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Accepted by M. Vences: 9 May 2012; published: 15 Jun. 2012
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Copyright © 2012 · Magnolia Press
Zootaxa 3347: 63–68 (2012)
www.mapress.com/zootaxa/Article
63
Back from the dead: The world’s rarest toad Adenomus kandianus rediscovered
in Sri Lanka
L. J. MENDIS WICKRAMASINGHE1, 2, DULAN RANGA VIDANAPATHIRANA1 &
NETHU WICKRAMASINGHE1
1Herpetological Foundation of Sri Lanka, 31/5, Alwis Town, Hendala, Wattala, Sri Lanka
2 Corresponding author. E-mail: boiga2000@gmail.com
Abstract
Adenomus kandianus Günther (1872) was previously known only from two specimens both deposited in the British Museum,
the holotype BMNH1947.2.20.63, and the syntype of A. kelaarti BMNH1947.2.20.62. The only record of A. kandianus since
the initial description in 1872 was by Ferguson in 1876, who mentions two specimens resembling Bufo kandianus in his
collection, making A. kandianus the world’s rarest toad. The species had not been reported since, and was considered extinct.
Here we report on its rediscovery.
Key words: Adenomus, extinct amphibian, rediscover, Peak Wilderness, Sri Lanka
Introduction
Adenomus kandianus is one of the 21 amphibian species known to be extinct from Sri Lanka after extensive
searches over a ten-year period failed to locate this species in the wild (Manamendra-Arachchi and Pethiyagoda,
1998, 2005; Manamendra-Arachchi and de Silva, 2004; Stuart, et al., 2008; Meegaskumbura, et al., 2007). A
global amphibian hotspot (Meegaskumbura, et al., 2002), the island of Sri Lanka consists of 111 species of
amphibians described so far, and it also carries the dubious distinction of contributing the highest proportion (60%)
to the global list of extinct amphibians (Manamendra-Arachchi and Pethiyagoda, 1998, 2005; Manamendra-
Arachchi and de Silva, 2004; Stuart, et al., 2008; Meegaskumbura, et al., 2007). These extinctions belong to the
following taxa: one to the family Bufonidae (Adenomous kandianus), one to the family Dicroglossidae
(Nannophrys guentheri), and nineteen species to the family Racophoridae (Pseudophylautus species) (Stuart, et al.,
2008).
The Sri Lankan endemic genus Adenomus is represented by the three species A. dasi, A. kandianus, and A.
kelaarti (Manamendra-Arachchi and Pethiyagoda, 1998) all of which are stream dwelling toads. Gunther first
described A. kandianus from a single specimen under the genus Bufo and provided a concise description with vital
diagnostic characters important in identifying the species. Later publications synonymized A. kandianus as A.
kelaartii Kirtisinghe, (1955), but according to the latest bufonid synopsis A. kandianus was once again considered
a valid yet extinct species. Furthermore, in all publications there after the species was listed as extinct
(Manamendra-Arachchi and Pethiyagoda, 1998; Manamendra-Arachchi and de Silva, 2004; Stuart, et al., 2008;
IUCN and MENR 2007).
The Peak Wilderness Sanctuary is one of the few remaining areas in Sri Lanka with a continuous natural forest
cover of altitudinal graded forest types, ranging from lowland mixed Dipterocarp forests to montane cloud forests,
having its own forest vegetation and is an area of great biological diversity (Singhakumara, 1995). It covers a large
altitudinal range and different climate conditions which is well reflected by its forest type and biodiversity. Forests
ranging from Tropical Lowland Forests (<1050 m) to Tropical Montane Forests (>1650) can be identified within
the area (Fernando and Ranasinghe, 1997). The Peak Wilderness Sanctuary, in particular, harbors the majority of
the endemic and threatened bird species of Sri Lanka (Ranawana and Bambaradeniya, 1998; Wickramasinghe, et
al., 2007). We here report on the rediscovery of A. kandianus during a survey of the Peak Wilderness Sanctuary in
the Central Province, Sri Lanka.
WICKRAMASINGHE ET AL.
