Italian water frog

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Italian water frog
Pelophylax cf. bergeri

Pelophylax cf. bergeri

Systematics
without rank: Amphibians (Lissamphibia)
Order : Frog (anura)
Subordination : Neobatrachia
Family : Real frogs (Ranidae)
Genre : Water frogs ( pelophylax )
Type : Italian water frog
Scientific name
Pelophylax bergeri
( Günther in Engelmann, Fritzsche, Günther & Obst, 1986)

The Italian water frog ( Pelophylax bergeri , synonym : Rana bergeri ) belongs to the family of real frogs (Ranidae) within the order of the frog auger. In addition, it is reckoned according to appearance, way of life and relationships to the water frogs , which are now placed in their own genus Pelophylax . The species is recognized. It can be found on the Apennine Peninsula as well as in Sicily and Corsica .

features

The Italian water frog has a body length of about 40 to 80 mm, with the males reaching sizes between 40 and 70 and the females between 50 and 80 mm. The back color is very variable and ranges from yellow to brownish; mostly there is a light green median. The black spots on the upper side are polygonal and of very different sizes, on the rear legs dark color patterns are often designed as transverse bands. Sometimes dark color patterns are completely absent on the back and are only present on the hind legs. The ventral side is whitish, yellowish or light gray and often spotted with gray. The inner thighs are conspicuously colored yellow to orange and marbled brown. The males have paired, white vocal sacs . The heel bumps are quite large, but flatter and much shorter than in P. lessonae . They are also never completely semicircular.

It differs from the little water frog, to which it is very similar overall, in its mating call and in its longer hind legs. It is difficult to distinguish from the sympatric and often syntopically occurring Italian hybrid frog ( P. "hispanicus" ), which can be reliably differentiated from a molecular-biological point of view.

distribution and habitat

The distribution area of ​​the Italian water frog includes most of the Italian boot south of the Po Valley near Genoa and Rimini as well as Elba and Sicily. It is also widespread in Corsica, where it may have been introduced. As a habitat, the Italian water frog prefers vegetation-rich still and flowing waters in open plains and low mountain ranges up to a maximum of 1200 m (in Sicily).

Behavior and calls

The observations on the behavior of the frogs and the registration of the mating calls took place at three locations in mainland Italy: at water ditches near Lesina , Province Foggia, Region Puglia (N41 ° 51'40.33 ", E15 ° 21'44.67", 61 m above sea level), near Palude di Colfiorito , Province of Perugia, Region Umbria (N43 ° 01'41.57 ", E12 ° 52'39.08", 805 m above sea level), and on the Chiascio River in Bastia Umbra , Province of Perugia, Region Umbria (N43 ° 04'15.65 " , E12 ° 32'28.98 ", 193 m above sea level). During the tape recordings of the mating calls of the frogs at the three locations, the water temperatures were 17.2 to 26.0 ° Celsius. Since several call features are correlated with the water temperature, it is important to know the influence of the temperature on the calls in order to be able to make exact statements about the structure of the pairing calls.

The Italian water frogs were in the pre-spawning season at the three locations during the observations. The majority of the males had chosen places between algae mats or other plants, some sat on the edge of the bank outside the water and sunbathed. The calling started around mid-morning, increased and was repeatedly interrupted by general breaks. Call activity decreased in the early afternoon. Only a few males gave a few short series of calls. Call activity increased again in the late afternoon and continued into the evening hours.

The calling males largely retained their chosen call positions and maintained a minimum distance of around 50 centimeters from neighboring males. Because of the low level of locomotor activity, interactions between the males were relatively rare, and calls to territory were therefore rare.

Mating call

Sound image (oscillogram) of a mating call from Pelophylax bergeri, recorded on tape at Lesina (Foggia) at a water temperature of 17.9 ° Celsius.

The males almost always give their mating calls in series. Often there are those with 15 to 30 calls. When call activity begins in the morning, the series of calls are usually short, but long in the evening when there is high call activity. At 20 ° Celsius, a temperature that occurs frequently in the course of the propagation period, the calls have a duration of 1553 milliseconds, the intervals between the calls and the call period measure 1665 milliseconds and 3196 milliseconds respectively. Call duration, call interval and call period are negatively correlated with the water temperature. As the temperature rises, these call characteristics shorten according to linear equations. The values ​​given for 20 ° Celsius were calculated from the regression equations. Another characteristic call feature is the number of pulse groups per second. It increases with increasing temperature and also obeys a linear regression. According to the equation, it is 30.64 Hertz at 20 ° Celsius.

The mating calls consist of impulse groups like in most other Pelophylax species. The average number is 50.2 impulse groups per call. The groups of impulses are not separated from one another by intervals, but they can still be heard easily, as the volume of the impulses that build up the groups changes rhythmically. The mating calls therefore sound rasping. On the sound images (oscillograms), the pulse groups can be clearly recognized due to the rhythmically changing amplitude. The pulse groups themselves are made up of an average of 3.9 pulses.

