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Prionotropis rhodanica 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Insecta Orthoptera Pamphagidae

Scientific Name: Prionotropis rhodanica Uvarov, 1923
Common Name(s):
English Crau Plain Grasshopper, Crau Stone Grasshopper
Synonym(s):
Prionotropis hystrix ssp. rhodanica Uvarov, 1923
Taxonomic Source(s): Massa, B., Ünal, M. and Lo Verde, G. 2015. A revision of the genus Prionotropis Fieber, 1853 (Orthoptera: Pamphagidae: Thrinchinae). Zootaxa 4059(3): 499-524.
Taxonomic Notes: Prionotropis hystrix subsp. rhodanica Uvarov, 1923 was raised to species level by Massa and Ünal (2015).

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(i,ii,iii,iv,v)c(iv) ver 3.1
Year Published: 2016
Date Assessed: 2016-04-20
Assessor(s): Hochkirch, A. & Tatin, L.
Reviewer(s): Bushell, M. & Cálix, M.
Contributor(s): Danielczak, A.
Justification:
The Crau Plain Grasshopper (Prionotropis rhodanica) is endemic to a very small area in southern France. This species is assessed as Critically Endangered since it has an extent of occurrence (EOO) of ca 40 km², the population is severely fragmented and shows extreme fluctuations in the number of mature individuals. In addition, a continuing decline in the EOO, area of occupancy (AOO), number of subpopulations, extent and quality of the habitat and in the number of mature individuals has been observed. In the past, this species declined mainly because of the destruction of its habitat, which has been transformed into meadows, orchards, olive yards or industrial areas. One of the remaining subpopulations is found in a military area and another within a car training course, where the construction of a new road is planned. The reasons for the decline of this species within the nature reserve "Réserve naturelle nationale des Coussouls de Crau" are poorly understood and are being studied. A conservation strategy was developed in 2014 and is currently being implemented. A captive breeding programme has been established at Thoiry Zoo and the first experimental reintroductions of egg pods were performed in 2015. Suitable habitat management needs to be implemented as soon as the major threats are understood. Remaining unprotected habitats should be integrated into the reserve. Destroyed habitats need to be restored and the plans for new road constructions need to be stopped.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Crau Plain Grasshopper is endemic to the Crau Steppe in southern France (Foucart and Lecoq 1998). Its extent of occurrence (EOO) is ca 40 km², and its area of occupancy (AOO) is ca 12 to 16 km².
Countries occurrence:
Native:
France (France (mainland))
Additional data:
Estimated area of occupancy (AOO) - km2:12-16Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):UnknownEstimated extent of occurrence (EOO) - km2:40
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):Unknown
Number of Locations:1Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:Unknown
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The Crau Plain Grasshopper has dramatically declined during the 20ᵗʰ century as a consequence of the destruction of its habitat (Foucart et al. 1999). Since the beginning of the 21ˢᵗ Century the species has strongly declined even within the protected area ("Réserve naturelle nationale des Coussouls de Crau"). A population reduction of 70% during the last ten years is suspected from the reduction of its area of occupancy (AOO). The remaining subpopulations are very isolated and separated by roads (Streiff et al. 2005). The species is flightless, not able to recolonise sites rapidly, and subpopulations may go extinct with a reduced probability of recolonization. The population is therefore considered severely fragmented. The species is also known to show extreme fluctuations in the number of mature individuals (A. Foucart pers. comm. 2015). Based on a recent mark-recapture experiment, the complete population size is likely to smaller than 5,000 mature individuals.
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:This species occurs only in a stone steppe habitat. It prefers areas which are rich in stones and scarce in vegetation. The generation length is one year, nymphs hatch in April and become adult at the end of May. Adults can be found until the beginning of July. Eggs appear to take two years for development (L. Bröder, L. Tatin and A. Foucart pers. comm. 2016).
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):0
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: This species is not utilised.

Threats [top]

Major Threat(s): In the past, this species declined mainly because of destruction of its habitat, which has been transformed into meadows, orchards, olive yards or industrial areas. One of the remaining subpopulations is found in a military area. Recent plans of the French army to construct new buildings on one of the sites have been stopped. Another subpopulation is found within a car training course, where currently the construction of a new road is planned. The reasons for the decline within the nature reserve are poorly understood. It is currently being studied whether it might have been affected by predation (by birds, e.g. cattle egret, which has strongly increased in this area), by sheep medication (since many grasshoppers regularly feed on sheep faeces), by general changes of the grazing regime (e.g. overgrazing), or by climate change (e.g. droughts during the egg period).

Conservation Actions [top]

Conservation Actions: Parts of the Crau Steppe are protected in the "Réserve naturelle nationale des Coussouls de Crau" since 2001, but other parts are not protected. It is listed as Critically Endangered on the French Red List (Sardet and Defaut 2004). A strategic conservation plan for the Crau Plain Grasshopper has been developed in 2014 and is currently being implemented (Hochkirch et al. 2014). This includes research into the population size and threats as well as a captive breeding program at Thoiry Zoo. Furthermore, the site of one of the remaining subpopulations has been excluded from grazing during the activity period of the grasshopper, while grazing in spring (before eggs were hatching) has been applied at another site that was overgrown with vegetation. Awareness programs are also underway. Suitable habitat management needs to be implemented as soon as the major threats are understood. Remaining unprotected habitats should be integrated into the reserve. Destroyed habitats need to be restored and the plans for new road constructions need to be stopped. Reintroduction is planned at sites where the species became extinct recently as soon as the reasons for its disappearance are understood. The species should be protected by law.

Citation: Hochkirch, A. & Tatin, L. 2016. Prionotropis rhodanica. The IUCN Red List of Threatened Species 2016: e.T15038481A47713628. . Downloaded on 20 June 2018.
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