''Paedophryne swiftorum'' is a species of

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

from

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

discovered in 2008 and formally described in January 2012. It lives among leaf litter on the

tropical rainforest Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...

floor and was named after the Swift family who had provided funds for establishing the Kamiali Biological Station where the new species was found.

Discovery

''Paedophryne swiftorum'' was first discovered by a student on a 2008

Cornell University Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...

expedition to Papua New Guinea. The male frog makes a series of double clicks which the investigators had previously heard but had thought to be made by

cricket Cricket is a Bat-and-ball games, bat-and-ball game played between two Sports team, teams of eleven players on a cricket field, field, at the centre of which is a cricket pitch, pitch with a wicket at each end, each comprising two Bail (cr ...

s. Hearing this sound at close quarters while examining a

millipede Millipedes (originating from the Latin , "thousand", and , "foot") are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derive ...

in the

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...

, Michael Gründler turned his head and saw a minute frog rhythmically inflating its

vocal sac The vocal sac is the flexible Biological membrane, membrane of skin possessed by most male frogs and toads. The purpose of the vocal sac is usually as an amplification of their mating or advertisement call. The presence or development of the voca ...

. Measuring just , it might have been thought not to be fully grown except for the fact that calling is normally only done by mature male frogs as an advertisement to attract females. ''Paedophryne swiftorum'' is one of the smallest

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s in the world but the following year, an even smaller species was discovered. The closely related ''

Paedophryne amauensis ''Paedophryne amauensis'', also known as the New Guinea Amau frog, is a species of microhylid frog endemic to eastern Papua New Guinea. At in snout-to-vent length, it was once considered the world's smallest known vertebrate. (See also Ecolo ...

'', measuring just , was discovered in the same vicinity on the forest floor. These frogs are very difficult to spot because they are so well camouflaged and are hidden among the dead leaves. However, their presence is detectable by the shrill insect-like calls they emit. ''Paedophryne swiftorum'' is also among the smallest frog in the Southern Hemisphere, and ''Paedophryne swiftorum'' body length () is also smaller than ''Brachycephalus didactylus'' body length , but ''Paedophryne swiftorum'' is not listed in the Smallest organisms list, is not included in the smallest vertebrates known with other nine species of frogs.

Description

The average length of ''Paedophryne swiftorum'' is . The back is dark brown irregularly marked with pale or rusty brown mottling, sometimes with a tan dorsal stripe. The underside is dark brown with a paler belly. The head is short and broad with a blunt snout and large eyes. The legs are fairly long, the fingers and toes unwebbed and the first digits of hands and feet truncated. Some of the other digits are also reduced in size. The call consists of a series of four, six or eight double notes and is made at dawn and dusk but also during the day in wet weather.

Habitat

Similar to all species of ''

Paedophryne ''Paedophryne'' (from the Ancient Greek language, Ancient Greek ''paedos'' (παίδος) "child" and ''phryne'' (φρύνος) "toad, frog") is a genus of Microhylidae, microhylid frogs from Papua New Guinea, including D'Entrecasteaux Islands. ...

'' so far described, ''Paedophryne swiftorum'' lives in the leaf litter on the floors of tropical forests where it is well camouflaged by its mottled brown colouring. It seems to be a fairly common species judging by the fact that calling males occur at separations of approximately . It feeds on tiny invertebrates such as

mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...

s and

springtail Springtails (class Collembola) form the largest of the three lineages of modern Hexapoda, hexapods that are no longer considered insects. Although the three lineages are sometimes grouped together in a class called Entognatha because they have in ...

s and is likely to be preyed on by birds, small mammals and even large invertebrates. Reproduction is likely to be by direct development without an aquatic

tadpole A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...

stage.

References

{{Taxonbar, from=Q2169503 Amphibians of Papua New Guinea Amphibians described in 2012 Microhylidae