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''Duttaphrynus melanostictus'' is commonly called Asian common toad, Asian black-spined toad, Asian toad, black-spectacled toad, common Sunda toad, and Javanese toad. It is probably a complex of more than one
true toad A true toad is any member of the family Bufonidae, in the order Anura (frogs and toads). This is the only family of anurans in which all members are known as toads, although some may be called frogs (such as harlequin frogs). The bufonids now ...
species that is widely distributed in
South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...
and
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland ...
. The species grows to about long. Asian common toads breed during the monsoon, and their tadpoles are black. Young toads may be seen in large numbers after monsoon rains finish.


Characteristics

The top of the head has several bony ridges, along the edge of the snout (canthal ridge), in front of the eye (preorbital), above the eye (supraorbital), behind the eye (postorbital), and a short one between the eye and ear (orbitotympanic). The snout is short and blunt, and the space between the eyes is broader than the upper eyelid width. The ear drum or tympanum is very distinct and is at least as wide as two-thirds the diameter of the eye. The first finger is often longer than the second and the toes are at least half webbed. A warty tubercle is found just before the junction of the thigh and shank (subarticular tubercle) and two moderate ones are on the shank (metatarsus). No skin fold occurs along the tarsus. The “knee” (tarsometatarsal articulation) reaches the tympanum or the eye when the hind leg is held parallel along the side of the body. The dorsal side is covered with spiny warts. The parotoids are prominent, kidney-shaped, or elliptical and elongated, and secrete milky white Bufotoxin. The dorsal side is yellowish or brownish and the spines and ridges are black. The underside is unmarked or spotted. Males have a subgular vocal sac and black pads on the inner fingers that help in holding the female during copulation.


Ecology and behaviour

Asian common toads breed in still and slow-flowing rivers and temporary and permanent ponds and pools. Adults are terrestrial and may be found under ground cover such as rocks, leaf litter, and logs, and are also associated with human habitations. The
larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. T ...
are found in still and slow-moving waterbodies. They are often seen at night under street lamps, especially when winged
termite Termites are small insects that live in colonies and have distinct castes ( eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blat ...
s swarm. They have been noted to feed on a wide range of
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s, including
scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always en ...
s. Tadpoles grown in sibling groups
metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...
faster than those that were kept in mixed groups. Tadpoles have been shown to be able to recognize kin. The 96h
LC50 In toxicology, the median lethal dose, LD50 (abbreviation for " lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is ...
of commercial grade
malathion Malathion is an organophosphate insecticide which acts as an acetylcholinesterase inhibitor. In the USSR, it was known as carbophos, in New Zealand and Australia as maldison and in South Africa as mercaptothion. Pesticide use Malathion is a pe ...
for the tadpoles is 7.5 mg/L and sublethal levels of exposure can impair swimming.


Distribution and habitat

Asian common toads occur widely from northern
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
through
Nepal Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne, सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is ma ...
,
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mo ...
,
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
including the Andaman and
Nicobar Islands The Nicobar Islands are an archipelagic island chain in the eastern Indian Ocean. They are located in Southeast Asia, northwest of Aceh on Sumatra, and separated from Thailand to the east by the Andaman Sea. Located southeast of the Indian ...
,
Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...
,
Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...
,
Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is b ...
,
Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist s ...
,
Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making ...
,
Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand ...
, southern
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
,
Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the no ...
,
Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a List of cities in China, city and Special administrative regions of China, special ...
and
Macau Macau or Macao (; ; ; ), officially the Macao Special Administrative Region of the People's Republic of China (MSAR), is a city and special administrative region of China in the western Pearl River Delta by the South China Sea. With a pop ...
to
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federal constitutional monarchy consists of thirteen states and three federal territories, separated by the South China Sea into two regions: Peninsular Malaysia and Borneo's East Mal ...
,
Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, bor ...
, and the
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
n islands of
Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
,
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...
,
Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and e ...
,
Anambas Anambas Islands Regency ( id, Kabupaten Kepulauan Anambas) is a small archipelago of Indonesia, located northeast of Batam Island in the North Natuna Sea between the Malaysian mainland to the west and the island of Borneo to the east. Geograp ...
and
Natuna Islands ''(Sacred Ocean, Fortune Land) , image_map = , pushpin_map = Indonesia Riau Islands#Indonesia Sumatra#Indonesia#South China Sea , pushpin_map_caption = Location in Riau Islands##Location in Sumatra##Location in I ...
. They have been recorded from sea level up to altitude, and live mostly in disturbed lowland habitats, from upper beaches and riverbanks to human-dominated agricultural and urban areas. They are uncommon in closed forests.


