Aquatic Coleoptera distribution patterns and their environmental drivers in central Portugal, Iberian Peninsula

Here, we present the distribution patterns of aquatic Coleoptera species collected in Central Portugal (240 samples, 136 stream sites) and their most important environmental drivers. A total of 81 species were identified from which 16 were endemic of the Iberian Peninsula confirming the high species richness and importance for conservation of this area. The families with higher species richness were Dytiscidae (24 species), Hydraenidae (16 species), Elmidae (13 species) and Hydrophilidae (12 species). We found six groups mainly based on altitudinal, conductivity and lithology gradients. We found a replacement of families, filling different niches over the catchments environmental gradients. According to the distribution maps, the families Dytiscidae and Hydrophilidae appeared in lowland streams while Hydraenidae were collected in upper stretches of the rivers. Various species appeared widely distributed along the different watersheds, most of them belonging to the families Elmidae and Hydraenidae. The highest species richness was found for the Hydraena, represented by 13 species in our study area. Some Hydraena species tend to co-occur at the same sites and have a high similarity in their distribution. This first study of ecological patterns of Coleopteran species in Portugal brought thus new insights to knowledge of this invertebrate group.