o:5909 Centaurea ozrenii (Asteraceae) ‒ a new local endemic and extremely rare species from Mt. Ozren near Sjenica in Serbia en Abstract: A new species of Centaurea sect. Acrocentron (Asteraceae) was found on the Ozren mountain in southwestern Serbia near Sjenica and named as Centaurea ozrenii. It inhabits xerophilous and steppe-like habitats, on ultramafic geological substrate. Morphologically, it is close to C. calocephala, C. chrysolepis, C. orientalis, C. murbeckii, C. kotschyana and the recently described C. zlatiborensis. The most distinctive morphological features of the new species are undivided to simply pinnatisect (non lyrate) subglabrous leaves, with linear segments, upper leaves with an aristate apex and cream coloured to pale yellow florets of which the outer are much longer than the inner ones. The phyllaries are intermediate in relation to C. calocephala and C. kotschyana. The chromosome number of the new species is 2n = 22. Thorough field investigations confirmed the presence of C. ozrenii only at this localized site on Mt. Ozren with a population of 13 clusters of individuals with 23–52 flowering stems in an area of about 50 m2. Applying the IUCN Red List categories and criteria to the available data categorised C. ozrenii as a Critically Endangered (CR) species. Balkan flora, sect. Acrocentron, new species, taxonomy, chromosome number 1552099 10.2298/BOTSERB2402263B 2024-10-31T07:39:51.959Z 44 no 46 Uroš Buzurović Institute of Soil Science 0009-0000-7702-659X 46 Gordana Tomović Institute of Botany and Botanical Garden, Faculty of Biology, University of Belgrade, Belgrade, Serbia 46 Ksenija Jakovljević Department of Ecology, Institute for Biological Research “Siniša Stanković” - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia 46 Snežana Vuksanović Natural History Museum of Montenegro, Podgorica, Montenegro 46 Maja Lazarević Institute of Botany and Botanical Garden, Faculty of Biology, University of Belgrade, Belgrade, Serbia 46 Snežana Dragićević Montenegrin Academy of Sciences and Arts, Podgorica, Montenegro 46 Marjan Niketić Natural History Museum, Belgrade, Belgrade, Serbia; Natural History Museum, Belgrade, Belgrade, Serbia application/pdf 1602570 https://unilib.phaidrabg.rs/o:5909 no yes 1 70 92000001 71A05 Botanica Serbica 236 271 2024