64 · Zootaxa 3347 © 2012 Magnolia Press
Materials and methods
Study area: Peak Wilderness was designated a sanctuary on 25th October 1940 (Gazette Notification No. 8,675),
having an area of about 55,300 acres (22,379 ha). According to the current management plan, the geographical area
of the sanctuary is about 24,000 ha, of which 21,175 ha comprises natural or semi-natural vegetation, the rest is no
longer forest and includes tea estate and village settlements (de Alwis, et al., 2007). The sanctuary lies in the centre
of the western ridge of the Central Highlands, north-east of Ratnapura and straddling the border of Central and
Sabaragamuwa provinces. Its eastern boundary is contiguous with Horton Plains National Park. Peak Wilderness
occupies the escarpment that rises steeply from the lowlands to the south and west. Much of the terrain is very rug-
ged, with altitudes ranging from 50 m near Ratnapura to 2,238 m at Adam’s Peak (6° 48' 26.93" N, 80° 30' 03.06"
E), Sri Lanka’s fourth highest peak (de Alwis, et al., 2007).
A systematic survey was carried out in order to document the amphibian diversity across an elevation gradient,
in the Sripada massif, Peak Wilderness (part of the Central Hills World Heritage Site) of the Central province, of
Sri Lanka. Mainly focusing in terrains, where not much light has been shed to the diversity by scientists, because of
the difficulty to reach these sights due to harsh weather conditions and tough trails. The field survey was carried out
over a two year period. A single specimen each from all three congeners were collected, and are deposited in the
Department of Wildlife Conservation (DWC), Girithale National Wildlife Research and Training Center (Adeno-
mus kandianus DWC201201001, SVL 32.24 mm: A. dasi DWC201201002, SVL 28.85 mm: A. kelaarti
DWC201201003, SVL 32.17 mm).
The following morphological characteristics were used in distinguishing each species, and were critically com-
pared against the descriptions for each species: specimen size; shape, and orientation of nostril; shape of internarial
space; shape and orientation of canthus rostralis; shape of snout; loreal region; presence/absence of ridges on head;
size and shape of tympanum; shape and orientation of parotid gland; interorbital area; shape of upper eyelid and
distribution of tubercles; tubercles on head; skin on dorsum; distribution of warts, and granules on dorsum; charac-
ters on ventral aspect (throat, margin of throat, chest, belly, and limbs); tips of fingers, and toes; dermal fringes;
extent of webbing on limbs; presence/absence of tubercles; characteristics of skin on lower and upper parts of
flank.
Series of photographs were made on all members of the genus Adenomus. The extent of webbing on toes were
critically compared with corresponding sketches (Manamendra-Arachchi and Pethiyagoda, 1998) of the respective
holotype specimens except for A. kelaarti which is a lectotype specimen. The original line drawings were given in
black on white background, here we have inverted the colours to fit background. Geographical coordinates were
determined from GPS readings (Gamin eTrex Vista) at the locality where collected.
Results and discussion
Specimens resembling A. kandianus were recorded from the Peak Wilderness Sanctuary (06° 48' 34.16" N, 080°
30' 19.07" E, Altitude 1879 m) on the 23rd October 2009, as a result of a survey carried out in the region to
document the amphibian diversity. During a nocturnal sampling session, about four specimens of an unusual
species were observed, which were sympatric with A. dasi on rocks close to fast flowing streams where a single
specimen was collected in order to taxonomically clarify its identity.
A. kandianus was identified by smooth finger edges, slender habitus and lack of a supraorbital ridge
characteristic of the genus Adenomus (Manamendra-Arachchi and Pethiyagoda, 1998) fully webbed toes diagnostic
of A. kandianus (Günther, 1872) and in addition, a uniform golden yellow venter (absent in A. dasi and A. kelaarti).
Additionally according to its original description (Appendix 1) the following combination of characters; presence
of a cutaneous fold along the edge of tarsus, a long very narrow parotoid gland, hidden tympanum, and yellow
snout confirmed its identity.
