Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 October 2021 | 13(12): 19818–19823
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.7384.13.12.19818-19823
#7384 | Received 01 May 2021 | Final received
24 September 2021 | Finally accepted 05 October 2021
Field identification characters
to diagnose Microhyla mukhlesuri
from closely related M. mymensinghensis (Amphibia: Microhylidae)
and range extension of M. mukhlesuri up to
West Bengal State, India
Suman Pratihar
& Kaushik Deuti 2
1 Department of Zoology, Sukumar
Sengupta Mahavidyalaya, Keshpur,
West Bengal 721150, India.
2 Zoological Survey of India,
Herpetology Division, 27 JL Nehru Road, Kolkata, West Bengal 700016, India.
1 pratihar_vu@rediffmail.com (corresponding
author), 2 kaushikdeuti@gmail.com
Editor: S.R. Ganesh,
Chennai Snake Park, Chennai, India. Date
of publication: 26 October 2021 (online & print)
Citation: Pratihar,
S. & K. Deuti (2021). Field identification
characters to diagnose Microhyla mukhlesuri from closely related M. mymensinghensis (Amphibia: Microhylidae)
and range extension of M. mukhlesuri up to
West Bengal State, India. Journal of
Threatened Taxa 13(12): 19818–19823. https://doi.org/10.11609/jott.7384.13.12.19818-19823
Copyright: © Pratihar
& Deuti 2021. Creative Commons Attribution 4.0 International License. JoTT allows
unrestricted use, reproduction, and distribution of this article in any medium
by providing adequate credit to the author(s) and the source of publication.
Funding: None.
Competing interests: The authors
declare no competing interests.
Acknowledgements: SP wishes to thank the principal
of Keshpur College for this study while KD wishes to
thank Dr. Kailash Chandra, Director, Zoological Survey of India for use of
laboratory facilities like microscope and magnanoscope.
We also like to thank to Dr. Nirupam Acharya,
Vidyasagar University for his help regarding preparation of the map. We thank Debayan Gayen, junior research
fellow, ZSI canning station, WB for doing the PCA analysis.
Abstract: Microhyla
mymensinghensis and Microhyla
mukhlesuri were recorded from West Bengal, also analyzed 12 characters to separate the species. We also
hereby first time confirm the presence of Microhyla
mukhlesuri from the main land in India
Keywords: Amphibia, first record, frogs.
Twenty-seven species have been
described within the last 15 years (Frost 2021), yet Microhyla
remains one of the most taxonomically exciting groups of Asian frogs. Microhylidae is one of the most species rich family of Anura, comprising 690 species in 12 subfamilies (Frost
2020). Previous mitochondrial phylogenies have confirmed that Microhyla mukhlesuri
Hasan, Islam, Kuramoto, Kurabayashi
& Sumida, 2014 is sister to M. fissipes Boulenger, 1884 and that together they are sister to M. mymensinghensis Hasan, Islam, Kuramoto,
Kurabayashi & Sumida, 2014 (Hasan et al. 2014; Howlader et al. 2016; Yuan et al. 2016). Asian congeners, M.
chakrapanii Pillai, 1977, M. mukhlesuri, and M. mymensinghensis
are nested along with M. fissipes Boulenger, 1884 and together these four species are the
sister group to the clade containing M. mixtura and
M. okinavensis (Garg et al. 2019). The M. fissipes species group consists of two subclades (Poyarkov et al. 2019). Clade one species reported from
Laos, Thailand, Myanmar, Philippines, Singapore, southrn
Asia, and the Andamans (M. fissipes, M. mukhlesuri, M. mymensinghensis,
M. chakrapanii). And the other clade comprising
species from mainland China (Garg et al. 2019).
Microhyla mymensinghensis was first described from
Mymensingh, Bangladesh together with M. mukhlesuri
(see Hasan et al. 2014). Microhyla mymensinghensis was recorded from Manipur, Meghalaya,
Nagaland, Tripura, and West Bengal in India. But M. mukhlesuri
has been listed only from Mizoram state in the northeastern
India (Garg et al. 2019). No details were reported to confirm the finding. Our study confirms the presence of both
species in West Bengal, by analyzing 16 morphometric characters to separate
these species. We also hereby confirm the presence of Microhyla
mukhlesuri from the Gangetic Plain of West Bengal
in India, as it was described from Bangladesh (Hasan et al. 2014).