Systematics

Biochemical studies showed that two previously unknown forms of water frogs occur on the Italian peninsula south of the Po Valley. One was called Southern Italian non-hybrid and has a resemblance to Pelophylax lessonae , the other turned out to be a hybrid and was therefore called Southern Italian hybrid. It is a hybrid of Southern Italian non-hybrid and Pelophylax ridibundus . Paolucci et altera studied morphological and biochemical characteristics in water frogs from six locations, five of them on the Italian peninsula and one on Sicily. At the locations on the Italian peninsula, only frogs with the characteristics of Southern Italian non-hybrid occurred, while at the locality in Sicily both forms occurred, Southern Italian non-hybrid and Southern Italian hybrid.

1986 Günther describes the Italian water frog as a possible subspecies of the small water frog, Rana lessonae bergeri . The further statement that calls and behavior are like those of the little water frog does not apply to the mating call. The mathematical comparison of the mating calls from three locations on the Italian peninsula with those of a topotypical population of Pelophylax lessonae near Casanova, Province of Turin, revealed large differences, which led to the conclusion that the Italian water frog has the status of a species, Pelophylax bergeri . Pelophylax bergeri is listed as a species. It is named after the herpetologist Leszek Berger from Poznań, Poland. A formal description of Pelophylax bergeri , as well as the definition of a holotype and a type locality are still pending.

In the mathematical comparison of the mating calls of the water frogs on the Italian peninsula with the mating calls of the little water frog near Casanova , Province of Turin, the mating calls of the little water frogs were also included, which were recorded in the Kottenforst near Bonn , North Rhine-Westphalia, near Virpazar at the northern end of the Skadar Lake, Montenegro , and occur in three locations in Albania, near Shkodër at the southern end of Lake Skadar , near Durrës and Poshnië . In contrast to the findings with the water frogs on the Italian peninsula, the mating calls of the frogs in these locations proved to be consistent with each other and with those of the frogs of the topotypical population at Casanova. The mating calls of the water frogs, which occur at the type locality of the biochemically based Pelophylax shqiperica at the northern end of Lake Skadar, Montenegro, differ only slightly from those of the topotypical Pelophylax lessonae and correspond to intraspecific variability. Since the mating calls are innate, species-specific characteristics and are therefore very informative, it is justified to assign the water frogs from all these locations to Pelophylax lessonae . The bioacoustic findings obtained in Albania also confirm the results of Haxhiu, who determined through morphological investigations that Pelophylax lessonae is native to Albania .

In a large part of Italy the species is associated with the Italian hybrid frog ( Pelophylax "hispanicus" ), a hybridogenic hybrid of the Italian water frog and the sea ​​frog ( P. ridibundus ), which does not occur in Italy .

There are two theses on the question of how the two water frog species, which are now completely allopatric in distribution, could hybridize . Either Pelophylax bergeri occurred further north before the last Ice Age , so that the cross between it and the sea frog would have taken place outside of what is now Italy. The hybrid P. "hispanicus" would then have immigrated to Italy. Another explanation is that the sea frog genome of the Italian hybrid frog could not come directly from sea frogs, but from another hybridogenic hybrid of water frogs, the pond frog ( P. "esculentus" ). This would have acted as a representative transmitter of the ridibundus genome without Pelophylax bergeri and P. ridibundus ever meeting each other .

Danger

The Italian 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 overall population. The main threat to this species comes from draining suitable habitats.

