Balkan Edible Frog

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Balkan Edible Frog
Balkan Edible Frog (Pelophylax kurtmuelleri)

Balkan Edible Frog ( Pelophylax kurtmuelleri )

Systematics
without rank: Amphibians (Lissamphibia)
Order : Frog (anura)
Subordination : Neobatrachia
Family : Real frogs (Ranidae)
Genre : Water frogs ( pelophylax )
Type : Balkan Edible Frog
Scientific name
Pelophylax kurtmuelleri
( Gayda , 1940)

The Balkan Pool Frog ( Pelophylax kurtmuelleri , Synonym : Rana kurtmuelleri , Rana balcanica ) is within the order of Anura the family Real frogs (Ranidae), where it meets the water frogs is assigned. The species is distributed over large parts of Greece as well as in Albania and the south of Serbia .

features

The Balkan water frog has a body length of around 75 to 100 millimeters, with the males reaching a maximum size of around 80 millimeters and the females a maximum of 100 millimeters. These are comparatively large water frogs from the family group of sea ​​frogs with a pronounced sexual dimorphism .

The back color is mostly green, but can also be partially or completely brown in individual individuals. The back side usually has a light green stripe that stretches across the middle of the back and has irregularly distributed dark green, brown, gray or blackish spots. The ventral side is light and mostly unstained. The eyes are relatively close together, the eardrums are bronze or gray with a green central area. The males have paired light or dark gray sound bladders at the corners of the mouth.

The Balkan water frog can be distinguished from the sea ​​frog ( Pelophylax ridibundus ) mainly by the mating calls of the males. These are shorter than those of the sea frog and usually consist of only 3 to 5 clearly audible pulse groups, while those of the sea frog are longer and consist of 7 pulse groups. From the partially in western Greece sympatrically occurring Epirus Water Frog ( pelophylax epeiroticus ) the Balkan water frog and marsh distinguished by its distinctive mating call, which is composed of individual pulses and not from pulse groups. Furthermore, the Epirus water frog is characterized by light-green to yellowish flank coloration and by yellow-orange coloration of the webbed feet , features that the Balkan water frog and the sea frog lack.

distribution

Distribution area of ​​the Balkan water frog

The species occurs in large parts of Greece , Albania and southern Serbia, as well as on various Greek islands such as Zakynthos and Kythira . In addition, the species was introduced to the province of Imperia in Liguria , northern Italy , around 1941 , where it was able to establish itself and spread further. In the Aspromonte National Park on the southern tip of the Italian mainland, the Balkan frog , Pelophylax kurtmuelleri , was found in eight bodies of water, in three of them it alone, in five syntopically with Pelophylax bergeri . The waters have different altitudes, the highest is at 1350 meters above sea level. The Balkan frogs come from southwest Greece and were imported by workers in the early 1980s as part of a construction project to use them as a source of food. There were other colonies as neozoa in France , Denmark , Switzerland and in southern Germany.

The height distribution of the species ranges from sea level to a maximum of about 1000 meters.

Way of life

Balkan Edible Frog
Balkan Edible Frog in its typical habitat

The way of life of the Balkan water frog largely corresponds to the other species of the genus, above all the sea ​​frog ( Pelophylax ridibundus ). It is a largely aquatic type of permanent wetland and it lives in slow-flowing waters, ponds and permanent ponds, among other things. It can also be found in the surrounding moist terrestrial habitats. It is relatively adaptable and able to live in areas with organic pollution as well as in anthropogenic and disturbed waters. The species is largely diurnal, but is also seen or heard at night. Like other frogs, the Balkan water frog also feeds unspecifically on insects, spiders, woodlice and snails , the composition of which depends heavily on the respective habitat and the availability of food.

The males begin calling in February. Reproduction is seasonal and mating occurs in shallow, permanent waters from March. The tadpoles reach a length of up to 10 centimeters and only leave the water after the complete metamorphosis .

