Hyperolius marmoratus Rapp 1842, is an amphibian species whose habitat preference and appearance reflect its name, the Marbled Reed Frog. The frog displays a marbled appearance with intricate patterns across its skin. Their ability to change colour makes them hard to describe (du Preez & Carruthers, 2009). Beyond their striking appearance, these small frogs play a crucial role in wetland ecosystems, serving both as biological indicators of environmental health and as a natural control of insect populations (Collins & Storfer, 2003).
How to recognize the marbled reed frog
Adult Marbled Reed Frogs typically range from 2.5 to 3.5 cm in length, with females slightly larger than males (Channing, 2019). They are characterized by their variable colouration, with patterns displaying shades of green, brown, and white in marbled arrangements. The species’ skin can change patterns between day and night (du Preez & Carruthers, 2009). Despite differences in colours and patterns, all Marbled Reed Frogs are slender, with large eyes on either side of the head and thin legs. Their eardrums are not visible, and their pupils are horizontal. Their snouts are tapered, rounded at the end and thin at the front. The toes have enlarged toe pads, with webbing between them. The belly is usually white but may sometimes be pink and in dry weather they often become white. Males have a characteristic yellow gular (throat) patch used in vocalization (Wager, 1986).
Getting around
These frogs are skilled climbers, their specialized toe pads allow them to navigate through reeds and other vegetation. During the day, they often remain motionless on reed stems or leaves, their colouration acting as camouflage. At night, they become more active, moving through vegetation while searching for food or seeking potential mates (Channing & Howell, 2006). The species’ ability to move at a speed of 300 m h-1, while intermediate compared to other amphibians, allows for significant dispersal, especially when combined with human-mediated transport (Davies, 2014; Hillman et al., 2008).
Distribution
The species is distributed across most of sub-Saharan Africa, with established populations ranging from Kenya southward to South Africa (Passmore & Carruthers, 1995). There are 13 geographical variants or subspecies. Three of these subspecies have documented distributions in South Africa. Limpopo, Mpumalanga and Swaziland, southward to St Lucia is occupied by H. m. taeniatus. H. m. marmoratus ranges from St Lucia southward to west of Port Edward. H. m. verrucosus on the other hand, is found along the coast, extending from the south coast of KwaZulu-Natal, southward along the Eastern Cape coast to Tsitsikamma in the Western Cape. The species has extended beyond its original distribution through human-mediated translocation, effectively establishing new populations on the Cape Peninsula and across interior regions of the Western Province (Bishop, 2024).
Habitat
As habitat generalists, marbled reed frogs can be found in a range of vegetation types, including savanna, grassland, and forest biomes. They are also found marginally in the fynbos biome. They mate and lay their eggs in wetland habitats, including reed beds, marshes, swamps, and the vegetated areas surrounding ponds and lakes (Bishop, 2024; Davies, 2014). They are frequently found among tall reeds and grass stems, because they offer cover and protection (du Preez & Carruthers, 2009).
Food
Predominantly insectivorous, these frogs feed on a variety of small invertebrates. Their diet consists of mosquitoes, flies, and other small insects they encounter while climbing through vegetation (Channing, 2019).
Sex and Life Cycles
Mating season occurs during the rainy season, triggered by increased rainfall and humidity. Males and females reach sexual maturity in their first and second year of life, respectively. Males form breeding choruses at night, where they broadcast their distinctive mating calls to attract potential mates. Females respond by laying two or three clutches of eggs, attaching them to vegetation above water. Five to seven days after hatching, the benthonic and herbivorous tadpoles drop into the water below, where they undergo metamorphosis over two to six weeks before emerging as metamorphs (froglets) about 1cm long (Davies, 2014; du Preez & Carruthers, 2009)
The Big Picture
Friends and Foes
Marbled Reed Frogs face threats from numerous predators, often falling prey to birds, young crocodiles, terrapins, snakes, and other larger amphibians. Their population are also threatened by the global chytrid fungus, a pathogen that has negatively affected amphibian populations worldwide (du Preez, 2017).
Smart Strategies
The species has developed several survival strategies, such as their ability to shift colour patterns between day and night, providing camouflage. The strategy of laying eggs above water offers protection from aquatic predators during their egg stage. Synchronizing their breeding during rainy seasons ensures that tadpoles emerge when water conditions are optimal for development and survival (Channing & Howell, 2006).To rest in the sun without drying out and dying, the species can coat its body in a specific mucus that hardens into a waterproof, protective covering.
