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Order: Anura
Family: Alytidae
The Alytidae are an ancient family found in Europe, the Middle East and northwestern Africa, and are comprised of the midwife toads (Alytes) and painted frogs (Discoglossus). Overall, this family is now named after the midwife toads. The family name was formerly Discoglossidae or ‘disc-tongued frogs’ because, unlike the slender tongues of many amphibians, midwife toads and painted frogs possess a round and flattened tongue. They diverged from all other amphibians about 210 millions years ago at the end of the Triassic period, around the same time that the first primitive mammals started to appear. The midwife toad family therefore evolved at the feet of some of the earliest dinosaurs, and survived the dinosaur’s demise nearly 150 million years later.
Within the family Alytidae, the midwife toads diverged from their closest relatives, the painted frogs, about 155 million years ago, about 5 million years before the first birds started to appear in the fossil record. Midwife toads are therefore more different from their closest relatives than kangaroos are to elephants, as they started to evolve independently about 10 million years before the common ancestor of these two mammal groups.
There are just five species of midwife toad surviving today. The Iberian midwife toad diverged from the ancestor of all the other midwife toad species around 14 million years ago, around ten million years before the divergence of chimpanzees and humans.
Within the family Alytidae, the midwife toads diverged from their closest relatives, the painted frogs, about 155 million years ago, about 5 million years before the first birds started to appear in the fossil record. Midwife toads are therefore more different from their closest relatives than kangaroos are to elephants, as they started to evolve independently about 10 million years before the common ancestor of these two mammal groups.
There are just five species of midwife toad surviving today. The Iberian midwife toad diverged from the ancestor of all the other midwife toad species around 14 million years ago, around ten million years before the divergence of chimpanzees and humans.
Midwife toads are in fact frogs with stout bodies and toad-like warty skin. They have short, unwebbed fingers and long toes which are webbed at the base. Their eyes are large, with vertical slit-shaped pupils.
Iberian midwife toads are usually brownish with dark spots and a dirty white underside. They have small warts on the upper eyelids and a row of large warts from the tympanum (ear drum) to the groin area, which are often reddish in colour.
Males grow up to 36mm in total length, whilst females are larger and can reach 42mm. The size difference between males and females of this species is not larger than that seen in other species of anurans (frogs and toads) which do not display male parental care, discrediting the theory that their smaller size is a result of a reduction in sexual selection amongst males, as the maximum number of mates for any one male is limited due to this behavioural trait.
Iberian midwife toads are usually brownish with dark spots and a dirty white underside. They have small warts on the upper eyelids and a row of large warts from the tympanum (ear drum) to the groin area, which are often reddish in colour.
Males grow up to 36mm in total length, whilst females are larger and can reach 42mm. The size difference between males and females of this species is not larger than that seen in other species of anurans (frogs and toads) which do not display male parental care, discrediting the theory that their smaller size is a result of a reduction in sexual selection amongst males, as the maximum number of mates for any one male is limited due to this behavioural trait.
Midwife toads are nocturnal and highly terrestrial, living in the water only as tadpoles. To avoid drying out, Iberian midwife toads dig into the soil and bury themselves. They are particularly efficient forward burrowers and spend most of their time below ground. They use their forelimbs to scrape away the sandy soil, and can also use their head to scoop it out of the way. Once underground, they do push-ups to pack the soil above them into the roof of the tunnel. It is thought that forward burrowing evolved in midwife toads as a result of the use of the hind limbs in egg carrying.
Males call out to nearby females for several hours every night during breeding season, which peaks in October/ November. Females call back in response (unusual amongst the frogs and toads), and seek out the male of their choice. Competition between males is strictly non-aggressive and occurs only during the vocalisation stage; females prefer the males whose calls are most frequent.
A female will then present herself to a male by positioning herself in front of him, at which point the male will mount the female and clasp her around the waist. The male then uses a series of rocking body movements to prepare the female for ovulation, and then squeezes her sides causing her to release her eggs all at once. The female bends her hind limbs and presses her heels together and against her body to form a cup-shaped receptacle, into which a string of eggs is ejected. The male then fertilises the eggs. This method of sudden egg release and fertilisation is another adaptation to terrestrial life and conservation of water.
Once fertilised, the male moves his hind limbs through the sting of eggs, tangling it around his ankles. He carries the eggs for several weeks, keeping them moist by visiting pools of water, and discards them into a water body as the larvae hatch into tadpoles. Males can breed with more than one female per season, carrying up to four clutches of eggs around their legs, collecting a total of 180 eggs or more. The emergent tadpoles grow from 13mm up to 70mm in length, before metamorphosing into toadlets of around 24mm. It is at least two years until sexual maturity is reached.
