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Cordulegaster bidentata

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA ARTHROPODA INSECTA ODONATA CORDULEGASTRIDAE

Scientific Name: Cordulegaster bidentata
Species Authority: Selys, 1843
Common Name(s):
English Sombre Goldenring
French Cordulegastre Bidenté
Taxonomic Notes: Sicilian populations have more extended yellow marks and have been described as a distinct subspecies, C. bidentata sicilica Fraser, 1929. Populations from Calabria have been ascribed to this subspecies, but they show smaller yellow spots and an obvious variability, so that they are intermediate between this subspecies and the nominal one. The populations in the southern Balkans are distinct from C. b. sicilica but have larger yellow spots than the nominal subspecies. The overall systematic organisation of the various members of this taxon remains presently unclear (Boudot, 2001; Boudot et al., 2009).

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2010
Date Assessed: 2009-04-21
Assessor(s): Boudot, J.-P.
Reviewer(s): Bernard, R., Conze, K.-J., Dyatlova, E., Ott, J. & Sahlen, G.
Justification:
European regional assessment: Near Threatened (NT)
EU 27 regional assessment: Near Threatened (NT)

The species has a very wide extent of occurrence, but its specialized habitat means its area of occupancy is much smaller. Due to its sensitivity to habitat changes and the possibility of declining permanency of sources in its range, it is assessed as Near Threatened. However, the Sicilian subspecies, C. b. sicilica, is very rare and might be endangered.

In the Balkans and eastern Carpathians, C. bidentata is sometimes found in strong populations. Further genetic work is required to determine the taxonomic status of the different populations.

Geographic Range [top]

Range Description: Cordulegaster bidentata is endemic to Europe occurring in western, south, southeast and central Europe. The eastern limit of the species are the Carpathians in the west of the Ukraine.
Countries:
Native:
Albania; Andorra; Austria; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Czech Republic; France (France (mainland)); Germany; Greece (Greece (mainland)); Hungary; Italy (Italy (mainland), Sicilia); Liechtenstein; Luxembourg; Macedonia, the former Yugoslav Republic of; Moldova; Montenegro; Poland; Romania; Serbia (Serbia); Slovakia; Slovenia; Spain (Spain (mainland)); Switzerland; Ukraine (Ukraine (main part))
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is much more localised than Cordulegaster boltonii but is moderately scattered in central and western Europe. It shows very variable densities from one locality to another, ranging from only one visible (reproducing) individual to obviously flourishing populations.

Adults are often hidden and are quite difficult to find. Their larval sites are sometimes difficult to access or recognize, particularly in mountainous areas. As a result, this is a poorly known species that is often overlooked by odonatologists and was in the past erroneously considered to be extinct in some countries.

There is no recent record referring to the Sicilian subspecies (Cordulegaster bidentata sicilica) in Sicily, which was always very rare - the last record from Sicily was in 1981 (Galletti and Pavesi 1985, Verschuren 1989). Only few records of C. b. sicilica may correspond to identified breeding sites.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: The larvae are confined to the sources and upper courses of brooks. The species is thus highly specialized and reproduces mainly in headwater streams, with the best habitats in tufa springs and calcareous small brooks. Its reproducing habitat is often difficult to find. In some areas it seems to have been extirpated in acidified brooks as a result of acid rains, but in other areas it is still recorded in streams with a pH <4.
Systems: Terrestrial; Freshwater

Threats [top]

Major Threat(s): The major threats to this species are drought as a result of global warming, particularly in the south of its range, and water extraction for human use and irrigation. Some populations are threatened by water acidification due to acid rains or conifer plantations and forest closure whereas other populations show not to be affected by this. In the south of France, former flourishing populations are known to be extinct as a result of rainfall deficit and recent very hot summers and related spring exhaustion. In north Greece and other Mediterranean countries, some populations were extinct as a result of water capture directly at the source for irrigation.

Conservation Actions [top]

Conservation Actions: Necessary conservation measures include the preservation of good quality water resources, particularly in headwaters, and the preservation and restoration of broadleaved open forests. A better knowledge of the breeding sites of the Sicilian subspecies is in need.

Citation: Boudot, J.-P. 2010. Cordulegaster bidentata. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 30 July 2014.
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