Hewitt's ghost frog
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Order: Anura
Family: Heleophrynidae
The ghost frogs of the family Heleophrynidae comprise only 6 species and represent the most basal or ancient members of the “Neobatrachia” (the modern frogs and toads) – a suborder of within the order “Anura” (the frogs and toads) containing all of the more recently evolved families within the frogs and toads. The older lineages, of which they are many fewer (just 9 out of the 45 currently recognised families of frogs and toads), are found in the suborder “Archaebatrachia” (the ancient frogs and toads). Despite being classed with the modern frogs and toads, the ghost frogs diverged from their closest ancestors over 160 million years ago in the Jurassic period. They therefore differentiated from the rest of the amphibians around 10 million years before the origin of the birds!
Hewitt’s ghost frog therefore has very few close relatives and is one of the only surviving members of the earliest lineage that gave rise to the modern frogs and toads. The closest ancestors of Hewitt’s ghost frog were the first modern frogs. Prior to 1988, the ghost frogs were thought to be the only African representatives of the Leptodactylidae (Leptodactylid frogs – a family of frogs otherwise entirely found in the Americas) and they were placed in a subfamily called the Heleophryninae. However, they have been moved to their own, much smaller family based on numerous morphological distinctions and are a much more ancient lineage than the Leptodactylidae. The Leptodactylid frogs diverged from their nearest common ancestors over 100 million years after ghost frogs split from the rest of the modern frogs and toads. The fact that the closest relatives of the ghost frogs are thought to be in South America (the Leptodactylid frogs) and Australia (the Myobatrachidae or Australian toadlets and waterfrogs) provides further evidence of continental drift and is indicative of the great age of this amphibian family.
Hewitt’s ghost frog therefore has very few close relatives and is one of the only surviving members of the earliest lineage that gave rise to the modern frogs and toads. The closest ancestors of Hewitt’s ghost frog were the first modern frogs. Prior to 1988, the ghost frogs were thought to be the only African representatives of the Leptodactylidae (Leptodactylid frogs – a family of frogs otherwise entirely found in the Americas) and they were placed in a subfamily called the Heleophryninae. However, they have been moved to their own, much smaller family based on numerous morphological distinctions and are a much more ancient lineage than the Leptodactylidae. The Leptodactylid frogs diverged from their nearest common ancestors over 100 million years after ghost frogs split from the rest of the modern frogs and toads. The fact that the closest relatives of the ghost frogs are thought to be in South America (the Leptodactylid frogs) and Australia (the Myobatrachidae or Australian toadlets and waterfrogs) provides further evidence of continental drift and is indicative of the great age of this amphibian family.
This is a moderately sized species of frog with a fairly flattened body that allows Hewitt’s ghost frog to hide in confined spaces during the day when it is inactive. Breeding males, at about 47 mm in length, are slightly smaller than females, which reach 50 mm. Hewitt’s ghost frog has long legs, large eyes with vertical pupils, and the tips of the fingers and toes are expanded and spatulate (or disc-like). Their front feet lack webbing but the rear feet are strongly webbed. The colour pattern consists of darker spots with a pale margin on a light brown background. Male ghost frogs tend to have horny spines on various surfaces of the body, especially the hands and forelimbs. During the reproductive and more aquatic period of their lives, males also tend to develop folds of loose skin that increase their respiratory surface area so they can take up more oxygen from the water during this particularly active phase of their life cycle.
The ghost frogs are found in mountain streams within their distribution and both the adult frogs and their tadpoles have various morphological adaptations suited to surviving on the rocks in and around these streams. The adults are poor jumpers but are excellently adapted for swimming in the strong currents of mountain streams with their long, powerful legs, flattened bodies and webbed feet. Their disproportionately large toe discs help them to cling onto rocks surrounding their streams. The mouthparts of the tadpoles are modified into a sucking disc, which allows them to cling to substrates in the stream and prevents them from being washed away. They can also use their mouths to climb up wet, vertical rock surfaces around their streams at night. Hewitt’s ghost frog tadpoles also have strong, muscular tails for swimming in fast-flowing water.
The ghost frogs are found in mountain streams within their distribution and both the adult frogs and their tadpoles have various morphological adaptations suited to surviving on the rocks in and around these streams. The adults are poor jumpers but are excellently adapted for swimming in the strong currents of mountain streams with their long, powerful legs, flattened bodies and webbed feet. Their disproportionately large toe discs help them to cling onto rocks surrounding their streams. The mouthparts of the tadpoles are modified into a sucking disc, which allows them to cling to substrates in the stream and prevents them from being washed away. They can also use their mouths to climb up wet, vertical rock surfaces around their streams at night. Hewitt’s ghost frog tadpoles also have strong, muscular tails for swimming in fast-flowing water.
