MEXICO BURROWING TOAD Rhinophrynus dorsalis – Dumeril & Bibron 1841

IDENTIFICATION:

DISTRIBUTION: R. dorsalis is found from the United States to Costa Rica. [...]]]>
Adult Male, Atlantic Versant Color Variant, 500′, Oaxaca, Mexico

Adult Male, Pacific Versant Color Variant, 100′, Oaxaca, Mexico

Adult Male, Pacific Versant Aberrant, 100′, Oaxaca, Mexico

Adults in Amplexus, 200′, Oaxaca, Mexico

Close-Up of Hind Foot Spade, an Effective Burrowing Tool

MEXICO BURROWING TOAD
Rhinophrynus dorsalis – Dumeril & Bibron 1841

IDENTIFICATION:

DISTRIBUTION:
R. dorsalis is found from the United States to Costa Rica. In Mexico it occurs on both coasts: on the Pacific from the mouth of the Rio Balsas in Guerrero to the Guatemala border in Chiapas; on the Atlantic from the Rio Grande (Texas border) south along the gulf lowlands through the Yucatan Peninsula to Guatemala and Belize. Elevational distribution from sea level to 500 m.

HABITAT:

Temporary Pond Oviposition Site, 500′, Oaxaca, Mexico

Pacific Lowland Habitat, 100′, Guerrero, Mexico

NATURAL HISTORY:

TAXONOMY:
The sole member of the family Rhinophrynidae. Populations of this frog on the Atlantic and Pacific versants of Mexico display distinct differences in color – Pacific animals being yellow and black, while Atlantic animals are orange/red and black. Further investigation in geographic variation within R. dorsalis may reveal the presence of unnamed species.

TYPE:
Described as Rhinophrynus dorsalis by Dumeril and Bibron (1841). Holotype: MNHNP 693. Type locality: “Vera-Cruz”, Mexico.

PERSONAL NOTES:
In July, 2005 I had the good fortune in finding my first breeding choruses of R. dorsalis in the Atlantic foothills of Oaxaca, Mexico. The combined calls coming from a roadside pond was absolutely eerie, and unnerved my hunting partner a bit. The frogs called from floating positions along waters’ edge, usually from within mats of floating grass cuttings. Other species calling from this pond were Phrynohyas venulosa, Scinax staufferi, Smilisca baudinii, and Leptodactylus melanonotus.
A few nights later, on the coast of Oaxaca (Hwy 200) we were lucky enough to witness a mass breeding migration of Rhinophrynus. Intense thunderstorm activity had ocurred earlier in the evening, and the road was swarming with R. dorsalis, Triprion, Bufo, and several other species of amphibians. Every roadside ditch from Salina Cruz to Huatulco seemed to have R. dorsalis calling from it’s muddy water, and in some places the road was covered with so many individuals that it was impossible to miss them all. Many Rhinophrynus were crossing the road while in amplexus (see photo above). Thankfully traffic was light on this evening, reducing the number of amphibians killed on the highway.

CONSERVATION STATUS:
IUCN Red List status is currently that of “Least Concern” due to this species’ wide geographic distribution, tolerance of a wide variety of habitats (including those modified by humans) and a presumed large, stable worldwide population.

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