Overview

Comprehensive Description

Summary

Pelobates varaldii is known only from fragmented localized areas along the Atlantic coastal plains of northwestern Morocco, within the Mediterranean forests and woodlands ecoregion. This small fossorial toad is particularly associated with sandy plains near cork oak forests. Diagnostic features include vertical pupils and webbed toes. Breeding sites are ephemeral lentic water bodies, which are scarce in this region. This endangered species is under threat from an expanding human population in the region, with proximate drivers of urbanization, conversion of coastal plains to farmland, and extraction of scarce water resources for human use.

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Description

Pelobates varaldii is a wide-headed Pelobates with an average male snout-vent length of 43.9 - 60.6 mm and body mass of a 10 - 24 g while average female snout-vent length 45.0 - 64.1 mm and body mass of 11 - 27 g (Guarino et al. 2011). The head is slightly concave between the eyes and the nostril is midway between the snout and anterior border of the eye. The eyes have vertical pupils and the tympanum is inconspicuous. This species has three inconspicuous palmar tubercles, and a lack of articular tubercles. The dorsum lacks both dorsolateral folds and paratoid glands. The skin is smooth with small reddish warts on the dorsum and eyelids (Salvador 1996).

The dorsum is grayish brown with irregular dark spots. The venter is whitish. Pelobates varaldii has blackish metatarsal tubercles with whitish bases. The irises are a yellowish copper or black-spotted greenish (Salvador 1996).

  • Alfredo Salvador, David Donaire-Barroso, Tahar Slimani , El Hassan El Mouden, Philippe Geniez 2004. Pelobates varaldii. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. Downloaded on 09 March 2013.
  • Guarino, FM; de Pous, P; Crottini, A; Mezzasalma, M; Andreone, F. 2011. Age structure and growth in a population of Pelobates varaldii (Anura, Pelobatidae) from northwestern Morocco. Amphibia-Reptilia 32(4): 550-556
  • Salvador, A. (1996). ''Amphibians of Northwest Africa.'' Smithsonian Herpetological Information Service, (109), 1-43.
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Distribution

Range Description

This species is known only from fragmented localized areas on the coastal plains of north-western Morocco. The northernmost location is the town of Larache, while the southernmost population is known from the north-eastern part of the salt marshes of Oualida. The species may range further south than Oualidia, and this possible range extension requires further investigation. Yus Ramos and Cabo Hernandez (1986) mentioned the presence of Pelobates cultripes in the Melilla region (Spain), which might refer to P. varaldii, though this record is far outside the known range of any Pelobates species. P. varaldii is not found above 350m asl.
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P. varaldii is known only from fragmented localized areas along the coastal plains of northwestern Morocco. The northernmost location is the town of Larache, while the southernmost population is the northeastern part of the salt marshes of Oualida. The range may continue further south than Oualidia, and this potential range extension merits further field research. Ramos and Hernandez (1986) noted the presence of Pelobates cultripes in the Melilla region of Spain, which observation could refer to P. varaldii, though this record is far outside the known range of any Pelobates species.

While the IUCN classifies the species as freshwater, it is sometimes found in brackish coastal waters.The population of P. varaldii is inherently disjunctive, with the largest contiguous area stretching from the coastal zone north of Larache, Morocco to south of Rabat, Morocco; smaller habitat patches are found further south reaching almost as far as Safi, Morocco. P. varaldii is endemic to the Mediterranean forests and woodlands ecoregion, but is found only on the Atlantic side of that ecoregion, especially on sandy plains near cork oak (Quercus suber) forests (World Wildlife Fund & Hogan, 2007).

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Distribution and Habitat

Pelobates varaldii has a fragmented distribution in the coastal plains of northwestern Morocco (Guarino et al. 2011). It ranges from as far north as Larache to as far south as the northeastern salt marshes of Oualida (Salvador 2004). This toad is confined to sandy soil habitats (Salvador 1996), preferring uncultivated soils sometimes in the vicinity of cork woodlands. Pelobates varaldii has not been found in habitats altered by humans or above 350 m above sea level (Salvador 2004).

