Description
[This species was originally described as Bufo japonicus formosus; read the current Bufo praetextatus species account.]

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan

View distribution map in BerkeleyMapper.

Formerly the subspecies range of Bufo japonicus formosus in eastern Honshu, Japan (Dufresnes and Litvinchuk 2022). It has also been introduced in extreme southern Hokkaido, Japan (Suzuki et al 2020).

Comments
This species was featured in News of the Week January 22, 2024:

When toads invade an environment, they arrive armed with a chemical weapon: bufadienolides (BDs). Toads synthesize these potent cardiotoxins and store them in their lumpy skin as a defense against predators. Sawada et al. (2023) demonstrate for the first time that invasive toads can serve as a toxin source for a sequestering predator. The Tiger Keelback, Rhabdophis tigrinus, is a poisonous snake that eats toads and concentrates the consumed BDs in specialized glands that run along its back. R. tigrinus living on Sado island in Japan have been isolated from toad prey for 120,000 to 800,000 years, until the introduction of the Eastern Japanese Common Toad, Bufo formosus (formerly Bufo japonicus formosus) in 1966. The researchers detected bufadienolides in the gland extracts of more than half of the snakes sampled from toad-infested areas of Sado, but found no poison in the snakes sampled from parts of the island not yet invaded by toads. Intriguingly, the BD composition largely matched that of keelbacks which predate native Japanese Common Toad in other regions of Japan, and differed from keelbacks which eat a different toad species, Bufo praetextatus (formerly Bufo japonicus japonicus). This strengthens the case that B. formosus is indeed the source of BDs in Sado island keelbacks. The Tiger Keelback snakes from historically nontoxic populations exhibit different antipredator behaviors than historically poisonous ones, thus the re-toxicification of Sado island keelbacks may have interesting effects on fitness and the microevolution of behavior. While its frequency of occurrence is yet unclear, the phenomenon of invasive species as toxin sources is a novel paradigm for the study of chemical ecology and evolution in a changing world. (Written by Kannon Pearson)

References

Dai Suzuki, Toshiaki Kawase, Takashi Hoshina, and Tatsuhiro Tokuda. 2020. "Origins of Nonnative Populations of Bufo japonicus formosus (Amphibia: Bufonidae) in Hokkaido, Japan, as Inferred by a Molecular Approach," Current Herpetology 39(1), 47-54. https://doi.org/10.5358/hsj.39.47

Dufresnes C and Litvinchuk SN. (2022). " Diversity, distribution and molecular species delimitation in frogs and toads from the Eastern Palaearctic." Zoological Journal of the Linnean Society, 195, 695 - 760.

Species Account Citation: AmphibiaWeb 2024 Bufo formosus: Eastern Japanese Common Toad <https://amphibiaweb.org/species/9827> University of California, Berkeley, CA, USA. Accessed Apr 27, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 27 Apr 2024.

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