Materials and Methods
Field work was conducted during
late evening in the months of May–July 2020 in Kharagpur, Medinipur
Sadar (22.2500˚N, 87.6500˚E), Ghatal
and Jhargram (22.0559˚N, 87.1518˚E) areas of West
Midnapore district in the state of West Bengal, India. Habitats searched
included marshes, pools, riverbanks and sandy soils inside grass, leaf litter
and under boulders. Morphometric and meristic studies on the preserved
specimens were done at the laboratory of the Herpetology Division, Zoological
Survey of India, Kolkata using a LEICA EZ-4 stereo binocular microscope and a Heerburg magnanoscope.
Measurements were done with Mitutoyo Digital caliper to the nearest 0.1 mm.
Four specimens were collected (ZSI A 14818, ZSI A 14819, ZSI A 14871 and ZSI A
14872) and identified as Microhyla mukhlesuri (Image 1a, Table 1a). Five specimens were
collected (ZSI A 14680, ZSI A 14681, ZSI A 14682, ZSI A 14873 and ZSI A 14874)
and identified as Microhyla mymensinghensis (Image 1b, Table 1b). We found no Microhyla ornata in
the sampling site (Midnapore, West Bengal) during our survey.
For species-level analysis we
examined 16 morphological characters to elucidate species identification (1)
Body size (SVL) (2) Head length and head width (HL/HW) (3) extent of Tibiotarsal articulation (4) Shape of Terminal phalanges on
toes (5) Shape and size of Inner and outer metatarsal, metacarpal tubercle; (6)
Webbing on toes (7) length of femur and tibia (8) Dorsal spotting. (9) extent
of Lateral stripe (10) pattern on the anus. (11) FAL= Forearm length, LAL=
Lower arm length, HAL= Hand length, FAW= Forearm width 12. Axilla-Groin
distance (A-G) (Table 1). We also have added HL, HW, FAW, TL and A-G ratios
with SVL (Table no 2). We have grouped the species based on characters
described by Hassan et al. (2014).
Principal Component Analysis
(PCA) was performed on 16 morphometric measurements from specimens of both Microhyla mukhlesuri
(n= 4) and Microhyla mymensinghensis
(n= 5) using PAST 3.0 Software.
Before doing the PCA, a normality test was done for all the variables.
PCA factor scores for principal components (PC) with eigenvalues >1.0 were
reported. Factor scores of the first two components were visualized on
scatterplots to assess the degree of morphological differentiation between
specimens of the two species.
Results
Two Microhyla
species were collected during the present study Microhyla
mukhlesuri (n= 4) and M. mymensinghensis
(n= 5). The specimens were identified to belong to the genus Microhyla by the following morphological
characters: absence of vomerine teeth, hidden tympanum, elliptical tongue,
short snout, small eyes not protuberant and invisible from the ventral side,
indistinct canthus rostralis and fingers free of
webbing. Four specimens were identified as Microhyla
mukhlesuri (Image 2a) based on size, extent of tibio-tarsal articulation, mark on anus, forearm width,
tibia length and shape of terminal phalanges (Garg et al. 2019; Hasan et al.
2014). This is the first record of Microhyla
mukhlesuri from entire Gangetic plains of India,
West Bengal (Nayagram, 22.0361˚N, 87.1717˚E) (Image
1) which extends its range by 494 km from its type locality (Rhozan, Chittagong, Bangladesh) and by 568 km away from
Mizoram, India (which was the only record from India Garg et al. 2019). Whereas
M. mymensinghensis (Image 2b) is
identified based on size, tibia length, mark on anus and forearm width (Garg et
al. 2019; Hasan et al. 2014). We found M. mukhlesuri
differs from M. mymensinghensis by its
relatively larger adult size (Garg et al. 2019) and inverse U-shaped black mark
above the anus for M. mukhlesuri
whereas crescent-shaped black mark present above the anus in M. mymensinghensis as described by Hassan et al.
(2014).