Introductions


Madagascar

''D. melanostictus'' arrived in
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Afric ...
in 2011 at the port of
Toamasina Toamasina (), meaning "like salt" or "salty", unofficially and in French Tamatave, is the capital of the Atsinanana region on the east coast of Madagascar on the Indian Ocean. The city is the chief seaport of the country, situated northeast of it ...
, and by 2014, was found in a zone around that city. Since its discovery on the east coast, a grave fear has developed that if the Asian toad is not eradicated from Madagascar and stronger quarantines are not developed to prevent reinvasion, it could have comparable impacts to those of
cane toads in Australia The cane toad in Australia is regarded as an exemplary case of a " feral species", including rabbits, foxes, cats, and dogs, among others. Australia's relative isolation prior to European colonisation and the industrial revolution, both of w ...
. Because – like Australia's – Madagascar's native predators have been isolated from bufonids since the
Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
, they are thought to lack resistance to toad toxins as found in natural
varanid The Varanidae are a family of lizards in the superfamily Varanoidea within the Anguimorpha group. The family, a group of carnivorous and frugivorous lizards, includes the living genus '' Varanus'' and a number of extinct genera more closely rela ...
and snake predators of ''D. melanostictus'' in its native range. One study analyzed the sequences of the Na+/K+-ATPase gene (sodium-potassium pump) in dozens of Malagasy species that may be feeding on ''D. melanostictus.'' It was found that all but one out of 77 species failed to show evidence of resistance to the toad toxin, which strongly suggests that these alien toads can significantly impact the native Malagasy animal life and contribute to the worsening
biodiversity crisis Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, de ...
in the region. Nevertheless, evidence from one Australian species, the
bluetongue lizard Bluetongue Lizard is an old man in Australian Aboriginal mythology. He is a trickster and a powerful sorcerer, as well. The myth involving him is the wellspring of the Warlpiri fire ceremonies. He is often regarded as a deity, but this notion ...
, ''Tiliqua scincoides'', produces the possibility that some Malagasy animals do possess resistance to bufotenin because almost identical cardiac glycosides are produced by native plants of the genus '' Bryophyllum''.


Wallacea and West Papua

''D. melanostictus'' was introduced to the Indonesian island of
Bali Bali () is a province of Indonesia and the westernmost of the Lesser Sunda Islands. East of Java and west of Lombok, the province includes the island of Bali and a few smaller neighbouring islands, notably Nusa Penida, Nusa Lembongan, and ...
in 1958,Reilly, Sean B.; Wogan, Guinevere O. U.; Stubbs, Alexander L.; Arida, Evy; Iskandar, Djoko T. and McGuire Jimmy A.; ‘ Toxic toad invasion of Wallacea: A biodiversity hotspot characterized by extraordinary endemism’; ''Global Change Biology''; August 2017, pp. 1-3
Sulawesi Sulawesi (), also known as Celebes (), is an island in Indonesia. One of the four Greater Sunda Islands, and the world's eleventh-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Mindanao and the Sulu ...
in 1974, then subsequently to Ambon,
Lombok Lombok is an island in West Nusa Tenggara province, Indonesia. It forms part of the chain of the Lesser Sunda Islands, with the Lombok Strait separating it from Bali to the west and the Alas Strait between it and Sumbawa to the east. It is ...
,
Sumba Sumba ( id, Pulau Sumba) is an island in eastern Indonesia. It is one of the Lesser Sunda Islands and is in the province of East Nusa Tenggara. Sumba has an area of , and the population was 779,049 at the 2020 Census; the official estimate as a ...
,
Sumbawa Sumbawa is an Indonesian island, located in the middle of the Lesser Sunda Islands chain, with Lombok to the west, Flores to the east, and Sumba further to the southeast. Along with Lombok, it forms the province of West Nusa Tenggara, but th ...
,
Timor Timor is an island at the southern end of Maritime Southeast Asia, in the north of the Timor Sea. The island is divided between the sovereign states of East Timor on the eastern part and Indonesia on the western part. The Indonesian part, ...
and Indonesian New Guinea at
Manokwari Manokwari is a coastal town and the capital of the Indonesian province of West Papua. It is one of only seven provincial capitals of Indonesia without a city status. It is also the administrative seat of Manokwari Regency. However, under pro ...
on the
Vogelkop Peninsula The Bird's Head Peninsula ( Indonesian: ''Kepala Burung'', nl, Vogelkop) or Doberai Peninsula (''Semenanjung Doberai''), is a large peninsula that makes up the northwest portion of the island of New Guinea, comprising the Indonesian provinces o ...
. The species is now common at Sentani in far eastern
Papua Province Papua is a province of Indonesia, comprising the northern coast of Western New Guinea together with island groups in Cenderawasih Bay to the west. It roughly follows the borders of Papuan customary region of Tabi Saireri. It is bordered by ...
. The absence of resistance to toad toxins in native snake and varanid predators means that these species could suffer severe declines from the inadvertent spread of the Asian common toad via human traffic, and the currently
near threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...
New Guinea quoll is also almost certain to be further affected in the lower-altitude portion of its range.Covacevich, Jeanette, and Archer, Mike; ‘The distribution of the cane toad, ''Bufo marinus'' in Australia and its effects on indigenous vertebrates’; ''Memoirs of the Queensland Museum'', volume 17 (1975), pp. 305–310.


