Spotlight on Threatened Rain Frogs in South Africa

For decades the identification of rain frogs (Breviceps) remained a challenge. With limited interspecies morphological variation and substantial intraspecies variation, a positive identification based on morphology remains challenging. To complicate matters, the taxonomy of this group of frogs is not yet fully resolved and undescribed cryptic species exist. However, gradually the puzzle pieces come together. The description of the Boston Rain Frog (Breviceps batrachophiliorum) is one such puzzle piece that shed light on an old problem (1).

The breakthrough came thanks to three passionate frog enthusiasts: Nick Evans, Dylan Leonard and Cormac Price, who set themselves a challenge to spot and document every frog species known from the KwaZulu-Natal Province in South Africa, as listed in Du Preez and Carruthers (2). On 23 September 2018, following a prediction of possible good rains in the Boston area, they set off in search of the elusive Bilbo’s Rain Frog (Breviceps bagginsi) (3), named after Bilbo Baggins from The Lord of the Rings, who also lived in a hole in the ground. At this stage the species was known from three areas (4).

While driving with open windows they came to a spot where they heard rain frogs calling from the steep grassy banks on both sides of the road, where the road cuts through a hill. After scouting the ground surface for 45 minutes, they spotted a rain frog clinging to grass, about a foot above the ground. Of the six specimens they found, five were collected clinging to grass.

To confirm that they had found Bilbo’s Rain Frog, they sent a photograph with an accompanying call recording to Louis Du Preez. There was something curious. He thought they had mixed up the collected images and the sound recordings, as the call did not match, but when they sent a video we realized we were looking at a new species.

What followed was a meticulous process of analyzing call recordings, sequencing and comparing DNA samples, and documenting a set of more than 20 measurements from each specimen. The molecular evidence and the frog’s call turned out to be vital identifiers. Genetically, these specimens showed a 7.5% difference in mitochondrial 16S rRNA from its closest sister taxon, Breviceps verrucosus. This provided a clear signal that this frog was new to science.

While analyzing the calls we discovered that the species had been recorded before by the herpetologist Marius Burger, in 1999, and at that stage it was tentatively assigned to Bilbo’s Rain Frog. We named this newly discovered species Breviceps batrachophiliorum, Latin for “frog-loving people”, in recognition of the enthusiastic frog lovers who went out in search of the species.

This new Boston Rain Frog, once misidentified as Bilbo’s Rain Frog (Breviceps bagginsi), carries conservation implications: the discovery means that Bilbo’s Rain Frog is now known from only a single population in a highly transformed area, and as a result its conservation status jumped to Critically Endangered, while the Boston Rain Frog is listed as Endangered (5).

The full extent of Bilbo’s Rain Frog’s distribution, its habitat requirements and its reproductive biology are still poorly understood, and this forms the basis of Tiaan Botha’s doctoral study.

Just like the Boston Rain Frog, Bilbo’s Rain Frog prefers damp, grassland habitat. To be more specific, B. bagginsi favors grassland habitat within the eastern sub-escarpment biome of South Africa above a certain altitude. In effect, suitable habitat is narrowed down to a very limited mistbelt area around a small town known as eMtonjaneni (formerly known as Melmoth).

Unfortunately, timber companies also value this region, and more than 75% of the natural grassland in this area has been lost to plantations. Habitat loss is the number one threat to amphibians worldwide (6). Currently, the remaining grassland now functions as the five-meter-wide grassy verges between highways and plantations, and small “green zones” between plots, only a few hectares big, that are left undeveloped and unutilized. These are the only areas where Bilbo’s Rain Frog can be found.

The fact of the matter is that, although the Extent of Occurrence (EOO) of B. bagginsi is a little over 400 km², its Area of Occupancy (AOO) is severely under 100 km². Less than 1% of this species’ global population can be found in protected areas, and an estimated 20 years or less remains before this species could become extinct if nothing is done to protect it. The future for this species looks very gloomy, but there is light at the end of the tunnel.

Tiaan Botha has entered research agreements with key stakeholders that operate in the Area of Occupancy of B. bagginsi, and he has discovered critical evidence of the in situ condition of this species. All stakeholders that he approached were surprised at the presence of this species right at their doorstep, and were very keen on participating in, and enabling, effective research and conservation on Bilbo’s Rain Frog. We have already identified the conditions that prompt peak breeding behavior and the time of day at which they are most active. This project is in collaboration with Anura Africa who are supporting the project through provision of acoustic recording equipment and securing habitat protection in the longer term. During the next season, Tiaan Botha will attempt to document population sizes and densities across multiple sites of occurrence that will directly dictate the outcome of land management plans and legal protection of this species: the next milestone in this conservation journey.

References

1. Du Preez, L. H., Netherlands, E. C., & Minter, L. R. (2025). A new Rain Frog (Anura: Brevicipitidae; Breviceps) from the KwaZulu-Natal Midlands, South Africa. African Journal of Herpetology, 74, 188–209. https://doi.org/10.1080/21564574.2025.2478896
2. Du Preez, L. H., & Carruthers, V. C. (2017). Frogs of Southern Africa: A Complete Guide. Penguin Random House, Cape Town.
3. Minter, L. R. (2003). Two new cryptic species of Breviceps (Anura: Microhylidae) from southern Africa. African Journal of Herpetology, 52, 9–21. https://doi.org/10.1080/21564574.2003.9635473
4. Minter, L. R. (2004b). Breviceps bagginsi Minter, 2003. In L. R. Minter, M. Burger, J. A. Harrison, H. H. Braack, P. J. Bishop, & D. Kloepfer (Eds.), Atlas and Red Data Book of the Frogs of South Africa, Lesotho and Swaziland. SI/MAB Series No. 9. Smithsonian Institution, Washington, D.C.
5. IUCN. (2026). The IUCN Red List of Threatened Species. Version 2026-1. https://www.iucnredlist.org
6. Re:wild, Synchronicity Earth, & IUCN SSC Amphibian Specialist Group. (2023). State of the World’s Amphibians: The Second Global Amphibian Assessment. Re:wild, Texas, USA.