Betic midwife toad (Alytes dickhilleni)

Description

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Betic midwife toad fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Betic midwife toad description

A small, distinctive species belonging to an ancient family of amphibians, the Betic midwife toad (Alytes dickhilleni) is one of just five surviving species of midwife toad. The common name of the midwife toads (species in the genus Alytes) refers to the unusually high level of parental care exhibited by the male ⁽³⁾.

The Betic midwife toad is generally greyish in colour and is scattered with a mixture fine black, grey and pale dots on the back, which give it a somewhat ‘dusty’ appearance ^{(2) (3)}. It has large eyes with vertical, slit-shaped pupils, a round, flattened tongue, long limbs, and long, unwebbed fingers and toes. The skin is generally fairly smooth and shiny, except for a defined line of white glandular bumps or warts running along the sides of the back ⁽³⁾.

This species has a distinctive area of grey between the eyes, as well as short, slim, raised glands on the back of the head behind each eye. Unlike other Alytes species, the Betic midwife toad does not have reddish-orange glandular spots ^{(2) (3)}.

Spanish

Sapo Partero Bético.

Size

Snout-vent length: 3.5 cm ⁽²⁾

Betic midwife toad biology

The Betic midwife toad is a rather shy, nocturnal amphibian, spending much of the day hidden away in damp underground refuges, close to water ⁽³⁾. Like other midwife toads, this species displays a rather unusual breeding behaviour, in which the male provides all of the parental care ⁽⁶⁾.

During the breeding season, the male Betic midwife toad has a rather distinctive, ringing call and will also make short, ‘peeping’ calls from its underground burrow to attract the female ⁽³⁾. Calls are the primary mating display of this species ⁽⁷⁾, and the male may also call from open ground or from crevices, usually within 50 metres of where the tadpoles will eventually develop ⁽⁶⁾. The female midwife will respond to the advertising male by calling back in reply, which is fairly unusual among most species of frogs and toads ⁽⁶⁾.

During mating, the male grasps the female firmly in a mating embrace known as amplexus, during which the female will produce a long string of eggs. As in other midwife toads, the male Betic midwife toad then begins a complicated procedure to fertilise the eggs and then wrap the string around its hind legs ^{(3) (6)}. The male will often mate with several females during the breeding season, and is typically able carry up to three clutches of eggs at a time ⁽⁶⁾. 

The eggs remain bound to the hind legs of the male for around a month, with the male providing all of the care for the eggs, protecting them from predation and preventing them from drying out ^{(3) (6)}. During this time, the male will frequently shelter in damp refuges or under stones, sometimes visiting pools of water to keep the eggs moist ⁽³⁾. Once the eggs are ready to hatch, the male will deposit them in water. Betic midwife toad tadpoles develop over a long period of time ⁽¹⁾, often up to a year ⁽⁶⁾, in permanent mountain streams, man-made reservoirs or cattle troughs ⁽¹⁾.

The Betic midwife toad has a fairly varied diet. The adult toad typically feeds on a range of invertebrates, including beetles, crickets, flies, caterpillars, centipedes and millipedes. Tadpoles of this species feed mainly on plant matter ⁽³⁾.

The Betic midwife toad is unusual among amphibians in having a powerful defence mechanism against predators. Like other members of its family, the back of the midwife toad is covered in small warts which produce a potent, strong-smelling poison when threatened ⁽³⁾.

Betic midwife toad range

An endemic amphibian of south-eastern Spain ^{(1) (2) (4)}, the Betic midwife toad has a rather fragmented distribution ⁽¹⁾. It is largely restricted to the mountain ranges of the Sierra Tejeda, Sierra Almijara, Sierra de Gádor, Sierra de Baza, Sierra Mágina and the Sierra de Alcaraz ^{(2) (3)}. 

A number of other isolated populations occur elsewhere in the Iberian Peninsula, including populations in the Sierra Nevada, Sierra de Filabres, Sierra de Castril, Sierra Magina and Sierra de Cazorla, as well as in parts of Jaén and southwest Granada ⁽⁴⁾.

The Betic midwife toad occurs at elevations of 700 to 2,140 metres ⁽¹⁾. 

Betic midwife toad habitat

Many of the Betic midwife toad’s populations are confined to isolated mountains and valleys. It is typically found in pine and oak forests and in rocky, open landscapes, and is commonly encountered on rock fissures, eroded soils and on or under stones next to water ^{(1) (2)}. It may also be found in the cracks and crevices of cliffs, and on slopes of loose soil on the verge of roads and highways ⁽⁴⁾. The Betic midwife toad is often rare in the drier parts of its range, and populations in these areas are typically associated with springs ⁽¹⁾.

The Betic midwife toad breeds in clear mountain streams ⁽⁵⁾, as well as in man-made reservoirs and artificial pools such as cattle troughs ^{(2) (3)}.

Betic midwife toad status

The Betic midwife toad is classified as Vulnerable (VU) on the IUCN Red List ⁽¹⁾.

Betic midwife toad threats

Across Europe, habitat loss and degradation have had a huge impact on amphibian populations ⁽⁸⁾. The Betic midwife toad is particularly threatened by loss of suitable breeding habitat as a result of excessive water withdrawal, drought, and changing agricultural practices which have led to man-made water bodies, particularly cattle troughs, being abandoned or removed ^{(1) (2) (3)}.

