The Family Ranidae are another large and worldwide distributed family, being absent only from the poles, some parts of South America, the Arabian peninsula and parts of North Africa. In Europe the family is represented by several Rana species, which are traditionally divided into "brown" and "green" or "water" frogs (although some are both brown and water-dwelling!). An interesting problem is that of the three hybrid species, which unlike most hybrids are actually fertile and produce viable offspring - see below.
European Rana species, with the exception of the introduced R. catesbiana species, can be distinguished by their horizontal pupils and dorsolateral folds [Arnold, 1978].
A word needs to mentioned about those species with the abbreviation kl. in their species name. The kl. stands for klepton (the Greek word for thief - hence kleptomaniac!) and denotes a hybrid species that has two or more sets of chromosomes, one from each parent. For example, Edible Frogs (Rana kl. esculenta) are produced by the interbreeding of Rana lessonae, the Pool Frog, and Rana ridibunda, the Marsh Frog. Thus first-generation Edible Frogs, have two sets of chromosomes, one from the Marsh Frog parent and one from the Pool Frog parent. However, before the eggs and sperm of the Edible Frog are formed, one set of chromosomes (usually that of the species with which the individual Edible Frog mates) is destroyed. Thus an individual female Edible Frog mating with a male Pool Frog would usually have already lost the Pool Frog chromosomes, but receives a fresh set via her new mate. In some populations males and females of the hybrid species breed with one another without resorting to individuals of the "parent" species. Triploid individuals (containing three sets of chromosomes) are also known.
Owing to the increased number of species, this page is currently an ongoing work.
NB Unlike the pages for the other Reptile and Amphibian families, where measurements were given in inches or feet, measurements for the families here are given in centimetres, owing to the generally small size of the subjects.
Either click on a frog in the Quick Links section or scroll down for the whole table.
|R. arvalis, Moor Frog
|R. balcanica, Greek Marsh Frog
|R. bedriagae, Levant Water Frog
|R. bergeri, Italian Pool Frog
|R. catesbiana, American Bullfrog
|R. cerigensis, Karpathos Water Frog
|R. cretensis, Cretan Water Frog
|R. dalmatina, Agile Frog
|R. epeirotica, Epirus Water Frog
|R. kl. esculenta, Edible Frog
|R. graeca, Stream Frog
|R. kl. grafi, Graf's Hybrid Frog
|R. kl. hispanica, Italian Hybrid Frog
|R. iberica, Iberian Frog
|R. italica, Italian Stream Frog
|R. latastei, Italian Agile Frog
|R. lessonae, Pool Frog
|R. macrocnemis, Long-Legged Wood Frog
|R. perezi, Iberian Water Frog
|R. pyrenaica, Pyrenean Water Frog
|R. ridibunda, Marsh Frog
|R. shquiperica, Albanian Pool Frog
|R. temporaria, Common Frog
|France, Belgium, Netherlands, Germany, Denmark, Sweden as far as beyond Arctic Circle, SE Norway, Finland; Central Europe to L. Baikal (Siberia):
|The Moor Frog looks very similar to the Common Frog but is in fact one of the rarest frogs of Europe despite its large area of distribution. Its favoured habitats are peat bogs or damp meadows in areas where ponds are fairly abundant, and this dependence on a certain type of habitat caused its decline. Hibernation takes place either at the bottom of a pool or on dry land, presumably in similar habitats to young Common Frogs (see above). Diet is also similar to the Common and other frogs. Upon awaking in the cold nights of early spring, moor frogs assemble in small groups in pools and small ponds. In larger bodies of water they will choose an area in the shallowest part of the water and not mix with other groups. As the breeding season commences, males turn blue due to lymph concentrating in the subcutaneous spaces. If it feels threatened while on dry land, a Moor Frog will make a long high jump and then burrow beneath a clump of grass. Moor Frogs can be distinguished from Common Frogs by their narrow snouts, and also by the larger tubercle on the medial aspect of the sole of the hind foot. Moor Frogs also tend to lack the ventral spotting of the Common Frog.
|R. a. arvalis
|Northern part of range
|R. a. wolterstorffi
|SE Poland, S & E Austria, Slovakia, Croatia, Slovenia Hungary, N Romania,
|Distinguished by larger size and long legs.
|Greek Marsh Frog
|Albania, Greece (not NE), Thasos and Zakynthos (Greek)
|Levant Water Frog
|Greece (Aegean islands), Turkey, Syria, Israel, Jordan, Egypt: introduced in Belgium, poss. UK
|Like the Marsh Frog, R. ridibunda, but distinguished from it by its calling voice and certain molecular differences (obviously not visible in the field!). May also be referred to as R. levantina.
|Italian Pool Frog
|Italy S of Genoa-Rimini, Sicily, Corsica
|Usually rather smaller than its maximum size. May also be referred to as R. maritima or R. lessonae bergeri.