Hewitt’s ghost frog breeds in permanent, fast-flowing rivers and streams with rocky beds. Adults and tadpoles can be found beneath submerged and partly submerged rocks in these waterways, and occasionally at the edge of small waterfalls and cascades. Tadpoles attach to rocks using their sucker-like mouthparts to avoid getting washed away in fast water and at night they use their mouths to climb wet, vertical rocks. Eggs are laid in clutches of 93 to 150 under rocks in quiet backwaters of their stream habitat. One batch was found attached to the underside of a rock in a shallow fast-flowing stream.
The diet of the adults consists of a range of insects, arthropods, snails and smaller species of frog. Their tadpoles feed on aquatic algae by grazing over algae-covered rocks. They use their sucker-like mouths to cling to substrates and remain still while they are feeding. The tadpoles develop slowly, taking up to two years to complete their metamorphosis into the adult form.
Adult Hewitt’s ghost frogs are crepuscular (active at dusk and dawn) and nocturnal (or night active). Adults remain concealed in hole or rock cracks during the day, emerging at night to feed or mate during the breeding season, which runs from October to January. They divide their time between their aquatic habitat and the land, where they are sometimes found long distances away from water. The advertisement call of Hewitt’s ghost frog consists of 8 or 9 notes, where each note is a soft whistle lasting only 60-110 milliseconds (ms) each. An initial longer whistle, lasting 250 ms, may precede this call.
The diet of the adults consists of a range of insects, arthropods, snails and smaller species of frog. Their tadpoles feed on aquatic algae by grazing over algae-covered rocks. They use their sucker-like mouths to cling to substrates and remain still while they are feeding. The tadpoles develop slowly, taking up to two years to complete their metamorphosis into the adult form.
Adult Hewitt’s ghost frogs are crepuscular (active at dusk and dawn) and nocturnal (or night active). Adults remain concealed in hole or rock cracks during the day, emerging at night to feed or mate during the breeding season, which runs from October to January. They divide their time between their aquatic habitat and the land, where they are sometimes found long distances away from water. The advertisement call of Hewitt’s ghost frog consists of 8 or 9 notes, where each note is a soft whistle lasting only 60-110 milliseconds (ms) each. An initial longer whistle, lasting 250 ms, may precede this call.
The natural habitats of Hewitt's ghost frog are Mediterranean-type shrubby vegetation, temperate grassland, and permanent fast-flowing, shaded mountain rivers and streams at an altitude of 400 to 550 metres above sea level. The shrubland and heathland of this species’ habitat occur in a small belt of vegetation in the Western Cape of South Africa. This vegetation is specifically referred to as fynbos shubland or heathland and it occurs in coastal and mountainous areas with a Mediterranean climate that mainly experience winter rainfall. The fynbos forms half of the surface area of the Cape Floristic Region biodiversity hotspot (an area of exceptionally rich and threatened plant and animal life) and contains 80% of this area’s plant species. The Cape Floristic Region contains over 9,000 species of plant, 70% of which are found nowhere else on earth. Hewitt’s ghost frog therefore contributes yet another remarkable endemic species to this important reserve of biodiversity. Unfortunately, the area where this frog is found has been partially planted with exotic pine trees which is reducing stream flow and impacting negatively upon the species.
Hewitt’s ghost frog appears to bee restricted to four perennial rivers that have their headwaters in the Elandsberg mountain range in the Eastern Cape Province, South Africa. These rivers include the Geelhoutboom River, the Martin's River, the Klein River and the Diepkloof River. Within this range, the species is present at an altitude of 400 to 550 metres above sea level.
There is no current population estimate for Hewitt’s ghost frog but the species is known to be uncommon.
No population data are currently available for Hewitt’s ghost frog, although the population trend is assumed to be in decline in the IUCN Red List of Threatened Species.
Hewitt’s ghost frog is listed as Critically Endangered in the IUCN Red List of Threatened Species because its area of occupancy of less than 10 km², all individuals are in a single location, and there is a continuing decline in the extent and quality of its habitat, area of occupancy, number of locations, and number of mature individuals.
This species is mainly threatened in the wild by the loss of suitable non-breeding and breeding habitat as a result of the creation of exotic pine plantations within the species’ range, which are having the detrimental affect of reducing stream flow as less precipitation reaches the channel of the waterways. Hewitt’s ghost frog is also threatened by fires, soil erosion and the ensuing siltation of their streams, dams, and road building. Introduced predatory fish are also thought to be a threat as they feed upon both the tadpoles of this species and, potentially, the adults. The virulent fungal disease chytridiomycosis, responsible for catastrophic amphibian declines globally, is also an insidious threat to this species.
