Polyalthia

Abstract: The tribe Miliuseae (Annonaceae) comprises six genera distributed in Asia: Alphonsea, Mezzettia, Miliusa, Orophea, Platymitra, and Phoenicanthus. A phylogenetic study to investigate the putative monophyly of the tribe and the intergeneric relationships is presented here. Nucleotide sequences of the plastid gene rbcL, trnL intron, and trnL-trnF intergenic spacer were analyzed from 114 Annonaceae taxa, including 24 Miliuseae species and two outgroups using maximum parsimony and Bayesian inference. The two data sets (rbcL and the trnL-trnF regions) were analyzed separately and in combination. Miliuseae were found to be polyphyletic due to the position of Mezzettia and are part of a large, predominantly Asian and Central-American clade (miliusoid clade). Although intergeneric relationships were poorly resolved, all genera, except Polyalthia, were monophyletic, supporting previous generic delimitation based on morphology. A group of three Polyalthia species seems the most likely sister group of Miliusa. Several infrageneric groups of Miliusa, Orophea, and Polyalthia are supported by both molecular and morphological data. No morphological synapomorphies have yet been found for the miliusoid clade. Molecular clades within the miliusoid clade, however, can be characterized by size and the shape of the outer petals, number of ovules per carpel, and the size of the fruits.

Abstract: Summary To evaluate hypotheses on pollen evolution in Annonaceae, we present a cladistic analysis, using both palynological and non-palynological characters, and including other Magnoliales as outgroups. As previously proposed, the inferred basic pollen type is single (monads) and monosulcate, with granular infratectal structure (interstitium), but with a few nexinal foliations. Permanent tetrads originated in two major lines: the xylopioids, corresponding to part of Walker's Fusaea subfamily but excluding Fusaea, with granular structure and a nexine of fused granules; and the annonoids, corresponding to Walker's Annona subfamily, with columellar structure and a complexly foliated nexine. The single grains of Isolona are secondarily derived from tetrads. Sulculate pollen arose in both monosulcate and inaperturate lines. The genus Polyalthia, which has unusually diverse pollen, appears to be polyphyletic. Columellar structure originated in smooth monosulcates with granular structure, leading to the malmeoi...