Middle American Burrowing Toad, Rhinophrynus dorsalis

Photo by Keese Quist, Tikal, Guatemala, May 2006.

Photo by Keese Quist, Tikal, Guatemala, May 2006.

Photo by Keese Quist, Tikal, Guatemala, May 2006, prepared to call.

Photo by Keese Quist, Tikal, Guatemala, May 2006, calling.

Note:  If these frogs don’t get you excited, be sure to seek medical attention when you get home!

Among the weirder critters in the Neotropics are the Middle American Burrowing Toads of the monotypic family Rhinophrynidae.  They burrow by using cornified spades on their hallux and metatarsals, and they back into the soil as they dig – often spiraling down.  During the wet season, they may only be about 2-5 inches beneath the surface, but it is presumed they go much deeper during the dry season.  Once underground, they create a little room whose diameter is near the total length of the frog.  They do not form a cocoon, and if unearthed become immediately active. The toads do feed on ants and termites while burrowed.

With the first heavy rains of the wet season, burrowing toads are known to began vocalizing in their burrows.  Once the rains are heavy enough to fill their ephemeral breeding ponds, they boil up out of the soil, become very vocal, and may amplex (see Amplexus in Frogs) on their way to the pond.  Fertilized eggs generally sink to the bottom, but sometimes stick together in small clusters.  Tadpoles feed on algae and the like in the water column and may school to facilitate suspension of food.  Metamorphosis tends to be synchronous, with most toadlets hopping out of the water at the same time.

Their glandular skin may produce a white, sticky secretion that presumably gives them protection from predation.  Be careful, Foster and McDiarmid say some people have allergic reactions to the secretions, and the stuff can rapidly rot the cloth in collecting bags – even if washed.  That means never put a bushmaster in a bag that once held Rhinophrynus!

A good resource:
Foster, Mercedes S. and McDiarmid, Roy W. 1983. Rhinophrynus dorsalis (Alma de Vaca, Sapo Borracho, Mexican Burrowing Toad). In: Costa Rican Natural History. Univ. Chicago Press, pp.419-421.

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