Mediterranean tree frog

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Mediterranean tree frog
Mediterranean tree frog (Hyla meridionalis)

Mediterranean tree frog ( Hyla meridionalis )

Systematics
Subordination : Neobatrachia
without rank: Tree frogs (arboranae)
Family : Tree frogs i. w. S. (Hylidae)
Subfamily : Hylinae
Genre : Tree frogs ( hyla )
Type : Mediterranean tree frog
Scientific name
Hyla meridionalis
Boettger , 1874

The Mediterranean tree frog ( Hyla meridionalis ) is a small, smooth-skinned tree frog that belongs to the species-rich family Hylidae and is widespread in the western Mediterranean and the Canary Islands. Type locality is the valley of Orotava, Tenerife, Canary Islands. Most of these tree frogs are colored light green on the upper side, sometimes also dark green or brown spotted. The black side stripe that begins at the nostril is limited to the front part of the body and soon ends behind the eardrum. This distinguishes the Mediterranean tree frog from the other European tree frog species, in which the lateral strip extends into the groin. The male's single, throat-like vocal sac is very large when inflated. The mating call is species-specific. Due to its external morphology and especially its mating call, the Mediterranean tree frog differs more strongly from the other tree frog species native to Europe than they do from one another.

In and around Europe, six tree frog species are distinguished today - in addition to Hyla meridionalis and H. arborea , the Italian , Tyrrhenian and Middle Eastern tree frogs ( H. intermedia, H. sarda and H. savignyi ), as well as the Hyla perrini in northern Italy , which was only described in 2018 . In Africa, the Mediterranean tree frog is the only member of the Hylidae family that has its focus in the New World .

features

Exact information about the size of the Mediterranean tree frogs is contained in the species description by Boettger. For five tree frogs from the Orotava Valley, he names body lengths between 29 and 37 mm. For Mediterranean tree frogs from Morocco the body length is given as 45 mm for the males and just under 50 mm for the females. According to other, general information, males are up to 50 mm long, females a maximum of 65 mm long. The head is relatively short and rounded at the front. The eyes have horizontally elliptical pupils. Behind the eyes are rounded, outer eardrums. The length of the front and rear legs is very different. In a tree frog with a total length of 35 mm, the front legs measure 26 mm, the rear legs 65 mm. The limbs end at the tips of the fingers and toes in widened adhesive discs. There are receding webs between the toes of the hind legs. The top of the body is smooth and mostly uniformly light green in color, sometimes tree frogs appear with interspersed dark green or brown spots on their backs. Behind the crack in the mouth, the green color extends to the sides of the throat. The extremities are also colored green on the upper side up to the tips of the toes, the inner thighs have a yellow-orange color and are occasionally darkly speckled. Mediterranean tree frogs have a physiological color change that enables them to adapt their color to that of the subsurface. The back color can change from green to brown or gray. Yellow or blue tree frogs are rare (see picture). In north-east Spain, 24 out of 502 Mediterranean tree frogs were found to be completely or partially blue on the back. According to current opinion, the blue colored tree frogs lack the yellow pigment in the skin. Blue-colored animals are more common in the Mediterranean tree frog than in the other tree frog species in Europe.

In the females, the skin of the abdomen and throat are white to whitish-gray and have a granular structure, in the males the ventral side is also white and granulated, but the throat is yellow during the reproductive period and has wrinkles if the vocal sac is not filled with air and therefore the skin of the throat is not stretched. Even after the calling period, this yellow coloration does not go away completely, so that females and males can be easily distinguished.

distribution

Distribution of the Mediterranean tree frog

The range of the Mediterranean tree frog has three large areas, two on the European and one on the African mainland, furthermore populations on islands and some isolated occurrences (see figure). The northern area mainly comprises southern France. It stretches from the Atlantic coast of southern France as a broad zone along the mountain range of the Pyrenees to the Mediterranean coast, extends here to Spain to the Ebro Delta, also along the French and Italian Mediterranean coast to the east and extends in Italy to the Cinque Terre. Manarola is currently the southernmost site in Italy. The area along the Italian Mediterranean coast is narrow and mostly only includes the immediate coastal zone. The Mediterranean tree frog is common in the province of Imperia due to the abundance of ponds.