Call behavior

The recordings of the mating calls of Pelophylax kurtmuelleri were made from March 24 to April 1, 1982 on small bodies of water in the valley of the Gallikos River, about 25 kilometers northwest of Thessaloniki. The water frogs of these locations were then considered sea frogs, Rana ridibunda, as in all of Greece.

When observations began, the water frogs were at the end of the pre-spawning period, followed by the spawning period during which the frogs mated. The females each laid several egg packages on the water surface between plants.

Mating call

Sound image (oscillogram) of a mating call with four pulse groups, recorded on tape at 20.3 ° Celsius in the valley of Gallikos near Thessaloniki.

During the observation period, mating calls between 14.5 and 21.5 ° Celsius water temperature were recorded on tape and subsequently analyzed.

Mating calls of the males are specific. The number of impulse groups that make up the pairing calls (figure) is low, with an average of 4.05 ± 0.64 impulse groups per call. This call characteristic remains unaffected by the water temperature. The pulse groups consist of an average of 25.72 pulses, the repetition rate of which is high, which is why only the highest deflections of the pulses can usually be seen on the sound images. The frequency spectrum of the pairing calls has two components, a low frequency at 400 to 500 Hertz and a high frequency at 1.5 to 2.3 kilohertz.

Several call characteristics are negatively correlated with water temperature. If the water temperature rises, the values ​​decrease. These changes obey linear equations. For a water temperature of 20 ° Celsius, which often occurs during the spawning season, the following values ​​result from the equations: The calls have a duration of 551.53 milliseconds, the intervals between the mating calls measure 1277 milliseconds. The pulse groups that set up a pairing call last 77.73 milliseconds, the intervals between them 68.65 milliseconds. Another important call characteristic is the number of pulse groups per second, which increases as the water temperature rises. At 20 ° Celsius the value is 7.74 pulse groups per second.

Systematics

The Balkan water frog was scientifically described in 1940 by the herpetologist Henrik Gayda under the name Rana kurtmuelleri , but later regarded as a synonym for the sea ​​frog ( Pelophylax ridibundus , then Rana ridibunda ). In 1993, a working group led by the Bonn zoologist Hans Schneider described a new species of water frogs from northern Greece under the name Rana balcanica , which was later synonymous with Rana kurtmuelleri . The species is recognized.

The mating call of the water frogs in northern Greece turned out to be identical to the mating call of the water frogs in the former South Yugoslavia, but compared to the mating call of the water frogs in Israel the difference was large. The attached figure shows that for the duration of the pulse groups call feature. This difference, which is present in all the analyzed reputation characteristics, led to the proposal to give the water frog in Israel the status of a subspecies of Rana ridibunda. At the same time, the question arose which of these two water frogs represents Rana ridibunda , the eastern one in Israel or the western one in northern Greece. To answer them, a mating call analysis was carried out among the sea frogs in Atyrau, formerly Guryev, at the northern end of the Caspian Sea, Kazakhstan, the type locality of Rana ridibunda .

Sound images (oscillograms) of mating calls in water frogs. Above: sea frog, Pelophylax ridibundus , middle: Balkan water frog, Pelophylax kurtmuelleri , below: Levant water frog, Pelophylax bedriagae .

The mathematical processing of nine characteristics of the mating calls of the three groups each provided a clear, at the same time surprising result, because neither the mating call of the eastern nor the western form corresponds to the mating call of the typical Rana ridibunda . The large, computationally proven differences in the mating calls led to the conclusion that both the eastern and western forms have the status of a species. The eastern one was called Rana levantina , the western Rana balcanica , which have since been renamed Pelophylax bedriagae and Pelophylax kurtmuelleri due to priority .

