Chiromantis xerampelina Peters, 1854

Species Identity

Description: The grey foam-nest tree frog, scientifically known as Chiromantis xerampelina, is an arboreal species.

Limb Morphology

Like other members of the genus Chiromantis, it has adhesive discs on its toes, and the outer two fingers on each hand are widely spaced, positioned nearly at a right angle to the inner two fingers.

Size Measurements

This species has a reported snout length of 50–80 mm, with males having a snout-vent length of 43–75 mm, and females having a snout-vent length of 60–90 mm.

Skin Traits

Its skin is relatively impermeable, a trait that lets it survive dry spells sheltered under tree detritus. The skin itself is slightly bumpy and dry.

Coloration

Its coloration ranges from white to brown, and changes in response to temperature. Individuals typically turn white after death.

Habitat Types

Distribution and habitat: Grey foam-nest tree frogs live in a range of habitats including savannah, shrubland, forests, pastureland, and urban areas.

Geographic Range

In addition to their native range in southern Africa, there have been reports of populations living in Australia.

Breeding Habitat Requirements

They are classified as habitat specialists, meaning they only breed in undisturbed, unsettled environments.

Dry Habitat Adaptations

While they avoid arid conditions and require humidity to survive, they can still be found in dry environments such as dry forests, miombo woodlands, mopane woodlands, savannah, and cultivated areas at low altitudes. They can survive dry seasons sheltered under loose bark, which aligns with their classification as tree frogs.

Breeding Trigger

Large rainstorms stimulate increased breeding activity, because high humidity reduces egg mortality and improves survival across multiple life stages.

Breeding Threats

Habitat destruction and disturbance negatively impact the species' ability to breed.

Mating Period

Reproduction: Mating activity typically occurs at night between October and February, during the wet summer months of southeastern Africa.

Mating & Nest Location

These frogs mate in arboreal locations, creating foam nests on tree branches that overhang bodies of water.

Mate Choice Constraints

Female mate choice is often limited, because males force copulations. Mating primarily takes place on tree branches, which makes females easily visible to males.

Male Interception Mating

Unpaired males may also intercept females by waiting at the base of a tree; matings from these intercepting males are often with genetically undesirable males.

Polyandry Prevalence

Over 90% of females mate with ten or more males to produce a single clutch.

Foam Nest Production

To start reproduction, the female produces a thick, mucus-like fluid from her cloaca, a cavity at the end of the amphibian digestive tract. She uses her hind legs to whip this mucus into an elastic froth, which will act as physical protection for developing eggs.

Nest Construction Timeline

The female leaves temporarily to rehydrate before returning to the nest, and nest construction takes around five to six hours.

Egg Fertilization

Males then add their sperm to the newly laid foam to fertilize the eggs.

Nest Protection Layer

The next day, the female returns to the egg-laying site and adds an extra layer of foam to protect the eggs from drying out.

Foam Nest Evolution

Foam-nest building behavior has evolved multiple times independently, and the foam nest created by the female serves different purposes for aquatic versus terrestrial breeding.

Aquatic Nest Function

For grey foam-nest tree frogs that breed exclusively in water, the foam nest holds eggs suspended in oxygenated water.

Terrestrial Nest Function

For individuals that reproduce on land, the nest minimizes egg drying out, temperature swings, and predation.

Polyandry Survival Benefit

Polyandry is a well-documented characteristic of this species, and it has been shown to substantially increase offspring survival.

Seminal Fluid Nutrient Benefit

Polyandrous matings may provide eggs with additional nutrients via seminal fluid from multiple males; these nutrients increase yolk availability for post-hatching development and improve tadpole survival.

Sperm Competition Growth Benefit

Sperm competition may also increase the interaction between eggs and steroids found in seminal fluids, which can accelerate yolk metabolism and increase tadpole growth rate.

Polyandry Offspring Outcome

Offspring produced from polyandrous matings are more likely to survive than offspring from single-male matings.