Another large area is located in the southwest of the Iberian Peninsula. In Portugal it covers the part of the country south of the Tagus, in Spain it extends on the coast to Ada in the province of Almería, in the north and east the Mediterranean tree frog occurs in several provinces, including Badajoz, Madrid and Toledo.

The third sub-area is located in North Africa and includes several countries in the Maghreb. It extends from northern Algeria to Morocco, where it reaches the Atlantic coast, in the south it ends south of Agadir. The tree frogs found in northern Tunisia were separated from the Mediterranean tree frog at the beginning of 2019 and described as a separate species under the name Hyla carthaginiensis .

The Mediterranean tree frog is also found on all the large islands of the Canary Islands as well as on Menorca in the Balearic Islands and on the Îles d'Hyères. Madeira is also said to belong to the distribution area, but according to reliable information it is extinct there. There are small, isolated occurrences in France and near San Sebastián in Spain.

In the northern part of the distribution area in Portugal, the recently independent species Hyla molleri is also native, both species occur both sympatric and parapatric. A hybrid of the two species has been demonstrated bioacoustically. Sympatric occurrence with Hyla arborea is known from the valley of the Río Tiétar, Spain, parapatric occurrence from the area north of Arcachon.

The majority of the distribution area is at heights below 500 m, in Portugal most of the sites are below 450 m, in Italy around 35% of the sites are even below 50 m. Nevertheless, the Mediterranean tree frog is not a pure lowland dweller. In the Serra de Monchique, Portugal, it was found on the 900 m high plateau, in the High Atlas in Morocco at 2150 m and 2650 m, in Spain there are several sites between 965 m and 1250 m, in Tenerife at 1150 m.

Habitat and way of life

Mediterranean tree frogs live in stream valleys, swamps, meadows, gardens, plantations, vineyards and similar semi-open habitats with loose vegetation of woody plants and shrubs. They prefer to stay in bushes, reed beds and tree tops. The spawning waters and habitats for larvae are standing, plant-rich small bodies of water - often with temporary water flow -, water reservoirs (Canary Islands), as well as wells, ditches, cisterns and cattle troughs.

The food spectrum of adult Hyla meridionalis includes insects, especially beetles, ants, flies, mosquitoes and bugs, as well as woodlice and spiders. They themselves are mainly preyed on by grass snakes and cattle egrets, tadpoles by predatory insects and insect larvae that live in the water.

The latitude and altitude of a population and the local climate are decisive for the beginning and duration of winter dormancy. In areas with a mild year-round climate, such as the Canary Islands, the Mediterranean tree frog does not seem to hibernate significantly. From Mediterranean tree frogs near Marseille it is reported that in autumn the activity of the frogs is limited to the time from 10 a.m. to 4 p.m., when the daytime temperature reaches high values. The resting places of the tree frogs are in the vicinity of the resting places between dead leaves, twigs or in ivy bushes. There is currently no information on the hibernation of the Mediterranean tree frogs living in high altitudes.

Reproductive biology

Calling Mediterranean tree frog: At the end of a call, the vocal sac is inflated

The beginning and the duration of the reproductive period are very different. In southern France it extends from April to June, in Portugal from December to January (and later), in North Africa from March to April, in Tenerife from December to May. Sometimes she experiences an interruption due to bad weather. This is not uncommon for the Mediterranean tree frogs of the Camargue, France, when the mistral brings cold air from the Massif Central to the coast and causes a sudden drop in the weather there.

Call behavior

During the calling period, the males ready to mate call every day, provided that the ambient temperature is above the lower call threshold (approx. 6 ° C air temperature). The daily calling phase begins at dusk, when the males migrate from the day quarters into the spawning water. The places that you choose to call are mainly in the flat, plant-rich shore region. When they arrive in the water, they immediately start calling. As it gets darker, more males migrate, so that a loud, widely audible chorus soon emerges. Sometimes two, mostly neighboring tree frogs practice changing calls (alternating calls). Both place their calls very precisely in the intervals of the other. During the initial phase it is not uncommon for an immigrating male to choose a call place close to an already calling tree frog. The placeholder reacts to the calls of the newcomer with district calls that differ significantly from the mating calls. This causes the newcomer to move further away from the neighbor. In the Mediterranean tree frogs on Tenerife, the minimum distances between two calling males are small, sometimes only 8-10 cm, sometimes even less.

