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Il genere Austropotamobius

Molto probabilmente il genere Austropotamobius ha avuto origine in una vasta area rappresentata l'Istria, la zona a sud di Ljubljana ed il bacino del fiume Kolpa. In seguito, attraverso il processo di speciazione, si sono originati A. torrentium sul versante pannonico ed A. pallipes in quello adriatico. Nonostante i molti lavori pubblicati sulla tassonomia e la distribuzione dei gamberi d'acqua dolce, inclusi i lavori recenti sulla filogenesi, la situazione resta alquanto confusa. In modo particolare riguardo al genere Austropotamobius. Per questo genere sono state segnalate varie sottospecie, molte delle quali rivelatesi delle varietà. Austropotamobius torrentium, descritto per la prima volta nel 1803, è stato spesso confuso con la sua specie sorella (A. pallipes) descritta nel 1858. Fino agli anni venti la letteratura riportava "Astacus torrentium" o "Astacus saxatilis" per indicare A. pallipes o A. torrentium.

Within the two species of the genus Austropotamobius, variable conditions of the habitat have been recorded. Perhaps some restrictions may occur when the size of the waterbody is considered. Several studies have identified smaller streams to be a typical habitat for the two species A. pallipes and A. torrentium. Whereas the white-clawed crayfish A. pallipes is less specific for a specific biotope -it can be found in all kinds of lentic waters, as well as in mountain streams and small brooks draining through meadows, the stone crayfish A. torrentium typically inhabits smaller running water systems with rocky substrate. Its ecological spectrum is not only enriched by locations in smaller lakes, (e.g. Bavaria, Tyrol) but also in rivers in the former Yugoslavia providing habitat for stone crayfish. The white-clawed erayfish is also less specific with regard to its preferred substrate type. Considering the water quality characteristics, both the white-clawed crayfish and the stone crayfish, like the noble crayfish, do not inhabit waters with certain conditions. Several studies have shown that this is true for the main parameters, i.e. temperature, oxygen content, pH and hardness, but also for the pollution indieators ammonia, nitrite and nitrate. These species show relatively high tolerance values. An exception could be the stone crayfish where tolerance values for temperature and oxygen content are lower than in the other species. When the specific biotope is considered, stone crayfish show a tendency to occupy streams or upper reaches of rivers, whereas noble crayfish and white-clawed crayfish may inhabit all kinds of freshwater.

  Genere Specie  
Austropotamobius

Austropotamobius pallipes

Austropotamobius torrentium

 


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