Perhaps the most important player in the Kloof Frog saga, was Father Paschal Boneberg, a missionary of the Roman Catholic Church who, in 1912, found himself at Mariannhill Church, just south of Pinetown in KZN. Marianhill was at the time one of the largest mission stations in the country, and I imagine that Boneberg esecaped the day-to-day stresses of the clergy by exploring the forests and streams around the church, collecting and cataloguing specimens of reptiles, amphibians and insects. Indeed, in 1912 he sent a batch of specimens to the Albany Museum, which included the first examples of the little hero of this story. Also in this shipment, were some bizarre and hitherto unknown tadpoles with big sucker-mouths that clung to the undersides of rocks like leeches.
Hewitt and Methuen decided to name the new froggy after its discover, and so Natalobatrachus bonebergi came into being. Their findings were published in an article entitled ‘Descriptions of some new Batrachia and Lacertilia from South Africa’ in the journal Transactions of the Royal Society of South Africa, Volume 3, pages 107–111. Incidentally, the weird tadpoles belonged to one of the ghost frogs – specifically in this case the Natal Cascade Frog, Hadromophryne natalensis, which was described by Hewitt in the same year as the Kloof Frog. Professional herpetologists were a small community back in those days, and it is not too surprising that there is another species of ghost frog named after Hewitt, namely Heleophryne hewitti, which is a highly localised species essentially endemic to four rivers in the Elandsberg mountain range near Port Elizabeth.
You may ask ‘what makes this frog so unique? It looks just like all the others’, and that’s a great question. Some other doubters have argued that the genus Natalobatrachus should be merged with Phrynobatrachus, the puddle frogs. However, some of the features that set Kloof Frogs apart from others is that they have horizontal pupils, a marked ‘overbite’ in that their snouts project over their lower jaws (see picture above) and broad flattened disks on their fingers. They also lack ‘vomerine teeth’ which I had to google. These are small bumpy projections on the roof of the mouth (in addition to the tiny maxillary teeth on the edge of the upper jaw). I also find it difficult to believe that these specialised, partly arboreal frogs with unique breeding habits and ecological preferences could be lumped with the rather lethargic, terrestrial puddle frogs. New studies based on genetics suggest that Kloof Frogs may be allied to Arthroleptella, the Moss Frogs endemic to the Western Cape (or perhaps KZN’s Chirping Frogs in Anhydrophryne??). At the family level, Kloof Frogs are placed in the family Petropeditidae, along with the groups mentioned above plus the cacos (Cacosternum), Montane Marsh Frog (Poyntonia) and Micro Frog (Microbatrachella).
In addition to Kloof Frog (a ‘kloof’ being the Afrikaans word for a deep valley or ravine), the species has several alternative names: Natal Frog, Natal Diving Frog, Boneberg’s Frog and even Gloomy Kloof Frog. Nice.
The purpose of those expanded, T-shaped toe-tips is to give the frogs better grip on slippery surfaces, such as slick rockfaces, leaf blades or twigs. Not surprisingly, a large part of their breeding strategy revolves around being able to reach places inaccessible to the main predators of their eggs. These are laid in batches of about 75-95, in sticky jelly balls that attach to twigs, trunks, leaves or rocks overhanging open water. Clumps may be placed quite low over the water surface, or as high as 2 m up. Often it is easier to look for the fairly conspicuous eggs clumps first, and then to search for the adult frogs hiding nearby. Old egg clumps may leave stains on the surfaces to which they were attached. Egg clumps measure about 75-108 mm, and the individual eggs are 1.5-2.0 mm in size and protected in a 4 mm diameter jelly capsule. The tadpoles take only about 6 days to develop to a stage where they can wriggle out of their jelly sanctuaries and drop into the water. Adults often perch in the vicinity of their egg clumps, and females have been seen to urinate over the eggs to keep them moist. They have a protracted breeding season, and may lay eggs from October to May (probably an attribute of the pleasant, warm, humid East Coast weather).
Kloof Frogs are endemic to South Africa, where they occur in the Eastern Cape from about Dwesa-Cwebe northwards along the coast, below 900 m in altitude, up to about the forests inland of Richards Bay. As their name suggests, they frequent deep, forested gorges with rocky streams; however, they may be found in swamp forests or even around small concrete reservoirs along forest streams. The species was not previously considered threatened, but in view of its restricted range and very specific habitat, a prudent approach is required. It is currently listed as Endangered, and is thought to have lost more than half of its habitat in the last century. Fortunately it does occur in several nature reserves, but much of its habitat outside protected areas has been replaced by sugar cane agriculture. An important conservation initiative is simply to raise awareness of this fascinating frog – and to monitor known populations and discover new ones. Make sure to submit your data to the Virtual Museum and Frog Map!