Identifying taxonomic characters
to differentiate M. mukhlesuri and
M. mymensinghensis is problematic. Both
species exhibit similar extent of tibiotarsal
articulation (when the hind leg is adpressed) up to
the snout or between the eye and snout and a lateral stripe that also extends
to near the snout. Garg et al. (2019) paid attention to the shape of terminal
phalanges, though the holotype description by Hassan et al. (2014) focused on
forearm width, tibial length and mark on anus. We would like to focus on five
putative distinguishing characteristics (a) an inverse U shape mark on the anus
for M. mukhlesuri (vs crescent shaped mark in M.
mymensinghensis) (Hassan et al. 2014); (b) a
larger SVL in M. mukhlesuri (19.92–20.86 mm)
(n= 4), vs. shorter (17.22–18.86 mm) (n= 5) in M. mymensinghensis,
(c) Microhyla mymensinghensis
has longer Tibia (TL) than Microhyla mukhlesuri, (d) Microhyla
mymensinghensis has thicker fore-arm (FAW) than Microhyla mukhlesuri (Hassan
et al. 2014), and (e) terminal phalanges of fourth toe tip knobbed but
flattened in M. mukhlesuri (vs. knobbed
but not flattened in M. mymensinghensis)
(Garg et al. 2019) (Table 1). Based on these characters we have identified and
classified the specimens examined in this study.
In addition to aforementioned
described characters, we identified a few supplementary characters to
differentiate two species more confidently: (a) shape of inner metacarpal
tubercle elongated in M. mukhlesuri vs.
rounded in M. mymensinghensis; (b) large inner
metatarsal tubercle, i.e., about 0.76 (±.08) mm in M. mukhlesuri
vs about 0.57 (±.06) mm in M. mymensinghensis;
(c) most significantly, axilla-groin distance 47% of SVL in M. mukhlesuri vs 38% of SVL in M. mymensinghensis.
Both these species were observed co-occurring in humanized / agricultural
habitats in the sampled areas (Image 3a, b).
Microhyla mukhlesuri
showed
differences with M. mymensinghenis in terms of
morphology. Principal Component Analysis (PCA) for the specimens of both the
species (M. mukhlesuri, n= 4; M. mymensinghensis, n= 5) recovered two Principal
Components (PC) with eigenvalues > 1.0 that accounted for 85.8% of the total
variance. PC1 explained 74.09% variance with highest loadings for A-G, TL, SVL
and FoL. PC2 explained 11.71% variance with highest
loadings for A–G, and HW. The remaining factors explained 14.2% of the
variations. For the combined data set for both male and female projections of
the factor planes 1 and 2 showed distinct clusters for the two species (Figure
1).
Discussion
Previously, Microhyla
‘ornata’ like species were grossly grouped with
four known species—M. mukhlesuri, M. mymensinghensis, M. nilphamariensis,
and M. ornata. In 2018 two well-supported
species groups were established – (1) M. mukhlesuri
and M. mymensinghensis, along with M. fissipes from southeastern and eastern Asia, and (2) M.
nilphamariensis and M. ornata,
along with M. taraiensis from Nepal (Garg et
al. 2018). A prominent lateral stripe extends from belly to nostril in M. mukhlesuri and M. mymensinghensis
whereas a less prominent lateral stripe extends from shoulder to belly in M.
nilphamariensis and M. ornata.
An inverse U shape mark on the
anus for M. mukhlesuri (vs crescent shaped
mark in M. mymensinghensis); larger SVL in M.
mukhlesuri (19.92–20.86 mm) vs. shorter
(17.22–18.86 mm) in M. mymensinghensis and
terminal phalanges of toes knobbed but tip flattened in M. mukhlesuri (vs. knobbed but not flattened in M. mymensinghensis) are used to group the two species. In
addition to this we have identified axilla-groin distance, size of metatarsal
tubercle and shape of metacarpal tubercle to differentiate these two species
more confidently. The PCA results reveal two different clusters on the
scatterplot, representing two different species –Microhyla
mukhlesuri (n= 4) and M. mymensinghensis
(n= 5).
Microhyla mukhlesuri has been reported only from
Mizoram state in the northeast India (Garg et al. 2019). With two males
and two female specimens we hereby for first time confirm the presence of Microhyla mukhlesuri
from the Gangetic Plain in West Bengal, apart from Mizoram. We are optimistic
about the wider distribution of Microhyla mukhlesuri in the Gangetic plains. Nevertheless we do
encourage genetic studies of these Microhyla
frogs, especially after finding geographic contact zones where two
similar-looking, genetically-allied congeners Microhyla
mukhlesuri and M. mymensinghensis
co-occur, throwing open necessity for further fine-scale diagnosis, preferably
morphological, between them.