  • Alfredo Salvador, David Donaire-Barroso, Tahar Slimani , El Hassan El Mouden, Philippe Geniez 2004. Pelobates varaldii. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. Downloaded on 09 March 2013.
  • Guarino, FM; de Pous, P; Crottini, A; Mezzasalma, M; Andreone, F. 2011. Age structure and growth in a population of Pelobates varaldii (Anura, Pelobatidae) from northwestern Morocco. Amphibia-Reptilia 32(4): 550-556
  • Salvador, A. (1996). ''Amphibians of Northwest Africa.'' Smithsonian Herpetological Information Service, (109), 1-43.
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Physical Description

Morphology

The species head is wide, with a concave element between the eyes. Nostrils are equidistant between the snout and anterior eye edge. The eyes are prominent, with horizontal diameter greater than distance between eye and nostril. The iris is a yellowish-copper or greenish with black spots. Digits lack articular tubercles. Three inconspicuous palmar tubercles are present. The metatarsal tubercle exhibits a whitish base. The exterior skin is smooth, with small reddish warts on the eyelids and dorsum. The dorsum itself is grayish-brown with irregular dark spots; the venter is whitish.

Some P. varaldii individuals exhibit a metatarsal tubercle that is totally keratinized. Furthermore, a number of the adult population may manifest red spots on their upper eyelids, although such spots are lacking in most individuals (Salvador, 1996).

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Size





The adult snout-vent length may achieve 65 millimeters (mm) in the male and 70 mm in the female.(Salvador. 1996)
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Diagnostic Description

In all of northwestern Africa, there are thirteen species of anurans. P. varaldii is the only anuran with vertical pupils that lacks adhesive tips on fingers and toes and that has the following additional features: black keratinous spade (modified metatarsal tubercle) evident along with two rather small, inconspicuous palmar tubercles and webbed toes. The closest other anuran in morphology is Alytes obstetricians, who lacks webbing, has three palmar tubercles and lacks the keratinous spade (Salvador, 1996).

Further diagnostics of the species are smooth skin, lack of dorsolateral glandular folds, lack of paratoid glands and inconspicuous tympanum (Salvador, 1996).

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Ecology

Habitat

Habitat and Ecology

P. varaldii is fundamentally fossorial in habit, dwelling chiefly in sandy lowland uncultivated soils, frequently found in the vicinity of cork woodlands. The species breeding sites are most often lentic temporary water bodies, such as, dayas and rain puddles. P. varaldii is not known to be adaptive to anthropogenically modified habitats (Salvador et al. 2004). This species is known to occur only between sea level and 350 meters above sea level (Salvador et al. 2004).

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Habitat and Ecology

Habitat and Ecology
It is generally fossorial, inhabiting lowland sandy uncultivated soils, sometimes in the vicinity of cork woodlands. The spawning sites are most often still temporary waterbodies (such as dayas and rain puddles). It does not occur in anthropogenically modified habitats.

Systems
  • Terrestrial
  • Freshwater
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Life History and Behavior

Behavior

Activity and Special Behaviors

P. varaldii is a nocturnal anuran, and is active in autumn and winter seasons only. This toad remains buried in the soil during the daytime, and appears to be confined to sandy soils. Prey consist of a variety of invertebrates (Salvador, 1996).

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Life Cycle

Metamorphosis

Metamorphosis generally occurs in May or June, and the young exit their surface water body with stubby tails. Newly metamorphosed individuals generally measure 21 to 34 millimeters as a snout-vent length (Salvador, 1996).

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Reproduction

Amplexus takes place in the surface breeding waters, with ova-deposition into the waters requiring only five to ten minutes, and eggs being laid in a string 1.0 to 1.5 meters in length. The species typically breeds in temporary ponds or puddles. The eggs themselves are dark grey in color, and each egg measuring 1.15 to 2.00 millimeters in diameter. Larvae hatch within a week after laying. The tadpoles feed on plankton and detritus (Salvador, 1996).

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Growth

Tadpole morphology

Tadpoles of P. varaldii can attain a length of 13 centimeters (Salvador, 1996).

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Pelobates varaldii

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 4
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Category and Justification of Conservation Status

P. varaldi has been classified as as Endangered (B2ab(iii) ver 3.1) by the IUCN since its Area of Occupancy is likely less than 500 square kilometers, and the species distribution is severely fragmented along the northwest Moroccan coastal zone; furthermore, there is a continuing decline in the extent and quality of its habitat in Morocco, due to the growth of the human population and associated exploitation of the coastal zone (Salvatore et al. 2004).

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IUCN Red List Assessment


Red List Category
EN
Endangered

Red List Criteria
B2ab(iii)

Version
3.1

Year Assessed
2004

Assessor/s
Alfredo Salvador, David Donaire-Barroso, Tahar Slimani , El Hassan El Mouden, Philippe Geniez

Reviewer/s
Global Amphibian Assessment Coordinating Team (Simon Stuart, Janice Chanson and Neil Cox)

Contributor/s

Justification
Listed as Endangered because its Area of Occupancy is probably less than 500km2, its distribution is severely fragmented, and there is a continuing decline in the extent and quality of its habitat in Morocco.
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According to the IUCN, there was no information on the population status of P. varaldi, although at that time the species population was thought to be declining (Salvador et al. 2004).