In the mathematical processing of the call data, data from call analyzes of the water frogs at other locations in Greece and other countries were also included. Sea frogs, Pelophylax ridibundus , occur in Armenia, also in Thrace including the island of Samothraki, Greece, and near Nessebar, Bulgaria. The mating call of Pelophylax ridibundus consists of an average of seven impulse groups / call, these of an average of 19 impulses. The eastern Levant water frog, Pelophylax bedriagae , is native to Israel, Egypt, southwestern Turkey, and Syria, according to recent results. The mating call of Pelophylax bedriagae consists on average of 10 impulse groups / call, the impulse groups are made up of an average of 11 impulses. The western Balkan water frog, Pelophylax kurtmuelleri , inhabits mainland Greece with the Peloponnese but excluding Thrace, the southern part of the former Yugoslavia (North Macedonia), Albania and has been found on Lake Skadar, Montenegro, and on Vransko Jezero, Croatia. The mating call of Pelophylax kurtmuelleri consists on average of four impulse groups / call with an average of 29 impulses / impulse group. In addition, these investigations revealed that Pelophylax ridibundus and Pelophylax kurtmuelleri are sister species, as are Pelophylax bedriagae and Pelophylax perezi .

Pelophylax kurtmuelleri and Pelophylax ridibundus in Thraks do not differ in size and color, but in six standardized indices, for example body length / length of the 1st finger or body length / length of the heel hump.

Based on information in the literature and his own observations, Günther (1990) writes that the countries of the Balkans and all countries of the Middle East including Egypt belong to the range of the sea frog, at that time Rana ridibunda . Due to the establishment of the two species Pelophylax kurtmuelleri and Pelophylax bedriagae as well as Pelophylax epeiroticus , the distribution area of Pelophylax ridibundus experiences a considerable change.

Danger

The Balkan Edible Frog is classified as Least Concern in the IUCN Red List of Threatened Species because it has a relatively large range, greater adaptability to habitat changes and a relatively large total population is assumed. Within the distribution areas, it can generally be found frequently in the area of ​​suitable freshwater habitats.

In its native range, the species is threatened by the drainage of wetland habitats and the pollution of many waterways by agrochemical and industrial pollution, partly from mining. In the northern parts of its native range, such as Lake Skadar , it is seriously threatened by excessive collection for commercial purposes. In addition, the species is partially displaced by the accidental introduction of commercially transported and non-native water frogs. The species is not listed in the appendices of the Washington Convention on the Protection of Species (CITES).