In preparation for calling, the males take in a considerable amount of air into their lungs, so that the body is distended. The sound bladder is also partially filled with air. When a call is made, lung air is transported through the larynx, which is equipped with vocal cords, through the contraction of the flank muscles into the sound bladder, which is extremely dilated at the end of a call (see illustration). Immediately afterwards, the air flows voicelessly back into the lungs.

The calling continues until after midnight, then subsides and finally ends entirely. During this time the frogs migrate back to their day quarters. The calling of the males is not equally strong every day. High temperatures and rainfall promote call activity, strong wind inhibits it.

Calls

Male Mediterranean tree frogs have four types of call: mating, territory, release and startle calls, female tree frogs only about the release and startle calls.

The mating call represents a sequence of individual sound events, which are also called calls or because of their structure of impulses, impulse groups that the males utter in slow succession. At an air temperature of 12.5 ° C, the sound events last an average of 473.6 ms, the pauses between them around 2.5 seconds. When the temperature rises, the calling accelerates because the duration of the pulse groups and especially the intervals decrease. The frequency spectrum ranges from around 600 Hz to almost 3500 Hz. Due to the structure of pulses, the calls sound creaky.

Territory calls are used to set a minimum distance between calling males, males respond to attempts to clasp other males with calls of release, and females defend themselves against attempts to clasp with calls to release if they are not yet ready to spawn or have already spawned. Scare calls are sounds that the frogs utter with their mouths open when they are grabbed roughly or caught by a predator. They rarely occur in the Mediterranean tree frog.

Mating, spawning

Females ready to mate migrate to the spawning grounds during the males' calling phase in order to mate with the males. They usually don't choose the next one, but swim past calling males to a distant tree frog. Once there, the male touches it briefly with the snout, usually in the shoulder area. The clasps immediately follow. Sometimes a female only swims into the immediate vicinity of a male, creating water waves and thereby triggering the male's attention and thus the clutching. The male clasps the female behind the front legs ( amplexus axillaris ).

The oviposition usually takes place in the same night, it lasts for almost two hours and shows a stereotypical course of behavior. The pair dives, the female grabs a plant with her front legs and takes the signaling or spawning position. It bends its back, stretches its hind legs and at the same time lets a packet of 10 to 30 eggs emerge from the cloaca, which the male inseminates. With the signal setting, the female indicates to the male that an egg packet has emerged. With vigorous movements of the heels, the female wipes away the egg packet, which sinks and sticks to plants. After a short pause, during which the couple remains completely calm, they reappear, remain on the surface for some time, and then drop another packet of eggs in the same way as before. A pair dives a total of 50–60 times until the female has spawned her eggs. It lays 800–1000 eggs. After the eggs are laid, the pair separate and the female leaves the water.

Phonotaxis

In phonotaxis experiments, female Mediterranean tree frogs ready to mate were played through loudspeakers, either native or foreign, or electronically reproduced mating calls. The females reacted to the sound signals and walked to the loudspeaker from which the species-specific mating call sounded, they distinguished between the species-specific mating call and that of Hyla arborea and they also responded to simulated mating calls. When they arrived at the loudspeaker, the females touched it briefly with their snouts and thus showed the same behavior with which they draw the attention of a male that they have selected in the spawning water.

For the first time in a European frog species, these investigations provided evidence that the mating calls of the males serve to attract females ready to mate.

development

Quite a lean young animal
This specimen lacks the yellow skin pigment, so it appears blue instead of green

With the surrounding jelly, the eggs measure 3–5 millimeters, without it 1.1–1.5 millimeters. The egg time lasts 8–15 days, the larvae are 5–8 millimeters long when hatched. In the course of their three to four month aquatic life, during which the larvae feed on organic material (algae, detritus ), occasionally also on the spawn of their own species and other amphibians, they grow up to 50-55 millimeters and then have one for Tree frog tadpoles typical appearance: a spherical belly, wide set eyes, a golden shimmering color and high fin edges. The upper fin edge extends at the front to the level of the breathing hole (not to between the eyes). After the metamorphosis , the young frogs have a size of 15 to 20 millimeters when they go ashore in summer. There is no information about the duration until sexual maturity.

