Metacrinia nichollsi is a species of Australian frog, commonly named as the Forest (or Nicholls') Toadlet. It is endemic to Southwest Australia

Southwest Australia

Southwest Australia is a biodiversity hotspot that includes the Mediterranean forests, woodlands, and scrub ecoregions of Western Australia. The region has a wet-winter, dry-summer Mediterranean climate, one of five such regions in the world...

, occurring between Dunsborough

Dunsborough, Western Australia

Dunsborough is a coastal town in the South West of Western Australia, south of Perth on the shores of Geographe Bay.Dunsborough is a popular tourist destination for Western Australians; in 1999 it was voted the state's best tourist destination. During the last decade the town has grown quickly and...

 and Albany

Albany, Western Australia

Albany is a port city in the Great Southern region of Western Australia, some 418 km SE of Perth, the state capital. As of 2009, Albany's population was estimated at 33,600, making it the 6th-largest city in the state....

.

Physical description

Metacrinia nichollsi is a squat frog with short limbs and reaches 25 mm in length. The dorsal colouration is very dark brown or black occasionally with pink flecks. The ventral surface is grey, dark blue or black with white marbling. There are yellow or orange markings at the base of each arm and on the underside of the thighs and lower belly. The skin on the dorsum is warty and the belly is granular. The tympanum

Tympanum (zoology)

The tympanum is an external hearing structure in animals such as frogs, toads, insects, and mammals, to name a few.-Anurans:In frogs and toads, it is located just behind the eye. It does not actually process sound waves; it simply transmits them to the amphibian's inner ear, which is protected...

 is visible and the fingers and toes are free of webbing.

It is the only described species

Monotypic

In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 in the genus Metacrinia. The toadlet is poorly studied, but the diverse appearance of the toadlet suggests there may be more than one species.

Ecology and behaviour

This species is found amongst leaf litter, under stones and logs in Karri

Karri

Eucalyptus diversicolor, commonly known as the Karri, is a eucalypt which is native to the wetter regions of south west of Western Australia.-Description:...

 and Jarrah

Jarrah

Eucalyptus marginata is one of the most common species of Eucalyptus tree in the southwest of Western Australia. The tree and the wood are usually referred to by the Aboriginal name Jarrah...

 forests. Breeding occurs in late summer with most activity after rain. The males make a short "ark" similar to that of species in the Pseudophryne

Pseudophryne

Pseudophryne is a genus of small Myobatrachid frogs. All of these frogs are small terrestrial frogs, and as such, most species are commonly called toadlets . The genus is comrpised of thirteen species, ten from eastern Australia, and three from Western Australia...

genus. 25 - 30 eggs are laid in damp ground cover where they develop directly without a larval stage. The species was assessed as Least Concern

Least Concern

Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...

 in 2004.

Similar species

Nicholls' Toadlet may be confused with Guenther’s Toadlet (Pseudophryne guentheri). It can be distinguished by the orange ventral markings.