Hewitt’s ghost frog is not known to occur in any protected areas but the Cape Floristic Region is considered to be a “biodiversity hotspot” (an area of exceptionally rich and threatened plant and animal life) and is therefore a conservation priority for the internationally active environmental non-governmental organisation Conservation International (CI). CI’s Critical Ecosystem Partnership Fund provides support for conservation projects in this (and other) hotspots. These act to preserve plant and animal species, together with their ecological processes, in the hotspot region. This is having positive repercussions for the protection of habitat for the Hewitt’s ghost frog. However, given the continued loss of non-breeding and breeding habitat for this species, much more need to be done to ensure the continues survival of Hewitt’s ghost frog in the wild.
Considering the current lack of formal conservation areas for Hewitt’s ghost frog, the maintenance of its remaining breeding and non-breeding habitat is essential. The establishment of protected landscapes is a fundamental necessity for the preservation of this species. This may be possible through working with local forestry services to manage Hewitt’s ghost frog habitat more sustainably by creating buffer zones of native vegetation around the streams. At present, pine plantations are extending right down to the banks of the streams and this is having a detrimental effect upon habitat quality for Hewitt’s ghost frog.
There is also a need for continued monitoring of known populations and survey work to search for any additional populations. Disease screening and monitoring of this species is also an important priority because the virulent amphibian disease chytridiomycosis has already been found affecting wild populations ghost frogs. This will contribute important information for the wild management of Hewitt’s ghost frog.
In addition to conserving native habitat for this species, the IUCN Technical Guidelines for the Management of Ex situ Populations, part of the IUCN Red List of Threatened Species, recommend that all Critically Endangered species should have an ex situ population managed to guard against the extinction of the species. An ex situ population is ideally a breeding colony of a species maintained outside of its natural habitat, giving rise to individuals from that species that are sheltered from problems associated with their situation in the wild. This can be located in the within the species range or in a foreign country that has the facilities to support a captive breeding programme for that species. Further investigation is therefore required into the possibilities of establishing a captive breeding programme for Hewitt’s ghost frog, which may be a difficult process because it is not considered to be a particularly good species for captivity, although a captive breeding effort for the Natal ghost frog is already underway.
There is also a need for continued monitoring of known populations and survey work to search for any additional populations. Disease screening and monitoring of this species is also an important priority because the virulent amphibian disease chytridiomycosis has already been found affecting wild populations ghost frogs. This will contribute important information for the wild management of Hewitt’s ghost frog.
In addition to conserving native habitat for this species, the IUCN Technical Guidelines for the Management of Ex situ Populations, part of the IUCN Red List of Threatened Species, recommend that all Critically Endangered species should have an ex situ population managed to guard against the extinction of the species. An ex situ population is ideally a breeding colony of a species maintained outside of its natural habitat, giving rise to individuals from that species that are sheltered from problems associated with their situation in the wild. This can be located in the within the species range or in a foreign country that has the facilities to support a captive breeding programme for that species. Further investigation is therefore required into the possibilities of establishing a captive breeding programme for Hewitt’s ghost frog, which may be a difficult process because it is not considered to be a particularly good species for captivity, although a captive breeding effort for the Natal ghost frog is already underway.
AmphibiaWeb: Information on amphibian biology and conservation [web application]. 2006. Berkeley, California: AmphibiaWeb. Available: amphibiaweb. Accessed: 08 December 2006.
Behler, J.L. and Behler, D.A. 2005. Frogs: A Chorus of Colors. Sterling Publishing, NY, U.S.A.
Boycott, R.C. 1988. Description of a new species of Heleophryne Sclater, 1899 from the Cape Provice, South Africa (Anura: Heleophrynidae). Ann. Cape Prov. Mus. (Nat. Hist.) 16: 309-319.
Branch, W.R. (ed.). 1988. South African Red Data Book - Reptiles and Amphibians. South African National Scientific Programmes Report 151.
Channing, A. 2001. Amphibians of Central and Southern Africa. Cornell University Press, Ithaca and London.
Duellman, W. E. and Trueb, L. 1986. Biology of Amphibians. McGraw-Hill, New York.
Frost, Darrel R. 2006. Amphibian Species of the World: an Online Reference. Version 4 (17 August 2006). Electronic Database accessible at:. American Museum of Natural History, New York, USA.
