AMPHIBIAWEB
Amietia angolensis
Angola River Frog
family: Pyxicephalidae
subfamily: Cacosterninae

© 2016 Dr. Joachim Nerz (1 of 14)
Conservation Status (definitions)
IUCN (Red List) Status Least Concern (LC)
CITES
Other International Status None
National Status None
Regional Status None

Country distribution from AmphibiaWeb's database: Angola

 

View distribution map using BerkeleyMapper.

   

From the Encyclopedia of Life account:

Etymology

The species name angolensis means "of Angola."


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Taxonomic Notes

This species is widespread and is almost certainly a complex of multiple cryptic species (Text from Harper et al., 2010). A. tenuoplicata and A. viridireticulata were recently split from A. angolensis by Pickersgill (2007).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Distribution

Poynton (1964) describes A. angolensis as being a widespread species distributed from Ethiopia, south through East Africa to southern Africa and westward to Angola (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/

Morphology

This species has long hind legs and a fair amount of webbing between the toes and is well adapted to jumping and swimming (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/

Size

Females are up to 90 mm (Harper et al., 2010).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Diagnostic Description

This is a large frog (up to 90 mm long) which can often be found along edges of large streams and rivers. The adults can be found along the banks throughout the year. In Kenya’s Taita Hills, adults of this species can be found in all of the permanent streams and rivers. Their brown and greenish blotched appearance blends in well with both mud and vegetation (Text from Measey et al. 2009, © SANBI).

This is a large frog with long legs. The dorsal color and markings are variable, usually browns, greens and yellows, sometimes with darker marks. Dorsal texture is also variable, from smooth to ridged. The tympanum is visible and slightly larger than ½ the diameter of the eye. A fold of skin curves from the eye to the arm over the tympanum. Toes are webbed, usually with only the last section of the longest toe free of webbing, but webbing is variable among populations (Text from Harper et al., 2010).


Authors: Zimkus, Breda; Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Habitat and Ecology

If you find a very large tadpole in quiet waters of a stream or river in the Taita Hills of Kenya, it is almost certainly the Angola river frog (Text from Measey et al. 2009, © SANBI).

This is a widespread species in forest, grassland, savanna and agricultural areas that is associated with permanent water (Harper et al., 2010).


Author: Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Habitat and Ecology

Amietia angolensis inhabits the Grassland and Savanna biomes, and forest fringe. Annual rainfall in these areas is 500–900 mm. The species tolerates some habitat disturbance and is frequently associated with human habitation, taking up residence in ditches and ponds, often where reeds and water lilies are present (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/

Associations

Amietia angolensis tested positive for Batrachochytrium dendrobatidis (chytrid fungus that causes the disease chytridiomycosis) in the South African city of Bela-Bela in 2004 (Weldon, 2005).


Author: Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Associations

Being a common species that is active all year round, these frogs consume large numbers of flying and crawling insects. In turn, they constitute an important prey item for otters, large birds and snakes ((Rowe-Rowe 1977a, b; Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/

Modes and Mechanisms of Locomotion

These frogs are strong swimmers with prominent webbed feet (Text from Measey et al. 2009, © SANBI).


Author: Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Activity and Special Behaviors

Tadpoles have been found in slow moving streams as well as in dammed ponds for community water schemes (Text from Measey et al. 2009, © SANBI).


Author: Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Activity and Special Behaviors

The adults spend the day floating amongst vegetation or basking on rocks above the water (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/

Metamorphosis

They take two years before they metamorphose into frogs, growing to a very large size (up to 60 mm long; Text from Measey et al. 2009, © SANBI).


Author: Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Reproduction

Breeding takes place in shallow water along the edges of pools, dams, streams and slow-flowing rivers. These frogs breed in both standing water in flat areas and running water traversing slopes of more than 14 degrees (Channing 1979). Amietia angolensis is active throughout the year and breeding has been recorded in all months of the year (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/

Advertisement Call

Males call during both rainy seasons in a series of ‘chirps’ followed by some ‘croaks’ often from sheltered spots under river banks or even floating in the water (Text from Measey et al. 2009, © SANBI).

Males call from the water’s edge, often partially submerged. Two different calls, usually emitted in succession, consist of a rattle and a brief croak (Harper et al., 2010).


Authors: Zimkus, Breda; Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Reproduction

Pairs of frogs lay single eggs in small still areas in streams from October to April (Text from Measey et al. 2009, © SANBI).

Eggs are laid in shallow water in ponds on the edges of streams in forest and in open areas (Harper et al., 2010).


Authors: Zimkus, Breda; Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Advertisement Call

Males typically call from floating vegetation or from shallow water at the edge. Clutches of 400–500 eggs are laid in shallow, standing water (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/

Tadpole morphology

The large tadpoles are brown with some flecking and can reach a total length of 80 mm or greater (Text from Harper et al., 2010).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Tadpole morphology

Wager (1986) found that tadpoles may grow to 80 mm in length (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/

IUCN Red List Category and Justification of Conservation Status

It is found in many protected areas. Localized threats include acid pollution from old gold-mine dumps. A. angolensis is not generally threatened (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).


Author: Channing, A.
License: http://creativecommons.org/licenses/by-nc/3.0/