18 January 2012

How Tiny Can They Be?

There has been a lot of excitement about the discovery of the word's tiniest frog in Papua New Guinea.   Froglife trustee Professor Roger Downie has been finding out more about this incredible animal.

"At the same time as amphibian populations are in decline around the world, new species are being discovered at a surprisingly high rate, especially in the less explored tropical rainforests: currently, over 100 new species are being described each year.

A report by Eric Rittmeyer and colleagues on two new species of frog raises the question: how small can adult frogs be?

In the UK, our Common frog Rana temporaria develops from small eggs into tadpoles that metamporphose into froglets about 8mm long.  They then grow into adults about 10 times longer.

Juvenile Common frogs leave the pond at about 8mm in length, with the potential to grow 10 times longer 
The frogs described by Rittmeyer (genus Paedophryne = child-like frog) are all extremely small as adults. They live in the damp leaf litter of lowland forests in eastern Papua New Guinea. Four species have been described so far, all since 2010, indicating the rich biodiversity still to be identified in that country.

So far, the smallest is Paedophryne amauensis with adults measuring in at 7.7 mm on average. These tiny frogs are direct developers (i.e. no tadpole stage) and have piercing insect-like calls. As in most miniaturised amphibians, they show specialised skeletal features such as reduced digits."

The smallest adult frog discovered in Papua New Guinea, measuring 7.7mm in length
Rittmeyer EN , Allison A , Gründler MC , Thompson DK , Austin CC , 2012 Ecological Guild Evolution and the Discovery of the World's Smallest Vertebrate. PLoS ONE 7(1): e29797. doi:10.1371/journal.pone.0029797

- You can read the full journal article at PLoS ONE here: Rittmeyer et al(2012) in Plos-1 volume 7 issue 1.
- You can find out more about the UK's species of frog at the Froglife website here

You can help support amphibian conservation and enable us to develop research through becoming a Froglife Friend.  Find out the difference you can make for just £1.50 a month here.

Photos: Sivi Sivanesan and Rittmeyer et al.

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