Marbled Reed Frog

A medium-sized Hyperolius with a maximum body length of about 33 mm. Pupil horizontal. The adult color pattern is extremely variable and has led to many systematic and nomenclatural uncertainties about this ‘superspecies’. Ongoing investigations into the ecology, call structure and genetics of populations from different parts of Africa will help to resolve the taxonomy of this group (Minter et al. 2004). The pattern varies from distinct stripes through to vermiculations, dots and splotches, and the colours of the patterns vary from dark brown or black through to yellow and peppermint green. Juvenile males appear to be overall brown during their first breeding season (see photograph of juveniles in combat).For another description of H. marmoratus, see the H. viridiflavus superspecies account (by A. Schiøtz).This species shows developmental changes in patterning, with two phases defined in Schiøtz (1999), J (juveniles and many mature males) and F (mature females and some mature males). All newly metamorphosed individuals are phase J, which is normally brownish to green with paired light dorsolateral lines, or an hourglass pattern. All females, and some males, develop into phase F before the first breeding season. Phase F is often colorful and variable, showing the diagnostic color characteristics for the species or subspecies. Either well-defined morphs may be present, or graded variation.

This species forms part of a large complex of geographical variants distributed across most of sub-Saharan Africa.

The major threat to this species is habitat loss through drainage of wetlands and afforestation. In several areas of prime habitat, the planting of exotic Eucalyptus forests has lowered the water table to such a degree that many ponds within the coastal dune forest have completely disappeared (Minter et al. 2004). The Painted Reed Frog is locally abundant and sub-populations often consist of hundreds or occasionally thousands of individuals. They occur in many protected areas including National Parks and appear not to require any further conservation action.

The adults aestivate during the dry season, and have been found sheltering some distance from their breeding sites in vegetation or under logs and stones. During this time they often take up residence inside houses, where they conceal themselves behind cupboards, pelmets, pictures and in toilet cisterns. The breeding behaviour of this species is arguably the most well documented for any African frog, with over 15 papers and numerous theses relating to the subject published within the last ten years. Although males will call after rain at any time of the year, breeding normally takes place from October to February. At low altitudes male calling behaviour is inhibited by temperatures below 16°C, while at higher altitudes breeding has been observed at temperatures below 10°C. During the day, adults usually move into the canopy of surrounding trees or bask in the sun on emergent vegetation at the edge of the breeding site. H. marmoratus utilise a wide variety of breeding sites, ranging from temporary ponds and seepages to permanent bodies of water such as dams, marshes, reedbeds, sluggish rivers and streams (Channing 2001). At dusk they descend to the pond where males take up specific call sites (which they return to on consecutive nights) and call consistently from dusk to just after midnight. Where present, tall emergent plants such as reeds and sedges (e.g. Eleocharis limosa, Cyperus papyrus and Typha latifolia) are favored as call sites, but males will also call from trees, grasses, bushes, floating vegetation or even bare soil at the water’s edge. On average, males only call for a few nights in a row, returning to the breeding chorus after a period of about 10 days (Dyson et al. 1992). Gravid females enter the pond shortly after dusk and usually select a mate within a few hours. After several hours in axillary amplexus, the eggs are laid in water. Females have been observed to lay more than one clutch of eggs per season with a month long interval between layings (pers. obs.). Between 150 and 650 eggs are laid in flattened clumps of about 20, on the surface of submerged leaves, stalks or stones or amongst the roots of aquatic plants (Channing 2001). Tadpoles hatch within 5 days and metamorphosis takes about 6-8 weeks.

In captivity Hyperolius marmoratus can live at least 4 years 9 months.

Typical lifespan
Status: captivity: 4.75 (high) years.

Hyperolius marmoratus adults rely on their agility and ability to leap great distances to escape from danger. They also have red skin on the inside of the thighs and the side of the belly, which functions as a startle mechanism, because it is only visible when the animal jumps.

Known Predators:

• frog-eating bats (Nycteris grandis)
• Angolan green snakes (Philothamnus angolensis)
• herald or red-lipped snakes (Crotaphopeltis hippocrepis)
• brown water snakes (Lycodonomorphus rufulus)
• fishing spiders (Araneae)
• young crocodiles (Crocodylus)
• predatory birds, such as kingfishers (Alcedinidae)
• tree frogs (Leptopelis)
• red-legged kassina (Kassina maculata)

Hyperolius marmoratus is small to medium in size, the male reaching 43mm in length. The side of its snout is curved and the head width is 32-38% of its body length. The toes end in toe pads that enable the frog to climb up stems of grass and reeds. They have an enormous variety of brightly colored markings, with a profusion of stripes, spots, or stippling. Currently, populations are grouped by shared color patterns into subspecies. Some may be pale brown with darker spots or striped with lighter and darker brown. Others may be striped with thick bands of black and white with a yellow stripe running down the center. While, still others have red-brown spots on a light background. There are many variations known.