supporting documents

  1. ↑ Balkan water frog ( Pelophylax kurtmuelleri ) on amphibiaweb.org; accessed on April 2, 2020.
  2. ↑ a b c d e f g h i Dieter Glandt: The amphibians and reptiles of Europe. All species in portrait. Quelle & Meyer 2015; Pp. 228-229. ISBN 978-3-494-01581-1 .
  3. ↑ a b c d e f g h Pelophylax kurtmuelleri in the Red List of Threatened Species of the IUCN 2020. Posted by: Thomas Uzzell, Franco Andreone, Petros Lymberakis, Milan Vogrin, Idriz Haxhiu, Jelka Crnobrnja Isailovic, Roberto Sindaco, Antonio Romano, 2008 Retrieved April 2, 2020.
  4. ↑ Roberta Bisconti, Giuseppe Martino, Andrea Chiocchio, Antonino Siclari, Daniele Canestrelli: Balkan marsh frogs (Pelophylax kurtmuelleri (Gayda, 1940) introduced in the Aspromonte National Park, southern Italy. In: BioInvasions Records. Volume 8 (1), 2019, Pp. 26-33.
  5. ↑ Panayiota Plitsi, Mando Koumaki, Vassiliki Bei, Panayiotis Pafilis, Rosa Maria Polymeni: Feeding ecology of the Balkan Water frog (Pelophylax kurtmuelleri) in Greece with emphasis on habitat effect. North-Western Journal of Zoology 12 (2), 2016; Pp. 292-298. Full text .
  6. ^ A b Robert Mertens, Heinz Wermuth: The amphibians and reptiles of Europe. Waldemar Kramer Verlag, Frankfurt am Main, 1960. 264 pp.
  7. ↑ a b c d Hans Schneider, Theodora S. Sofianidou: The mating call of Rana ridibunda (Amphibia, Anura) in northern Greece as compared with those of Yugoslavian and Israeli populations: proposal of a new subspecies. In: Zoologischer Anzeiger. Volume 214, 1985, pp. 309-319.
  8. ^ Hans Schneider, U. Sinsch, Theodora S. Sofianidou: The water frogs in Greece: evidence for a new species. Journal of Zoological Systematics and Evolutionary Research 31 (1), 1993: pp. 47-63. doi : 10.1111 / j.1439-0469.1993.tb00178.x .
  9. ↑ Frost, Darrel R. 2020. Amphibian Species of the World: an Online Reference. Version 6.0 (05-08-2020). Electronic Database accessible at http://research.amnh.org/herpetology/amphibia/index.html . American Museum of Natural History, New York, USA. doi.org/10.5531/db.vz.0001
  10. ↑ Birgit Kuhn, Hans Schneider: Mating and territorial calls of the frog Rana ridibunda and their temperature-dependent variability. In: Zoologischer Anzeiger. Volume 212, 1984, pp. 273-305.
  11. ↑ Eviatar Nevo, Hans Schneider: Structure and variation of Rana ridibunda mating call in Israel (Amphibia: Anura). In: Israel Journal of Zoology. Volume 32, 1983, pp. 45-60.
  12. ↑ Hans Schneider, Eduard Murasovitch Egiasarjan: The structure of the calls of lake frogs (Rana ridibunda: Amphibia) in the terra typica restricta. In: Zoologischer Anzeiger . Volume 227, 1991, pp. 121-135.
  13. ↑ a b c Hans Schneider, Ulrich Sinsch: Mating call variation in populations of Rana ridibunda (Anura: Ranidae): Statistical evaluations and taxonomic implications. In: Journal for Zoological Systematics and Evolutionary Research. Volume 30, 1992, pp. 297-315.
  14. ^ Hans Schneider, Ulrich Sinsch, Eviatar Nevo: The lake frogs in Israel represent a new species. In: Zoologischer Anzeiger. Volume 229, 1992, pp. 97-106.
  15. ^ A b Hans Schneider, Ulrich Sinsch, Theodora S. Sofianidou: The water frogs in Greece: evidence for a new species. In: Journal for Zoological Systematics and Evolutionary Research. Volume 31, 1993, pp. 47-63.
  16. ↑ a b Gerhard Joermann, Ibrahim Baran, Hans Schneider: The mating call of Rana ridibunda (Amphibia: Anura) in western Turkey: Bioacoustic analysis and taxonomic consequences. In: Zoologischer Anzeiger. Volume 220, 1988, pp. 225-232.
  17. ↑ a b Mamdouh Saad Ahmed Akef, Hans Schneider: The eastern form of Rana ridibunda (Anura: Ranidae) inhabits the Nile delta. In: Zoologischer Anzeiger. Volume 223, 1989, pp. 129-138.
  18. ↑ Hans Schneider, Eduard Murasovitch Egiasarjan: Bioacoustic investigations of lake frogs (Ranidae: R. ridibunda) in Armenia as a contribution to the study of distribution of the eastern form. In: Biological Journal of Armenia. Volume 42, 1989, pp. 926-935. Russian.
  19. ^ Hans Schneider, unpublished
  20. ↑ Eviatar Nevo, Hans Schneider (1983): Structure and variation of Rana ridibunda mating call in Israel (Amphibia: Anura). In: Israel Journal of Zoology. Volume 32, 1083, pp. 45-60.
  21. ^ Hans Schneider: Calls and reproductive behavior of the water frogs of Damascus, Syria (Amphibia: Anura: Rana bedriagae Camerano, 1882). In: Zoology in the Middle East. Volume 15, 1997, pp. 51-66.
  22. ↑ Hans Schneider, Idriz Haxhiu: mating call analysis and taxonomy of water frogs (Ranidae, Anura) in Albania. In: Zoological Yearbooks, Systematics. Volume 121, 1993, pp. 248-262.
  23. ↑ Hans Schneider, Gerhard. Joermann: Mating calls of water frogs (Ranidae) of Lake Skutari, Yugoslavia, and relationship to water frogs in Greece. In: Journal for Zoological Systematics and Evolutionary Research. Volume 26, 1988, pp. 261-27.
  24. ↑ Hans Schneider: Bioacoustic evidence of frogs in western Hungary, Slovenia and Croatia. In: Journal of Field Herpetology. Volume 14, 2007, pp. 63-76.
  25. ^ Rainer Günther: The water frogs of Europe. The New Brehm Library. Volume 600. A. Ziemsen Verlag, Wittenberg (Lutherstadt) 1990, ISBN 3-7403-0234-8 .
  26. ↑ Hans Schneider, Theodora S. Sofianidou, Pasqualina Kyriakopoulou-Sklavounou: Bioacoustic and morphometric studies of water frogs (genus Rana) of Lake Ioannina in Greece, and description of a new species (Anura, Amphibia). In: Journal for Zoological Systematics and Evolutionary Research. Volume 22, 1984, pp. 349-366

