Phylogenetic relationships of Abildgaardieae (Cyperaceae) inferred from chloroplast and nuclear DNA sequences and pollen data

Abstract

The need for a systematic study of the tribe Abildgaardieae became apparent when the boundaries between Abildgaardieae and Arthrostylideae in a previous study using morphological and physiological characters were unclear. Within Abildgaardieae, some species belonging to separate genera overlap in morphological and/or embryological characters (viz. 'Fimbristylis hispidula', 'Abildgaardia ovata', 'Bulbostylis pilosa') and their recognition in separate genera has been questioned. The focus of this study was to estimate phylogeny for Abildgaardieae and evaluate the circumscription of six genera (49 species) within Abildgaardieae and Arthrostylideae. Parsimony and maximum likelihood analyses were conducted separately on three different datasets (ITS (nuclear ribosomal), trnL-F (plastid) DNA sequence, and pollen morphological data). The data sets were also combined and analysed using the same techniques. The results showed that the three data sets produced different phylogenies. Separate data sets did not clearly resolve the relationships within Abildgaardieae or between Abildgaardieae and Arthrostylideae. By combining the three datasets, much higher resolution of the phylogenetic relationships was observed. ITS and trnL-F provided different insights into the relationships within Abildgaardieae and between the tribes disagreeing with the position of Arthrostylideae relative to Abildgaardieae and with the monophyly of Abildgaardia. Pollen morphology provided useful taxonomic characters for the Abildgaardieae--Arthrostylideae complex but it did not resolve the relationships further when analysed alone. When combined with ITS and trnL-F, pollen morphology further strengthened trnL-F results.