Distribution, habitat preferences and genetic diversity of Ametropus fragilis Albarda, 1878 (Ephemeroptera: Ametropodidae) in Croatia

Ametropus fragilis Albarda, Citation1878 is widely distributed in the Holarctic Region and recorded from only a few sites in Croatia. Given the considerable gaps in knowledge about its ecology and genetic diversity, this study analyses its distribution, (micro)habitat preferences, and genetic variation in Croatia. Our results showed that the species occurs in two large lowland rivers in Croatia, preferring microhabitats with fine sediments (such as sand and particulate organic matter) which is in accordance with its known habitat preferences. The COI sequences of A. fragilis from Croatia grouped within the same genetic cluster as the A. fragilis sequence from Slovakia. Despite the low genetic distances within this cluster, each specimen possesses a distinct haplotype. Our findings highlight the high conservation value of large European lowland rivers, which play an essential role in preserving endangered species, such as A. fragilis.