Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 May 2020 | 12(8): 15916–15921
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
doi: https://doi.org/10.11609/jott.6092.12.8.15916-15921
#6092 | Received 03 May 2020 | Finally
accepted 18 May 2020
Life-history traits and courtship
behaviour of four poorly known endemic bush frogs (Amphibia: Anura: Rhachophoridae) from the
Western Ghats of India
A.V. Abhijith
1 & Shomen Mukherjee 2
1,2 Azim Premji
University, PES Campus, Pixel Park, B Block Hosur Road, beside NICE Road,
Electronic City, Bengaluru,
Karnataka 560100, India.
2 Ashoka Trust for Research in
Ecology and the Environment, PO, Royal Enclave, Srirampura,
Jakkur, Bengaluru, Karnataka 560064, India.
1 abhijith.manoj9@gmail.com
(corresponding author), 2 shomenm@gmail.com
Editor: Neelesh Dahanukar, IISER, Pune,
India. Date of
publication: 26 May 2020 (online & print)
Citation: Abhijith,
A.V. & S. Mukherjee (2020). Life-history traits and courtship behaviour
of four poorly known endemic bush frogs (Amphibia: Anura:
Rhachophoridae) from the Western Ghats of India. Journal of Threatened Taxa 12(8): 15916–15921. https://doi.org/10.11609/jott.6092.12.8.15916-15921
Copyright: © Abhijith
& Mukherjee 2020. 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: Azim Premji
University, Science and
Engineering Research Board (grant number TAR/2018/001233 to SM).
Competing interests: The authors
declare no competing interests.
Acknowledgements: The authors would like to thank Manoj Kumar A.V. and Dr Anil
Zachariah for their help and support.
Abstract: The Western Ghats have a high
level of anuran endemism. Although there
has been an extensive focus on their taxonomy, the ecology of most species are
poorly known. In this note we describe
the reproductive life-history traits and breeding behavior of four species of
endemic bush frogs, Pseudophilautus wynaadensis, Raorchestes
akroparallagi, Raorchestes
glandulosus, and Raorchestes
ponmudi (Amphibia: Anura:
Rachophoridae) from Wayanad region of Western Ghats.
Keywords: Clutch-size, reproduction,
metamorphosis, direct metamorphosis, coffee plantation, Pseudophilautus wynaadensis,
Raorchestes akroparallagi, Raorchestes
glandulosus, Raorchestes
ponmudi
The Western Ghats mountain ranges is one of the global
biodiversity hotspots (Myers et al. 2000).
The area has a high diversity of amphibians, many of which are endemic
(Das et al. 2006; Dahanukar & Molur
2020). In the past two decades, while
researchers have extensively focused on amphibian taxonomy and systematics, the
knowledge about their basic life-history traits (e.g., time to first
reproduction, clutch size, weight at hatching) are still limited. This information can be vital for
understanding both the ecology and conservation status of a species.
In this note,
we describe the egg-laying behavior, and two life-history traits (clutch size,
and time to metamorphosis) for four species of endemic bush frogs, Pseudophilautus wynaadensis,
R. akroparallagi, R. glandulosus,
and R. ponmudi, all of which have direct development (Vijayakumar et al.
2016). All these species are known to
breed during the monsoon season.
Previously, one paper each has described the breeding
behavior of R. akroparallagi (originally
reported as R. glandulosus by Biju (2003) but
species identity rectified in Biju & Bossuyt (2009)) and R.
glandulosus (Krishnamurthy
et al. 2002). However, after reviewing Krishnamurthy et al. (2002),
we realized that R. glandulosus had been
misidentified (it is likely R. tuberohumerus
since the groin and anterior surfaces of
thighs in their Figure 1 is dark brown with yellow blotches). No article,
to the best of our knowledge, has reported the breeding behavior or
life-history traits of the other two species (R. ponmudi
and P. wynaadensis).