literature

  • Dieter Glandt: The amphibians and reptiles of Europe. All species in portrait. Quelle & Meyer 2015; Pp. 228-229. ISBN 978-3-494-01581-1 .
  • Eviatar Nevo, Hans Schneider: Structure and variation of Rana ridibunda mating call in Israel (Amphibia: Anura). In: Israel Journal of Zoology. Volume 32, 1983, pp. 45-60.
  • Hans Schneider, Theodora S. Sofianidou: The mating call of Rana ridibunda (Amphibia, Anura) in northern Greece as compared with those of Yugoslavian and Israeli populations: proposal of a new subspecies. In: Zoologischer Anzeiger. Volume 214, 1985, pp. 309-319.
  • Hans Schneider, Eduard Murasovitch Egiasarjan: The structure of the calls of lake frogs (Rana ridibunda: Amphibia) in the terra typica restricta. In: Zoologischer Anzeiger. Volume 227, 1991, pp. 121-135.
  • Hans Schneider, Ulrich Sinsch: Mating call variation in populations of Rana ridibunda (Anura: Ranidae): Statistical evaluations and taxonomic implications. In: Journal for Zoological Systematics and Evolutionary Research. Volume 30, 1992, pp. 297-315.
  • Hans Schneider, Ulrich Sinsch, Theodora S. Sofianidou: The water frogs in Greece: evidence for a new species. In: Journal for Zoological Systematics and Evolutionary Research. Volume 31 1993, pp. 47-63.
  • Theodora S. Sofianidou, Hans Schneider, Ulrich Sinsch: Comparative electrophoretic investigation on Rana balcanica and Rana ridibunda from northern Greece. In: Alytes. Volume 12, 1994, pp. 93-108.
  • Hans Schneider: Bioacoustic studies in European anurans. In: P. Lymberakis, E. Valakos, P. Pafilis and M. Mylonas (eds.). Herpetologia Candiana. Societas Europaea Herpetologica, Irakleio, 2001, pp. 21-32.
  • Hans Schneider: Bioacoustics of the Froschlurche - native and related species. With audio CD. Supplement to the Zeitschrift für Feldherpetologie 6. Laurenti Verlag, Bielefeld 2005. ISBN 3-933066-23-9 . Audio samples 72–74.
  • Hans Schneider, Ulrich Sinsch: Contributions of bioacoustics to the taxonomy of the Anura. In: Harold Heatwole and Michael J. Tyler (Eds.): Amphibian Biology, Systematics. Volume 7, 2007, pp. 2893-2932. Chipping Norton NSW, Australia, (Surrey Beatty & Sons).

Web links

Commons : Balkan Edible Frog ( Pelophylax kurtmuelleri )  - Collection of images, videos and audio files