Anaxyrus Tschudi, 1845

Class: Amphibia > Order: Anura > Family: Bufonidae > Genus: Anaxyrus
25 species

Anaxyrus Tschudi, 1845, Arch. Naturgesch., 11: 170. Type species: Anaxyrus melancholicus Tschudi, 1845, by monotypy.

Dromoplectrus Camerano, 1879, Atti Accad. Sci. Torino, Cl. Sci. Fis. Mat. Nat., 14: 882. Type species: Bufo anomalus Günther, 1859 "1858", monotypy. Synonymy with Bufo (sensu lato) by Boulenger, 1882, Cat. Batr. Sal. Coll. Brit. Mus., Ed. 2: 282.

English Names

North American Toads (Frost, McDiarmid, and Mendelson, 2008, in Crother (ed.), Herpetol. Circ., 37: 2; Liner and Casas-Andreu, 2008, Herpetol. Circ., 38: 7; Frost, McDiarmid, Mendelson, and Green, 2012, in Crother (ed.), Herpetol. Circ., 39: 11; Frost, Lemmon, McDiarmid, and Mendelson, 2017, in Crother (ed.), Herpetol. Circ., 43: 6).


Alaska and southern Canada south to the highlands of Mexico west of the Isthmus of Tehuantepec.


Removed from the synonymy of Bufo by Frost, Grant, Faivovich, Bain, Haas, Haddad, de Sá, Channing, Wilkinson, Donnellan, Raxworthy, Campbell, Blotto, Moler, Drewes, Nussbaum, Lynch, Green, and Wheeler, 2006, Bull. Am. Mus. Nat. Hist., 297: 363, where it had been placed by Peters, 1873, Monatsber. Preuss. Akad. Wiss. Berlin, 1873: 624; Boulenger, 1882, Cat. Batr. Sal. Coll. Brit. Mus., Ed. 2: 281; Pramuk and Mendelson, 2003, Southwest. Nat., 48: 676. The literature of Anaxyrus is deeply intertwined with that of "Bufo" (sensu lato) and most references to "Bufo" in North America refer either to Anaxyrus or to Incilius. Literature and work to 1972 on Bufo (sensu lato, including Anaxyrus) were summarized in Blair (ed.), 1972, Evol. Genus Bufo. Savage, 1954, Texas J. Sci., 6: 83–112, and Zweifel, 1970, Am. Mus. Novit., 2407: 1–10, discussed the former Bufo debilis group. Ferguson and Lowe, 1969, Am. Midl. Nat., 81: 435–466, discussed the Bufo punctatus group (including the Bufo debilis group). Tihen, 1962, Am. Midl. Nat., 62: 157–183, discussed osteological variation and species groups. Green, 1996, Israel J. Zool., 42: 95–109, discussed the systematics of hybridizing members of the former Bufo americanus group (Bufo hemiophrys, Bufo baxteri, Bufo fowleri, Bufo americanus). Graybeal, 1997, Zool. J. Linn. Soc., 119: 297–338, discussed phylogeny in the group (as part of Bufo, sensu lato), as did Pauly, Hillis, and Cannatella, 2004, Evolution, 58: 2517–2535. Maxson, Song, and Lopata, 1981, Biochem. Syst. Ecol., 9: 347–350, discussed the immunological relationships of North American "Bufo". Smith and Chiszar, 2006, Herpetol. Conserv. Biol., 1: 6–8, implied that this taxon should be considered a subgenus of Bufo; see comment under Bufonidae. Van Bocxlaer, Biju, Loader, and Bossuyt, 2009, BMC Evol. Biol., 9 (e131): 1–10, provided molecular evidence that Anaxyrus is the sister taxon of Incilius and together distant from Rhinella, as did Van Bocxlaer, Loader, Roelants, Biju, Menegon, and Bossuyt, 2010, Science, 327: 679–682 (but see comment under Incilius). Pauly, Hillis, and Cannatella, 2009, Herpetologica, 65: 115–128, on the basis of a largely undisclosed analysis (and in ignorance of the Van Bocxlaer et al., 2009, paper) considered Anaxyrus, Incilius, and Rhinella as subgenera within a redelimited Bufo to form a single genus, Bufo. This was rejected as without a sufficient evidential basis by Frost, McDiarmid, and Mendelson, 2009, Herpetologica, 65: 136–153, compared with other analyses based on substantially more evidence. Fontenot, Makowsky, and Chippindale, 2011, Mol. Phylogenet. Evol., 59: 66–80, reported on broad-scale hybridization within the eastern members of the Anaxyrus americanus group. Pyron and Wiens, 2011, Mol. Phylogenet. Evol., 61: 543–583, confirmed the monophyly of this taxon (although this is obscured by their explicit adoption of an out-dated and non-monophyletic taxonomy), its placement as the sister taxon of Incilius, and provided a tree of exemplar species. Powell, Collins, and Hooper, 2011, Key Herpetofauna U.S. & Canada, 2nd Ed.: 39–42, provided a key to the species of North America north of Mexico. Fouquette and Dubois, 2014, Checklist N.A. Amph. Rept.: 290, considered Anaxyrus as subgenus of Bufo, cherry-picking their citation to literature (excluding any reference to  Van Bocxlaer, Biju, Loader, and Bossuyt, 2009, BMC Evol. Biol., 9 (e131): 1–10, or [except for noting the effects of one rogue taxon in InciliusVan Bocxlaer, Loader, Roelants, Biju, Menegon, and Bossuyt, 2010, Science, 327: 679–682, which provided results not congruent with the story that Fouquette and Dubois wanted to tell) to avoid recognizing that treating Anaxyrus as a subgenus of Bufo which current understanding of phylogeny requires all Old-World bufonids, such as Sabahphrynus, Nectophryne, and Ansonia to be treated as subgenera of Bufo as well. 

Contained taxa (25 sp.):

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