A remarkable example of suspected Batesian mimicry of Gaboon Vipers (Reptilia: Viperidae: Bitis gabonica) by Congolese Giant Toads (Amphibia: Bufonidae: Sclerophrys channingi)

ABSTRACT

Batesian mimicry is a phenomenon in nature whereby a non-toxic animal emulates a noxious one, seeking to deter predators by deception. This type of mimicry occurs in many animals, with numerous documented examples of invertebrates, harmless squamates, and even birds that mimic venomous snakes. However, no observations of anurans mimicking venomous snakes have been reported. Based on comparative data from colour pattern, morphology, geographic distribution and behaviour, we propose that the Congolese Giant Toad (Sclerophrys channingi), endemic to Democratic Republic of Congo, is a Batesian mimic of the geographically widespread Gaboon Viper (Bitis gabonica). Although the colour pattern similarity between these taxa is not an exact match, aposematism and precise imitation are not required for Batesian mimicry to be effective, especially when the model (B. gabonica) is dangerously venomous and carefully avoided by other vertebrates. Given the morphological similarity between S. channingi and two other African toad species (S. brauni and S. superciliaris) that are sympatric with B. gabonica and its sister taxon (B. rhinoceros), similar examples of Batesian mimicry are likely.

KEYWORDS:

• Batesian mimicry
• behaviour
• natural history
• predation
• Africa
• Democratic Republic of Congo

Acknowledgements

Fieldwork by EG and CK in eastern Democratic Republic of Congo was funded by the sources listed below; EG and CK thank their field companions W.M. Muninga, M.M. Aristote, M. Zigabe, A.M. Marcel, M. Luhumyo, J. and F. Akuku, F.I. Alonda, and the late A. M’Mema. Three toad specimens were donated by a Congolese team of researchers working with Andy Plumptre under the auspices of the Wildlife Conservation Society. The Centre de Recherche en Sciences Naturelles and Institut Congolais pour la Conservation de la Nature provided project support and permits. The following people provided outstanding feedback and encouragement at the earliest stages of this project: C. Lieb, J. Johnson, A. Khan, M. Zhuang, H. Greene, S. Spawls, R. Brown, and A.M. Bauer. We acknowledge J-L. Amiet for information about vocalisation of Sclerophrys superciliaris, C. Liedtke for detailed data of node dates of toads, O. Da Cunha for confirmation of French translations, and J. Reyes for assistance with specimen photographs. For loans of specimens, we are grateful to C. Raxworthy, D. Kizirian and L. Vonnahme (AMNH), J. Sheridan and S. Rogers (CM), and A. Resetar (FMNH). Photographs in life of Bitis gabonica and Sclerophrys channingi from eastern DRC were kindly provided by C. Tilbury and W. Böhme, respectively.

Disclosure statement

No potential conflict of interest was reported by the authors.

Geolocation Information

Democratic Republic of Congo from 4°N, 18°E to 5°S, 30°E

Supplementary materials

Supplemental data for this article can be accessed here.

Additional information

Funding

EG was supported by the Percy Sladen Memorial Fund, an IUCN/SSC Amphibian Specialist Group Seed Grant, K. Reed, M.D., research funds from the Department of Biology at Villanova University, two National Geographic Research and Exploration Grants (nos. 8556-08 and WW-R018-17), the University of Texas at El Paso, and grants from the Howard Hughes Medical Institute (no. 52008125), and the US National Science Foundation (DEB-1145459).