Crete water frog
| Crete water frog | ||||||||||||
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Cretan water frog ( Pelophylax cretensis ) |
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| Scientific name | ||||||||||||
| Pelophylax cretensis | ||||||||||||
| ( Beerli , Hotz , Tunner , Heppich & Uzzell , 1994) |
The Crete water frog ( Pelophylax cretensis or Rana cretensis ) belongs to the family of real frogs (Ranidae) within the order of the frog auger. In addition, it is counted according to appearance, way of life and relationships to the water frogs , which are now placed by many authors in their own genus Pelophylax . The species is endemic to the Greek Mediterranean island of Crete .
features
It is a medium-sized water frog, with the males apparently remaining significantly smaller than the females. While these showed head-torso lengths of about 52 to 86 mm (arithmetic mean: 67.6) in an investigation in south-east Crete, the males there only reached sizes between 40.5 and 61 mm (mean: 53.2). Males weighed between 8 and 31 grams, females between 20 and 96 grams.
The upper side is sand-colored with an olive-green sheen or brown-gray, less often green with large brown or olive-green, irregular spots. Some animals have the beginnings of a yellowish dorsal center line, which, however, is never completely continuous. The abdomen and throat are whitish or ivory in color, occasionally with slight gray pigmentation. The inside of the thighs and the flanks are interspersed with yellow, which is particularly intense in the axillary region. The heel hump is slightly rounded, in adolescent animals it is also flat and triangular - similar to that of Central European sea frogs . The males have paired vocal sacs that can be dark gray, dark green, or almost black.
distribution and habitat
The Crete water frog occurs exclusively on the Greek island of Crete, where it predominantly inhabits the lowland regions. The highest location is at Skinias in the southeast of the island at 214 m above sea level. Most of the deposits exist in the western island area.
The species seems to primarily colonize oxygen-rich streams and rivers, but also reservoirs and artificial water basins. Young animals can also be found in small water holes and on flooded banks. Polluted waters, as they are numerous on Crete, are evidently avoided.
The animals are very shy and, if alarmed, immediately flee into the water, where they hide under stones or in the mud. The call activity of the males (the spawning season begins around February) is greatest in the late evening and night hours. This could also be related to high enemy pressure; for example, turtles such as Mauremys caspica are very numerous in many habitats .
Systematics
The Crete water frog belongs to the complex of forms of the water frogs ( Pelophylax ), which has not yet been systematically processed and is difficult to determine due to the diverse hybrid formations . Other closely related and recognized water frog species on the southern Balkan Peninsula including the Mediterranean islands are the Epirus water frog ( Pelophylax epeiroticus ) and the scutari water frog ( P. shqipericus ). The Karpathian water frog ( P. cerigensis ) is called a form with an unexplained status. Bedriaga's water frog ( Rana cf. bedriagae ) also occurs in the Near East , which, according to now dubious opinions, should also occur in Turkey, Cyprus and several Greek islands.
Danger
The Cretan water frog is classified as endangered in the IUCN's Red List of Threatened Species because it has a relatively small range of less than 500 km² and this is highly fragmented. In addition, an increasing deterioration of its habitats is noted. The main threat to this species comes from the loss of suitable habitats through agriculture, tourism and the settlement of their habitat. The water from the rivers they need is used to irrigate agricultural areas, especially for growing bananas . As a result, many rivers dry up during the summer. The introduced North American bullfrog ( Rana catesbeiana or Lithobates catebeianus ) represents an additional threat, as it competes with the smaller Cretan water frog for habitat and threatens it through predation .
supporting documents
- ↑ a b c d Jörg Plötner: The West Palearctic Water Frogs - From Martyrs of Science to Biological Sensation . Supplement to the magazine f. Feldherpetologie 9, Bielefeld 2005. ISBN 3-933066-26-3
- ↑ Pelophylax cretensis in the endangered Red List species the IUCN 2009. Posted by: Beerli, P. & Uzzell, T., of 2008.
