupplementaryFigureS1E).
Skin texture and skin glands: Dorsal surface of head and
body shagreened with evenly scattered small flat granules,
dorsal surfaces of forelimbs smooth, hindlimbs dorsally with
small granules on shanks and thighs; flanks of body and
lateralsidesofheadsmooth;uppereyelid lackingsupraciliary
tubercles; supratympanic fold flat, thin; ventral surfaces of
bodyandlimbssmooth.Cloacalopeningunmodified, directed
posteriorly.
Coloration:Inlife, dorsum reddish-brown with largemerging
irregular-shaped brown blotches edged in light-beige
resembling military camouflage print; no black spots on
dorsum; body flanks brown with large black spots edged in
whitish mottling, two large black blotches in axillary and
inguinalareasoneachside;lateralsidesof headdark-brown,
withwhitepatchesonupperlipsabsent,tympanumregionand
axillary region with whitish mottling; supratympanic fold
ventrally edged in black with large black spot behind eye;
dorsal surfaces of forelimbs uniform golden-yellow on upper
arms, pinkish-brown with few brown spots on lower arms;
dorsal surfaces of thighs and shanks golden-brown with
pinkish mottling and dark-brown blotches not forming
transversebands;fingersandtoesdorsallygraywithbrownish
dusting; ventral surfaces pinkish to bluish-gray, translucent,
laterallywithdark-brownmarbledpattern,mediallyimmaculate
(Figure 1D); throat dark-gray with sparse white mottling
laterallyin lowerjaw area;irisdark-brownwithcopper-orange
sparkles in upper and lower thirds (Supplementary Figure
S1C). In preservative, colors fade to gray-brown, though
pattern generally remains unchanged (Supplementary Figure
S2).
Variation and sexual dimorphism: Individuals of the type
series are generally quite similar in appearance and agree
well with the description of the holotype but with some
variation in coloration (Supplementary Figure S3). Female
paratype AUP01696 has less contrasting brown pattern on
dorsum, fewer black blotches on flanks and translucent skin
on belly through which the large bicolored white and black
eggsarevisible(SupplementaryFigureS4). Variationsinsize
andbodyproportions ofthetype seriesaregiven in Table1.
Femalesaredistinctly larger than males:SVL20.3–22.4mm
inmales(n=7) and24.4–26.7mm infemales(n=2). Females
have comparatively larger bodies swollen with eggs, and
comparatively shorter head length: HL/SVL mean ratio 0.34
(0.33–0.37, n=7) in males vs. 0.29 (0.28–0.30, n=2) in
females. Males bear a single internal vocal sac. Skin texture
appears to be less tuberculate in preservative than in life
(SupplementaryFiguresS2,S3).
Natural history notes: Micryletta dissimulanssp. nov.
inhabits secondary disturbed lowland tropical forests
dominated by bamboo at elevations of 100–150 m a.s.l.
(SupplementaryFigureS5). Itis anelusivefrog species,with
all type specimens collected at night from 1900 h to 2 300 h
afterheavyrain and mostly recordedwhilehiding in bamboo
leaf litter. Reproduction (pairs in amplexus) was observed in
August. Advertisement calls were not recorded, and clutch
size, larval morphology, diet, and predators are unknown. At
thetypelocality,Micryletta dissimulanssp.nov.was foundin
sympatry with the following microhylid frogs: Microhyla
superciliaris Parker, M. heymonsi Vogt, M. mantheyi Das,
Yaakob & Sukumaran, Kaloula latidisca Chan, Grismer &
Brown, and Kalophrynus cf. kiewi Matsui, Eto, Belabut &
Nishikawa.
