The stuttering frog (''Mixophyes balbus'') is a large

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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

that inhabits temperate and sub-tropical

rainforest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...

and wet

sclerophyll Sclerophyll is a type of vegetation that is adapted to long periods of dryness and heat. The plants feature hard leaf, leaves, short Internode (botany), internodes (the distance between leaves along the stem) and leaf orientation which is paral ...

forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

in Australia.

Distribution

This frog's historical distribution ranged from the Timbarra River near Drake in northern

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

, to the

Cann River The Cann River is a perennial river located in the East Gippsland region of the Australian state of Victoria. Course and features The Cann River rises southwest of Granite Mountain in remote country on the eastern boundary of the Errinundra N ...

catchment in eastern

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

and covered an area of approximately 110 000 km². Populations south of

Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...

have declined dramatically and the Victorian populations are believed to be extinct. It has also disappeared from a number of sites in NSW where it was once common. It occurs at altitudes between 20 m and 1400 m. In the north of its range the species occurs only at high altitudes while in the south both upland and lowland populations have been recorded.

Description

This frog can reach up to 80 mm in length. Its dorsal surface is

brown Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing or painting, brown is usually made by combining the colors orange and black. In the RGB color model used ...

and diffuses laterally to merge with a pale

yellow Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the R ...

on the ventral surface. An irregular shaped blotch starts between the eyes and finishes mid-dorsal and may be broken up. There is a dark head stripe that starts before the nostril as a triangle, it then continues from the

nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

to the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

, then from the eye over the tympanum and finishes over the shoulder. The tympanum is slightly oval shaped and distinct. The

iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants *Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional enti ...

is light

blue Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when obs ...

, diffusing into

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...

above the

pupil The pupil is a black hole located in the center of the iris of the eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company. It appears black ...

and dark brown below. The 4-6 bars on the hind limbs are pale and indistinct. Toes are three quarters webbed and fingers are free from webbing.

Ecology and behaviour

This species is associated with flowing creeks and streams in temperate and sub-tropical rainforest, wet sclerophyll forest and

Antarctic Beech Antarctic beech is a common name of two species in the genus ''Nothofagus'': *''Nothofagus antarctica'', native to South America *''Nothofagus moorei ''Nothofagus moorei'', commonly known as Antarctic beech, is an important Gondwana relict of t ...

forests. The call is a "kook kook kook kra-a-ak kruk kruk" - lasting one to two seconds. The male calls while next to the stream, often on leaf litter, and spawn is deposited in dug-out, gravel nests in shallow, flowing water. Tadpoles usually reach 65 mm but may be up to 80 mm in length. Tadpoles are dark brown or black with large spots and flecks on the

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, r ...

. Metamorphosis may take 15 months and the metamorphs closely resemble the adults, but have less distinct dorsal pattern and a rusty red iris.

Similar species

This frog can be distinguished from all other '' Mixophyes'' species by the blue crescent in the upper iris, except for ''

Mixophyes fleayi Fleay's barred frog (''Mixophyes fleayi'') is a large species of frog restricted to small pockets of rainforest in northern New South Wales and south-eastern Queensland, Australia. Distribution This species has a fragmented distribution in wet f ...

''. It can be distinguished from ''Mixophyes fleayi'' by the lack of mottling on the flanks.

References

*Anstis, M. 2002. ''Tadpoles of South-eastern Australia''. Reed New Holland: Sydney. *Barker, J.; Grigg, G.C.; Tyler, M.J. (1995). ''A Field Guide to Australian Frogs''. Surrey Beatty & Sons.
Department of Environment and Heritage - Stuttering FrogFrogs Australia Network - Frog call available here
{{Taxonbar, from=Q2274761 Amphibians of New South Wales Amphibians of Victoria (Australia) Mixophyes Vulnerable fauna of Australia Amphibians described in 1968 Frogs of Australia