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BackgroundFlowering plants (angiosperms) are dominant components of global terrestrial ecosystems, but phylogenetic relationships at the familial level and above remain only partially resolved, greatly impeding our full understanding of their evolution and early diversification. The plastome, typically mapped as a circular genome, has been the most important molecular data source for plant phylogeny reconstruction for decades.ResultsHere, we assembled by far the largest plastid dataset of angiosperms, composed of 80 genes from 4792 plastomes of 4660 species in 2024 genera representing all currently recognized families. Our phylogenetic tree (PPA II) is essentially congruent with those of previous plastid phylogenomic analyses but generally provides greater clade support. In the PPA II tree, 75% of nodes at or above the ordinal level and 78% at or above the familial level were resolved with high bootstrap support (BP ≥ 90). We obtained strong support for many interordinal and interfamilial relationships that were poorly resolved previously within the core eudicots, such as Dilleniales, Saxifragales, and Vitales being resolved as successive sisters to the remaining rosids, and Santalales, Berberidopsidales, and Caryophyllales as successive sisters to the asterids. However, the placement of magnoliids, although resolved as sister to all otherMesangiospermae, is not well supported and disagrees with topologies inferred from nuclear data. Relationships among the five major clades ofMesangiospermaeremain intractable despite increased sampling, probably due to an ancient rapid radiation.ConclusionsWe provide the most comprehensive dataset of plastomes to date and a well-resolved phylogenetic tree, which together provide a strong foundation for future evolutionary studies of flowering plants.

Inter- and intrafamilial relationships among the Megapodiidae are presented and discussed based on their host-specific chewing louse fauna, in particular the Goniodidae (Ischnocera). Use is made of both empirical evidence and statistical methods. So far, 53 species of chewing lice have been described which are found only on megapodes, a number which is still growing. The relationships among the Goniodidae genera on megapodes have been analysed using Wagner parsimony analysis rooted by character polarity (51 morphological features). Based on their chewing lice, the Megapodiidae seem to be more closely related to the Phasianidae than to the Cracidae. Megapodes share no Ischnocera with the cracids, while they share a single genus Goniocotes Burmeister, 1838 (one species only, on Macrocephalon maleo S. Müller, 1846) with the Phasianidae. The distribution of 18 Ischnocera genera support the following intrafamilial division: Alectura Latham, 1824, and Aepypodius Oustalet, 1880, on the one hand and Megapodius Gaimard, 1823, and Eulipoa Ogilvie-Grant, 1893, on the other form respective sister groups. The relationships between Leipoa Gould, 1840, Talegalla Lesson, 1828, and Macrocephalon S. Müller, 1846, remain unclear.

Inter- and intrafamilial relationships among the Megapodiidae are presented and discussed based on their host-specific chewing louse fauna, in particular the Goniodidae (Ischnocera). Use is made of both empirical evidence and statistical methods. So far, 53 species of chewing lice have been described which are found only on megapodes, a number which is still growing. The relationships among the Goniodidae genera on megapodes have been analysed using Wagner parsimony analysis rooted by character polarity (51 morphological features). Based on their chewing lice, the Megapodiidae seem to be more closely related to the Phasianidae than to the Cracidae. Megapodes share no Ischnocera with the cracids, while they share a single genus Goniocotes Burmeister, 1838 (one species only, on Macrocephalon maleo S. Müller, 1846) with the Phasianidae. The distribution of 18 Ischnocera genera support the following intrafamilial division: Alectura Latham, 1824, and Aepypodius Oustalet, 1880, on the one hand and Megapodius Gaimard, 1823, and Eulipoa Ogilvie-Grant, 1893, on the other form respective sister groups. The relationships between Leipoa Gould, 1840, Talegalla Lesson, 1828, and Macrocephalon S. Müller, 1846, remain unclear.

Hypotheses regarding the phylogenetic relationships between megapodes and other birds are reviewed, and it is concluded that the available evidence supports a sistergroup relationship between megapodes and all other galliforms. Current studies in this direction are discussed. The resolvement of intrafamilial relationships has gained less attention so far and the most probable hypothesis based on traditional characters is presented.