The Croatian National Diatom Collection – an overview and future challenges

Knowledge of the importance of algae in the Earth's hydrosphere emerged after the discovery of the microscope and microorganisms at the beginning of the 18th century. Due to the beauty and morphological distinctiveness of diatoms, the majority of protist research has been focused on those intriguing silicate cells. Today, the vast species diversity of diatoms can only be estimated, but the taxa that have been explored over the years are stored in collections that represent an important resource for modern taxonomy, phylogeny and evolution, ecology, paleoecology, biogeography, phylogeography, applied biology, monitoring and conservation. The Croatian National Diatom Collection (HRNDC) was established in 2018 on the basis of long-term work by Croatian algologists. Today it represents a collection of 2883 permanent specimens that store valuable information on the diatom biodiversity of all waterbodies and store important holotypes, isotypes and paratypes of described new species for science. The future brings the challenge of keeping the collection sustainable, digitalized, and more accessible to the scientific community as well as capable of meeting the challenge of the omics era. The HRNDC is a priceless contribution to the legacy of the Croatian natural heritage.