A taxonomic assessment of the initial branching appendages in the liverwort genus Frullania Raddi
von Konrat, Matthew J.; Braggins, John E.
The liverwort genus Frullania is large and complex with over 1000 described taxa and the subgeneric boundaries, in particular, remain largely unresolved. Previous studies have alluded to the potential significance of the initial appendages borne on Frullania-type branches. However, the use of initial branching appendages has almost routinely been ignored or overlooked in Frullania systematics. Here, we have assessed and examined in detail the initial appendages for over 2000 lateral branches for 60 taxa representing 9 subgenera, which was expanded to a total of 100 species from twelve subgenera after surveying relevant literature. Characters investigated include: number of segments or lobes, position of insertion, orientation, symmetry, depth of incision, and features associated with size, shape, and the apex of the lobe or segment. Key criteria that are taxonomically informative both at a species and subgeneric level include: the presence or absence of saccate appendages, the number of saccate appendages, and the number of lobes or segments at the first branch underleaf and first branch leaf. We have also developed a novel means of classifying this otherwise complicated suite of characters. On the basis of these characters we recognise 13 discrete categories and easily recognisable names have been applied to each of these categories. A key and descriptions are provided. Speculation is also made regarding possible phylogenetic relationships between taxa based on characters associated with the initial branching appendages.