New invader colonises the Danube: Quistadrilus multisetosus (Smith, 1900) (Clitellata: Naididae) population settled in the Slovakian stretch of the Danube floodplain

This study reports the establishment of a population of Quistadrilus multisetosus (Smith, 1900), a new addition to the Slovak fauna, in the Danube floodplain. This finding also identifies the species as a new inhabitant of the Danube river-floodplain system. Its presence in this new area confirms its high potential for dispersal, as previously documented in other European countries. The Danube could therefore serve as the main corridor for the species' spread in this region. Although Q. multisetosus occurs only occasionally worldwide, established populations, as observed in large river surveys, can become very numerous and potentially impact indigenous species communities.