The disease chytridiomycosis is likely to become a serious threat to amphibians in the Mediterranean basin in future, and has already been implicated in catastrophic amphibian declines in many parts of the world ⁽⁸⁾. It is probable that chytridiomycosis may begin to affect populations of the Betic midwife toad, especially as the deadly disease is already impacting populations of closely-related species such as the common midwife toad (Alytes obstetricans) in Spain ^{(1) (3)}.

Many populations of the Betic midwife toad are extremely small and isolated and, as this species’ habitat is highly fragmented, there is little or no movement of individuals between populations. As a result, it is likely that there is an ongoing loss of genetic variation in this species, and its fragmented populations are also at greater risk from environmental disasters and disease ⁽³⁾.

Climate change may also become an important factor governing this species’ distribution in the future ⁽⁵⁾. Pollution has also been identified as having a major impact on amphibian populations in Europe, with the potential to impact the Betic midwife toad ⁽⁸⁾.

Betic midwife toad conservation

The Betic midwife toad is listed under Alytes obstetricans on Appendix II of the Bern Convention ⁽¹⁾, which aims to ensure conservation and protection of wild plant and animal species and their natural habitats ⁽⁹⁾. It is also included in regional Red Data Books as a threatened species ^{(1) (3)}. There have been calls for this species to be given immediate legal protection due to its restricted range and the small size of its populations ⁽²⁾. 

The Betic midwife toad occurs in a number of protected areas, including the Parque Nacional Sierra Morena, Parque Nacional de Sierra Nevada, and the Natural Park of Cazorla, Segura y las Villas, thus affording this species some level of protection ⁽¹⁾.

Current conservation actions for the Betic midwife toad include closely monitoring and researching the effects of the deadly fungal disease chytridiomycosis on its populations, especially as occurrences of the disease have already been identified in other closely-related species. The possibility of establishing a captive breeding programme for the Betic midwife toad in response to the threat of disease should also be considered ⁽³⁾.

Protecting existing breeding habitat and creating areas of new breeding habitat have been identified as priorities for the conservation of the Betic midwife toad ⁽³⁾. A number of protection measures for this species are currently underway in Castilla-La Mancha, Andalusia, including the restoration and construction of new breeding habitat ⁽¹⁾. The EDGE programme has recommended that additional breeding habitat, such as ponds and refuges, should be created, particularly in areas where agricultural practices have reduced the number of accessible water bodies ⁽³⁾.

The EDGE team have also suggested that an initiative to move individuals between isolated populations, or connect up the fragmented habitat of the Betic midwife toad, would greatly benefit conservation efforts, although care would have to be taken to prevent the spread of disease between different populations ⁽³⁾.

In addition to current and planned conservation measures, the Spanish Institute for Nature Conservation (ICONA) has commissioned a study to assess the conservation status of the Betic midwife toad ^{(2) (3)}.

Find out more

Find out more about the Betic midwife toad:

• EDGE - Betic midwife toad:
  http://www.edgeofexistence.org/amphibians/species_info.php?id=601
• AmphibiaWeb - Betic midwife toad:
  http://amphibiaweb.org/cgi/amphib_query?where-genus=Alytes&where-species=dickhilleni

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Glossary

Amplexus

The mating position of frogs and toads, in which the male clasps the female around the back or waist.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Fertilisation

The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.

Genetic variation

The variety of genes within a particular species, population or breed causing differences in morphology, physiology and behaviour.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Gland

An organ that makes and secretes substances used by the body.

Glandular

Relating to or bearing glands, organs that make and secrete substances used by the body.

Invertebrates

Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones), echinoderms, and others.

Larvae

The stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Nocturnal

Active at night.

References

1. IUCN Red List (October, 2011)
   http://www.iucnredlist.org/
2. AmphibiaWeb - Betic midwife toad (October, 2011)
   http://amphibiaweb.org/cgi/amphib_query?where-genus=Alytes&where-species=dickhilleni
3. EDGE - Betic midwife toad (October, 2011)
   http://www.edgeofexistence.org/amphibians/species_info.php?id=601
4. García-París, M. and Arntzen, J.W. (2002) Alytes dickhilleni Arntzen & García-París, 1995. Sapo partero bético. In: Pleguezuelos, J.M., Márquez, R. and Lizana, M. (Eds.) Atlas y Libro Rojo de los Anfibios y Reptiles de España. Dirrección General de Conservación de la Naturaleza - Asociación Herpetologica Española, Madrid. Available at: 
   http://www.marm.es/imagenes/es/0904712280003ce5_tcm7-21362.pdf
5. Egea-Serrano, A., Oliva-Paterna, F.J., Tejedo, M. and Torralva, M. (2006) Breeding habitat selection of an endangered species in an arid zone: the case of Alytes dickhilleni Arntzen & García-París, 1995. Acta Herpetologica, 1(2): 81-94.
6. Wells, K.D. (2007) The Ecology and Behaviour of Amphibians. University of Chicago Press, Chicago.
7. Bosch, J. and Boyero, L. (2003) Precopulatory behaviour and the evolutionary relationships of Discoglossidae. Journal of Zoological Systematics and Evolutionary Research, 41: 145-151.
8. Cox, N., Chanson, J. and Stuart, S. (2006) The Status and Distribution of Reptiles and Amphibians of the Mediterranean Basin. IUCN, Gland, Switzerland and Cambridge, UK.
9. Council of Europe: Bern Convention (October, 2011)
   http://conventions.coe.int/Treaty/EN/Treaties/Html/104.htm