Adult females have a snout vent length ~60 mm while males are ~50 mm in length. They are characterized by a squat, compressed body allowing for concealment in small crevices. Highly webbed hind limbs make Heleophryne rosei a strong swimmer but a poor jumper. Toes are spatulate providing for a firm grip on rocky substrates. An enlarged metacarpal tubercle is also present, resembling a vestigial thumb. Adults have mottled pigmentation consisting of reddish-brown patches on a green background. Their pupils are vertically elliptical. Males secondarily develop nuptial pads and dorsal skin folds. Both sexes develop asperities (spiny structures allowing for better contact during amplexus). Tadpoles can be identified by brown stipple on fins and body. They possess a suctorial mouth, similar to that of Ascaphus, which is used for algal feeding and securing a grip on rocky substrates in swift-moving streams.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: South Africa
Heleophryne rosei is confined to a very small area of approximately 7-8 km2 on the eastern and southern slopes of Table Mountain, Cape Province, South Africa. Tadpoles have been recorded at Window Gorge, Skeleton Gorge, Nursery Ravine, Cecilia Ravine, the Original Disa Stream, Disa Gorge, and Disa Stream. The species is endemic to this region. Individuals have been recorded only in wet and mesic mountain fynbos – areas of high rainfall (300-600 mm per year). Within their broader range, H. rosei is concentrated in wooded ravines and valleys in clear, swift-flowing, perennial streams. The year-round water supply is necessary to facilitate the approximately year-long development of tadpoles. Typical microhabitat consists of steep, algae-covered rocks in areas of fast-moving, cascading water. Adults have been recorded traveling away from streams over open land.
Life History, Abundance, Activity, and Special Behaviors
Heleophryne rosei is a rare species known from few adults and only a slightly larger number of tadpoles. Egg masses have never been found. Reproductive activity has been inferred based on examination of gravid females. Breeding occurs in the spring and summer months during the period of low stream flow. This likely ensures that eggs will not be laid in streams that will later dry up. During the mating season, the male’s asperities reach peak emergence.
Tadpoles of the species develop slowly over a period of ~12 months in cold water. They are torrent adapted, using their suctorial mouths to gain purchase on the rocky surfaces of the streambed. Tadpoles feed on algae covering these rocks. After metamorphosis, individuals leave the streams before the onset of winter rains.
Adult behavior has not been well-studied. It is known, however, that adults do stray from streams, traveling across land.
Trends and Threats
The narrow range of H. rosei makes it an extremely vulnerable species. Although its distribution currently exists within the confines of protected lands (the National Botanic Gardens and Department of Forestry), many factors still threaten the species’ persistence. Plantations of exotic Pinus, Eucalyptus, and Populus have clogged the streams that serve as H. rosei’s primary habitat, creating stagnant waterways not conducive to the frog’s life cycle. Along certain such stretches, H. rosei has gone locally extinct. Poor forestry practices may also lead to the clogging of these waterways.
At the beginning of the 20th century, dams were constructed along many waterways on Table Mountain, including those that function as H. rosei habitat. Reduced water flow from these dams may lead to a decline in this torrent-adapted species. It is imperative that policy continue to mandate that the dams permit a continuous flow downstream of a quantity sufficient to preserve H. rosei sites. Global climate change may also threaten the existence of H. rosei as the number of dry years not supporting sufficient perennial streams increases. Preservation of H. rosei will be aided by continued efforts to maintain swift-flowing perennial streams in the Table Mountain region. It has also been suggested that translocation of individuals may be of great importance as many suitable sites are currently uninhabited by H. rosei.
Possible reasons for amphibian decline
General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Dams changing river flow and/or covering habitat
Subtle changes to necessary specialized habitat
Baard, E. H. W. (1989). ''The status of some rare and endangered endemic reptiles and amphibians of the southwestern Cape Province, South Africa.'' Biological Conservation, 49, 161-168.
Boycott, R.C. (1988). ''Heleophryne rosei Hewitt: Species account.'' South African Red Data Book – Reptiles and Amphibians. W.R. Branch, eds., South African National Scientific Programmes: Report No. 151, Port Elizabeth, 36-37.
Boycott, R.C. and de Villiers, A.L. (1986). ''The status of Heleophryne rosei Hewitt (Anura:Leptodactylidae) on Table Mountain and recommendations for its conservation.'' South African Journal of Wildlife Research, 16(4), 129-34.
Channing, A., Boycott, R., and van Hensbergen, H.J. (1988). ''Morphological variation of Heleophryne tadpoles from the Cape Province, South Africa (Anura: Heleophrynidae).'' Journal of Zoology, London, 215, 205-216.
Written by Christopher Streeter (streeter AT fas.harvard.edu), Fall 2002 Amphibian Decline Seminar - Harvard
First submitted 2003-01-09
Edited by Meredith Mahoney (2003-02-03)
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