A. kandianus can be confused with A. dasi, because of similar body size, morphological characters and geo-
graphical distributions. But the former can be easily distinguished by the presence of complete webbing on toes
(versus half webbed toes), comparatively large warts on dorsum (versus small warts). Apart from the characters
previously mentioned A. kandianus, can be easily distinguished from A. kelaarti by the absence of a cranial ridge
Zootaxa 3347 © 2012 Magnolia Press · 65
REDISCOVERY OF THE RAREST EXTINCT TOAD FROM SRI LANKA
FIGURE 1. Photographic analysis amongst all congeners, and a comparison of the ventral view of foot with the corresponding
type material sketch (Manamendra-Arachchi and Pethiyagoda, 1998). (A) Adenomus kandianus in life. A. kandianus, (B)
holotype BMNH1947.2.20.63, (C) complete webbing of voucher specimen DWC201201001, (D) dorsum with prominent
warts, (E) golden yellow venter, image has been mirrored. A. dasi (F) holotype WHT2267 (G-I) voucher specimen
DWC201201002. A. kelaarti (J) lectotype BMNH1947.2.20.60, (K-M) voucher specimen DWC201201003. Scale bars: 5 mm.
WICKRAMASINGHE ET AL.
66 · Zootaxa 3347 © 2012 Magnolia Press
(present in A. kelaarti), presence of cutaneous fold along the edge of tarsus (versus undulating less prominent
cutaneous fold), long and very narrow parotoid gland (versus short and narrow), hidden tympanum (versus
prominent), comparatively large dorsal warts (versus smaller warts), and chest and belly rough granular (versus
smooth granular) (Fig. 1).
Its characteristic full webbing can only be observed on close examination when the toes are stretched out, and
is not visible when live specimens are hand held. Although Manamendra-Arachchi and Pethiyagoda mentions the
distribution of warts in an hour glass shape as a diagnostic character for A. dasi, this character was not observed on
all specimens of A. dasi, hence we feel that this character should not be used in identifying the species.
Natural History: The species was recorded on rocks of river banks close to fast flowing streams at a very high
altitude above 1800 m asl. All specimens were observed within an area of 200 m2, during nocturnal sampling
sessions from around 1900 h. The canopy cover was that of a montane cloud forest.
Colour in life: Dorsum uniform dark brown, between eyes slightly yellowish tinge, this area sharply defined
by an interorbital dark brown cross bar as stated in original description, light brown band from sacrum to vent mid-
dorsally; laterally dark brown; limbs dorsally light brown, fore limbs, hind limbs, fingers and toes with broad dark
brown cross bands; ventral surface in males uniform golden yellow, and in females dark brown blotching all over
on golden yellow background.
The type locality of A. kandianus is gives as “Ceylon” Günther, (1872) (former Sri Lanka), a vague description
where an area was not specified. The species was originally found in a collection of reptiles and amphibian owned
by Mr. G. H. K. Thwaites, while he was the director of the Royal Botanical Gardens of Peradeniya. Considering the
species epithet and the collector, Manamendra-Arachchi and Pethiyagoda (1998) suggested that the specimen may
have been collected from Kandy. However, the entire central province was referred to as Kandy in the late 19th
Century whereas today it denotes Kandy City and District. Thwaites’ collection includes other specimens not found
in the environs of Kandy. For instance Ixalus femoralis (Pseudophilautus femoralis), I. temporalis (P. temporalis),
and I. schmardanus (P. schmarda) are species found only from the Central Hills at high altitudes above 2000 m asl.
Similar altitudes from the Kandy area are not available, and this collection may well have been collected from all
parts of the country as some other species are only restricted to the dry zone. Therefore, the original specimen of A.
kandianus may have been collected from a high altitude location in the central hills rather than the environs of
Kandy City or District
The species was recorded close to fast flowing streams, at relatively high altitudes, suggesting their preference
to an aquatic life. Also the presence of complete webbing on the toes, most probably facilitates their ease of
swimming in fast flowing streams unlike the other species of the same genus. After the initial sampling session,
close to 100 individuals were recorded in an area of 200 m2.
