The "Gulf Coast Toads"
Incilius nebulifer and Incilius valliceps

The "Gulf Coast Toads" Face Off
Incilius nebulifer vs. Incilius valliceps
There is quite a bit of confusion about the gulf coast toads in print and online.  The problem is that until the late 1990s, all Gulf Coast Toads were the same species, Bufo valliceps.   At that time, Joe Mendelson was studying this group and determined that the populations north of central Veracruz, Mexico (i.e. the US and NW Mexican populations) were actually a different species that correctly should be referred to as Bufo nebulifer.  The species in the southern part of the range, from central Veracruz, through the Yucatan and south to Costa Rica was the "real" Bufo valliceps.

To add another layer of confusion, in an effort to split up the cosmopolitan genus Bufo to more accurately reflect the phylogeny of toads, these Gulf Coast Toads were moved to the genus Ollotis.  It was later shown that the correct genus for these toads should have been Incilius.  There is a synopsis of these changes with references on the Amphibian Species of the World Online Reference.

So over the last 15 years of so, the northern populations of Gulf Coast Toads have gone from:

Bufo valliceps --> Bufo nebulifer --> Ollotis nebulifer --> Incilius nebulifer

And the southern, meso-American populations have gone from:

Bufo valliceps --> Ollotis valliceps --> Incilius valliceps.

So if you are doing any reading about these toads, you might find them under different names in different sources.  The correct names are Incilius nebulifer for the US and northern Mexican populations and Incilius valliceps for the southern Mexico and Central American populations.

All that said, they look pretty much the same.  Here is some examples of I. nebulifer from around Texas -

And an I. valliceps from CaƱo Negro, Costa Rica

and from Campeche, Mexico - 

and Chiapas, Mexico -

As for their calls, they sound very similar.  

Here is a Incilius nebulifer from Texas -

Incilius nebulifer call  

and an Incilius valliceps from Costa Rica - 

Incilius valliceps call

So how do you tell which species you are dealing with?  Simple, look on a map!

Of course, at the southern end of its range, the third species in the species group, the Wet Forest Toad (Incilius melanochlorus) appears.  It looks a bit different than I. valliceps but the call is almost identical.

© Chris Harrison 2014

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