We report observations that were made in a coffee
plantation situated next to Kalloor, Sulthan Bathery (Wayanad,
Kerala), around half a kilometer away from Wayanad Wildlife Sanctuary, Kerala
(11.6640N & 76.3310E). For detailed observations, each amplecting pair
was transferred to a terrarium (a plastic circular 20L tub – 80cm diameter and
~1m height), which was installed outdoors in a shaded area to maintain the
ambient temperature and humidity. The
terrarium was covered with a mesh and consisted of a layer of soil collected
from the same area (7–8 cm thick), leaf litter, and vegetation (a few branches
of a coffee tree with intact leaves, grass).
All the adult individuals were released back to the same location from
which they were captured the previous night, assuming there is no parental care
(as suggested by Biju 2003). All
the observations were done using a LED torch whenever necessary.
Pseudophilatus wynaadensis
Two amplecting pairs were found on coffee plant (about
50–100 cm from the ground), the first on 15 May 2016 and second on 15 July 2019
(Image 1a). Both the pairs were
transferred to the terrarium, and by morning the pairs had finished laying
eggs. The frogs had transformed into a
duller brown color over the night in both cases.
After inspecting the terrarium, in both cases the eggs
(Image 1b) were found underneath a small layer of soil (1–2 cm deep). The number of eggs in the first and second
clutch were 29 and 33, respectively. In
the successive days, the froglets underwent direct development (Image 1c) and
hatched synchronously after 22 and 25 days, respectively (Image 1d).
We weighed the eggs from the 2019 clutch throughout
the developmental period. The average
weight of the eggs was 0.074g (N=10; measured on 11th, 18th,
22th, and 25th day after the egg laying). A newly hatched froglet weighed 0.019g (N=3).
Raorchestes akroparallagi
An amplecting pair of R. akroparallagi
(Image 2a) was found during late evening (20.25h) on 10 June
2019, during a slight drizzle. The pair
was observed sitting on a coffee plant leaf (about 160cm above ground). After around half hour of observation, they
were transferred to a terrarium. The
frogs were inspected every few hours, and throughout the night the male
remained attached to the female’s dorsum.
The greenish colored frogs had transformed into shades of brown by
morning (Image 2b).
At 11.54h, we found that the female had already
started laying eggs (5 eggs were visible).
The pair was closely observed throughout the egg-laying period (Image
2b). After egg-laying (12.17h), the male
detached himself from the female and positioned himself in a restful manner on
one of the coffee leaves. Meanwhile, the
female covered up the eggs with soil particles that surrounded it. During this process, the female rolled the
eggs in the soil such that the whitish-cream colored egg turned into a
reddish-brown color (same as the soil).
An earlier study had recorded the egg-laying on a coffee leaf (Biju
2003).
On 11 June 2019, we carefully exposed all
the eggs (a total of 49 eggs) from the soil.
The eggs underwent direct development (Image 2c), and after 21 days of
laying the eggs, all the froglets hatched synchronously (Image 2d).
Raorchestes glandulosus
On 07 June 2019, at around 19.30h a female R. glandulosus was located on the leaf of a coffee plant
at a height of approximately 200cm. The
female approached a calling male (also situated around 2m from the ground
level) on the same plant. After about 15
minutes, the male gave out a distinct call and pounced onto the female. The female reacted by jumping away from the
male after which the male started calling again. The male and female responded to each other
in this manner three times. On the
fourth try, the male managed to successfully hold onto the female’s dorsum
facing the opposite direction (Image 3a). After a while, the male realigned
himself facing towards the female, head following which the amplecting pair was
transferred to a terrarium.
The amplecting pair laid eggs inside the soil (1–2 cm
in depth; Image 3b), even though they had the choice to lay their eggs on the
leaf of a branch. The yellowish-green
frogs transformed into shades of brown during the process of egg-laying (at
02.33h), and the female covered the eggs using soil particles that surrounded
the egg clutches. A total of 55 eggs
were laid and underwent direct development (Image 3c). The froglets synchronously hatched after 21
days (Image 3d).
