Re-evaluating the presence of Carex microcarpa (Cyperaceae) in Italy based on herbarium material and DNA barcoding

Carex microcarpa (sect. Rhynchocystis) is a Central Mediterranean endemic known from Corsica, Sardinia and the Tuscan archipelago, that has been also reported from scattered localities in mainland Italy (Abruzzo, Lazio and Apulia). We tested by molecular means the identification of three specimens classified as C. microcarpa from continental Italy, as well as a voucher from the Montecristo island (Tuscany) and one from Sardinia, whose taxonomic identity could not be determined with certainty by morphological examination. We performed a DNA barcoding study based on four DNA regions (two nuclear, two plastid). Our results reveal that none of previous mainland Italian records corresponds to C. microcarpa, but to C. pendula, which also belong to section Rhynchocystis, and in other cases possibly to C. acutiformis, from a different species group (sect. Paludosae). The specimen from Montecristo island was confirmed to be C. microcarpa. We conclude that C. microcarpa is likely a Tyrrhenian endemic exclusively known with certainty in Corsica, Sardinia and the Tuscan Archipelago. The presence of C. microcarpa in the Italian peninsula remains highly doubtful and we recommend its exclusion from checklists. Our study highlights the utility of DNA barcoding approaches in Carex when a reliable morphology-based identification is not possible.