An international team led by Ludwig-Maximilians-Universität München scientist Mark Scherz has described a new genus and five new species of tiny frogs from the island of Madagascar.
“The five new species belong to Microhylidae (‘narrow-mouthed’ frogs), a highly diverse family found on every continent except Antarctica and Europe,” explained Scherz and his colleagues from Germany, the United States, Madagascar, the United Kingdom and Portugal.
“Although most narrow-mouthed frogs are small to moderately large, many are tiny. In fact, the group includes the smallest frog in the world — Paedophryne amauensis from Papua New Guinea, mature specimens of which reach a length of only 7.7 mm.”
The researchers discovered a total of five new species of ‘narrow-mouthed’ frogs in Madagascar.
“Finding tiny frogs in the leaf litter is hard work. Calling males often sit one or two leaves deep and stop calling at the slightest disturbance,” said Dr. Frank Glaw, from the Zoologische Staatssammlung München, Germany.
“It can take a lot of patience to find the frog you are looking for.”
Three of the new species were so unique that the team decided to establish a new genus for them, Mini.
“Mini mum from Manombo in eastern Madagascar is one of the smallest frogs in the world, reaching an adult body size of 9.7 mm in males and 11.3 mm in females,” the researchers said.
Mini scule from Sainte Luce in southeastern Madagascar is slightly larger and has maxillary teeth.
Mini ature from Andohahela in southeast Madagascar is larger than its sister species but is similar in build.
“When frogs evolve small body size, they start to look remarkably similar, so it is easy to underestimate how diverse they really are. Our new genus name, Mini, says it all,” said Scherz, lead author of a paper published in the journal PLoS ONE.
The other two new species, Rhombophryne proportionalis and Anodonthyla eximia, are also just 11–12 mm long, and are much smaller than their closest relatives.
“Rhombophryne proportionalis from Tsaratanana in northern Madagascar is unique among Madagascar’s tiny frogs in being a proportional dwarf, exhibiting far less advanced signs of paedomorphism than other species of similar size,” the researchers said.
“Anodonthyla eximia from Ranomafana in eastern Madagascar is distinctly smaller than any of its sister species and is secondarily terrestrial, providing evidence that miniaturization and terrestriality may be evolutionarily linked.”
M.D. Scherz et al. 2019. Morphological and ecological convergence at the lower size limit for vertebrates highlighted by five new miniaturised microhylid frog species from three different Madagascan genera. PLoS ONE 14 (3): e0213314; doi: 10.1371/journal.pone.0213314