Australian forest frog

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Australian forest frog
Systematics
without rank: Amphibians (Lissamphibia)
Order : Frog (anura)
Subordination : Neobatrachia
Family : Real frogs (Ranidae)
Genre : Real frogs ( Rana )
Type : Australian forest frog
Scientific name
Rana daemeli
( Steindachner , 1868)

The Australian forest frog ( Rana daemeli , Syn .: Papurana daemeli , Hylarana daemeli ) is a species of amphibian from the genus of real frogs found in New Guinea and in northeastern Australia . It is the only representative of the world's very species-rich family of real frogs (Ranidae) on the Australian continent. Among other things, it is similar to the European brown frogs .

features

Australian forest frogs are small to medium-sized, elongated frogs with a rather inconspicuous color and smooth to flat black skin. The males reach head-trunk lengths of 43 to 58 millimeters, the females are 58 to 81 millimeters - there is therefore a clear sexual dimorphism . The top is colored pale, olive or chocolate brown and marked with irregular dark spots and dots. On both sides of the head, which is elongated and triangular when viewed from above, a dark line runs from the tip of the snout to the eyes and widens behind them to form a dark field within which the outer eardrum is also located. This drawing element merges with the back color at the level of the front legs. Above the dark band there is a fold of skin that extends from the eyes to the groin area. A white stripe runs below the eyes to the base of the arms. The underside is colored whitish and dotted brown; Forearms and hind legs have dark transverse ligaments. There are no webs between the fingers, but there are well defined webs between the toes. The males have paired, lateral vocal sacs .

The species can be confused with some bottom-dwelling, also pointed-nosed representatives of the Australian tree frogs ( Litoria spec.), For example with Litoria nasuta . These also have elongated skin folds (glandular ridges).

distribution

Rana daemeli inhabits large parts of the island of New Guinea (both in the Indonesian western part and in Papua New Guinea ), the neighboring island to the east of New Britain and the northeast of Australia. There the Cape York Peninsula belonging to Queensland is settled (to the southeast to about the city of Townsville ) and on the other side of the Carpentariagolfes a disjoint area in the northeast of Arnhem Land in the northern territory .

Habitat, way of life

The species lives terrestrial and semi- aquatic on the ground in dense vegetation of tropical rainforests , other forest forms, swamps , moors and cultivated landscapes including human settlements. Rivers are usually in the immediate vicinity. In New Guinea, lakes, swamps and rivers are also settled in savannah grasslands . During the day, the animals hide mainly under fallen leaves and dead wood in order to hunt invertebrates and smaller frogs at night. They like to sit in exposed places above water bodies. If they are disturbed there, they jump into the water and dive.

Reproduction, individual development

The spawning season is extended in the spring and summer months. Then calm water points such as ponds, swamp pools and retention basins are sought out. The males' mating calls are not particularly loud despite the double sound bubbles. The calls are described as a series of seven to eight sounds such as "qaaak-qak-qak". As with all "modern frogs" ( Neobatrachia ), attracted females are clasped from the back in the armpit area (compare Amplexus ). Later on, the pair lays externally fertilized, shapeless spawn , which floats in large quantities on the surface of the water. The black-and-gold tadpoles soon hatch from the eggs, which are surrounded by a gelatinous layer, of which each female produces over 1,000 pieces , which means that they develop indirectly in the open water. Shortly before their metamorphosis into land animals, they measure around six centimeters in length including the long tail. They are characterized by an edged mouth disk with elongated protuberances (papillae) on the posterior edge. They prefer to stay in deeper water between algae and aquatic plants.

Existence, endangerment

The Australian forest frog is still a fairly common, adaptable species with a stable range. This frog is one of the most common amphibian species in New Guinea. For Australia, the pollution or destruction of habitats by humans is given as the main risk factor and a slightly declining population trend is assumed. The total population of the species is in the red list of the IUCN classified but with "LC" (= least concern safely).

Sources and further information

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