Piebald Alpine Toad
(Scutiger maculatus)
The piebald alpine toad is a poorly understood species because only 3 individuals have ever been collected since its formal discovery 1950. It is moderately sized and rotund, with special spiny patches on the chest of the males to help them attach to females during mating. It is associated with streams running through alpine meadows and forest, and has not been found since the 1970s, despite repeated searches by scientists. Ongoing agricultural expansion and settlement has resulted in habitat loss for the species. Its high altitude locality means that climate change may pose a future threat if this species is not already extinct.
Urgent Conservation Actions
Surveys to determine whether this species survives in the wild; development of a Conservation Action Plan.
North-western Sichuan province and eastern Xizang province, China
Evolutionary Distinctiveness
Order: Anura
Family: Megophryidae
The Megophryidae family (commonly known as the “Asian toadfrogs”) is one of the largest and most diverse family-level group of “archeobatrachian” frogs, a small sub group of the Anura or “frogs and toads” which contains all of the most ancient families. This sub group (also called the Archaeobatrachia) comprises less than 7% of all of the frogs and toads, including some of the most evolutionarily distinct amphibian species. The more recent frogs and toads (also called the “Neobatrachia”) diverged from the Archeobatrcahia about 220 million years ago – 10 million years before the origin of the mammals! The Asain toadfrogs account for for 40% of this tiny and outlandish complement of the ancient frogs and toads. These species are found in India, Pakistan, and eastward into Southeast Asia, Borneo and the Philippines to the Sunda Islands.

They are the largest and most ecologically diverse group of frogs in the region. Ranging in size from about 20 to 125 mm, many are large, highly-camouflaged, forest-floor dwellers with adaptations for hunting large prey. Their skin is often modified so that they closely-resemble dead leaves on the forest floor, complete with mottled brown colouration and raised lines across the skin that mimic leaf veins. Some species have pointed projections of skin above their eyes, which further enhances the dead leaf illusion. Others are small, with adhesive discs on their fingers and are found on rocks along streams. The large horned frogs (genus Megophrys) of this family can perform impressive defensive displays – they inflate their lungs, elevate their bodies, open their mouths and scream loudly, before jumping at their adversary.

There are about 136 known species of Asian toadfrog. They diverged from all other amphibian families about 70 million years ago, which makes them as different from their closest relatives in the Pelobatidae family (the spadefoot toads) as pigs are from giraffes! There are 18 species in the Scutiger genus (commonly known as the “alpine toads”). They are thought to be most closely related to the Oreolalax species (or “toothed toads”) – the major difference being that they do not have teeth.
The piebald alpine toad is a moderately sized species, with a relatively large and fat body. The male is about 65.4 mm in length, with the female being slightly larger at about 69 mm. Round warts are present across the back, although none are present on the lower sides of the body. The back is a shady greyish/olive green, while the belly is a greyish/yellowish white. A triangular mark is present between the eyes, and the surrounding area is black-brown, extending to the back of the head. The back legs are short. The male has nuptial (or mating-associated) spines on the inner side of each third finger, and the arms of courting males become very swollen. Large groups of nuptial spines are also present on the chest, forming two pairs of “nuptial pad fields”. The inner pair is black and is larger than the outer pair. The nuptial spines are thin and dense, their main purpose being to increase the security of amplexus, which is the mating embrace where the male grabs the female tightly from behind so that he may fertilise any eggs she releases.
The piebald alpine toad inhabits and breeds in small hill streams, low-gradient spring-fed streams and low-gradient medium-sized streams, and is closely associated with these waterbodies throughout the year. However, this is a poorly understood species because only 3 individuals have ever been collected since its formal discovery 1950, and so very little is known about its ecology and behaviour. Alpine toads are generally described as lethargic ground-dwellers found in close proximity to the streams, or mountain creeks, where they breed. During the day, piebald alpine toads are usually hidden under stones where the stream flows. Spawning behaviour in this species is probably similar to that in the toothed toads (genus Oreolalax), whereby mating occurs in the stream and eggs are laid on the underside of stones to protect them from light and predators. Alpine toad tadpoles have muscular tails, as well as clasping or sucking mouthparts for holding onto rocks in flowing water. Some alpine toad tadpoles are known to be at least partially carnivorous, feeding on aquatic invertebrates and other tadpoles.

Courting males have a two-part, rough “nuptial pad field” (also known as “nuptial excrescences”) on either side of the chest. These develop during the breeding season as a result of a rise in testicular (or male) hormones. Seasonal variation in their development has been correlated with reproductive activities. These nuptial patches are formed from modified skin cells and are often densely pigmented with melanin, and they appear darker and more raised than the surrounding skin. They are associated with mating, specifically amplexus (the mating embrace in amphibians). It is thought that they help a male to maintain amplexus, especially when other males are trying to dislodge them to get to the female. The shape and spinosity (or density and size of the spiny projections in the nuptial patch) seems to be correlated with the difficulty of maintaining amplexus, which would seem to be most challenging in torrential streams.
This species lives at high altitude near hill streams or medium to small low gradient spring-fed streams, where it also breeds. The surrounding environment is composed of alpine meadows and forest.
This species is known only from Garze County, in north-western Sichuan province, and Jiangda, in eastern Xizang province, China, at an altitude of 3,300-3,500 metres above sea level.
Population Estimate
Only three individuals of this species have ever been collected since its discovery in 1950, two of which were collected in the 1970s. It has not been found in its natural range since the 1970s despite repeated searches by scientists, and it is possible that it is now extinct.
Population Trend
This species is thought to be in decline by the IUCN Red List of Threatened Species.
The piebald alpine toad is listed as Critically Endangered in the IUCN Red List of Threatened Species because its area of occupancy is probably less than 10 km sq., its distribution is severely fragmented, and there is a continuing decline in the extent and quality of its habitat, and in the number of mature individuals.
The piebald alpine toad may be extinct as it has not been found since the 1970s. Ongoing agricultural expansion and settlement has resulted in habitat loss for the species. Its high altitude locality means that climate change may pose a future threat if this species is not already extinct. Poor breeding success might also be a factor contributing to this species' disappearance.
Conservation Underway
This species is not known to occur in any protected areas, and there are currently no conservation measures ongoing for the piebald alpine toad.
Conservation Proposed
Further survey work of all potential habitat is urgently needed to determine whether this species survives in the wild. A Conservation Action Plan should be prepared addressing the major threats to this species if it is still extant. The creation of a formal protected area may be beneficial to this species, taking into account the needs of local stakeholders and ensuring that local people have access to information about the importance and uniqueness of this species.

In addition to conserving native habitat for this species, the IUCN Technical Guidelines for the Management of Ex situ Populations, part of the IUCN Red List of Threatened Species, recommend that all Critically Endangered species should have an ex situ population managed to guard against the extinction of the species. An ex situ population is ideally a breeding colony of a species maintained outside of its natural habitat, giving rise to individuals from that species that are sheltered from problems associated with their situation in the wild. This can be located within the species’ range or in a foreign country that has the facilities to support a captive breeding programme for that species. Since the piebald alpine toad is categorised as Critically Endangered and is threatened by climate change given its high altitude range, the possibility of a captive breeding programme for this species should be investigated.
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