Frog teeth are not particularly noteworthy— in fact, most people aren’t even aware that frogs have teeth. These teeth are generally small and sharp, lining the upper jaw. But in Southeast Asia, a unique set of frogs exhibit an intriguing adaptation: they possess two prominent bony protrusions, akin to fangs. These fangs play a crucial role in territorial disputes, mating rituals, and hunting strategies. Recently, scientists have discovered a new species within this fascinating group, notable for being the tiniest fanged frog identified to date.
Jeff Frederick, a postdoctoral researcher at the Field Museum in Chicago and the study’s lead author, said the new species is tiny compared to other fanged frogs on the island where it was found. “Many frogs in this genus are giant, weighing up to two pounds. This new species weighs about the same as a dime,” he said in a news release.
Working with the Bogor Zoology Museum and a team from the University of California, Berkeley, Frederick found the frogs on Sulawesi, a rugged, mountainous island that accounts for a large part of Indonesia. “It’s a giant island with a vast network of mountains, volcanoes, lowland rainforest, and cloud forests up in the mountains,” Frederick said.
Frederick and his team found nests of frog eggs on the leaves of tree saplings and moss-covered boulders while trekking on the island. Frogs lay eggs that are encapsulated by jelly, rather than a hard shell. To keep them from drying out, most amphibians lay their eggs in water. But in this case, the researchers found them raised above the forest floor.
Shortly afterwards, the researchers started to spot the small frogs. “Normally when we’re looking for frogs, we’re scanning the margins of stream banks or wading through streams to spot them directly in the water. After repeatedly monitoring the nests though, the team started to find attending frogs sitting on leaves hugging their little nests,” Frederick said.
Maintaining close contact with the eggs allows the frog parents to coat them with compounds that keep them moist and free from bacterial and fungal contamination, the researchers said. A closer look at the parents also showed that they were small members of the fanged frog family and that the frogs caring for the clutches of eggs were all male.
Frederick and his team believe that the unusual reproductive behavior might be related to the smaller-than-usual fangs for the frogs’ size. Some of the frog’s relatives have bigger fangs, which help them to keep away the competition for spots to lay their eggs in the water. As these frogs have evolved a way to lay their eggs above the ground, they may have lost the need for such big fangs.
The researchers called the new species Limnonectes phyllofolia, with phyllofolia meaning “leaf-nester.” The finding shows the importance of conserving tropical habitats like the one on the island of Sulawesi, which they argue has as much biodiversity as the Amazon. “Most of the animals that live in places like Sulawesi are quite unique, and habitat destruction is an ever-looming conservation issue,” Frederick said.
The study was published in the journal PLoS ONE.