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Population

Population
There is no information on the population status of this species, although it is believed to be declining.

Population Trend
Decreasing
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Life History, Abundance, Activity, and Special Behaviors

Pelobates varaldii is fossorial and seasonally nocturnal, spending the day buried in the soil and becoming active at night only in the autumn and winter to feed on assorted selection of invertebrates. Breeding and amplexus is carried out in temporary ponds. Egg-laying lasts 5 - 10 minutes, resulting in a 1 - 1.5 m long string of dark grey eggs with a diameter of 1.15 - 2 mm. Hatching takes place within a week after laying, resulting in tadpoles that reach 130 mm in length that feed on detritus and plankton. Metamorphosis occurs in May and June, giving rise to individuals with a snout-vent length of 21 - 34 mm and a stubby tail (Salvador 1996).

  • Alfredo Salvador, David Donaire-Barroso, Tahar Slimani , El Hassan El Mouden, Philippe Geniez 2004. Pelobates varaldii. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. Downloaded on 09 March 2013.
  • Guarino, FM; de Pous, P; Crottini, A; Mezzasalma, M; Andreone, F. 2011. Age structure and growth in a population of Pelobates varaldii (Anura, Pelobatidae) from northwestern Morocco. Amphibia-Reptilia 32(4): 550-556
  • Salvador, A. (1996). ''Amphibians of Northwest Africa.'' Smithsonian Herpetological Information Service, (109), 1-43.
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Threats

Significant threats are at play, since this part of Morocco is under intense pressure from an expanding human population. Chief manifestations of this pressure is urbanization of the coastal zone, agricultural land conversion on the coastal plain and extraction of surface water resources, which are in scarcity within the species range. In addition there are instances of overgrazing, arising from the pressure of developing food resources for an expanding human population (World Wildlife Fund & Hogan, 2007). These threats are exacerbated by a trend in the last three decades, in which snowmelt has occurred earlier in the season, reducing the amount of late spring runoff and thus reducing formation of ephemeral ponds.

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Major Threats
The major threats include habitat loss and degradation due to the conversion of land to livestock pasture, and the pollution of stagnant waters with livestock droppings (Schleich, Kästle and Kabisch 1996). In addition, arable agriculture may be leading to the loss or disturbance of the sandy substrate soil habitat, with which the species is strongly associated. Populations of the species are now often restricted to temporary ponds, and those remaining in permanent waterbodies are being eliminated through the presence of predatory fishes (specifically Gambusia holbrooki).
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Life History, Abundance, Activity, and Special Behaviors

Pelobates varaldii is listed as 'Endangered' with a declining population by the IUCN Red List. Pelobates varaldii populations may be declining as a result of the propagation of pasture for livestock and the contamination of stagnant water with livestock waste, leading to degradation and loss of habitat. The sandy substrate soil that they inhabit may also be degraded or lost by arable agriculture. The few remaining populations inhabiting permanent bodies of water face elimination through predation by Gambusia holbrooki and other fish (Salvador 2004).Pelobates varaldii has also been listed in the Evolutionary Distinctive and Globally Endangered (EDGE) program of the Zoological Society of London on place 36 of their global amphibian top 100 based on the species Evolutionary Distinctiveness and Global Endangerment scores (Guarino et al. 2011).

  • Alfredo Salvador, David Donaire-Barroso, Tahar Slimani , El Hassan El Mouden, Philippe Geniez 2004. Pelobates varaldii. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. Downloaded on 09 March 2013.
  • Guarino, FM; de Pous, P; Crottini, A; Mezzasalma, M; Andreone, F. 2011. Age structure and growth in a population of Pelobates varaldii (Anura, Pelobatidae) from northwestern Morocco. Amphibia-Reptilia 32(4): 550-556
  • Salvador, A. (1996). ''Amphibians of Northwest Africa.'' Smithsonian Herpetological Information Service, (109), 1-43.
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Wikipedia

Varaldi's Spadefoot Toad

The Moroccan Spadefoot Toad, Varaldi's Spadefoot Toad, Pélobate De Varaldi, or Pélobate Marocain (Pelobates varaldii) is a species of frog in the Pelobatidae family. It is found in Morocco and possibly Spain. Its natural habitats are subtropical or tropical dry shrubland, rivers, intermittent rivers, freshwater marshes, and intermittent freshwater marshes. The species is threatened by habitat loss.

According to C.Michael Hogan, the species breeding sites are ephemeral lentic water bodies, which surface waters are scarce in the species range.

References

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