Description of tadpole stages of the Malabar Tree Toad Pedostibes tuberculosus Günther, 1875 (Anura: Bufonidae)
K.P. Dinesh 1 & C. Radhakrishnan2
1 Southern Regional Centre, Zoological
Survey of India, Chennai, Tamil Nadu 600028, India
2 Western GhatRegional Centre, Zoological Survey of India, Kodhikode,
Kerala 673006, India
2 present address: 33/5267-D, Devika, Golf links Road, Chevayur,
Kozhikode 673 017, Kerala, India
1 kpdinesh11@gmail.com (corresponding author), 2 radhakrishnan.zsi@gmail.com
doi: http://dx.doi.org/10.11609/JoTT.o3398.4910-2 | ZooBank:urn:lsid:zoobank.org:pub:BF771B39-57CE-4155-B78F-48FD2A55BCAE
Editor: Anonymity requested. Date of
publication: 26 October 2013 (online & print)
Manuscript details: Ms # o3398
| Received 25 October 2012 | Final received 15 May 2013 | Finally accepted 04
October 2013
Citation: K.P. Dinesh & C. Radhakrishnan (2013).Description of
tadpole stages of the Malabar Tree Toad Pedostibes tuberculosus Günther, 1875 (Anura: Bufonidae). Journal of Threatened Taxa5(14): 4910–4912; http://dx.doi.org/10.11609/JoTT.o3398.4910-2
Copyright: © Dinesh & Radhakrishnan 2013. Creative Commons Attribution 3.0 UnportedLicense. JoTT allows unrestricted use of this
article in any medium, reproduction and distribution by providing adequate
credit to the authors and the source of publication.
Funding: The work is based on the annual research programme of
Zoological Survey of India (ZSI), Ministry of Environment & Forests,
Government of India.
Competing Interest:Authors declare no competing interests.
Acknowledgements: We are grateful to the Director, Zoological Survey of
India (ZSI), Kolkata, for encouragement and support. We thank Dr. (Mrs.) Rajmohana,
Scientist-C, ZSI, Kozhikode, for helping us in the photographic work of
tadpoles and Mr. V. ManikantanNair, ZSI, Kozhikode, for his assistance in field work.
We also thank the anonymous referee for critical comments on an earlier version
of the manuscript.
The publication of this article is
supported by the Critical Ecosystem Partnership Fund (CEPF), a joint initiative
of l’Agence Française de Développement, Conservation International, the
European Commission, the Global Environment Facility, the Government of
Japan, the MacArthur Foundation and the World Bank.
Pedostibes tuberculosus is a
member of the toad family Bufonidae exhibiting a phytotelmatic mode of life (leading an arboreal mode for
the most part of its life). This toad was described by Günther in 1875 from
southern India with the type locality mentioned as ‘Malabar’ (now part of
coastal Kerala). The species is
commonly known as the Malabar Tree Toad and is endemic to the Western
Ghats. This toad was not known from
any of its natural environs for more than a span of 100 years since its
description, till it’s rediscovery by S.K. Bhattacharya from the Silent Valley
National Park in 1980 (Pillai 1986). There was no information on its natural
history and life cycle and the only information available was its range of
distribution and advertisement call details (Gururaja& Ramachandra 2006; Dinesh & Radhakrishnan 2008). However, Boxclaer et al. (2009) mentioned a
specialized development and an egg clutch size of 250 eggs laid at the edge of
streams, wherein the tadpoles develop by bottom feeding.
The species is placed under the ‘Endangered’ category in the IUCN Red
List (Biju et al. 2004).
On 2 July 2009, during our search for the reed associated
frogs at Kakkayam Reserve Forest (11.548750N
& 75.9237880E), Kozhikode District, Kerala, we encountered nine
motile tiny tadpoles (assignable to Stage 21 of Gosner1960), inside the culm of a standing, dried, Ochlandra plant with some water trapped in the nodal region. All the nine tadpoles were collected and
moved to a laboratory for further observation.
Materials and Methods: The tadpoles were kept
in a petri dish containing rain water and maintained at
room temperature between 220C and 240C. The tadpoles were fed with boiled
chicken egg yolk. The tadpole stage
numbers were assigned as per Gosner (1960). Live tadpole images were captured using
a Leica M 205A stereo microscope, with a Leica DFC 500
camera. The tadpoles were observed
periodically (but not on a daily basis) for 26 days from the date of
collection. From the1stday of collection from the field, significant changes seen on the 7th,
14th, 18th, 20th, 22nd, 24thand the 26th day were studied and recorded.
Observations: On the day of the collection from the
field, the tadpoles were at Stage 21 (Image 1) and were creamy white in colour,
fragile and motile. The body of the
tadpoles was transparent, dorso-laterally compressed,
with a narrow head and distinct oral disc, and a sucker median in position (a
in Image 1). The eyes were dark
circular (b in Image 1) and abdomen with a mass of yolk in a sac like structure
bulging towards the tail musculature (c in Image 1). Tail muscle axis, tail musculature (d in
Image 1) and vent tube, were clearly visible and the tail fin was transparent
(e in Image 1).