|N. Italy: N. America, Carribean
|Originally a native of N. America, but introduced into the Carribean and then Europe. It is similar in appearance to its European relatives and also takes small vertebrates as part of its diet. Its common name derives from its call, which is more of a bellow than a croak.
|Karpathos Water Frog
|Greece (Karpathos Island in the Aegean)
|Cretan Water Frog
|N. Spain, C. & S. Europe through to Turkey, Caucasus and Urals
|The Agile Frog prefers warm climates and places and also almost only inhabits low-lying areas. Favoured habitats are damp shaded spots at the edge of woods (except totally coniferous) or in riverside meadows. It only enters the water during the breeding season, and has limited webbing between its toes. One of its most striking features is its very long and slim hind legs. Thanks to these limbs, the Agile Frog has been recorded leaping up to 2 metres distant and 0.75 metres high. Like the Common Frog, it has a black 'mask' behind each eye, but has fewer spots than either the Common or the Moor Frog. Other distinguishing features are its flattened snout and the closeness of the eardrums to the eyes. Size seems to be climate dependent, with the larger individuals being found in the south of its range. Interestingly the sexes hibernate separately, the males in still water and the females in terrestrial hiding places. Mating takes place in March-April, but again this seems to be climate dependent, as mating in the south may begin as early as February. This is the only time that the males croak, and their call is not very audible. The female lays 600-1,000 eggs in clusters, usually at night. Tadpoles are a light olive brown and at a pre-metamorphosis size of 6cm are one of the biggest in Europe. Metamorphosis takes place in C. Europe in June-August, possibly earlier in the south: the young frogs leave the water soon after. Diet consists mainly of invertebrates (especially spiders), but occasionally small vertebrates may be taken.
|Epirus Water Frog
|Greece (W of Pindos mtns, NW Peloponnese, Corfu, Lefkos, Kefallinia and Zakinthos), Albania (prob. only Plain of Saranda)
|R. kl. esculenta
|Europe (exc. Iberia and N. Scandinavia) east to Volga
|One of the so-called "green frogs". The Edible Frog is fairly catholic in its habitats, preferring shallow ponds but also living in small, isolated lakes and pools. However, they never occur above 1,000 metres. Their diet is also very varied and is caught on land or in the water: insects and other invertebrates and small vertebrates. Cannibalism is known in this species. Large specimens may reach 12 cm in size: males are smaller than the females. Despite this hardiness and lack of special preferences, however, the Edible Frog is being displaced in some areas by the Marsh Frog, which is larger. Furthermore the Edible Frog has the unenviable distinction of being the chief provider of "frog's legs" for human populations. Mating takes place in spring: the females lay 5,000-10,000 eggs in clusters of up to 300, all within the space of 1-2 days. Larvae hatch in about 10 days, but development is thereafter temperature dependent: in warm weather metamorphosis takes place in about 3 months, but in some cases the larvae hibernate and complete their metamorphosis the following year. Colouring of the Edible Frog is an overall green, with prominent and variably coloured ridges on their backs and often a yellow-green dorsal stripe. The croaking of a male causes its vocal sac (white or grey in colour) to swell out at both corners of its mouth. There is some debate about the "green frog" complex, with some if not most authorities believing R. esculenta to be a fertile hybrid of interbreeding between R. lessonae and R. ridibunda.
|C. & S. Balkans, Italy, S. Switzerland
|The Stream Frog is mainly a montane species and is rarely encountered at low altitudes. It favours habitats near forest streams in coniferous forests or mixed woodlands. It is closely related to the Common Frog (both in biology and colouring) and can similarly tolerate a wide temperature range. Although the first night frosts usually send the Stream Frog into hibernation, subsequent warm weather will bring it out again. Hibernation takes place in a wide range of places: deep in loose forest soil, under fallen trees or in tree stumps, under boulders or in a hole in the ground. In spring the frogs enter the water only to breed. The females lay their eggs in clusters in areas where the current is slow or absent, such as stream backwaters or forest lakes. For the rest of the year the frogs live on their own, a common characteristic of the Ranidae. Diet is mainly insects and their larvae, various annelids and slugs. Although similar in appearance to the Common Frog, the Stream Frog can be distinguished by its generally smaller size and a dark spot on its throat. The Stream Frog has no subspecies, but individuals from Italy have a shorter body and limbs than those from the Balkans.
|R. kl. grafi
|Graf's Hybrid Water Frog
|S France, NE Spain (Basque Country, Aragon and Catalonia)
|This species probably originated from a cross between R. kl. esculenta, the Edible Frog, and R. perezi, the Iberian Water Frog. Generally similar to the Marsh Frog R. ridibunda, with which it mixes: however, the eardrum of R. kl. grafi is relatively further back from the eye than in R. ridibunda. It also resembles its other relative R. perezi but is somewhat larger and has more fully webbed feet and a larger metatarsal tubercle. The hybrid survives by reproducing with R. perezi.