Evidence cited

  1. ↑ a b Frost, Darrel R. 2020. Amphibian Species of the World: an Online Reference. Version 6.0 (04-25-2020). 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
  2. ↑ a b c d Ulrich Sinsch, Hans Schneider: Bioacoustic assessment of the taxonomic status of pool frog populations (Rana lessonae) with reference to a topotypical population. In: Journal of Zoological Systematics and Evolutionary Research. Volume 34, 1996, pp. 63-73.
  3. ↑ Thomas Uzzell, Leszek Berger: Electrophoretic phenotypes of Rana ridibunda, Rana lessonae and their hybridogenetic associate Rana-esculenta. In: Proceedings of the Academy of Natural Science. Philadelphia. Volume 127, 1975, pp. 13-24.
  4. ↑ Thomas Uzzell, Hansjörg Hotz: Electrophoretic and morphological evídence for two forms of green frogs (Rana esculenta complex) in peninsular Italy (Amphibia, Salientia). In: Messages from the Zoological Museum Berlin. Vol. 55, 1979, pp. 13-27.
  5. ↑ Hansjörg Hotz, G. Mancino, S. Bucci-Innocenti. M Ragghianti, L. Berger, T. Uzzell: Rana ridibunda varies geographically in inducing clonal gametogenesisis in interspecies hybrids. In: Journal of experimental Zoology. Volume 236, 1985, pp. 199-210.
  6. ^ ID Graf, F. Karch, MC Moreillon: Biochemical variation in the Rana esculenta complex: A new hybrid form related to Rana perezi and Rana ridibunda. In: "Experientia." Volume 33, 1977, pp. 1582-1584.
  7. ↑ Marina Paolucci, Matilde Borriello, Virgilio Botte, Massimo Zerani, Alberta Polzonetti Magni: Taxonomic investigations on six populations of the water frog, Rana esculenta complex from peninsular Italy and Sicily. In: Italian Journal of Zoology. Vol. 54, 1987, pp. 341-346.
  8. ↑ Wolf-Eberhard Engelmann: amphibians and reptiles of Europe . Neumann Verlag, Leipzig Radebeul, 1985, 420 pp.
  9. ↑ Hans Schneider (1996): Mating calls and calling behavior in pond and pond frogs in the Kottenforst Nature Park. In: Decheniana (Bonn) , Volume 149, 1996, pp. 124-138.
  10. ↑ Hans Schneider, Gerhard Joermann (1988): Mating calls of water frogs (Ranidae) of Lake Scutari, Yugoslavia, and relationship to water frogs in Greece. In: Journal for Zoological Systematics and Evolutionary Research. Volume 26, 1988, pp. 261-275.
  11. ↑ Hans Schneider, Idriz Haxhiu (1993): Mating-call analysis and taxonomy of water frogs (Ranidae, Anura) in Albania. In: Zoological Yearbooks, Systematics. Volume 121, 1993, pp. 248-262.
  12. ↑ Idriz Haxhiu: Studim për bretkosat e gjelbra të vendit tonë. 1. Të dhëna morfologjike të krahasuara ndërmjet Rana lessonae Cam., R. ridibunda Pall. dhe R. esculenta L. In: Buletin i Shkencave të Natyrës. Volume 3, 1986, pp. 47-55.
  13. ↑ Jörg Plötner: The West Palearctic Water Frogs - From Martyrs of Science to Biological Sensation . Supplement to the magazine f. Feldherpetologie 9, Bielefeld 2005, page 108. ISBN 3-933066-26-3
  14. ↑ Pelophylax bergeri in the endangered Red List species the IUCN 2009. Posted by: Andreone, F. et al. , 2008.

literature

  • Christophe Dufresnes: Amphibians of Europe, North Africa & Middle East. Bloomsbury Wildlife, Bloomsbury Publishing Plc, London, 2019, 224 pp., ISBN PB: 978-1-4729-4137-4
  • Frost, Darrel R. 2020. Amphibian Species of the World: an Online Reference. Version 6.0 (04-25-2020). 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
  • Dieter Glandt: The amphibians and reptiles of Europe. All species in portrait. Quelle & Meyer 2015; Pp. 216-2018, ISBN 978-3-494-01581-1 .
  • Rainer Günther: Europe's water frogs. The New Brehm Library. Volume 600. A. Ziemsen Verlag, Wittenberg (Lutherstadt) 1990, ISBN 3-7403-0234-8
  • Axel Kwet: Reptiles and Amphibians of Europe . Franckh'sche Verlagsbuchhandlung, Stuttgart 2005, p. 112, ISBN 3-440-10237-8
  • Marina Paolucci, Matilde Borriello, Virgilio Botte, Massimo Zerani, Alberta Polzonetti Magni: Taxonomic investigations on six populations of the water frog, Rana esculenta complex from peninsular Italy and Sicily. In: Italian Journal of Zoology. Vol. 54, 1987, pp. 341-346.
  • Jörg Plötner: The western Palearctic water frogs - from martyrs of science to a biological sensation . Supplement to the magazine f. Feldherpetologie 9, Bielefeld 2005, ISBN 3-933066-26-3
  • 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 82–83.
  • Hans Schneider, Ulrich Sinsch: Contributions of bioacoustics to the taxonomy of the Anura. In: Harold Heatwole and Michael J. Tyler (Eds.): Amphibian Biology, Volume 7, Systematics. 2007, pp. 2893-2932. Chipping Norton NSW, Australia, (Surrey Beatty & Sons).
  • Ulrich Sinsch, Hans Schneider: Bioacoustic assessment of the taxonomic status of pool frog populations (Rana lessonae) with reference to a topotypical population. In: Journal of Zoological Systematics and Evolutionary Research. Volume 34, 1996, pp. 63-73.
  • Thomas Uzzell: An immunological survey of Italian water frogs (Salientia: Ranidae). In: Herpetologica. Volume 39, 1983, pp. 225-234.

Web links

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