Extinct or Not? Confirming the “Extinct” Status of <i>Hieracium tolstoii</i> (Asteraceae) with Integrated Taxonomic Investigation
2024
Federico Fainelli | Giacomo Baldesi | Mattia Pallanza | Simone Orsenigo
<i>Hieracium</i> is one of the largest flowering plant genera that has recently experienced a rapid evolutionary radiation. Due to the massive morphological variation among species, frequent hybridization, and polyploidization events, combined with apomictic reproduction in polyploids, the concept of species in <i>Hieracium</i> is widely debated, and species identification is incredibly challenging. Taxonomic investigation can lead to changes in conservation status or, in some cases, to de-extinctions of species. Taxa with doubtful classification are particularly sensitive to this kind of problem. <i>Hieracium tolstoii</i> was a narrow Italian endemic species that is nowadays considered extinct. Described as a morphological intermediate form between two other species, no further investigations were conducted after its first description. To clarify <i>H. tolstoii</i>’s origin and ensure the validity of its current conservation status, we conducted a taxonomic investigation on herbaria specimens of the early XX century. Specimens were studied using a morphometric analysis that compared <i>H. tolstoii</i> with other closely related taxa. Moreover, we performed phylogenetic investigations using three plastid intergenic spacers to evaluate the relationship between species. Plastid markers revealed the presence of indels and SNPs in <i>H. tolstoii</i> sequences that differ from sequences of the supposed parental species. Morphometry revealed differences among species that led us to confirm the validity of <i>H. tolstoii</i> as an independent apomictic species and, therefore, unfortunately, its extinction.
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