For more than a century, one of Europe’s most extraordinary amphibians has concealed a remarkable secret beneath the Dinaric Karst. The olm, Proteus anguinus—often affectionately known as the “baby dragon” or “human fish”—was traditionally regarded as a single, unusually widespread species. Yet decades of genetic, morphological and biogeographic research increasingly suggested a very different picture: behind the apparently uniform appearance of Proteus lay several deeply divergent evolutionary lineages, some separated for millions of years.

Resolving this long-standing taxonomic problem became an important priority for the Societas Europaea Herpetologica (SEH).