Paedophryne amauensis

Paedophryne amauensis, on a dime ( coin of 17.91 millimeters in diameter )

Paedophryne amauensis is a frog of the family -mouthed. He was discovered in August 2009 in Papua New Guinea, but first described only in January 2012. With a head-body length of 7-8 millimeters, it is the smallest described so far only viable vertebrate in the world.

Description

Size classification

The small size of the frog Paedophryne amauensis with a length of 7-8 millimeters has triggered discussions about where the limits in the ratio of volume to surface area could be for a country living vertebrate, so still a regulated metabolism can be maintained. In particular, the release of water through the skin could thereby be a limiting factor. For aquatic life, the outer surface plays a less important role. The fish Paedocypris progenetica whose females have a length of from 7.9 millimeter, was thought to be the world's smallest free- living vertebrate, but is replaced by amauensis Paedophryne. The males of the deep-sea angler fish Photocorynus spiniceps, which was already described in 1925 by Regan, indeed reach a length of only 6.2 millimeters, these dwarf males but were not viable, but parasitize at the much larger, 46 -millimeter-long females.

Features

The dorsal coloration of Paedophryne amauensis is dark brown with irregular rust-brown spots. The flanks and belly are dark mottled brown to slate gray and bluish white. The first finger and toe members are reduced to a single one. Before the sacrum are only seven vertebrae, unlike most other members of the subfamily of Papua mouthed. The second and fourth fingers, and the second and fifth toes are also reduced. The mouth is relatively broad and short, the eyes are relatively large.

Similar Species

This frog species differs from related species of the genus Paedophryne that are also present in Papua New Guinea, mainly due to their smaller size ( 7-8 mm ) and longer legs. In December 2011, the two species were Paedophryne dekot and described Paedophryne verrucosa by Fred Kraus from the Bishop Museum in Hawaii. A snout-vent length ( SVL) was dekot In Paedophryne measured from 8.5-9.0 mm in females, males have not yet been discovered. The females of Paedophryne verrucosa reach a length of 8.8 to 9.3 millimeters, the males of 8.1 to 8.9 millimeters. Fred Kraus in 2010 described the first two Paedophryne species. They are slightly longer than an inch. In Paedophryne kathismaphlox the females reach 10.4 to 10.9 mm in length, the males by 10.1 millimeters. Paedophryne oyatabu is still larger, the females of this species reach 11.3 millimeters. The also in the work of Ritt Meyer et al. 2012 newly described species Paedophryne swiftorum is 8.3 to 8.9 millimeters long.

Dissemination

The occurrence of Paedophryne amauensis is restricted to Papua New Guinea. The specific epithet refers to the amauensis located near the first reference Amau village in the Central Province of Papua New Guinea.

Way of life

The habitat of this species is not dependent on the presence of bodies of water. She lives on the ground in leaf litter. There is no tadpole stage, the young frogs hatch fully developed from the egg. It is assumed that the clutch of this type consists of only one or two eggs. How many eggs are laid in the year, has not yet been studied. In any case, a small number of eggs per clutch only a slow increase in the population result. If it comes to cuts in the population dynamics, these are only slowly rebalance.

Paedophryne amauensis is crepuscular. The calls of the males will only sound in the morning or at dusk. The Rufhöhe is 8400-9400 Hz and is similar to the stridulation of insects.

The small size of these animals raises not only anatomical but also physiological problems. Paedophryne amauensis has in relation to its volume a very large skin surface. Therefore, dehydration is one of the biggest threats to this terrestrial vertebrate. However, life in the damp leaves on the floor of tropical rainforest provides this frogs an ecological niche to which they are well adapted. Due to their small size and adapted to the withered foliage camouflage they are difficult to be perceived by predators and also from researchers. 2009, they were therefore discovered by Christopher Austin and Eric Meyer ride from Louisiana State University only because of their acoustic signals.