Family Brevicipitidae

Genus Breviceps Merrem, 1820

By L.R. Minter

Currently accepted name: Breviceps indet.
Red listing status:

Description

The genus name, Breviceps, is derived from the Latin: brevis = short; ceps = head.

These frogs have globose bodies and flattened faces with a narrow, down-turned mouth. The pupil is horizontal. The limbs are very short with well-developed metatarsal tubercles on the heels. The digits lack webbing (except in B. macrops), and the inner and outer toes are very short (Poynton 1964; Poynton and Broadley 1985a; Passmore and Carruthers 1995). These frogs do not hop or jump but walk, run or climb. They burrow backwards into the soil by moving the soil away beneath their bodies using the metatarsal tubercles, and slowly rotate like a corkscrew as they disappear below the surface.

Distribution

These species are found in South Africa, northward to Angola, southern Zaire and Tanzania (Poynton and Broadley 1985a). Of the 14 described species, 10 are endemic to the atlas region, three are more widespread and one is entirely extralimital.

Habitat

Although largely absent from the Nama Karoo and large areas of the highveld grasslands, Breviceps species are found in all biomes of the region and in a wide variety of vegetation types. Some are restricted to moist forests and grasslands, while others are adapted to living in arid environments. Most species seem to prefer sandy, well-drained soils and a few, such as B. adspersus, B. gibbosus, B. sylvestris and B. verrucosus, appear to breed successfully in urban parks and gardens (pers. obs.).

Life history

Our knowledge of the biology of most species of Breviceps is largely incomplete. This is hardly surprising for these frogs are cryptic, slow moving animals that spend long periods underground. Consequently the following remarks are, in many cases, based on a few isolated observations rather than an extensive data set. The gaps in our knowledge represent a challenge to amateur and professional naturalists.

Breviceps spend dry periods, sometimes as long as six months, underground, sometimes in groups (Milstein 1967; Jacobsen 1989). During this time they become torpid, and some species are known to produce a cocoon which protects them against desiccation (Channing 2001). Species living in loose, humus-rich soils, construct extensive winding and branching tunnels and chambers just below the surface or under rocks or logs. They leave these tunnels to forage on the surface or, in the case of males, to call, returning to them at dawn or to escape danger (pers. obs.). When alarmed, as when handled roughly, they inflate their lungs, secrete a sticky, white substance on the back, and sometimes emit a piercing alarm call (Minter 1998).

Breeding takes place after rain when the ground is moist and suitable for nest construction during spring and early summer in summer-rainfall areas, and from mid-winter to spring in winter-rainfall areas. Some species begin to call before rain, apparently in response to a drop in barometric pressure (Poynton and Pritchard 1976). Large choruses develop and may be sustained for several days and nights during suitable weather conditions. Calling usually takes place from shallow depressions on the surface, well concealed beneath vegetation or leaf litter, but also from exposed sites and sometimes from an elevated position in grass tussocks or shrubs (Minter 1998).

All species (for which this information is available) are terrestrial breeders, undergoing their entire larval development and metamorphosis underground. A sticky secretion, produced by dermal glands on the dorsal and ventral surfaces of both sexes, facilitates amplexus by adhesion, and acts as a deterrent to predators (Visser et al. 1982). Egg masses are usually covered by a layer of eggless jelly capsules that presumably provide additional moisture during development. The female, or sometimes the male, remains in the vicinity of the egg chamber until metamorphosis is completed (Wager 1965; Minter 1998; Channing 2001).

Breviceps feed on a wide variety of arthropods and other invertebrates. The diets of individual species vary with habitat and time of year. In forests, crustaceans, centipedes, millipedes and other components of the leaf litter fauna may form a large part of their diet, while in savanna, termites and ants may predominate (Loveridge 1925; Barbour and Loveridge 1928; FitzSimons 1935, 1958; Wager 1965; Poynton and Pritchard 1976; Jacobsen 1982, 1989; Channing and Van Wyk 1987). Coleoptera, lepidopteran larvae and spiders form a smaller proportion of their diet (Jacobsen 1982). Predators of Breviceps include Bushpig (Palmer 1982), Black-backed Jackal (Botma 1971; Viljoen and Davis 1973), Fiscal Shrike (Hewitt and Power 1913), Boubou Shrike (pers.obs.), Olive Thrush (Oatley 1970), Hadeda Ibis (Wager 1957, 1965), Temminck’s Courser (pers. obs.), Vine and White-lipped snakes (Loveridge 1953a), Night Adder (Blake 1965) and Mozambique Spitting Cobra (Broadley 1971).

Conservation

Ten (77%) of the 13 Breviceps species that occur in the atlas region are endemic to it. Three species, B. gibbosus, B. macrops and B. sylvestris, are listed as Vulnerable (this publication). These are restricted-range species threatened by habitat loss due to urbanization and crop agriculture, strip mining and afforestation, respectively. Two recently described species, B. bagginsi and B. sopranus are listed as Data Defiicient.

Our knowledge of the amphibian fauna of the atlas region is so poor that new species are still being described regularly (Channing 1999). This ignorance is unfortunate in view of the rapid loss and degradation of natural habitats in southern Africa. With regard to the genus Breviceps, it is likely that cryptic species await discovery in Lesotho, the Western Cape Province and KwaZulu-Natal.