The newly-discovered frog species belong to the subgenus Brygoomantis within the mantellid frog genus Mantidactylus.
Until now, the Brygoomantis subgenus contained just 14 described species of small, mostly brown frogs.
These amphibians are ubiquitous along streams in Madagascar’s humid forests, but are inconspicuous to the eye.
The males emit very subtle advertisement calls to attract females.
“The calls typically sound like a creaking door, or a gurgling stomach,” said Dr. Mark Scherz, curator of herpetology at the Natural History Museum of Denmark.
“Finding, recording, and catching calling individuals of these frogs is a real challenge, but has proven critically important for the discovery and description of these many new species. That means a lot of time on hands and knees in the mud.”
“This is the culmination of intensive fieldwork across Madagascar over more than 30 years,” added Dr. Frank Glaw, curator of herpetology at the Zoologische Staatssammlung München.
“Our dataset contains genetic data from over 1,300 frogs, and measurements of several hundred specimens.”
One key tool in the team’s arsenal was the use of cutting-edge ‘museomics,’ where DNA is sequenced from old museum material.
This is often difficult, because DNA degrades over time and due to various chemicals that are used to preserve animal specimens.
But using an approach called ‘DNA barcode fishing,’ the researchers were able to get useable DNA sequences from most of the relevant museum material.
“Museomics gave definitive identifications of sometimes very ambiguous-looking specimens,” said Professor Miguel Vences, a researcher at the Technische Universität Braunschweig.
“This gives us a level of confidence in our species descriptions that was not previously possible based on morphology alone.”
“There are still several Brygoomantis lineages that are probably separate species, but that we didn’t have enough data or material for,” said Dr. Andolalao Rakotoarison, co-chair of the Amphibian Specialist Group for Madagascar.
“Even for those species for which we have names, we know almost nothing about their biology or ecology.”
“We need a lot more field research on these frogs, and more specimens in museum collections, to really gain a good understanding of them.”
The team’s paper was published in the journal Megataxa.
Mark D. Scherz et al. 2022. An inordinate fondness for inconspicuous brown frogs: integration of phylogenomics, archival DNA analysis, morphology, and bioacoustics yields 24 new taxa in the subgenus Brygoomantis (genus Mantidactylus) from Madagascar. Megataxa 007 (2): 113-311; doi: 10.11646/megataxa.7.2.1