Comparisons:Micryletta dissimulanssp. nov.differsfromM.
aishani from northeast India by the following combination of
characters: snout rounded in dorsal and ventral view (vs.
nearly truncate); comparatively larger tympanum, TYD/EL
ratio0.42–0.49 (vs.TYD/EL 0.14–0.29);dorsumwithmerging
irregular-shaped brown blotches edged in beige (vs. dorsum
reddish-brown with faint median band); lateral dark spots
scattered from tip of snout to lower abdomen on either side
(vs. prominent dark-black streak); ventral surface pinkish to
bluish-gray,translucent,laterally bearing dark-brown marbled
pattern,mediallyimmaculate (vs.ash-gray withpurplishtinge
and brown mottling towards margin); dorsum weakly
granulated to shagreened (vs. minute spinules on dorsum);
white spots on upper lip absent (vs. present); and tibiotarsal
articulation of adpressed limb reaching to tympanum (vs. to
armpit).
Zoological Research41(X):1−8,2020 5

ThenewspeciesdiffersfromM. erythropoda fromsouthern
Vietnamby acombination ofthefollowingcharacters:smaller
body size in males (SVL 20.3–22.4 mm vs. up to 30 mm);
outermetatarsaltubercle absent(vs.present); dorsal surface
slightlygranulatedto shagreened(vs.smooth);dorsumbrown
toreddish-brown(vs.grayorbeigetosaturatedochreorbrick-
red); dorsum pattern of merging brown blotches edged in
beige (vs. extremely variable and formed by black spots on
reddish background); flanks brown with dark spots edged in
whitish mottling (vs. dark-brown to gray with white patches);
venterpinkishtobluish-gray,laterallywithdark-brownmarbled
pattern(vs.dark brownish-violet); andwebbingbetween toes
absent(vs.rudimentarywebbingpresent).
Micryletta dissimulanssp. nov.differsfromM. inornatafrom
northern Sumatra, Indonesia, by: larger body size (20.3–
22.4 mm in males, 24.4–26.7 mm in females vs. 16.8–20.5
mm in males, 19.5 mm in females); interorbital distance two
times wider than upper eyelid width (vs. interorbital distance
slightly wider than upper eyelid); dorsum reddish-brown (vs.
dark-brown or brownish-gray with silver tinge); dorsal pattern
of merging brown blotches edged in beige (vs. irregular
blackish blotches); dorsum slightly granulated to shagreened
(vs. smooth, covered with small tubercles or warts); sides of
headdark-brownto black, withwhite patches alongupperlip
absent (vs. black with white spots along upper lip present);
body flanks brown with dark spots and whitish mottling (vs.
dark-brown with white patches); venter pinkish to bluish-gray
laterally with brown marbled pattern (vs. light reddish-gray
withoutmottling);andtibiotarsalarticulationofadpressedlimb
reachingtotympanum(vs.reachingtoeye).
The new species differs from M. lineata from Peninsular
Thailand by: dorsum reddish-brown with merging brown
blotchesedged inbeige(vs.grayish-brownwiththreestraight
continuousor brokenlines); tibiotarsalarticulation reachingto
tympanum(vs.reaching toeye); sidesofhead dark-brownto
black, with white patches along upper lip absent (vs. cream
stripe of irregular width from snout to axilla); body flanks
brown with dark spots and whitish mottling (vs. black stripe
from axilla to groin with indistinct light stripe ventrally); and
venter pinkish to bluish-gray laterally with brown marbled
pattern(vs.immaculate).
Compared with M. nigromaculata from northern Vietnam,
Micryletta dissimulanssp. nov. can be distinguished by:
tibiotarsal articulation reaching to tympanum (vs. reaching to
eye);dorsalpatternconsistingofmergingbrown blotches(vs.
generally more prominent dark hourglass-shaped markings);
whitishspotspresentonheadflanksfromtympanumregionto
axilla (vs. immaculate dark-brown without white spots); body
flanksbrownwith dark spots andwhitemottling (vs. blackish
patchesedgedinwhite);pinkishtobluish-grayventer,laterally
with dark-brown marbled pattern (vs. whitish with indistinct
light-graymarbling).
