Grimmia shevockii and G. insolita, two new species endemic to California

Introduction. California is a biodiversity hotspot for bryophytes, and its northern counties are among the most endemic-rich areas for bryophytes in North America. Having 29 species in California, Grimmia Hedw. is the third richest moss genus in the state, but recent fieldwork suggests that this number is an underestimate. The identity of some specimens endemic to the Klamath Mountains of California and previously identified as G. brevirostris R.S.Williams remains unclear, and they potentially represent a new species. Two further specimens of Grimmia from Siskiyou County, California, do not correspond to any species described so far. Here we present morphological and phylogenetic arguments for recognising these plants as two new moss species in the genus Grimmia subg. Orthogrimmia Schimp.Methods. Morphological characters across potential new species were reviewed and compared with those of related species. Phylogenetic analyses based on the plastid trnS-trnF and nuclear ITS regions were conducted.Key results and conclusions. The molecular and morphological analyses revealed two new species of Grimmia for California, which are described and illustrated: G. shevockii J.Munoz, I.Solano & D.Quandt and G. insolita J.Munoz, I.Solano & D.Quandt. The former is resolved in a monophyletic clade with high support, whereas the latter has incongruent positions in the plastid and nuclear phylogenies, thus it is hypothesised that it could have a hybrid origin. Both of the two new species and G. hamulosa undoubtly pertain to Grimmia. The richness of the bryophyte flora of California provides a clear warrant for future research.

Automated summary

California is a biodiversity hotspot for bryophytes, with its northern counties being among the most endemic-rich areas for bryophytes in North America. Recent fieldwork suggests that there may be more than the currently known 29 species of the moss genus Grimmia in California. This study presents morphological and phylogenetic evidence for the recognition of two new moss species in the genus Grimmia, with one potentially having a hybrid origin.