Frost, D. R., Grant, T., Faivovich, J., Bain, R.H., Haas, A., Haddad, C. F. B., De Sá, R.O., Channing, A., Wilkinson, M., Donnellan, S.C., Raxworthy, C.J., Campbell, J.A., Blotto, B.L., Moler, P., Drewes, R.C., Nussbaum, R.A., Lynch, J.D., Green, D.M., and Wheeler, W.C. 2006. The Amphibian Tree of Life. Bulletin of the American Museum of Natural History 297: 1-370.
Groombridge, B. (ed.) 1994. 1994 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland.
IUCN, Conservation International and NatureServe. 2006. Global Amphibian Assessment. Global Amphibian Assessment. Accessed on 08 December 2006.
Mattison, C. 1987. Frogs and toads of the world. Blandford Press, U.K.
Minter, L., Channing, A. & Harrison, J. 2004. Heleophryne hewitti. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. IUCN Red List of Threatened Species. Downloaded on 20 September 2007.
Minter, L.R., Burger, M., Harrison, J.A., Braack, H.H., Bishop, P.J. and Knoepfer, D. 2004. Atlas and Red Data Book of the Frogs of South Africa, Lesotho and Swaziland. SI/MAB Series No. 9, Washington, D.C.
Obst, F.J., Richter, K. and Jacob, U. 1984. The Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium. T.F.H. Publication Inc., N.J., U.S.A.
Passmore, N.I. and Carruthers, V.C. 1995. South African Frogs. 2nd Edition. Southern Book Publishers and Witwatersrand University Press, Johannesburg.
Roelants, K., Gower, D. J., Wilkinson, M., Loader, S. P., Biju, S. D., Guillaume, K., Moiau, L. and Bossuyt, F. 2007. Global patterns of diversification in the history of modern amphibians. Proceedings of the National Academy of Sciences 104: 887-892.
Behler, J.L. and Behler, D.A. 2005. Frogs: A Chorus of Colors. Sterling Publishing, NY, U.S.A.
Boycott, R.C. 1988. Description of a new species of Heleophryne Sclater, 1899 from the Cape Provice, South Africa (Anura: Heleophrynidae). Ann. Cape Prov. Mus. (Nat. Hist.) 16: 309-319.
Branch, W.R. (ed.). 1988. South African Red Data Book - Reptiles and Amphibians. South African National Scientific Programmes Report 151.
Channing, A. 2001. Amphibians of Central and Southern Africa. Cornell University Press, Ithaca and London.
Duellman, W. E. and Trueb, L. 1986. Biology of Amphibians. McGraw-Hill, New York.
Frost, Darrel R. 2006. Amphibian Species of the World: an Online Reference. Version 4 (17 August 2006). Electronic Database accessible at:
Frost, D. R., Grant, T., Faivovich, J., Bain, R.H., Haas, A., Haddad, C. F. B., De Sá, R.O., Channing, A., Wilkinson, M., Donnellan, S.C., Raxworthy, C.J., Campbell, J.A., Blotto, B.L., Moler, P., Drewes, R.C., Nussbaum, R.A., Lynch, J.D., Green, D.M., and Wheeler, W.C. 2006. The Amphibian Tree of Life. Bulletin of the American Museum of Natural History 297: 1-370.
Groombridge, B. (ed.) 1994. 1994 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland.
IUCN, Conservation International and NatureServe. 2006. Global Amphibian Assessment. Global Amphibian Assessment. Accessed on 08 December 2006.
Mattison, C. 1987. Frogs and toads of the world. Blandford Press, U.K.
Minter, L., Channing, A. & Harrison, J. 2004. Heleophryne hewitti. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. IUCN Red List of Threatened Species. Downloaded on 20 September 2007.
Minter, L.R., Burger, M., Harrison, J.A., Braack, H.H., Bishop, P.J. and Knoepfer, D. 2004. Atlas and Red Data Book of the Frogs of South Africa, Lesotho and Swaziland. SI/MAB Series No. 9, Washington, D.C.
Obst, F.J., Richter, K. and Jacob, U. 1984. The Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium. T.F.H. Publication Inc., N.J., U.S.A.
Passmore, N.I. and Carruthers, V.C. 1995. South African Frogs. 2nd Edition. Southern Book Publishers and Witwatersrand University Press, Johannesburg.
Roelants, K., Gower, D. J., Wilkinson, M., Loader, S. P., Biju, S. D., Guillaume, K., Moiau, L. and Bossuyt, F. 2007. Global patterns of diversification in the history of modern amphibians. Proceedings of the National Academy of Sciences 104: 887-892.
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