Zooming in on amphibians: Which is the smallest vertebrate in the world?

Abstract

During the last decades several miniaturized frogs have been described from different parts of the world. Those frogs, measuring less than 25 mm, show similar miniaturization features as the loss of phalanges in both the anterior and posterior limbs and the reduction of bone elements. However, there seems to be a limit regarding the minimum size of frogs and here we wanted to find an answer to the question: which is the smallest amphibian in the world? In 2019, an endemic species of toad known only from two localities in southern Bahia, Brazil, was studied. When we compared the size of adult representatives of this species with those of other species discovered in various parts of the world in the last decade, we observed that individuals of Brachycephalus pulex are the amphibians with the smallest total length recorded, thus qualifying them to bear the title of the tiniest anuran amphibian, and also tiniest vertebrate in the world.