On the morphology, systematics and phylogeny of Noteroclada (Noterocladaceae, Marchantiophyta)
Crandall-Stotler, Barbara; Stotler, Raymond E.; Zhang, Li; Forrest, Laura L.
Noteroclada Taylor ex Hook. & Wilson has long been recognized as a unique leafy taxon having affinities to the north temperate, simple thalloid liverwort genus, Pellia Raddi. Although a suite of diagnostic characters clearly separate it from Fossombronia Raddi and other leafy, anacrogynous taxa, considerable confusion regarding its identity exists in historical treatments. There are unresolved questions in regards to the extent and significance of morphological variation within the genus, the number of species that should be recognized, the geographic range that it occupies and its position in liverwort phylogeny. Morphological, experimental and molecular techniques are employed to address these questions. These studies show that there are two forms of perennating tubers, which are geographically partitioned, that plants are always monoicous, that sporophytes are enclosed by a shoot calyptra and Fossombronia-like caulocalyx and that sporeling ontogeny is different from that of Pellia. Molecular analyses show some genetic variation within Noteroclada, but both morphological and molecular data support the recognition of but a single species, N. confluens Taylor ex Hook. & Wilson. It is confirmed that there are no reliable specimens of Noteroclada from Africa, Australasia or the Kerguelen sector and that the genus has two centers of distribution in Latin America, with disjunct populations in the Falkland Islands, South Georgia, Tristan da Cunha and Gough Island. Significant ontogenetic differences between Noteroclada and Pellia support their placement in separate monogeneric families of the Pelliales.