Poorer World Without Me
As vital components of wetland ecosystems, these frogs play dual roles. They help control insect populations and serve as prey for various predators. Additionally, their sensitivity to environmental changes makes them excellent indicators of ecosystem health (Stuart et al., 2004). Any decline in their population numbers could signal deteriorating habitat conditions, potentially disrupting the balance of the wetland food webs.
People and I
In numerous African communities, the evening calls of Marbled Reed Frogs signal approaching rainfall and seasonal change. They coexist well with humans and are also found in rural gardens and urban areas. In agricultural settings, these frogs are valuable due to their role in controlling insect populations that could damage crops or spread disease. Despite this, human activities such as wetland drainage, habitat degradation, and growing urbanization pose increasing challenges to their populations (Collins & Storfer, 2003).
Conservation Status and What the Future Holds
The species’ abundance and ability to adapt to altered environments, such as garden ponds and agricultural landscapes, have contributed to the maintenance of stable populations. Additionally, the species occurs in several nature reserves. Therefore the IUCN classifies the species as Least Concerned (IUCN, 2023). However, habitat loss, pollution, and the effects of climate change pose challenges for the species. Their long-term existence depends on ongoing monitoring and preservation of their wetland habitats.
Relatives
The Marbled Reed is a member of the genus Hyperolius. (Channing and Rödel, 2022; Frost, 2011). As of 2022, there are at least 145 species within the genus, but new species are still being described (AmphibiaWeb, 2022; Channing and Rödel, 2019). Some researchers classified H. marmoratus as part of the H. viridiflavus superspecies. While others consider the species to be a member of a closely related species complex (Channing, 2001). This classification is provisional until a more comprehensive taxonomic revision of the entire group can be done.
Scientific Name and Classification:
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Hyperoliidae
Genus: Hyperolius
Species: H. marmoratus Rapp, 1842
Common names: Marbled Reed Frog (English); Painted Reed Frog (English), Geverfde Rietpadda (Afrikaans) and Gestreepte Rietpadda (Afrikaans)
Author: Itumeleng Letlojane and Janine Baxter
References
- AmphibiaWeb, 2022. Hyperoliidae [WWW Document]. Inf. Amphib. Biol. Conserv.
- Bishop, P., 2024. Hyperolius marmoratus Rapp, 1842 [WWW Document]. FrogMAP – Atlas Afr. Frogs. URL http://frogmap.adu.org.za/Species_text.php?sp=590 (accessed 11.25.24).
- Channing, A., Rödel, M.-O., 2019. Field guide to the frogs & other amphibians of Africa. Penguin Random House South Africa.
- Davies, S.J., 2014. Geographic range, spread and potential distribution of the painted reed frog Hyperolius marmoratus in the Western Cape Province, South Africa.
- FrogMAP – The Atlas of African Frogs [WWW Document], n.d. URL http://frogmap.adu.org.za/Species_text.php?sp=590 (accessed 11.25.24).Frost, D.R., 2011. Amphibian species of the world: an online reference. Version 5, 01.
- Hillman, S.S., Withers, P.C., Drewes, R.C., Hillyard, S.D., 2008. Ecological and environmental physiology of amphibians. Oxford University Press.
- Channing, A., 2019. Amphibians of central and southern Africa. Cornell University Press.
- Channing, A. and Howell, K.M., 2006. Amphibians of east Africa. (No Title).
- Collins, J.P. and Storfer, A., 2003. Global amphibian declines: sorting the hypotheses. Diversity and distributions, 9(2), 89-98.
- Du Preez, L., 2017. Frogs of Southern Africa–A complete guide. Penguin Random House South Africa.
- Du Preez, L., Carruthers, V. and Burger, M., 2009. A complete guide to the frogs of southern Africa (196-199). Cape Town: Struik nature.
- IUCN 2023, The IUCN Red List of Threatened Species, Version 2023-2, viewed 13 November 2024, <https://www.iucnredlist.org>.
- Minter, L.R., 2004. Atlas and red data book of the frogs of South Africa, Lesotho, and Swaziland. Avian Demography Unit, University of Cape Town.
- Passmore, N.I. and Carruthers, V., 1995. South African frogs: a complete guide. (No Title).
- Stuart, S.N., Chanson, J.S., Cox, N.A., Young, B.E., Rodrigues, A.S., Fischman, D.L. and Waller, R.W., 2004. Status and trends of amphibian declines and extinctions worldwide. Science, 306(5702), 1783-1786.
- Wager, V.A., 1986. Frogs of South Africa: Their fascinating life stories. (No Title).