Aside from their highly unusual breeding behaviour, midwife toads are also known for having a powerful defence mechanism against potential predators. The warts on their back produce a strong-smelling toxin when the toad is threatened, with enough potency to kill an adder (a venomous snake) in a matter of hours.
Males call out to nearby females for several hours every night during breeding season, which peaks in October/ November. Females call back in response (unusual amongst the frogs and toads), and seek out the male of their choice. Competition between males is strictly non-aggressive and occurs only during the vocalisation stage; females prefer the males whose calls are most frequent.
A female will then present herself to a male by positioning herself in front of him, at which point the male will mount the female and clasp her around the waist. The male then uses a series of rocking body movements to prepare the female for ovulation, and then squeezes her sides causing her to release her eggs all at once. The female bends her hind limbs and presses her heels together and against her body to form a cup-shaped receptacle, into which a string of eggs is ejected. The male then fertilises the eggs. This method of sudden egg release and fertilisation is another adaptation to terrestrial life and conservation of water.
Once fertilised, the male moves his hind limbs through the sting of eggs, tangling it around his ankles. He carries the eggs for several weeks, keeping them moist by visiting pools of water, and discards them into a water body as the larvae hatch into tadpoles. Males can breed with more than one female per season, carrying up to four clutches of eggs around their legs, collecting a total of 180 eggs or more. The emergent tadpoles grow from 13mm up to 70mm in length, before metamorphosing into toadlets of around 24mm. It is at least two years until sexual maturity is reached.
Aside from their highly unusual breeding behaviour, midwife toads are also known for having a powerful defence mechanism against potential predators. The warts on their back produce a strong-smelling toxin when the toad is threatened, with enough potency to kill an adder (a venomous snake) in a matter of hours.
The Iberian midwife toad is behaviourally adapted to very dry environments. It is found in meadows and open oak forests with sandy soils and dry adapted vegetation such as small evergreens with thickened leaves. It is dependent on streams and other water bodies for the larval (tadpole) stage of development.
Endemic to the Iberian Peninsula, this species is found in an area covering southern and eastern Portugal and western and central Spain at elevations between 100 and 1,300m above sea level.
More abundant in the western part of its range, it can be locally common where suitable habitat remains. The Iberian midwife toad is one of the more common amphibian species of southern Portugal.
The IUCN Red List of Threatened Species lists A. cisternasii as having a decreasing population trend. Population declines have been observed in Spain, for example around Madrid where deforestation is high.
Classified as Near Threatened on the 2006 IUCN Red List of Threatened Species. It is believed to be in significant decline, although probably at a rate of less than 30% over ten years.
Threats to this species include habitat alteration and loss, through destruction of the Mediterranean forest, urbanisation and pollution of aquatic habitats, and construction of canals and dams. The introduction of non-native species such as predatory fish and the Louisiana Crayfish Procamabrus clarkii has caused compounding threats to the Iberian midwife toad. The devastating chytrid fungus has already affected A. cisternasii’s close relative A. obstetricans in Spain, and represents a potential future threat to the species.
The Iberian midwife toad is protected by national legislation in Spain, and is known to occur in Cabañeros and Doñana National Parks. It is also protected under the EU Natural Habitats Directive and is listed as ‘strictly protected’ under the Bern Convention.
This species should be monitored closely, especially given the potential threat of chytridiomycosis.
AmphibiaWeb http://amphibiaweb.org/
Global Amphibian Assessment http://www.iucnredlist.org/amphibians
Midwife Toad http://en.wikipedia.org/wiki/Midwife_toad
Tree of Life Web Project http://tolweb.org/tree/
Global Amphibian Assessment http://www.iucnredlist.org/amphibians
Midwife Toad http://en.wikipedia.org/wiki/Midwife_toad
Tree of Life Web Project http://tolweb.org/tree/
Amphibiaweb: Information on amphibian biology and conservation [web application]. 2008. Berkeley, California: AmphibiaWeb. Available: http://amphibiaweb.org/. Accessed: 22 December 2008.
Behler, J. L. and Behler, D. A. 2005. Frogs: A Chorus of Colours. Sterling Publishing, USA.
Brown, L. E., Crespo, E. G. 2000. Burrowing behaviour of the midwife toads Alytes cisternasii and Alytes obstetricans (Anura, Discoglossidae). Alytes 17(3-4): 101-113.
Fromhage, L., Vences, M. and Veith, M. 2004. Testing alternative vicariance scenarios in Western Mediterranean discoglossid frogs. Molecular Phylogenetics and Evolution 31: 308-322.
Frost, D. 2008. Amphibian Species of the World: an Online Reference. Version 5.2 (22 December 2008). Electronic Database accessible at: http://research.amnh.org/herpetology/amphibia/index.php. American Museum of Natural History, New York, USA.
