Morphological Diversification of the “Dasyphyllous” Stipa Species (Poaceae) from the Balkan Peninsula, with a Description of a New Species, S. stevanoviciorum

The interspecific relations that have been previously observed within the <i>Stipa dasyphylla</i> group are intricate and require further clarification. The aim of this study was to determine whether the specimens from Serbia deserve a separate taxonomic status. Various "dasyphyllous" <i>Stipa</i> species (those with hairy adaxial leaves) from the Balkan Peninsula were collected and analysed using morphological methods and microscopic observations of the macro- and micro-ornamentation of their leaves and lemmas. Based on analyses of 160 individuals from 17 populations belonging to three "dasyphyllous" <i>Stipa</i> species (<i>S. pontica</i>, <i>S. ucrainica</i>, and <i>S. dasyphylla</i>) which were collected in the central and eastern Balkan Peninsula (Serbia, North Macedonia, Bulgaria, Greece) and in Central Europe (Czech Republic, Slovakia, Hungary, Romania), <i>Stipa stevanoviciorum</i> is described as a new species from Serbia. This taxon includes the subspecies <i>stevanoviciorum</i>, which grows on ultramafic substrates, and the subspecies <i>pseudodasyphylla</i>, which is found on carbonate bedrock. These taxa differ from the closely related <i>S. dasyphylla</i> primarily in the length of their upper cauline leaves and the distance from the end of the dorsal line of the hairs to the top of the anthecium. The ecological and biogeographical characteristics of the taxa and a morphological comparison with similar species are given together with the key to the species' identification. Images of key morphological characters are included, along with information on their distribution, habitat, and conservation implications.