ACTA BOT. CROAT. 80 (1), 2021 S1 Social news The Croatian National Diatom Collection The Croatian National Diatom Collection was estab- lished on 1st March 2018 at the University of Zagreb, Fac- ulty of Science (Department of Biology, Division of Botany) and registered in the Index Herbariorum of the New York Botanical Garden (http://sweetgum.nybg.org/science/ih/ herbarium-details/?irn=252706). It was officially presented to the scientific and general public on 9th December 2019 in the Croatian Academy of Sciences and Arts. It is the first institutional collection of permanent microscopic speci- mens of diatoms in Croatia, currently containing 1000 mi- croscopic specimens and 200 wet samples and 16 type spec- imens (Fig. 1). Most importantly, the collection contains 16 type specimens of newly discovered species in Croatia, which are no longer sent to other European collections, but kept in Croatia as a treasure of national biodiversity. Diatoms are an exceptionally diverse group of mostly photosynthetic microorganisms and have a significant role in primary production and the fixation of atmospheric car- bon. They are present in both plankton and benthos, often as dominant organisms in both marine and freshwater eco- systems. As an integral part of the planktonic and benthic water communities, they serve as a biological indicator and an essential factor in assessing the ecological status of water. Biodiversity is the total variety of living organisms in a cer- tain ecosystem, and Croatia is considered to be one of the most biodiverse countries in Europe. This variety stems from the specific geographic location of Croatia, which en- tails exceptional ecological, climactic and geomorphologi- cal conditions. All scientific knowledge about its organisms – from the biggest and publicly most accessible plants and animals to the smallest microorganisms – is extremely im- portant for Croatia. The diversity of diatoms in Croatia has occupied the interest of many world-famous scientists in history (Adolf Steuer, Friedrich Hudstedt, Anto Jurilj), which has resulted in world-famous publications (Viličić and Ljubešić 2017, and references therein). Croatian algolo- gist, Professor Anto Jurilj (1910-1981), although he actively researched diatoms in Croatia, is remembered in science for a description of 44 new diatom taxa from Lake Ohrid in N. Macedonia. Equal interest in the study of diatoms in Croatia has been shown by scientists today, who have recently described a significant number of new species (Gligora et al. 2009, Mejdandžić et al. 2017, 2018, Gligora Udovič et al. 2018, Ca- put Mihalić et al. 2019, Majewska et al. 2019, 2020, Al- Handal et al. 2020, Mucko et al. 2020, Van de Vijver et al. 2020). A systematic inventory of the diatoms of the Krka River from source to mouth has been conducted, resulting in an impressive diatom collection. Newly described diatom species in Croatia, the diatom collection of the Krka River together with the historical diatom collection of the Profes- sor Anto Jurilj, provided the impetus for the Croatian Na- tional Diatom Collection in 2018. Fig. 2. Croatian National Diatom Collection logo by Nikola Koletić. Fig. 1. Permanent slides hosted in the Croatian National Diatom Collection. S2 ACTA BOT. CROAT. 80 (1), 2021 ciae sp. nov. A new species from Crveno jezero, Croatia. Phy- totaxa 351, 229–238. Gligora, M., Kralj, K., Plenković-Moraj, A., Hinz, F., Acs, E., Grigorszky, I., Cocquyt, C., Van de Vijver, B., 2009: Obser- vations on the diatom Navicula hedinii Hustedt (Bacillari- ophyceae) and its transfer to a new genus Envekadea Van de Vijver et al. gen. nov. European Journal of Phycology 44, 123–138. Majewska, R., Ashworth, M.P., Bosak, S., Goosen, W.E., Nolte, C., Filek, K., Van de Vijver, B., Taylor, J.C., Manning, S.R., Nel, R., 2020: On sea turtle‐associated Craspedostauros (Bac- illariophyta), with description of three novel species. Journal of Phycology, doi:10.1111/jpy.13086 Majewska, R., Bosak, S., Frankovich, T.A., Ashworth, M.P., Sul- livan, M.J., Robinson, N.J., Lazo-Wasem, E.A., Pinou, T., Nel, R., Manning, S.R., Van de Vijver, B., 2019: Six new epibiotic Proschkinia (Bacillariophyta) species and new insights into the genus phylogeny. European Journal of Phycology 54, 609–631. Mejdandžić, M., Bosak, S., Nakov, T., Ruck, E., Orlić, S., Gligora Udovič, M., Peharec Štefanić, P., Špoljarić, I., Mršić, G., Ljubešić, Z., 2018: Morphological diversity and phylogeny of the diatom genus Entomoneis (Bacillariophyta) in marine plankton: six new species from the Adriatic Sea. Journal of Phycology 54, 275–298. Mejdandžić, M., Bosak, S., Orlić, S., Gligora Udovič, M., Peharec Štefanić, P., Špoljarić, I., Mršić, G., Ljubešić, Z., 2017: Ento- moneis tenera sp. nov., a new marine planktonic diatom (En- tomoneidaceae, Bacillariophyta) from the Adriatic Sea. Phy- totaxa 282, 1–18. Mucko, M., Bosak, S., Mann, D.G., Trobajo, R., Wetzel, C.E., Pe- harec Štefanić, P., Ljubešić, Z., 2020: A polyphasic approach to the study of the genus Nitzschia (Bacillariophyta): three new planktonic species from the Adriatic Sea. Journal of Phycology, doi:10.1111/jpy.13085 Van de Vijver, B., Robert, K., Witkowski, A., Bosak, S., 2020: Ma- jewskaea gen. nov. (Bacillariophyta), a new marine benthic diatom genus from the Adriatic Sea. Fottea 20, 112–120. Viličić, D., Ljubešić, Z., 2017: Razvoj metoda istraživanja fito- planktona u Jadranskom moru. Hrvatske vode: časopis za vodno gospodarstvo 99, 49–58. Today, the Croatian National Diatom Collection is, in both professional and scientific terms, a testimony to the high diatom diversity in Croatia and is an invaluable data- base as well as a testament of our time for the future gen- erations. Collections like these offer an invaluable abun- dance of information on biological research and offer insights into the diversity of diatom taxonomy, biodiversity of a certain area, variety distribution and changes in time and space, which all together enable effective protection of the water ecosystems in Croatia. Supported by the Faculty of Science, it is now open to both experts and the public. It is recognizable by its official Herbarium Code – HRNDC and the official logo, which shows a combination of centric diatoms in the middle, three black semicircles representing C for Croatian, C for Collec- tion and D for Diatom, and stylized Croatian interlacing which represents the word National (Fig. 2). The Croatian National Diatom Collection acquires materials for the per- manent collection and all the information can be accessed on the website www. diatoms.biol.pmf.hr. Assoc. Prof. Marija Gligora Udovič Assoc. Prof. Zrinka Ljubešić University of Zagreb Faculty of Science Department of Biology References Al-Handal, A.Y., Mucko, M., Wulff, A., 2020: Entomoneis anna- godhei sp. nov., a new marine diatom (Entomoneidaceae, Bacillariophyta) from the west coast of Sweden. Diatom Re- search 35, 269–279. Caput Mihalić, K., Gligora Udovič, M., Galović, I., Stanković, I., Šušnjara, M., Žutinić, P., Kulaš, A., Špoljarić, I., Levkov, Z., 2019: Tetramphora croatica sp. nov. - A new brackish-water species from Lake Vransko, Croatia. Phytotaxa 401, 276–286. Gligora Udovič, M., Žutinić, P., Kavre Piltaver, I., Kulaš, A., Ozimec, R., Tofilovska, S., 2018: Gomphosphenia plenkovi-