Although the above mentioned observations were
recorded from a terrarium, similar observations have been reported from a
natural setting near Madikeri, Karnataka (Abhishek
Jain pers. comm. June 2019). A pair of
amplecting individuals was located on 12 June 2019. The female laid 39 eggs in a cluster about
3cm below the leaf litter mixed with soil.
The frogs changed their colours to dull brown
within 15 minutes of heading down to the leaf litter. Even in this case, all the eggs underwent
direct development and hatched synchronously.
Raorchestes ponmudi
We observed two different clutches of this species. The first pair of R. ponmudi
was found during late evening (19.55h) on 18 May 2019, after a short rain
(5.8mm). The temperature that night was
22.6˚C and a humidity of 86%. The pair
was observed in an amplexus, on a horizontal coffee branch about 150cm above
ground. Two other males were calling
from the same plant, frequently giving out a territorial call and showing a
tendency for fighting. The amplecting
pair (Image 4a) was observed for around an hour.
Following this, the pair was transferred to a
terrarium. The frogs were inspected
every few hours for around 15min, and their activities were recorded. The female carried the male from leaf to leaf
and finally settled down on a small patch of bare soil at around 02.30h. The male remained firmly attached to the
female’s dorsum. When the frogs were
inspected the following morning (~ 06.00h), the male had detached himself from
the female and was resting on a coffee leaf.
Since the previous observation was taken at 03.30h, the egg laying must
have happened sometime between 03.30h and 06.00h.
At 06.00h, the female looked lean (when compared to
the previous night), and was seen covering up the eggs using soil particles
that surrounded the egg clutch. This
activity went on for another one and a half hours, after which the individual
settled down and rested on the soil.
After a day (12 June 2019), a total of 81
eggs were carefully collected from the soil (1–2 cm). Each egg was unpigmented, whitish-cream
colored, and covered by a thick jelly coat (Image 4b). Water was sprayed once in two days to prevent
the eggs from drying. The egg clutch was
observed every day and photographs of its developmental phases were taken. The eggs underwent direct development (Image
4c), and after 19 days, the froglets hatched (Image 4d).
The second amplecting pair of R. ponmudi was found at 21.31h (same coffee plantation as
above), on 25 May 2019. The average rain
that night was 8mm, and the pair was located around 1m from the ground
level. Interestingly, the male was
sitting on the female facing the opposite direction. Only after a few hours did the male align
himself properly on the female. In both
the amplecting pairs, the frogs changed their color to dark brown during the
egg-laying process.
This pair was also transferred to a terrarium (similar
dimension as the previous pair), where the female laid the eggs in the soil at
a depth of around 1–2 cm. Egg-laying
started at approximately 05.00h. After
the male detached himself, the female covered the eggs with soil. The female laid a total of 78 eggs. This time, the eggs were not disturbed, and
the soil was sprayed with water to prevent it from drying up, however, after a
few days we observed fungal growth on the soil, and the development of the
froglets ceased. Later the eggs dried
up.
Conclusions
To summarize, all the four species of bush frogs laid
their eggs in moist soil, under a layer of leaf litter, where they underwent
direct metamorphosis. The clutch size
for the three Raorchestes species
ranged from 49 (R. akroparallagi), 55 (R. glandulosus) to an average of 83 eggs (for R. ponmudi). Their
time to hatching ranged from 19 (for R. ponmudi)
to 21 days (R. akroparallagi; R. glandulosus). Pseudophilatus wynaadensis,
on the other hand, had an average clutch size of 31 eggs and hatched
between 22 and 25 days. To the best of
our knowledge, there is only one record of the breeding biology of R. akroparallagi (Biju & Bossuyt 2009). Apart from
this, these are the only known records of some of the reproductive life-history
traits of the other three species of bush frogs.
References
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