Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"

It's been a long time since we featured a frog here. So today let us look at the Knysna Leaf-folding Frog, also known as the Knysna Banana Frog, Afrixalus knysnae. We've already seen its much larger cousin, the Greater Leaf-folding Frog. Compared to that one, the Knysna leaf-folding frog is only half the length, at about 2-2.5 cm/0.8"-1" snout-to-vent length. This makes it one of the smallest of Southern African frogs. It belongs to the family Hyperoliidae, called generally reed, sedge or bush frogs, most of which are arboreal or climbing about reeds and other vegetation. They frequently have expanded tips to their digits, and sticky mucus that helps them cling to leaves or twigs.

In this family, the leaf-folding frogs constituting the genus Afrixalus are fairly typical in build and lifestyle, clambering about vegetation at rather low levels. Over thirty species make up this genus, which is restricted to sub-Saharan Africa. They're noted for their 'nesting' behaviour. They deposit 20 to 50 eggs at a time in a jelly-like lump on broad leaves, and then fold the edges around and stick them together to enfold the egg mass in a protective nest. The nest is built above water, so that when the tadpoles are ready, the sticky stuff holding the leaf together dissolves so the tadpoles can drop into the water, from which point they lead typical tadpole lives before metamorphosing into new, tiny leaf-folding frogs. More about the intricacies of their reproductive behaviour can be read in the article on the greater leaf-folding frog.

The Knysna leaf-folding frog is rather typical in appearance, being a golden orange in appearance, with tiny black bumps or 'asperities' all over their bodies, especially in the males. They have two broad, brownish, lengthwise stripes running along their sides. Like other leaf-folding frogs, they have cat-like eyes with vertical pupils. They don't co-occur with any other leaf-folding frogs in nature, and look quite different from the similar-sized reed frogs. They have distinctive calls, consisting first of a short 'zip' and then a longer 'trill'. These calls can be heard during the breeding season, which is October to December.

Sadly, this is one of South Africa's more threatened frog species. They occur only in a small region, shared between the Western and Eastern Cape provinces. The town of Knysna, for which they're named, is close to the core of their distribution. They're restricted to the moist, year-round-rainfall region found to the south of the Outeniqua and Tsitsikamma mountains. This region is famed for its temperate lowland forests, the most extensive in South Africa, but the frogs are not in particular associated with the forests, also occurring in fynbos (small-leaved shrubs) and a variety of aquatic vegetation. They are only known from a few sites, though. They are adaptable and can even occur in well-vegetated suburban gardens, but are vulnerable to poor water quality. They are impacted by habitat loss through urban development and encroaching non-native vegetation, and chemical water pollution. They are especially harmed by livestock being kept around the ponds where they breed. Cows eat and trample the vegetation around the ponds, and also deposit urine and dung in the ponds which adversely affects the tadpoles. Though this region is moist and receives ample rainfall on average, unusually dry years may have serious consequences for these little frogs. They are in dire need of a project to monitor them and preserve their habitat.

Willem

10.06.24 Front Page

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