Thenewspecies differsfromM. steinegeriby:smallerbody
size in females (20.3–22.4 mm vs. 27.0–30.1 mm); dorsum
brownish (vs. dark-gray to violet); dorsum pattern of merging
brown blotches edged in beige with black inguinal spots (vs.
inguinal spots absent, dorsum with irregular dark blotches or
speckles); head sides uniform brown, with white patches on
upper lip absent (vs. gray-brown with white spots present);
body flanks brown with dark spots and white mottling (vs.
flanks gray brown with dark marbling); pinkish to bluish-gray
venter, laterally with dark-brown marbled pattern (vs. venter
pinkish to orange); and webbing between toes absent (vs.
rudimentarywebbingpresent).
Micryletta dissimulanssp. nov. differs from its putative
sister species M. sumatrana from southern Sumatra,
Indonesia, by: larger body size (20.3–22.4 mm in males,
24.4–26.7mmin females vs. 17.4mmin males, 22.8 mmin
females); relatively longer tibia length (TL/SVL 0.42–0.51
(mean 0.49) in males, 0.48–0.50 (mean 0.49) in females vs.
0.41 in males, 0.45 in females); dorsum reddish-brown (vs.
golden-brown); dorsum pattern of irregular-shaped merging
brown blotches edged in beige (vs. no dark pattern on
dorsum);skinon dorsum slightlygranularto shagreened (vs.
smooth);lateral sidesof headdark-brown, withwhite patches
on upper lip absent (vs. cream spots on lips, tympanum
region,and axillapresent); bodyflanks brownwith darkspots
edgedin whitishmottling (vs.dark-brownwithwhitepatches);
venterpinkishto bluish-graylaterallywithdark-brownmarbled
pattern(vs.venterwithdark-brownbackgroundcolorationwith
creammottling); tibiaandtarsuswithindistinctdarkspots not
forming cross band (vs. with dark cross bands); tibiotarsal
articulation of adpressed limb reaching to tympanum (vs.
reaching to eye); supratympanic fold less distinct, flat, not
glandular, ventrally edged in black with large black spot
behind eye (vs. supratympanic fold distinct, thick, glandular,
andblackish);andiriscopper-orangeinupperandlowerthirds
(vs.golden).
อึ่งจิ๋วลายพราง
Etymology: The specific epithet  “ dissimulans” is a Latin
adjective in the nominative case, feminine gender, derived
from the Latin verb  “ dissimulo” meaning  “to hide” or  “to
conceal”, and is given in reference to the iconic  “Frog Skin”
camouflagepattern,resemblingthecharacteristicmottledand
disruptivedorsalpatternofthenewspecies.Thenameisalso
given in reference to the new species being concealed for a
long time until its recent discovery. We recommend
“CamouflagedPaddyFrog”asthecommonEnglishnameand
“EungJiewLayPang”( )asthecommonThai
nameofthenewspecies.
Conservation status: To date, Micryletta dissimulanssp.
nov.isknownonlyfromasinglelocationinsouthernThailand;
the actual extent of distribution and population trends of the
new species remain unknown. We suggest Micryletta
dissimulanssp. nov. beconsideredas aData Deficient(DD)
species following the IUCN’s Red List categories (IUCN
StandardsandPetitionsCommittee,2019).
Distribution and biogeography:Todate, thenewspeciesis
known only from a single locality in the lowland areas of
SongkhlaProvinceinsouthernPeninsularThailand(SabaYoi
District)(see Figure1A, locality16), approximately6 kmfrom
the international border with Malaysia. Biogeographically, the
Songkhla Province is located southwards from the Kangar-
6www.zoores.ac.cn

Pattani Line, a well-known biogeographic barrier that bisects
the Thai-Malay Peninsula (Van Steenis, 1950), and thus the
occurrence of the new species to the south, in Peninsular
Malaysia, is highly anticipated. Similar patterns have been
observedinothermicrohylidsinhabitingthisregion(seeGorin
et al., 2020). Munir et al. (2020) discussed that some
Micrylettapopulations reportedfrom theMalay Peninsulaand
Singapore superficially resemble M. sumatrana in coloration,
butdiffer fromthe latterby fewercreamspotsonthelipsand
tympanum and by a different arrangement of black spots on
theflanks. Thepopulationfrom Johor(see Figure1A,locality
19)reportedbyWoodetal.(2008)isindeedsomewhatsimilar
toMicryletta dissimulanssp. nov.inhavingirregularbrownish
spotson thedorsumandlackingwhitespotson theupper lip
(Woodet al.,2008: Figure3, LSUHC7 626); however,further
studies are required to clarify the taxonomic status of
MicrylettafromPeninsularMalaysiaandSingapore.
