Unveiling the enigmatic and ambiguous: A new Frullania species from New Caledonia

Frullania is a large and taxonomically complex genus with over 300 accepted species. A new liverwort species, Frullania thouvenotiana sp. nov. from New Caledonia, is described and illustrated. The new species, and its placement in  Frullania  subg.  Microfrullania , is based on morphology with support from previously published sequence data. Diagnostic characters associated with the leaf, especially the leaf margin, distinguishes it from all other species of  Frullania , including similar species with a distribution comprising Fiji and New Zealand. A brief comparison is made with morphologically allied species, and an artificial key is provided. Frullania neocaledonica is also proposed to be a synonym of F . chevalieri .