Range length: 43 (high) mm.

Other Physical Features: ectothermic ; bilateral symmetry ; polymorphic

Sexual Dimorphism: sexes alike

Hyperolius marmoratus has an impressive vocal capacity. The male calls from vegetation around bodies of water. The call is a short whistle, only about 0.1 seconds long and has a frequency ranging from 2.8 to 3.1 kHz. The vocal sac of H. marmoratus is very large. This amplifies his call, making it very loud. Two males may call simultaneously, alternating with a third male. The call helps to maintain male spacing to a minimum of about 50 cm. Females prefer to select an isolated male as opposed to a male calling close to another male, as well as a male that is near to the female's release site. Females are also attracted to high call rates and greater intensities. Females select the male with the loudest call, so long as there is a noticeable difference between the calls of that area. It is speculated that females choose conspicuous males in order to reduce search time when under the risk of predation in the chorus. It has been found that chorus tenure duration has the most significant influence on mating success. Because calling is energetically expensive to H. marmoratus, by mating, males are able to conserve energy, which enables them to attend the breeding site more frequently and to call more energetically. Males will also return on successive evenings to exactly the same calling site.

Touch is used to initiate amplexus. These frogs also perceive the environment with their keen eyesight, attuned to perceiving motion.

Communication Channels: tactile ; acoustic

Other Communication Modes: duets ; choruses

Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical

Hyperolius marmoratus is found in savannas and open bush along water sources such as rivers and streams, as well as in lowlands that contain temporary pools during the rainy season.

Habitat Regions: tropical ; terrestrial ; freshwater

Terrestrial Biomes: savanna or grassland

Aquatic Biomes: rivers and streams; temporary pools

Other Habitat Features: riparian

Hyperolius marmoratus is widely distributed in sub-Saharan Africa.

Biogeographic Regions: ethiopian (Native )

Hyperolius marmoratus feeds on a variety of small insects.

Animal Foods: insects; terrestrial non-insect arthropods

Primary Diet: carnivore (Insectivore )

Hyperolius marmoratus is prey to many different species of animals in its ecosystem.

Hyperolius marmoratus is known to be a predator of the important citrus pest, the citrus psylla (Diaphorina citri).

Positive Impacts: controls pest population

There are no known adverse effects of these frogs on humans.

Hyperolius marmoratus tadpoles hatch in less than a week and develop into small froglets within 2 months. Tadpoles may grow to be 44mm in length. They are brown with speckled fins, and have tails that end in a sharp point tipped with black. The tadpoles are bottom dwellers, and prefer shallow, grassy pools. In captivity, metamorphosis takes 64-100 days. The adult color phase develops when the frog reaches sexual maturity. The identification of Hyperolius marmoratus depends largely on color pattern.

Development - Life Cycle: metamorphosis

These frogs are widespread and not currently considered threatened. Local populations may be threatened by water diversions, habitat disruption, and pesticide or herbicide use.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Males establish small calling territories in ponds in order to breed. Elevated calling sites are defended through intense kicking bouts against any male intruders. Hyperolius marmoratus females approach males in breeding ponds and initiate amplexus.

Mating System: polyandrous ; polygynous

This lasts for several hours making it possible for a male to mate with only one female each night. Fertilization is external during the period of egg laying. A Hyperolius marmoratus clutch consists of 150-600 small eggs that are between 1.3-1.5mm in diameter, and are within 2.5mm capsules. The eggs are laid in clumps of about 20, attached to underwater vegetation, during the rainy season. They are pale yellow with a dark brown end, although some have also been reported to be blue-green. In captivity, females are reported to produce eggs every 2 or 3 weeks for up to 14 months or longer, once they reach sexual maturity. In the field this may be variable depending on the weather.

Breeding interval: Females may produce eggs every 2 to 3 weeks.

Breeding season: Breeding seasons last from the first rains of spring to late summer.

Range number of offspring: 150 to 650.

Average number of offspring: 300-400.

Average time to hatching: 5 days.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Neither sex provides parental care.

Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)

The marbled reed frog or painted reed frog (Hyperolius marmoratus) is a species of frogs in the family Hyperoliidae found in Malawi, Mozambique, South Africa, Eswatini, and Zimbabwe, and Botswana, and Angola,Lesotho, and Tanzania. It occurs in a wide range of natural habitats, including forests, savannas, shrublands, grasslands, rivers, swamps, freshwater lakes, and intermittent freshwater lakes. It coexists well with humans, and is also found in pastureland, rural gardens, and urban areas. Its range appears to be expanding to the winter rainfall area of the Western Cape.

Species in the genus Hyperolius may display different colouration and patterns during day and night. Daylight colours are usually pale and drab, while their night-time appearance is colourful and eye-catching – see images below.