Shape-shifting frog discovered in Ecuador

Skin texture variation in one individual Pristimantis mutabilis; note how skin texture shifts from highly tubercular to almost smooth; also note the relative size of the tubercles on the eyelid, lower lip, dorsum and limbs. Image credit: Zoological Journal of the Linnean Society

From Sci-News.com:

Pristimantis mutabilis: Scientists Discover Shape-Shifting Frog in Ecuador

Mar 24, 2015

Case Western Reserve University PhD student Katherine Krynak, naturalist Tim Krynak of Cleveland Metroparks’ Natural Resources Division, and their colleagues from the Universidad Indoamerica, the University of Kansas, and organization Tropical Herping, have described a unique species of frog from Reserva Las Gralarias, Pichincha, north-central Ecuador. According to the team, the new species – named Pristimantis mutabilis (mutable rainfrog) – changes skin texture in minutes, appearing to mimic the texture it sits on.

Pristimantis mutabilis, described in the Zoological Journal of the Linnean Society, is believed to be the first amphibian known to have this shape-shifting capability.

It belongs to a large genus of approximately 470 frog species found in the southern Caribbean and in Central and South America from Honduras to northern Argentina and southern Brazil.

The scientists believe the ability to change skin texture to reflect its surroundings may enable Pristimantis mutabilis to help camouflage itself from birds and other predators.

Katherine and Tim Krynak originally spotted the small, spiny frog, nearly the width of a marble, sitting on a moss-covered leaf about a yard off the ground on a misty July night in 2009.

The scientists captured one specimen and tucked it into a cup with a lid before resuming their nightly search for wildlife. They nicknamed the frog ‘punk rocker‘ because of the thorn-like spines covering its body.

The next day, Katherine Krynak pulled the frog from the cup and set it on a smooth white sheet of plastic for Tim Krynak to photograph. “It wasn’t ‘punk’ – it was smooth-skinned,” they said.

The scientists found the frog shifts skin texture in a little more than 3 minutes. They then performed morphological and genetic analyses showing that the frog was a unique and undescribed species.

They also studied the frog’s calls, finding three songs the species uses, which differentiate them from relatives.

In addition, team members Dr Juan Guayasamin and Dr Carl Hutter discovered that Pristimantis sobetes – a previously known species of frog with similar markings but about twice the size of Pristimantis mutabilis – has the same trait when they placed a spiny specimen on a sheet and watched its skin turn smooth.

The team plans to continue surveying for Pristimantis mutabilis and to further document their behaviors, lifecycle and texture shifting, and estimate their population, all in effort to improve our knowledge and subsequent ability to conserve this paradigm shifting species. Further, they hope to discern whether more relatives have the ability to shift skin texture and if that trait comes from a common ancestor.

If Pristimantis mutabilis and P. sobetes are the only species within this branch of Pristimantis frogs to have this capability, they hope to learn whether they retained it from an ancestor while relatives did not, or whether the trait evolved independently in each species.

Yes, we’re looking at the horned treefrogs, horned frogs or casque-headed frogs (Hemiphractus), a group of six species of Central and South America, the most recently named of which is H. helioi Sheil and Mendelson, 2001: here.