Table 1a. Sixteen morphometric
character values (in mm) for Microhyla mukhlesuri.
|
Specimen No |
ZSI A 14819 |
ZSI A 14818 |
ZSI A 14871 |
ZSI A 14872 |
Mean |
|
Sex |
male |
male |
male |
female |
|
|
SVL |
20.86 |
18.92 |
19.84 |
20.76 |
20.09 |
|
HL |
4.28 |
4.71 |
3.98 |
3.78 |
4.18 |
|
HW |
4.56 |
5.44 |
4.35 |
4.36 |
4.67 |
|
SL |
2.39 |
2.57 |
2.27 |
2.58 |
2.45 |
|
FAL |
3 |
3.14 |
4.52 |
4.29 |
3.73 |
|
LAL |
3.09 |
3.05 |
3.5 |
3.67 |
3.32 |
|
HAL |
4.17 |
3.07 |
3.9 |
3.06 |
3.55 |
|
FAW |
1.08 |
1.13 |
1.2 |
1.33 |
1.17 |
|
IMC |
0.48 |
0.57 |
0.42 |
0.44 |
0.47 |
|
OMC |
0.42 |
0.51 |
0.32 |
0.38 |
0.4 |
|
A-G |
8.52 |
8.96 |
8.87 |
11.33 |
9.42 |
|
FL |
8.15 |
8.23 |
8.18 |
8.41 |
8.24 |
|
TL |
10.8 |
9.97 |
10.56 |
10.37 |
10.42 |
|
FoL |
9.89 |
10.16 |
9.41 |
9.35 |
9.7 |
|
IMT |
0.79 |
0.7 |
0.69 |
0.87 |
0.76 |
|
OMT |
0.53 |
0.38 |
0.52 |
0.46 |
0.47 |
Table 1b. Sixteen morphometric
character values (in mm) for Microhyla mymensinghensis.
|
Specimen No |
ZSIA 14680 |
ZSIA 14681 |
ZSIA 14682 |
ZSIA 14873 |
ZSIA 14874 |
Mean |
|
Sex |
male |
male |
female |
male |
male |
|
|
SVL |
17.72 |
18.07 |
17.97 |
18.86 |
17.22 |
17.96 |
|
HL |
3.79 |
3.9 |
3.74 |
3.83 |
3.43 |
3.73 |
|
HW |
4.45 |
5.71 |
4.42 |
4.72 |
5.23 |
4.9 |
|
SL |
1.97 |
2.41 |
2.35 |
2.5 |
2.22 |
2.29 |
|
FAL |
4.48 |
3.71 |
3.8 |
4.65 |
3.55 |
4 |
|
LAL |
3.27 |
3.02 |
3.4 |
4.02 |
3.37 |
3.41 |
|
HAL |
3.81 |
3.77 |
3 |
3.86 |
3.44 |
3.57 |
|
FAW |
1.11 |
1.2 |
1.02 |
1.45 |
1.34 |
1.22 |
|
IMC |
0.45 |
0.42 |
0.44 |
0.68 |
0.55 |
0.5 |
|
OMC |
0.37 |
0.34 |
0.38 |
0.55 |
0.48 |
0.42 |
|
A-G |
5.62 |
6.55 |
6.14 |
8.53 |
7.6 |
6.88 |
|
FL |
6.16 |
6.43 |
7.94 |
7.94 |
6.62 |
7.01 |
|
TL |
10.02 |
9.13 |
10.29 |
9.67 |
9.11 |
9.64 |
|
FoL |
8.4 |
7.53 |
8.64 |
8.67 |
8.13 |
8.27 |
|
IMT |
0.58 |
0.67 |
0.54 |
0.54 |
0.51 |
0.57 |
|
OMT |
0.34 |
0.42 |
0.38 |
0.42 |
0.36 |
0.38 |
Table 2. Ratios of morphometric
character values for Microhyla mukhlesuri and Microhyla
mymensinghensis. For character abbreviations see Materials
& Methods.
|
Ratios |
Microhyla mymensinghensis |
Microhyla mukhlesuri |
|
HL/SVL |
.21±.01 |
.22±.02 |
|
HW/SVL |
.27±.04 |
.24±.03 |
|
FAW/SVL |
.07±003 |
.06±.005 |
|
AG/SVL |
.38±.04 |
.47±.06 |
|
TL/SVL |
.54±.02 |
.51±.01 |
|
HL/HW |
.76±.09 |
.89±.03 |
For
figure & images - - click here
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