The present study further underlines our incomplete
understanding of Micryletta diversity. In addition to the
description of four new species of this genus in just the last
two years, our study, in agreement with earlier research
(Alhadi et al., 2019; Das et al., 2019; Munir et al., 2020;
Poyarkovetal.,2018),identifiedseverallineagesofMicryletta
that likely correspond to new species. The population of
Micryletta sp. 1 from Laos (Figure 1A, locality 6), initially
identified as M. inornata (Blackburn et al., 2013), but later
suggested as M. cf. nigromaculata by Das et al. (2019), is
geographically isolated and notably divergent from typical M.
nigromaculatain16SrRNAsequences(P=2.8%);thus,further
integrative studies are needed to clarify its taxonomic status.
Our study also confirms (Poyarkov et al., 2018) the close
genealogical relationship between M. erythropoda from
southernVietnamand samplesfrompeninsular Thailandand
Myanmar(Figure1A, localities13–14),originally identified as
M. i. lineatabyMatsuietal.(2011)andMuniretal.(2020),or
as M. lineata by Zug & Mulcahy (2020). However, these
samplesdonotoriginatefrom thetypelocality ofM. lineatain
NakhonSi ThammaratProvince,Thailand (Figure1A, locality
15), and are regarded as M. cf. lineata in our study. The
geographical complexity of the Thai-Malay Peninsula
compounds population estimations of M. cf. lineata and M.
erythropoda, which can only be resolved using integrative
taxonomicapproaches andcomparisons withtypespecimens
andgenetic analysesof topotypicmaterials.Ourstudyfurther
confirmsthatM. inornatasensustrictoisrestrictedtoSumatra
(Alhadi et al., 2019), and thus application of this name for
populations in northern Indochina and southern China (as in
Muniretal.,2020)ismisleading.We providefurtherevidence
thatalarge radiation ofMicrylettain this region iscomprised
of at least five divergent mtDNA lineages, including M.
steinegeri sensu stricto from Taiwan in southern China
(Figure 1B, lineage D). We herein suggest referring to this
groupastheM. steinegericomplex(Figure1B,lineagesA–E).
Though the mainland lineages of this complex from Thailand
and Laos (lineage A), central Vietnam and Laos (lineage B),
northernVietnam(lineage C),andLaos (lineageE)are likely
separatedgeographically(see Figure1A, B),eachpotentially
representsanundescribedspecies.Finally,ourmtDNA-based
genealogycouldnotprovidefullphylogeneticresolutionforthe
genus Micryletta; the tendency for a basal position of the
Sundaic clade comprised of Micryletta dissimulanssp.
nov.+M. sumatrana is only poorly supported. Further
multilocus phylogenies along with integrative taxonomic
analyses are needed to achieve a better understanding of
Micrylettataxonomicdiversityandevolutionaryhistory.
NOMENCLATURAL ACTS REGISTRATION
The electronic version of this article in portable document
format represents a published work according to the
InternationalCommissiononZoologicalNomenclature(ICZN),
andhence thenewnamescontainedintheelectronic version
are effectively published under that Code from the electronic
edition alone (see Articles 8.5–8.6 of the Code). This
published work and the nomenclatural acts it contains have
beenregisteredinZooBank,theonlineregistrationsystem for
the ICZN. The ZooBank LSIDs (Life Science Identifiers) can
be resolved and the associated information can be viewed
throughany standardwebbrowser byappending theLSIDto
theprefixhttp://zoobank.org/.
