A preliminary molecular phylogeny of the genus Riccia L. (Ricciaceae) in Australia

Several Australian Riccia taxa have been sequenced for the first time, with the majority from the monsoon tropics of the Northern Territory, north of 18 degrees latitude. This allowed testing of several infrageneric groupings within the genus as well as morphological species concepts. Molecular data from one nuclear and four plastid markers support the genus as a monophyletic group. However, the monophyly of the two largest subgenera, subgenus Riccia and subgenus Ricciella, are not supported, with the latter being polyphyletic and well nested within subgenus Riccia. Several currently accepted species such as Riccia inflexa and Riccia lamellosa were also found to be polyphyletic. A second tree reconstruction using only trnL-F sequences allowed comparison to several taxa collected outside of Australia. This showed that some species have a truly cosmopolitan distribution, whereas others have not.