|R. kl. hispanica
|Italian Hybrid Frog
|Italy (not N), Sicily, poss. Slovenia and NW Croatia
|Portugal, NW Spain, Andorra
|Found mainly in mountain forests at altitudes higher than 2,000 m.
|Italian Stream Frog
|Italy (Genoa E through the Appennines to the "boot" of Italy)
|Absent from much of the east of the country.
|Italian Agile Frog
|Distinguishable from other brown frogs mainly by the throat markings.
|C. & E. Europe
|Found in similar habitats to the above: exact status is under debate. The former Yugoslavian subspecies R. l. pannonica now longer appears to be recognised.
|Long-Legged Wood Frog
|Caucasus, Asia Minor and Central Asia
|Iberian Water Frog
|Range restricted to the Pyrenees, where it lives at altitudes of 1,100m and 1,700m in or close to cold, clear and well-oxygenated mountain streams. It is a rather timid creature.
|N. Africa across S. & C. Europe to W. Asia
|Avg 12cm (m), 14cm (f): max 15-18cm
|The largest of the original European Frogs, the Marsh Frog can occasionally reach sizes of up to 17cm. This, together with the variety of its diet which in addition to insects includes small vertebrates such as frogs, tadpoles, lizards and voles, makes it unsurprising that that Marsh Frog is progressively pushing westward and displacing the Edible Frog, both by competition for food and direct predation. Marsh frogs favour warm lowlands with a high incidence of shallow ponds or else large, slow-flowing rivers. Unusually for Ranidae species they often form large communities, up to 2,000 per hectare. The frogs hibernate in the mud at the bottom of the water and only awaken when water temperature reaches 6-9 deg. C. After mating, the females wait until the temperature reaches 15 deg. C before laying large clusters of eggs which sit at the bottom of the pool. The actual number of eggs laid is dependent upon the size of the female but can vary between 4,000-12,000. The tadpoles are light green and pear-shaped: they reach up to 9cm in size, but after metamorphosis (which takes three months in the water) the young frogs are only about 1.5-2.5 cm. Colouring is variable but is usually olive green or mainly brown. Markings are also variable, but the eardrums of the male (which is smaller than the female) are always grey or blackish-brown. R. perezi and R. saharica were previously considered subspecies of this species.
|Lake Scutari Water Frog, Albanian Pool Frog
|Montenegro (Lake Scutari and adj. SW coastal hinterland), W Albanian coastal hinterland
|N. & C. Europe, Asia, Japan
|The most common and widely distributed frog in Europe, thanks to its ability to live in seemingly any habitat and any type of water, and even at some distance from it. It can also live at altitudes of up to 4,000 metres. The frogs lead solitary lives most of the year, preying on various invertebrates including molluscs, worms and most arthropods. In winter most hibernate in the mud at the bottom of a body of water, but young frogs will often shelter instead under damp stones or fallen tree trunks. These are the first frogs to emerge from hibernation in spring. Breeding commences in March, even if there is still frost and ice present during the night. The vocal sacs of the males turn blue and their nuptial pads swell during the mating season, but their call is not very loud or distinct and interestingly they only call during the day, when in water, and not at night. The females lay up to 4,000 eggs each in clusters that float in the water. The tadpoles cling to the leaves of aquatic plants once they have hatched: development and metamorphosis take 2-3 months in total, upon which there is a large migration of young frogs from the water. Colouring is variable in this species but there are generally two basic schemes: a brownish back with a black area behind the eye and extending to the forelegs, or a green back without this 'mask'. The underside is usually light but often spotted.
|R. t. temporaria
|R. t. canigonensis
|Parts of the French E Pyrenees
|Currently seems to be accepted as a subspecies.
|R. t. honnorati
|Foot of the Alps
|Subspecies status doubtful as described by Engelmann et al: not listed in the AMNH database.
|R. t. parvipalmata
I would like to acknowledge the initially crucial part played in this page by Lanka and Vit's Amphibians and Reptiles, from which accounts of the more obscure frogs were sometimes lifted almost verbatim. Data and corrections were later added from the following sources:
Die Amphibien Europas, Andreas and Christel Nöllert, Franckh-Kosmos, Stuttgart 1992. Outstanding nature guide to every species of amphibian found in Europe.
Collins Field Guide: Reptiles & Amphibians of Europe, Arnold, Burton & Ovenden, Collins 1978, revised edition 2002/4. Contains a useful explanation of the diploid and triploid klepton species, to which I acknowledge my debt
Lurche und Kriechtiere Europas [Amphibians and Reptiles of Europe], Dr Wolf-Eberhard Engelmann, Jürgen Fritzsche, Dr sc. Rainer Günther and Dipl.Biol. Fritz Jürgen Obst, Ferdinand Enke Verlag, Stuttgart 1986. A German-language equivalent but with a rather wider definition of Europe which includes the Transcaucasus, and useful details on the distribution of subspecies. Now apparently out of print.
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