True toad

History

Bufonidae is thought to have originated in South America. Some studies date the origin of the group to after the breakup of Gondwana, about 78–99 million years ago in the Late Cretaceous. In contrast, other studies have dated the origin of the group to the early Paleocene. The bufonids likely radiated out of South America during the Eocene, with the entire radiation occurring during the Eocene to Oligocene, marking an extremely rapid divergence likely facilitated by the Paleogene's changing climatic conditions.

Taxonomy

The following phylogeny of most genera in the family is based on Portik and Papenfuss, 2015:, Chan et al., 2016, Chandramouli et al., 2016, and Kok et al., 2017

Ingerophrynus alongside Leptophryne was grouped as basal to the clade containing all other Southeast Asian toad genera and Ghatophryne by Portik and Papenfuss, but was found to group with Phrynoidis and Rentapia by Chan et al. Ghatophryne was grouped with Phrynoidis and Rentapia by Portik and Papenfuss but was found to group with Pelophryne and Ansonia by Chan et al. In addition, Sabahphrynus was grouped with Strauchbufo and Bufo by Portik and Papenfuss but was found to group with Pelophryne, Ansonia, and Ghatophryne by Chan et al.

Characteristics

True toads are widespread and are native to every continent except Australia and Antarctica, inhabiting a variety of environments, from arid areas to rainforest. Most lay eggs in paired strings that hatch into tadpoles, although, in the genus Nectophrynoides, the eggs hatch directly into miniature toads.

All true toads are toothless and generally warty in appearance. They have a pair of parotoid glands on the back of their heads. These glands contain an alkaloid poison which the toads excrete when stressed. The poison in the glands contains a number of toxins causing different effects. Bufotoxin is a general term. Different animals contain significantly different substances and proportions of substances. Some, like the cane toad Rhinella marina, are more toxic than others. Some "psychoactive toads", such as the Colorado River toad Incilius alvarius, have been used recreationally for the effects of their bufotoxin.

Depending on the species, male or female toads may possess a Bidder's organ, a trait unique to all bufonids except genera Melanophryniscus and Truebella. Under the right conditions, the organ becomes an active ovary.

The loss of teeth has arisen in frogs independently over 20 times. Notably, all members of Bufonidae are toothless. Another Anuran family with a comparable degree of edentulism is the family Microhylidae.

Reproduction

Internal fertilization occurs in four bufonid genera.

• Mertensophryne (some species)
• Nectophrynoides (presumably all species)
• Altiphrynoides malcolmi (one out of two species in the genus Altiphrynoides)
• Nimbaphrynoides occidentalis (the sole species in the monotypic genus Nimbaphrynoides)

Ascaphus (all species) and Eleutherodactylus (two species, E. coqui and E. jasperi) are the only other frog genera that have internal fertilization.

Taxonomy and genera

The family Bufonidae contains over 570 species among 52 genera.

The family also contains an incertae sedis species, "Bufo" scorteccii Balletto & Cherchi, 1970.

References

• Stebbins, Robert. Western Reptiles & Amphibians (3rd ed.). Houghton Mifflin Co., 2003.
• Halliday, Tim R., and Kraig Adler (editors). The New Encyclopedia of Reptiles & Amphibians. Facts on File, New York, 2002.

References

1. (2008). "Around the world in 10 million years: biogeography of the nearly cosmopolitan true toads (Anura: Bufonidae)". Global Ecology and Biogeography.
2. (2018). "Historical biogeography of the palaeoendemic toad genus Oreophrynella (Amphibia: Bufonidae) sheds a new light on the origin of the Pantepui endemic terrestrial biota". Journal of Biogeography.
3. (2015-08-06). "Historical biogeography resolves the origins of endemic Arabian toad lineages (Anura: Bufonidae): Evidence for ancient vicariance and dispersal events with the Horn of Africa and South Asia". BMC Evolutionary Biology.
4. (2016-01-20). "Polyphyly of Asian Tree Toads, Genus Pedostibes Günther, 1876 (Anura: Bufonidae), and the Description of a New Genus from Southeast Asia". PLOS ONE.
5. (2016-01-20). "A new genus and species of arboreal toad with phytotelmonous larvae, from the Andaman Islands, India (Lissamphibia, Anura, Bufonidae)". ZooKeys.
6. Zweifel, Richard G.. (1998). "Encyclopedia of Reptiles and Amphibians". Academic Press.
7. "The IUCN Red List of Threatened Species".
8. Piprek, Rafal P., et al. "Bidder's Organ – Structure, Development and Function." The International Journal of Developmental Biology, vol. 58, no. 10-11–12, 2014, pp. 819–27. Crossref, doi:10.1387/ijdb.140147rp.
9. (December 2002). "Bidder's organ in the toad Bufo marinus: Effects of orchidectomy on the morphology and expression of lamina-associated polypeptide 2". Development, Growth & Differentiation.
10. Paluh, Daniel J., et al. "Rampant Tooth Loss Across 200 Million Years of Frog Evolution." BioRxiv, 2021. Crossref, doi:10.1101/2021.02.04.429809.
11. (2014). "Herpetology: An Introductory Biology of Amphibians and Reptiles". Academic Press.
12. (2014). "A novel reproductive mode in frogs: a new species of fanged frog with internal fertilization and birth of tadpoles". PLOS ONE.
13. S. R. Chandramouli, Karthikeyan, Vasudevan, S Harikrishnan, Sushil Kumar Dutta, S Jegath Janani, Richa Sharma, Indraneil Das, Ramesh Aggarwal. "A new genus and species of arboreal toad with phytotelmonous larvae, from the Andaman Islands, India (Lissamphibia, Anura, Bufonidae)" ZooKeys (2016) 555: 57–90, https://doi.org/10.3897/zookeys.555.6522