Systematics, phylogeny

When Boettger founded the taxon meridionalis in 1874, the only weak black side stripe in comparison to Hyla arborea was the decisive feature. In 1880 Boscá described the Mediterranean tree frog again as Hyla perezii , followed by Héron-Royer in 1884, who called it Hyla barytonus . In establishing the new species, both relied on the mating call, which is very different from that of Hyla arborea . These species descriptions deserve recognition, because it is possible that they were the first in which a behavioral characteristic was decisive instead of the morphological characteristics customary at the time. Subsequently, great importance was again attached to the morphological characteristics, and because the differences are small, the Mediterranean tree frog was given the status of a subspecies, Hyla arborea meridionalis . The bioacoustic analysis of the mating call in the Mediterranean tree frogs of the Camargue, France, finally led to the recognition of the species status, subsequently confirmed by the mating call analysis in a topotypical population on Tenerife, only about 30 km away from the Orotava valley, the type locality of Hyla meridionalis , as well as the results of the phonotaxis experiments.

The question of the family relationship between the tree frogs native to Europe and the Mediterranean tree frog led to different attempts at explanation. According to popular belief, Hyla meridionalis should be derived from a species native to Europe. During the split, the development to Hyla meridionalis took place, followed by the settlement of the Iberian Peninsula and the northern regions. According to the analysis of the mating calls, Hyla meridionalis does not belong to the family group of Hyla arborea . Bioacoustic studies in Far Eastern tree frogs and the comparison with the tree frogs living in Europe led to the surprising result that the mating call of Hyla meridionalis corresponds very precisely to that of Hyla hallowelli , a species of tree frog that lives on the Japanese Ryūkyū Islands and Okinawa is endemic. It can then be assumed that the branch that led to Hyla meridionalis has already split off in the Far East.

Hazard and protection

The Mediterranean tree frog is listed in Appendix IV of the European Fauna-Flora-Habitat Directive , ie as a "species of Community interest to be strictly protected". Accordingly, in the German Federal Nature Conservation Act , for example, it is regarded as a “strictly protected” species. According to the IUCN, the entire population is not currently considered endangered (LC - “least concern”); regionally, however, populations can very well be threatened by civilizational factors such as habitat destruction and poisoning. For example, the discovery of 5000 dead Mediterranean tree frogs after using pesticides against mosquitoes on the French Mediterranean coast in 1958 is remarkable .

