Most of the time when taxonomists discover new species it is a gradual transition from ‘hmm, this looks a little different’ to ‘yes this is certainly new to science’—but not always! Today, my colleagues and I have described a new species of frog from northern Madagascar that was immediately recognised by us as a new species to science. The new species, Gephyromantis (Vatomantis) lomorina, is so different from its congeners that it cannot be confused with any of them, and it shares some characters with two different groups of frogs within the diverse genus Gephyromantis that could turn the subgeneric taxonomy of these groups on its head. The study is published in the open access journal Zoosystematics and Evolution—you can access the PDF here.
In 2012, a team from our group visited the mountainous area of Sorata in northern Madagascar to conduct a biodiversity survey of the reptiles and amphibians of the area. Whilst there, they happened across a small, mossy green frog with rough skin and a weirdly ‘snickety’ call. Immediately it was obvious that this was a new species to science. But as is so often the case, upon their return to Germany, it was not possible for them to describe the species quickly. So when I travelled with another team to Marojejy in November 2016 and we ‘re-‘discovered this species, it was very exciting. Here we had a frog that was still ‘new’ to science, and suddenly it had a much, much wider distribution than we at first thought. To be truthful, at the time we did not know that this species had already been discovered (making the whole thing all the more exciting for us at the time), and only when we returned to Germany were we able to establish that this was the same species discovered on the Sorata expedition.
The new species, which we dubbed Gephyromantis (Vatomantis) lomorina due to its mossy appearance (lomorina is a Malagasy word meaning ‘covered in moss’), is interesting for a number of reasons. First of all, it is not quite clear where it fits into the rest of the genus Gephyromantis. Genetically, it is somewhere in between the two subgenera Vatomantis (containing three species of smooth-skinned, green, riparian frogs with divided vocal sacs) and Laurentomantis (containing a handful of lumpy, brownish frogs with broad heads and single vocal sacs), sometimes coming out closer related to one of these than the other, but always it was found to be one of the more distant relatives of these two groups. The morphology and call fit this genetic weirdness as well; the call (which you can download and listen to here) is more similar to Laurentomantis species, but the morphology is a bit more like Vatomantis species, especially the green colour and the divided vocal sacs. So in the end we placed the new species in Vatomantis, but it hints that the relationships between these two subgenera are quite unclear, a point made in a previous study by Kaffenberger et al. (2012) based solely on genetic grounds.
A further species, Gephyromantis klemmeri, adds to this puzzle; it is morphologically quite different from both Laurentomantis and Vatomantis, and genetic results have so far failed to place it closer to one or the other with any certainty, so right now it is not assigned to a subgenus at all. Indeed, it has in the past been confused for a member of the subgenus Gephyromantis, but this was before good data were available on the species. In order to solve the problem once and for all, we will need more data on G. klemmeri, G. lomorina, and a few other members of these subgenera. But this is an achievable goal, and I hope that we will resolve it in the next few years.
Aside from the systematic revelations from the discovery of this new species, it also has interesting biogeographic implications. For a long time it has been held that Marojejy is strongly unique in terms of its herpetofauna, and indeed, the large number of endemic species to the mountain would seem to confirm that, yet repeatedly in the past few years numerous species from Marojejy have also been found to occur in Sorata. In the paper, we summarise the small list of species that are so far known to be shared, but no survey of the herpetofauna of Sorata has so far been published, so we are only gaining knowledge on this area in fits and starts. Understanding the biogeography of the north of Madagascar through the evolutionary history of species community composition across the network of massifs and mountains is really interesting, and the region could potentially host some interesting ring-like species complexes. But understanding this is going to take a lot more work in this part of Madagascar.
Scherz, M.D., Hawlitschek, O., Razafindraibe, J.H., Megson, S., Ratsoavina, F.M., Rakotoarison, A., Bletz, M.C., Glaw, F. & Vences, M. (2018) A distinctive new frog species (Anura, Mantellidae) supports the biogeographic linkage of the montane rainforest massifs of northern Madagascar. Zoosystematics and Evolution, 94(2):247–261. DOI: 10.3897/zse.94.21037 [pdf]
Kaffenberger N, Wollenberg KC, Köhler J, Glaw F, Vieites DR, Vences M (2012) Molecular phylogeny and biogeography of Malagasy frogs of the genus Gephyromantis. Molecular Phylogenetics and Evolution 62(1): 555–560. DOI: 10.1016/j.ympev.2011.09.023