We assessed the taxonomy and phylogenetic relationships of Hawaiian species of the neotropical genus Lobariella. A single species was previously reported from the archipelago, the widespread neotropical L. crenulata. We targeted three loci of the mitochondrial and nuclear ribosomal rDNA gene cistron (mtSSU, nuLSU, ITS) and also performed a molecular clock analysis. Our results show that L. crenulata s. str. is seemingly present in the archipelago based on older herbarium collections. However, Hawaiian Lobariella includes three additional, presumably endemic, species unrelated to L. crenulata and new to science: L. flynniana Lücking, Moncada & C. W. Sm., with richly branched marginal phyllidia giving the thallus a fruticose appearance; L. robusta Lücking, Moncada & C. W. Sm., with a rather thick thallus and abundant, large, laminal phyllidia; and L. sandwicensis Lücking, Moncada & C. W. Sm., with a delicate thallus producing apothecia. Lobariella flynniana represents a novel morphotype within the genus, thus far known only from Hawaii. All three species are very closely related, forming a well-supported, monophyletic clade in spite of their morphological differences, suggesting local micro-radiation. Molecular clock analysis indicates that this clade colonized the islands between 1–8 mya and diverged between 0–2 mya. We interpret recent colonization as one of the main reasons why this clade has not diversified further.