swell

Individual evidence

  1. ↑ Dufresnes C, Mazepa G, Rodrigues N, Brelsford A, Litvinchuk SN, Sermier R, Lavanchy G, Betto-Colliard C, Blaser O, Borzée A, Cavoto E, Fabre G, Ghali K, Grossen C, Horn A, Leuenberger J , Phillips BC, Saunders PA, Savary R, ​​Maddalena T, Stöck M, Dubey S, Canestrelli D, Jeffries DL. 2018. Genomic evidence for cryptic speciation in tree frogs from the Apennine Peninsula, with description of Hyla perrini sp. nov. Frontiers in Ecology and Evolution 6: October 144, 2018 | doi: 10.3389 / fevo.2018.00144
  2. ^ O. Boettger: Reptiles of Morocco and the Canary Islands . Treatises of the Senckenberg Natural Research Society 9, pp. 121–192, 1874
  3. ↑ a b c d Andreas Nöllert & Christel Nöllert: The amphibians of Europe. - Franckh-Kosmos, Stuttgart 1992. Mediterranean tree frog. ISBN 3-440-06340-2 , pp. 307-310.
  4. ^ A b Günter Diesener & Josef Reichholf: Lurche and crawling animals. - Steinbach's nature guide, Mosaik-Verlag, Munich 1986. Mediterranean tree frog. ISBN 3-570-01273-5 , pp. 78/79.
  5. ^ A b c d Hans Schneider: Hyla meridionalis Boettger, 1874 - Mediterranean tree frog. - Handbook of the reptiles and amphibians of Europe. Volume 5 / II Froschlurche (Anura) II (Hylidae, Bufonidae). AULA publishing house, Wiebelsheim. Pp. 97-140. ISBN 978-3-89104-655-5 .
  6. ↑ Christophe Dufresnes, Menad Beddekd, Dmitriy V. Skorinov, Luca Fumagalli, Nicolas Perrin, Pierre-André Crochet, Spartak N. Litvinchuk: Diversification and speciation in tree frogs from the Maghreb (Hyla meridionalis sensu lato), with description of a new African endemic. Molecular Phylogenetics and Evolution, February 2019, doi: 10.1016 / j.ympev.2019.02.009
  7. ^ IUCN Red List: Distribution map for Hyla meridionalis
  8. ↑ a b Arie van der Meijden: Hyla meridionalis at Amphibiaweb.org (accessed on Dec. 15, 2007)
  9. ^ Rudolf Malkmus: New data on the altitude distribution of the Mediterranean tree frog, Hyla meridionalis Boettger, 1874, in Portugal. - Herpetozoa, Vienna 1997, 10 (3/4): pp. 169-171.
  10. ↑ Dieter Glandt, Martin Schlüpmann & Burkhard Thiesmeier: Herpetological observations in the Algarve, southern Portugal. - Zeitschrift für Feldherpetologie, Bochum 1998, 5 (1/2): pp. 181-208. ISSN  0946-7998
  11. ↑ Hans Schneider and Institute for Scientific Film: Hyla meridionalis (Hylidae) - reputation behavior . Publ. Scientific Film, Sekt. Biol., Ser. 15, No. 18 / E 2692, 1982.
  12. ^ A b Hans Schneider: The mating call of the Tenerife tree frog: structure, variability and relationship to the mating call of the tree frog of the Camargue (Hyla meridionalis Böttger, 1874, Anura, Amphibia). - Zoologischer Anzeiger, Jena, 1978, 201: pp. 273-288.
  13. ↑ Wolf-Rüdiger Grosse: The tree frog. (= Die Neue Brehm-Bücherei. Volume 615). Westarp Sciences, Magdeburg 1994, ISBN 3-89432-407-4 .
  14. ↑ Hans Schneider: Bioacoustics of the Froschlurche. Native and related species. With audio CD. Zeitschrift für Feldherpetologie, Supplement 6: 135 pages, 146 illustrations, 2005. Laurenti Verlag, Bielefeld. ISBN 3-933066-23-9 .
  15. ^ Hans Schneider: Reproductive behavior of the Mediterranean tree frog (Hyla meridionalis) of the Canary Islands . Salamandra 17, pp. 119-129, 1981.
  16. ↑ Hans Schneider and Institute for Scientific Film: Reproductive behavior of the Mediterranean tree frog. Publ. Scientific Film, Sekt. Biol., Ser. 15, no., 39 / C 1459, 1982.
  17. ↑ Hans Schneider: Phonotaxis in females of the Canary tree frog , Hyla meridionalis. Zoologischer Anzeiger 208, pp. 161-174, 1982.
  18. ↑ Hans Schneider and Institute for Scientific Film: Acoustic orientation in the female of the Mediterranean tree frog . Film C 1500 of the IWF, Göttingen 1983. Publication by H. Schneider, Publ. Wiss. Film., Sekt. Biol., Ser. 17, No. 21 / C 1500, 1985.
  19. ↑ Thomas Mutz: Spawning predation by the tadpoles of the Mediterranean tree frog (Hyla meridionalis). - Zeitschrift für Feldherpetologie, Bielefeld 2005, 12 (2): pp. 260–265. ISSN  0946-7998
  20. ↑ Hans Schneider: Bio-acoustic studies on the Mediterranean tree frog . Journal for Comparative Physiology 61, pp. 369-385, 1968.
  21. ↑ Mitsura Kuramoto: Mating calls of treefrogs (Genus Hyla) in the Far East, with description of a new species from Korea . Copeia 1980, pp. 100-108.
  22. ^ René E. Honegger: Threatened Amphibians and Reptiles in Europe. - Supplementary Vol. Of Handbuch der Reptilien und Amphibien Europa , Akademische Verlagsgesellschaft, Wiesbaden 1981, ISBN 3-400-00437-5 , p. 14 (quotation).

