New taxa of Onosma L. (Boraginaceae, Lithospermeae) from Iran

This study describes three new species within the genus Onosma L. (Boraginaceae), from sect. Onosma, subsect. Asterotricha (Boiss.) Gürke, in Iran. These species, determined as O. ligniclada Attar & Mirtadzadini, sp. nov., O. elymaitica Attar & Mirtadz., sp. nov., and O. farsistanica Attar & Mirtadz., sp. nov., were distinguished based on detailed morphological and phylogenetic evidence. Onosma ligniclada Attar & Mirtadzadini, sp. nov. and O. elymaitica Attar & Mirtadz., sp. nov., originating from Ilam province, display distinct morphological features that differ from their closest known species, O. albo-rosea Fisch. & C.A.Mey., O. iransharii Ghahr. & Attar and O. bilabiata Boiss. & Buhse respectively. This differentiation is marked by variations in habit, corolla color and size, and leaf morphology on sterile shoots and indumentum of leaves. In contrast, O. farsistanica Attar & Mirtadz., sp. nov. identified in the Quercus L. forests of Fars province (Quercus brantii var. Persica (Jaub. & Spach) Zohary), exhibits notable distinctions from their closely related species, O. bilabiata, particularly in terms of habitat, growth form, tubercle characteristics, calyx and corolla dimensions. Additionally, the manuscript provides photographic documentation, a distribution map, IUCN conservation assessments, and a diagnostic key for these newly identified species.