Natal Ghost Frog
© 2011 Luke Verburgt (1 of 2)
This frog varies in color from brown to dark blue-black, with blotches of yellow or green (Channing 2001; Wager 1986). Limbs are barred (Wager 1986). The underside is whitish and the throat is marbled with light brown (Wager 1986).
Hadromophryne natalensis tadpoles reach 85 mm in total length, with the body 32 mm and the tail 53 mm (Wager 1986). The tadpole has a modified mouth, with only a lower beak (Channing 2001). Teeth of young tadpoles have been described as "fanglike", replaced by regular denticles as the larvae mature (Channing 2001). Tadpoles have four upper rows and generally 14 lower rows (range 12-17) of labial teeth (Wager 1986). The mouth is encircled by papillae, with two rows of papillae above the mouth and four rows below (for a drawing of the mouth, see Wager 1986). The oral disc is “suckerlike", allowing it to cling to rocks in fast-flowing streams (Channing 2001). A long, laterally flattened, and muscular tail is present (Burton 2002), with narrow fins that begin 1/3 of the way down the tail (Wager 1986). The coloration is brown with darker mottling and sometimes a black tail tip (Wager 1986).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Lesotho, South Africa, Swaziland
Life History, Abundance, Activity, and Special Behaviors
These frogs breed in late summer (March-May), when stream flow is lower (Boycott 2004). When breeding season begins, males begin to call from concealed spots under large boulders in streambeds, the splash zones of waterfalls, rock crevieces in waterfalls, rock ledges near waterfalls or cascades, or from under roots of trees growing in the stream (Channing 2001; Boycott 2004). Males do not call in close proximity to one another (Boycott 2004). The call has been described as similar to a faint ringing bell (Boycott 2004) or to the call of the Egyptian fruit bat Rousettus aegyptiacus (Channing 2001). A melodious "ting" is sounded around two times a second, lasting 140ms with a dominant frequency of 1.5 kHz, and repeated slowly about ten times (Channing 2001; Boycott 2004). Sometimes a "currick" sound precedes the series of bell-like "tings" (Boycott 2004). Amplexus is inguinal (Burton 2002). Heleophrynid females are oviparous, attaching clutches of 50-200 eggs to the underside of submerged rocks, with the eggs hatching in 4-5 days (Boycott 2004).
The tadpoles are algae-feeders, and leave a characteristic cleared grazing trail on algae-covered streambed rocks. Young H. natalensis tadpoles have fanglike teeth, which are replaced by regular denticles over time (Channing 2001). To effectively deal with swift flowing water, tadpoles are equipped with ventral, oral suction discs, which are used as an anchor (Channing 2003). The tadpoles can also use the ventral sucker in locomotion. By alternating movements of the upper and lower lips, the larvae can "walk" along rock surfaces both forwards and backwards, and even climb up out of the water along a wet rock face (Wager 1986). Adhesion is strong enough that it is very difficult to pry the tadpole loose (Wager 1986).
Generally tadpoles are found in very shaded sections of the stream, but at higher elevations they may sometimes be found in sunlit parts of the stream (Wager 1986). Metamorphosis takes up to two years, and thus perennial streams are required (Wager 1986; Boycott 2004).
Front legs appear at about 30 mm, at which stage the tail is still present but the suctorial mouth disappears; the froglet hides in partially submerged stream vegetation or in rock crevices until metamorphosis is complete (Wager 1986).
As adults, Natal Ghost Frogs consume insects, spiders, and other arthropods (Channing 2003).
This species has somewhat toxic skin secretions, with one component similar to a toxin in the wasp Vespa mandarina (Channing 2001).
Trends and Threats
Possible reasons for amphibian decline
General habitat alteration and loss
This species was formerly known as Heleophryne natalensis, but has recently been separated out into a new genus (van Dijk 2008).
Boycott, R. C. (2004). ''Heleophryne natalensis Hewitt, 1913.'' Atlas and Red Data Book of the Frogs of South Africa, Lesotho, and Swaziland. SI/MAB Series #9. L. R. Minter, M. Burger, J. A. Harrison, H. H. Braack, P. J. Bishop, and D. Kloepfer, eds., Smithsonian Institution, Washington, D. C..
Burton, M., and Burton, R. (2002). ''Ghost Frog.'' International Wildlife Encyclopedia. M. Burton and R. Burton, eds., Marshall Cavendish Corporation, New York.
Channing, A. (2001). Amphibians of Central and Southern Africa. Cornell University Press, Ithaca.
Channing, A. (2003). ''Natal ghost frog.'' Grzimek's Animal Life Encyclopedia, 2nd edition. Volume 6, Amphibians. M. Hutchins, W. E. Duellman, and N. Schlager, eds., Gale Group, Farmington Hills, Michigan.
Grobler, J. P., Mafumo, H. B., and Minter, L. R. (2003). ''Genetic differentiation among five populations of the South African ghost frog Heleophryne natalensis.'' Biochemical Systematics and Ecology, 31(9), 1023-1032.
Lambiris, A. J. L. (1989). ''A review of the amphibians of Natal.'' Lammergeyer, 39, 1-210.
Smith, K. G., Weldon, C., Meyer, L., and du Preez, L. (2007). ''COS 59-1: Patterns of amphibian chytrid prevalence and mortality in the Drakensberg Mountains of South Africa and Lesotho.'' Conference abstract, Ecological Society of America/Society for Ecological Restoration, 2007 meeting, San Jose.
Wager, V. A. (1986). Frogs of South Africa: Their Fascinating Life Stories. Delta Books, Craighall.
van Dijk, D. E. (2008). ''Clades in heleophrynid salientia.'' South African Journal of Herpetology, 57, 43-58.
Written by Jason Nies (JasonMNies AT st.bhsu.edu), Black Hills State University
First submitted 2008-12-19
Edited by Kellie Whittaker (2009-02-23)
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