literature

  • O. Boettger: Reptiles from Morocco and the Canary Islands. Treatises of the Senckenberg Natural Research Society 9, pp. 121–192, 1874.
  • Hans Schneider: Hyla meridionalis Boettger, 1874 - Mediterranean tree frog. - Handbook of the reptiles and amphibians of Europe. Volume 5 / II Froschlurche (Anura) II (Hylidae, Bufonidae). AULA publishing house, Wiebelsheim. Pp. 97-140. ISBN 978-3-89104-655-5 .
  • Günter Diesener & Josef Reichholf: Amphibians and reptiles. - Steinbach's nature guide, Mosaik-Verlag, Munich 1986, ISBN 3-570-01273-5 .
  • Miguel Tejedo, Ricardo Reques: Hyla meridionalis (Boettger, 1874). Ranita meridional. In: JM Plegezuelos, R. Márquez, M. Lizana (eds.): Atlas y libro rojo de los anfibios y reptiles de España. Madrid, 2nd edition, 2002, ISBN 84-8014-450-5 , pp. 117-119.
  • Andreas Nöllert & Christel Nöllert: The amphibians of Europe. - Franckh-Kosmos, Stuttgart 1992, ISBN 3-440-06340-2 .
  • Hans Schneider: The mating call of the Tenerife tree frog: structure, variability and relationship to the mating call of the tree frog of the Camargue (Hyla meridionalis Boettger, 1874, Anura, Amphibia). Zoologischer Anzeiger, Jena, 201, pp. 273-288 1978.
  • Hans Schneider and Institute for Scientific Film: Acoustic orientation in the female of the Mediterranean tree frog. Film C 1500 of the IWF, Göttingen 1983. Publication by H. Schneider, Publ. Wiss. Film., Sekt. Biol., Ser. 17, No. 21 / C 1500, 1985.
  • Hans Schneider: Bio-acoustic studies on the Mediterranean tree frog. Journal for Comparative Physiology 61, pp. 369-385, 1968.
  • Hans Schneider: Reproductive behavior of the Mediterranean tree frog (Hyla meridionalis) of the Canary Islands . Salamandra 17, pp. 119-129, 1981.
  • Hans Schneider and Institute for Scientific Film: Reproductive behavior of the Mediterranean tree frog. Publ. Scientific Film, Sekt. Biol., Ser. 15, no., 39 / C 1459, 1982.
  • Hans Schneider and Institute for Scientific Film: Hyla meridionalis (Hylidae) - reputation behavior . Publ. Scientific Film, Sekt. Biol., Ser. 15, No. 18 / E 2692, 1982.
  • Hans Schneider: Phonotaxis in females of the Canary tree frog, Hyla meridionalis. Zoologischer Anzeiger 208, pp. 161-174, 1982.
  • Hans Schneider and Institute for Scientific Film: Acoustic orientation in the female of the Mediterranean tree frog . Film C 1500 of the IWF, Göttingen 1983. Publication by H. Schneider, Publ. Wiss. Film., Sekt. Biol., Ser. 17, No. 21 / C 1500, 1985.
  • 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).
  • Hans Schneider: Bioacoustics of the frogfish. Native and related species. With audio CD. Zeitschrift für Feldherpetologie, Supplement 6: 135 pages, 146 illustrations, 2005. Laurenti Verlag, Bielefeld. ISBN 3-933066-23-9 . Audio samples 18.1–18.7
  • Hans Schneider: Hyla meridionalis Boettger, 1874 - Mediterranean tree frog. In: Kurt Grossenbacher (Ed.): Handbook of the reptiles and amphibians in Europe. Volume 5 / II Froschlurche (Anura) II (Hylidae, Bufonidae). AULA-Verlag, Wiebelsheim, 2009, pp. 97-140.
  • Mitsura Kuramoto: Mating calls of treefrogs (Genus Hyla) in the Far East, with description of a new species from Korea . Copeia 1980, pp. 100-108.

Web links

Commons : Mediterranean Tree Frog  - Collection of images, videos and audio files
This version was added to the list of articles worth reading on December 24, 2007 .