The Peak Wilderness although is a part of the recently declared Central Hills World Heritage Sites, is polluted
every year from a large number of pilgrims because of its religious importance, especially the streams, and is now
under severe anthropogenic pressures. The highest point of this mountain range, the Adam’s Peak, is a place of
worship by all religions in the country and a place of aesthetic beauty, hence millions visit this site every year
during the pilgrimage season which lasts for a period of 6 months. This is a time when a large amount of garbage
collects, and the natural forest gets over exploited. Illegal gem mining on either side of all major river banks within
the forest have become another potential threat to the amphibian diversity. Tea cultivations in the surrounding areas
are slowly expanding. Illegal tree felling to convert to tea cultivation, has become a major threat in the area. The
survival of this small population of aquatic species re-discovered from a single locality depends on the water
quality, and their breeding habitats. Because they are hyper endemic they are highly vulnerable to environmental
changes such as forest die-back which has spread during the past decade possibly due to pollution and or/ climate
change which has resulted in a decrease of natural forest cover.
Given the high degree of microendemism and species diversity in Sri Lanka, it cannot be fully excluded that
the toad population on which we here report might represent a new, undescribed species rather than Adenomus
kandianus. However, because no molecular data are available on the types of A. kandianus, its type locality is
doubtful as we argue herein, and the encountered specimens agree most closely with the A. kandianus types in
morphology, it is the taxonomically most parsimonious solution to actually consider these toads as A. kandianus
and this species thus rediscovered. Of the six known extinct bufonids of the world (Stuart, et al., 2008), A.
kandianus seems to be the only toad where a live specimen has never been documented since the initial type
description in 1872, for nearly 137 years. Except for Ferguson in 1876, where he mentioned two specimens
Zootaxa 3347 © 2012 Magnolia Press · 67
REDISCOVERY OF THE RAREST EXTINCT TOAD FROM SRI LANKA
resembling Bufo kandianus in his collection, where nothing else has been known, about this species until now, thus
making A. kandianus the world’s rarest toad.
Acknowledgments
The authors wish to acknowledge the Biodiversity Secretariat of the Ministry of Environment for funding and
collaborating the project, to Mr. Gamini Gamage (former Director, Bio diversity), Mr. K. A. I. de Silva (Director
Biodiversity), Mr. R. H. S. S. Samarathunga (Secretary-Ministry of Environment), Mr. N. K. G. K. Nannawaththa
(Additional Secretary-Natural Resources), Mr. R. A. R. Roopasinghe (Additional Secretary administration), Mrs
Dakshini Perera, and Mrs. Hasula Wickramasinghe for all their support rendered. The Department of Wildlife
Conservation for permission granted to carry out the survey (Permit no. WL/3/3/354), the Director of Operations
Mr. H. D. Rathnayake, and the Deputy Director Mr. S. R. B. Dissanayake (Research and Training) for all their
support. Staff of the Nallathanniya and Palabaddala Wildlife range offices, and also for partial funding received
from the Nagao Environment Fund. Heartfelt thanks goes to Dr. Channa Bambaradeniya, Dr. Prithiviraj Fernando,
Mr. Jerome Kiel for their valuable comments, and moral support. Mr. Lalith Senanayake for editing of images. Mr.
Jagath Krishantha, Mr. Ruwan Chinthaka and the late Dr. Amith Munindradasa are fondly remembered for their
support and encouragements. We also like to thank Mr. Sameera Suranjan, Mr. Gayan Chathuranga, Dr. M. D.
Gehan Rajeev, Mr. S. Chathuranga Ariyarathne, Mr. A. W. Amila Chanaka, Mr. L. L. Dharshana Priyantha, for
their support in the field work and our colleagues at the Herpetological Foundation of Sri Lanka for various
courtesies.
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68 · Zootaxa 3347 © 2012 Magnolia Press
Appendix 1
Günther, A. (1872) Descriptions of some Ceylonese reptiles and batrachians. Annals and Magazine of Natural History, Series
4, (9), 87.
Bufo kandianus.
Crown flat, without bony enlargement. Snout rather obtuse, with angular canthus rostralis. Limbs and fingers of moderate
length; the fourth finger longer than the second. Toes rather short, completely webbed. Metatarsus with two small flat cal-
losities: a cutaneous fold along the edge of tarsus. Skin with small tubercles in small number. Parotoid long and very nar-
row. Tympanum entirely hidden by the skin. Inner nares narrow; Eustachian tubes very narrow. Upper parts uniform
brownish grey, except the snout, which is yellowish, the yellowish part being sharply defined by an interorbital line. Lower
parts yellowish.
One specimen, apparently immature, is 30 millims. long; hind limb 40 millims.