At Stage 27 (on the 7th day from the date of collection of
the tadpoles from field) (Image 2) the tadpoles were active and motile, their
body dorsoventrally compressed (c in Image 2). The Dorsum of the body became brownish
and the eyes were distinct at the anterior part of the body (b in Image
2). The region behind the eyes was
wider and the sucker was in a ventral position (a in Image 2). The ventral side of the body appeared
transparent (a in Image 3) and the intestine was spirally coiled (b in Image
3). Distinct limb buds (d in Image 2 & c in Image 3) could be seen at the
junction of the body and a tail fin was present.
At Stage 41 (on the 14th day from the date of collection of
the tadpoles from the field) (Image 4), the body of the tadpoles appeared dorsolaterally compressed, brownish and with enlarged eyes
(b in Image 4). The width and
length of the tail were reduced (e in Image 4), the mouth region appeared
arched (rounded) (a in Image 4) and the skin over the forelimb transparent (c
in Image 4), the hind limbs had emerged out of the body (d in Image 4).
At Stage 42 (on the 18th day from the date of collection of
the tadpoles from the field) (Image 5), the body colour turned brownish; the
eyes grew large, round and black in colour (b in Image 5); the oral disc got dorso-laterally placed and the mouth region gained a
circular shape (a in Image 5). The
forelimbs were within the skin sac (c in Image 5), and the hind limbs nearly
completely grown (d in Image 5). The tail appeared rounded and tapered (e in Image 5).
At Stage 43 (on the 20th day from the date of collection of
the tadpoles from the field) (Image 6), the body of the tadpoles appeared
brownish dorsally with two lateral silvery yellow stripes. The eyes were rounded and clear (b in
Image 6) with a formation of snout and canthus rostralis(a in Image 6). The forelimbs and
hind limbs were completely formed (c & d in Image 6) with a clear
demarcation of fingers and toes. The tail became more tapered and appeared to
be sinking (e in Image 6).
At Stage 44 (on the 22nd day from the date of collection of
the tadpoles from the field) (Image 7), the body colour of the tadpole turned
brownish with the yellow silvery lateral band extended on to the head region;
the snout and canthus rostralis became distinct (a in
Image 7) and the region of the orbit flat; the hind and fore limbs were
completely developed (b & c in Image 7), with the tail further diminished. The tadpoles started moving to the
periphery of the water without much use of the tail.
At Stage 45 (on the 24th day from the date of collection of
the tadpoles from the field) (Image 8), the edges of the dorsum of the tadpoles
appeared silvery-yellow in colour (a & b in Image 8), the lateral sides
appearing blackish-brown; the snout was obtuse in
shape and the orbit region elevated. The fore and hind limbs were operational
(c & d in Image 8), and the tail size much diminished (f in Image 8) resembling
a young one of P. tuberculosus, climbing out
of the water.
At Stage 46 (on the 26th day from the date of collection of
the tadpoles from the field), the tail of the tadpoles was completely absorbed
into the body and the imagos resembled the adults of
the species and were seen hopping around.
Discussion: The IUCN Red List
(http://www.iucnredlist.org/details/16470/0) categorises P. tuberculosus as ‘Endangered’, in spite of the fact that
the species is known to have a confirmed distribution range from Cotegoa (14.9780N & 74.1480E) to Kalakkad (8.53050N & 77.4560E)
(Dinesh & Radhakrishnan in 2008). During many of
our field explorations in the Western Ghats, we have seen this species locally
abundant (seasonal) in certain pockets of evergreen forests. We suggest that a
re-assessment study based on authentic field work of
this tree toad is required to gather more information on the natural history of
this species.
During our visits to the collection site from 2009 to 2012, we came
across young ones of P. tuberculosus at
various stages inside the Ochlandrae culm and
the adults making advertisement calls on various occasions. However, we could not get amplecting pairs so as to observe the entire egg laying
procedure. Therefore, in our present observation we report only the
transformation of tadpoles from Stage 21 to independent young ones (imago),
taking 26 days to complete the process.
The present report forms the first record of some of the tadpole stages
for P. tuberculosus. In our general observations, we note
that this species breeds next to shallow streams of forests where the males
assemble next to streams and call in chorus during the monsoon showers of June. Our current observation of the
collection of eggs from the dried reed confirms its phytotelmaticmode of life and breeding. Our
observations are contrary to Boxclaer et al. (2009)
report of about 250 eggs in a clutch at the edge of streams and bottom feeding
tadpoles pertaining to this tree toad.
Our observations warrant further detailed investigations to understand amplexus and how an amplectedpair lays eggs inside the culm.
REFERENCES
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