Barbour frogs

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Barbour frogs
Philippines barbour frog (Barbourula busuangensis)

Philippines barbour frog ( Barbourula busuangensis )

Systematics
Row : Land vertebrates (Tetrapoda)
without rank: Amphibians (Lissamphibia)
Order : Frog (anura)
Superfamily : Disc tongue i. w. S. (Discoglossoidea)
Family : Toads and barbour frogs (Bombinatoridae)
Genre : Barbour frogs
Scientific name
Barbourula
Taylor & Noble , 1924

The barbourula ( Barbourula ) form an occurring on Southeast Asian islands and consisting of only two species of the genus amphibians , the phylogenetically "lower" to the primitive anurans ( Archaeobatrachia ) is counted. They are largely aquatic , inconspicuous frogs, about whose biology and ecology very little is known because of their rarity and their hidden way of life. Fossil finds are not known. The genus is named after the American herpetologist Thomas Barbour (1884-1946).

Features and way of life

Barbour frogs are inconspicuously dark (brownish) in color and have a flattened body, a rounded snout and a fine black skin. The eardrums are not externally visible. The eyes with round to inverted teardrop-shaped pupils are directed obliquely forward. The Philippines barbour frog is described as quite strong and plump built. So far, only about eleven individuals have been found of the Borneo Barbour frog, with males having a maximum length of 66 millimeters and females up to 77.7 millimeters in length. The animals not only have pronounced webbed feet between the toes of the hind feet, but also between the fingers, which indicates their highly aquatic way of life (compare also: dwarf clawed frogs ). They inhabit fast-flowing, oxygen-rich streams as well as rivers up to 50 meters wide within tropical rainforests ; in the event of danger, they dive quickly and hide under stones on the bottom at a depth of around 50 centimeters to 5 meters. This location also plays an important role in laying eggs.

The males have neither oestrus calluses nor vocal sacs . They are supposed to produce the mating calls by inhaling air. However, at least the Borneo Barbour frog apparently has no lungs, but - similar to the lungless salamander - only absorbs oxygen through the skin. Only a scientific expedition came to this conclusion in August 2007, during which nine specimens of the species were caught. The lack of lungs is interpreted as a further adaptation to the living space: This creates less buoyancy, which makes diving easier or prevents drifting in strong currents. The North American tail frogs , for example, have a very similar way of life . The lungs of the giant Titicaca frog are at least greatly reduced. The complete regression of the lungs seems to be a unique feature of the Borneo Barbour frog among the frogs.

Little is known about reproductive biology. It is known that Barbour frogs attach larger, pigmentless eggs to the bedrock of running waters, but their tadpoles are not yet known. According to some authors, this fact and the nature of the eggs could even point to a direct development, i.e. omitting the tadpole stage in free water.

Information about the Borneo Barbour frog, which was only detected and described in 1978, is particularly rare. After a second find published in 1995, further specimens were not caught until 2007.

distribution

Barbourula busuangensis lives on several islands in the Philippines , as far as known so far on Busuanga , Culion and Palawan . This group of islands is located to the north of the island of Borneo , where the second species occurs. Barbourula kalimantanensis has so far only been observed in an area of ​​less than 500  km² in West Kalimantan (Borneo, Indonesia ). There, among other things, two separate sites (a total of five locations) in the middle Kapuas river valley and in the Melawi river valley have been described.

Systematics

According to anatomical features, the barbour frogs mediate between the genera of the real disc beak ( Discoglossus ) and the toad ( Bombina ), but are related to the latter. The exact family association is mixed: While some older literature, the barbourula - as well as the toads - or the Scheibenzünglern counts (Discoglossidae), these two species are now often considered separate family Bombinatoridae treated. In 1993, the herpetologists Ford and Cannatella taxonomically split this off from the rest of the discoglossoms of the genera Alytes and Discoglossus , after one of these authors had postulated the discoglossids in the broader sense (including Bombina and Barbourula ) as paraphyletic since 1985 .

The genus Barbourula consists of the following two species :

Danger

Both barbour frogs are threatened in their population due to their limited distribution areas, their apparently small populations and due to diverse habitat destruction by humans. The rivers are polluted and poisoned by illegal mining mines (for example mercury flooding from gold panning ) and other industries as well as fertilizers and pesticides from agriculture. In addition, the rainforests of Southeast Asia are being decimated more and more through deforestation ( overexploitation of tropical timber , land reclamation). The IUCN classifies Barbourula busuangensis as "endangered" ( vulnerable ) and Barbourula kalimantanensis as ( "high risk" endangered ) a.

Sources and further information

Individual evidence

  1. ↑ Jan Osterkamp: snapping pore air. In: spectrum direct. April 8, 2008 (paid content)
  2. ↑ The standard: a matter of opinion
  3. ^ Bickford D., Iskandar, D., Barlian, A .: A lungless frog discovered on Borneo. Current Biology 18 (2008): 374-375. doi = 10.1016 / j.cub.2008.03.010
  4. ↑ Distribution map of the Philippines barbour frog on iucnredlist.org (Engl.)
  5. ↑ Distribution map of the Borneo Barbour frog on iucnredlist.org (Engl.)
  6. ↑ Tree of Life: Bombinatoridae (Engl.)
  7. ↑ Barbourula busuangensis in the endangered Red List species the IUCN 2009. Posted by: Arvin Diesmos u. a., 2004. Retrieved November 6, 2009.
  8. ↑ Barbourula kalimantanensis in the Red List of Threatened Species of the IUCN 2009. Posted by: Robert Ingersoll u. a., 2004. Retrieved November 6, 2009.

Web links

Commons : Barbourula  - collection of images, videos and audio files