The arum frog, Horstock's arum-frog, arum lily frog, or Horstock's reed frog (''Hyperolius horstockii'') is a species of

frog A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' is ...

in the family

Hyperoliidae The Hyperoliidae, or sedge frogs and bush frogs, are a large family of small to medium-sized, brightly colored frogs which contains more than 250 species in 19 genera. Seventeen genera are native to sub-Saharan Africa. In addition, the monotypic ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

Identification

Adults grow to 40 mm in length. They have bright orange feet and can change their colour to camouflage themselves. The top of the body is cream to brown, sometimes with small black spots. A distinctive, pale, dorsolateral line runs from the snout along the flanks, with a dark-brown lateral band underneath. A fine, dark line usually separates the pale line from the brown band. The concealed surfaces of limbs, webbing, and discs are orange to red. Underneath, the frog is creamy white and slightly granular. The gular flap in males is bright ochre. their pupils are horizontal. Tadpoles reach 40 mm. They are brown with longitudinal, darker bands on their tails.

Distribution and habitat

The arum frog is found in the southern coastal plain of South Africa from

Cape Town Cape Town ( af, Kaapstad; , xh, iKapa) is one of South Africa's three capital cities, serving as the seat of the Parliament of South Africa. It is the legislative capital of the country, the oldest city in the country, and the second largest ...

in the

Western Cape The Western Cape is a province of South Africa, situated on the south-western coast of the country. It is the fourth largest of the nine provinces with an area of , and the third most populous, with an estimated 7 million inhabitants in 2020 ...

to Port Elizabeth in the Eastern Cape. Its natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s are Mediterranean-type shrubby vegetation,

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...

s, swamps, intermittent freshwater

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

s, freshwater

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found a ...

es, intermittent freshwater marshes, and

pond A pond is an area filled with water, either natural or artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% emergent vegetation helps in distinguishing their ecology from ...

s. It is frequently found lying at the bottom of arum lilies (''

Zantedeschia aethiopica ''Zantedeschia aethiopica'', commonly known as calla lily and arum lily, is a species of flowering plant in the family Araceae, native to southern Africa in Lesotho, South Africa, and Eswatini. Description ''Zantedeschia aethiopica'' is a rhizo ...

''), trying to catch pollinating insects. It is assessed as

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

but some populations are threatened by

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

through the invasion of alien vegetation and fire. Contrary to popular belief it is not threatened by the collection and sale of arum lilies.

Behaviour

These frogs are sometimes found in arum lily flowers where they can change colour to perfectly match their surroundings. This makes them virtually invisible to predators, as well as to their insect prey. Their pale colour camouflages them in the white flowers, helped by hiding their bright orange feet and legs under their bodies during the day. Contrary to popular belief they do not use the pollen of the flowers to camouflage themselves. The breeding habitat of the arum frog includes large or small pans, dams, vleis and slow-flowing, quiet streams where there is sufficient emergent vegetation. Males usually call at night from elevated positions above water, normally in the emergent vegetation such as

sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus '' Carex'' ...

reed Reed or Reeds may refer to: Science, technology, biology, and medicine * Reed bird (disambiguation) * Reed pen, writing implement in use since ancient times * Reed (plant), one of several tall, grass-like wetland plants of the order Poales * ...

s, shrubs and grasses, although they may sometimes call from the pads of water lilies. The usually start calling just after sunset, but will call sporadically in the late afternoon on cloudy, rainy days. The arum frog occurs mostly in a winter rainfall region; however, its breeding season occurs over the spring and summer, in September–January. After mating the female lays clutches of 10–30 eggs which are attached to the submerged roots and stems of plants.

References

{{Taxonbar, from=Q596500 Hyperolius Frogs of Africa Endemic amphibians of South Africa Taxa named by Hermann Schlegel Amphibians described in 1837 Taxonomy articles created by Polbot