PublicationLSID:
urn:lsid:zoobank.org:pub:F6ABA4F9-93E2-4BA7-8B1C-
4939756C74B4
Micryletta dissimulansLSID:
urn:lsid:zoobank.org:act:2C8AF677-4ED6-4 588-9 944-
298430AED17B
SCIENTIFIC FIELD SURVEY PERMISSION INFORMATION
Specimen collection protocols were approved by the
Institutional Ethical Committee of Animal Experimentation of
theUniversityof Phayao(certificateNo.UP-AE61-01-04-0022
issued to Chatmongkon Suwannapoom) and Institute of
Animals for Scientific Purpose Development (IAD), Bangkok,
Thailand (permit number U1-01205-2 558, issued to
ChatmongkonSuwannapoom).
SUPPLEMENTARY DATA
Supplementarydatatothisarticlecanbefoundonline.
COMPETING INTERESTS
Theauthorsdeclarethattheyhavenocompetinginterests.
AUTHORS' CONTRIBUTIONS
C.S.andN.A.P.designedthestudy.P.P.andN.A.P.collected
specimens in the field. C.S., V.A.G., and N.A.P. performed
molecular experiments. C.S., T.V.N, V.A.G., and N.A.P.
performed data analyses. C.S., T.V.N., and N.A.P. wrote the
manuscript.T.V.N,V.A.G., C.J., S.C.,and N.A.P. revisedthe
manuscript.Allauthorsreadandapprovedthefinal versionof
themanuscript.
Zoological Research41(X):1−8,2020 7

ACKNOWLEDGEMENTS
We would like to thank the Laboratory Animal Research
Center(UniversityofPhayao),Instituteof AnimalforScientific
Purposes Development (IAD), and Department of National
Parks, Wildlife and Plant Conservation (DNP), Thailand, for
permission to do field work. The authors are grateful to Thai
Van Nguyen (SVW), Andrey N. Kuznetsov (JRVTTC),
Valentina F. Orlova and Roman A. Nazarov (ZMMU) for
supportingourstudy. WethankWatineeJuthong,Pattarawich
Dawwrueng, Kanokwan Yimyoo, Thiti Ruengsuwan, Kawin
Jiaranaisakul, and Akkrachai Aksornneam for help, support,
and encouragement during fieldwork. We also thank Jian-
HuanYangfor providing photos ofMicryletta inornata and to
Eki Aprilia Resdiyanti Devung for providing photos of M.
sumatrana.WearegratefultoMarkD.Scherz,PeterGeissler,
and Jian-Huan Yang for useful comments and corrections of
theearlierversionofthemanuscript.
ChatmongkonSuwannapoom1,TanVanNguyen2,
ParinyaPawangkhanant1,VladislavA.Gorin3,
SiriwadeeChomdej4,5,JingChe6,7,NikolayA.Poyarkov3,8,*
1Division of Fishery, School of Agriculture and Natural Resources,
University of Phayao, Phayao 56000, Thailand
2Department of Species Conservation, Save Vietnam’s Wildlife
Center, Ninh Binh, Vietnam
3Faculty of Biology, Department of Vertebrate Zoology, Moscow
State University, Moscow, Moscow 119234, Russia
4Department of Biology, Faculty of Science, Chiang Mai
University, Chiang Mai 50200, Thailand
5Research Center in Bioresources for Agriculture, Industry and
Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
6State Key Laboratory of Genetic Resources and Evolution,
Kunming Institute of Zoology, Chinese Academy of Sciences,
Kunming Yunnan 650223, China
7Southeast Asia Biodiversity Research Institute, Chinese
Academy of Sciences, Yezin Nay Pyi Taw 05282, Myanmar
8Laboratory of Tropical Ecology, Joint Russian-Vietnamese
Tropical Research and Technological Center, Hanoi, Vietnam
*Correspondingauthor,E-mail:n.poyarkov@gmail.com
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