An unwanted species in Australia

The Asian common toad has been detected in Australia at least four times since 2000.''
Sydney Morning Herald ''The Sydney Morning Herald'' (''SMH'') is a daily compact newspaper published in Sydney, New South Wales, Australia, and owned by Nine. Founded in 1831 as the ''Sydney Herald'', the ''Herald'' is the oldest continuously published newspaper ...
'', March 28, 2015, ‘Northern Sydney faces Asian black-spined toad plague’.
The most recent incursion, in 2015, was in suburban Sydney. The Asian common toad has been described as one of Australia's “10 most unwanted” species, and “potentially more damaging than the cane toad”. It may cause serious ecological problems due to “competition with native species, its potential to spread exotic parasites and pathogens and its toxicity”.Invasive Species Council, 2014, Biosecurity Failures in Australia, The Asian Black-Spined Toad, https://invasives.org.au/wp-content/uploads/2014/09/Biosecurity-failures-asian-black-spined-toads.pdf; retrieved 2017-05-28 Like cane toads, the Asian common toad secretes toxins from glands in their backs to deter predators. These toxins would beyond reasonable doubt severely affect native predators, such as
snakes Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more j ...
,
goannas A goanna is any one of several species of lizards of the genus '' Varanus'' found in Australia and Southeast Asia. Around 70 species of ''Varanus'' are known, 25 of which are found in Australia. This varied group of carnivorous reptiles ranges ...
and
quoll Quolls (; genus ''Dasyurus'') are carnivorous marsupials native to Australia and New Guinea. They are primarily nocturnal and spend most of the day in a den. Of the six species of quoll, four are found in Australia and two in New Guinea. Anoth ...
s. The recent rate of incursions suggests a high likelihood of establishment in Australia. So, experts are calling for the Australian government to develop a “high-priority contingency plan” that includes stronger environmental quarantine and surveillance strategies.Massam M, Kirkpatrick W and Page A (2010). ''Assessment and Prioritisation of Risk for Forty Introduced Animal Species''. Invasive Animals Cooperative Research Centre, Canberra


References


Further reading

*


External links

* * * See also '' Oligodon fasciolatus'' for: :* H. Bringsøe ''et al.''
Eviscerated alive: Novel and macabre feeding strategy in ''Oligodon fasciolatus'' (Günther, 1864) eating organs of ''Duttaphrynus melanostictus'' (Schneider, 1799) in Thailand
In: ''Herpetozoa''. Published online September 11, 2020. doi:10.3897/herpetozoa.33.e57096. :* Erin Garcia de Jesus
This snake rips a hole in living toads’ stomachs to feast on their organs
on: ScienceNews, October 2, 2020 {{Taxonbar, from=Q28031739 melanostictus Amphibians described in 1799 Amphibians of Bangladesh Amphibians of Myanmar Amphibians of Cambodia Amphibians of China Fauna of Hong Kong Frogs of India Amphibians of Indonesia Amphibians of Laos Amphibians of Malaysia Amphibians of Nepal Amphibians of Pakistan Frogs of Sri Lanka Amphibians of Taiwan Amphibians of Thailand Amphibians of Vietnam