Family Hyperoliidae

Hyperolius sp.

reed frogs, sedge frogs, rietpaddas (A)

By L.R. Minter

Species account was published under the name:
          Hyperolius Rapp, 1842
Red listing status:

Description

The genus name is derived from Greek: hyper = above; leio = soft (referring to the palate).

These small- to medium-sized climbing frogs are usually brightly coloured and conspicuously marked. Colour and markings may be extremely variable in some species and the ability to change colour in different lighting conditions is a common feature. Sexual dichromatism occurs in many species.

The absence of asperities on the skin, and the presence of a horizontal to round pupil, distinguishes Hyperolius from Afrixalus species, which often occupy the same habitats. The tympanum is inconspicuous. Fingers and toes are webbed, and the tips of the digits are expanded and flattened, allowing the frogs to cling to smooth, vertical surfaces (Poynton 1964; Stewart 1967; Poynton and Broadley 1987; Lambiris 1989a; Passmore and Carruthers 1995; Channing 2001).

Distribution

This is the largest genus of African frogs, comprising approximately 90 species distributed in suitable habitats throughout sub-Saharan Africa. The presence of numerous synonymies, cryptic species and species complexes, however, presents an enormous challenge to taxonomists and it will probably take some time before a stable taxonomy is attained (Poynton and Broadley 1987; Channing 2001).

Of the eight species that occur in the atlas region, three are endemic. Most occur along the east and south coast, but the ranges of a few extend inland, east of the Great Escarpment. H. marmoratus appears to be the most adaptable species, occurring at higher altitudes in Eastern Cape, KwaZulu-Natal, Swaziland, Mpumalanga and Limpopo provinces, although some of these populations may have arisen as a result of inadvertent translocations.

Habitat

Hyperolius species occur in Savanna and Forest biomes but are absent from drier areas such as the central and western parts of the atlas region. They favour permanent, standing water with emergent and/or floating vegetation, but also breed in temporary water bodies.

Life history

During dry periods individuals may be found in various sheltered sites: under loose bark, beneath logs, in the axils of leaves, and in buildings where they shelter, for example, behind picture frames and in toilet cisterns.

Breeding usually occurs over a prolonged period (September–April in the summer rainfall areas). During the day, individuals may be found in exposed positions on reeds or sedges. They conserve water by tucking their hands and feet under their bodies, and often turn pure white to reflect sunlight.

At night, dense choruses develop at breeding sites, often comprising several Hyperolius species. Males usually call from exposed positions on emergent or floating vegetation and defend their call sites from conspecific males. Individuals may return to the same site on consecutive nights.

Up to 500 eggs are laid in smaller batches below, or just above, the water surface. The eggs are attached to vegetation and, in the case of H. pusillus, may be concealed between the leaves of water lilies. Some species are known to lay several clutches per season.

In view of their abundance at breeding sites, Hyperolius species probably play a significant ecological role in wetlands, consuming large quantities of small insects and falling prey to a variety of bird species, reptiles, fish, spiders and predatory insects.

Conservation

Hyperolius species in the atlas region are widespread and locally abundant. Most do not require conservation attention at present, although declines in some species outside of conservation areas have been noted. An exception is H. pickersgilli which is listed as Endangered, because of its restricted distribution and habitat loss.

Habitat loss to urban development, sugar farming and afforestation is a major threat to Hyperolius species in coastal areas. These activities have resulted in the draining of wetlands and the drying up of natural pans, significantly reducing the number of breeding sites available to these species.