Halliday, T. and Adler, K. 2002. The New Encylopedia of Reptiles and Amphibians. Oxford University Press , UK.
IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 22 December 2008.
Martinez-Solano, I., Goncalves, H. A., Arntzen, J. W. and Garcia-Paris, M. 2004. Phylogenetic relationships and biogeography of midwife toads (Discoglossidae: Alytes). Journal of Biogeography 31(4): 603-618.
Marquez, R., Bosch, J. and Xavier, E. 2008. Intensity of female preference quantified through playback setpoints: call frequency versus call rate in midwife toads. Animal Behaviour 75(1): 159-166.
Marquez, R., Esteban, M. and Castanet, J. 1997. Sexual size dimorphism and age in the midwife toads Alytes obstetricans and A. cisternassi. Journal of Herpetology 31(1): 52-59.
Marquez, R. and Verrell, P. 1991. The courtship and mating of the Iberian midwife toad Alytes cisternasii (Amphibia: Anura: Discoglossidae). Journal of Zoology 225: 125-139.
Roelants, K., Gower, D. J., Wilkinson, M., Loader, S. P., Biju, S. D., Guillaume, K., Moriau, L. and Bossuyt, F. 2007. Global patterns of diversification in the history of modern amphibians. PNAS 104(3): 887-892.
Stuart, S. N., Hoffmann, M., Chanson, J. S., Cox, N. A., Berridge, R. J., Ramani, P. and Young, B. E. (eds.) 2008. Threatened Amphibians of the World. Lynx Edicions, Barcelona, Spain; IUCN, Gland, Switzerland; and the Conservation International, Arlington, Virginia, USA.
Tree of Life Web Project. 2008. Alytes. Version 25 November 2008 (temporary). http://tolweb.org/Alytes/17056/2008.11.25 in The Tree of Life Web Project, http://tolweb.org/
Distribution dataset: IUCN 2008. 2008 IUCN Red List of Threatened Species. http://www.iucnredlist.org
Behler, J. L. and Behler, D. A. 2005. Frogs: A Chorus of Colours. Sterling Publishing, USA.
Brown, L. E., Crespo, E. G. 2000. Burrowing behaviour of the midwife toads Alytes cisternasii and Alytes obstetricans (Anura, Discoglossidae). Alytes 17(3-4): 101-113.
Fromhage, L., Vences, M. and Veith, M. 2004. Testing alternative vicariance scenarios in Western Mediterranean discoglossid frogs. Molecular Phylogenetics and Evolution 31: 308-322.
Frost, D. 2008. Amphibian Species of the World: an Online Reference. Version 5.2 (22 December 2008). Electronic Database accessible at: http://research.amnh.org/herpetology/amphibia/index.php. American Museum of Natural History, New York, USA.
Halliday, T. and Adler, K. 2002. The New Encylopedia of Reptiles and Amphibians. Oxford University Press , UK.
IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 22 December 2008.
Martinez-Solano, I., Goncalves, H. A., Arntzen, J. W. and Garcia-Paris, M. 2004. Phylogenetic relationships and biogeography of midwife toads (Discoglossidae: Alytes). Journal of Biogeography 31(4): 603-618.
Marquez, R., Bosch, J. and Xavier, E. 2008. Intensity of female preference quantified through playback setpoints: call frequency versus call rate in midwife toads. Animal Behaviour 75(1): 159-166.
Marquez, R., Esteban, M. and Castanet, J. 1997. Sexual size dimorphism and age in the midwife toads Alytes obstetricans and A. cisternassi. Journal of Herpetology 31(1): 52-59.
Marquez, R. and Verrell, P. 1991. The courtship and mating of the Iberian midwife toad Alytes cisternasii (Amphibia: Anura: Discoglossidae). Journal of Zoology 225: 125-139.
Roelants, K., Gower, D. J., Wilkinson, M., Loader, S. P., Biju, S. D., Guillaume, K., Moriau, L. and Bossuyt, F. 2007. Global patterns of diversification in the history of modern amphibians. PNAS 104(3): 887-892.
Stuart, S. N., Hoffmann, M., Chanson, J. S., Cox, N. A., Berridge, R. J., Ramani, P. and Young, B. E. (eds.) 2008. Threatened Amphibians of the World. Lynx Edicions, Barcelona, Spain; IUCN, Gland, Switzerland; and the Conservation International, Arlington, Virginia, USA.
Tree of Life Web Project. 2008. Alytes. Version 25 November 2008 (temporary). http://tolweb.org/Alytes/17056/2008.11.25 in The Tree of Life Web Project, http://tolweb.org/
Distribution dataset: IUCN 2008. 2008 IUCN Red List of Threatened Species. http://www.iucnredlist.org
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