Data from: Resolving basal lamiid phylogeny and the circumscription of Icacinaceae with a plastome-scale data set

PREMISE OF THE STUDY: Major relationships within Lamiidae, an asterid
clade with ∼40000 species, have largely eluded resolution despite two
decades of intensive study. The phylogenetic positions of Icacinaceae and
other early-diverging lamiid clades (Garryales, Metteniusaceae, and
Oncothecaceae) have been particularly problematic, hindering
classification and impeding our understanding of early lamiid (and
euasterid) character evolution. METHODS: To resolve basal lamiid
phylogeny, we sequenced 50 plastid genomes using the Illumina sequencing
platform and combined these with available asterid plastome sequence data
for more comprehensive phylogenetic analyses. KEY RESULTS: Our analyses
resolved basal lamiid relationships with strong support, including the
circumscription and phylogenetic position of the enigmatic Icacinaceae.
This greatly improved basal lamiid phylogeny offers insight into character
evolution and facilitates an updated classification for this clade, which
we present here, including phylogenetic definitions for 10 new or
converted clade names. We also offer recommendations for applying this
classification to the Angiosperm Phylogeny Group (APG) system, including
the recognition of a reduced Icacinaceae, an expanded Metteniusaceae, and
two orders new to APG: Icacinales (Icacinaceae + Oncothecaceae) and
Metteniusales (Metteniusaceae). CONCLUSIONS: The lamiids possibly radiated
from an ancestry of tropical trees with inconspicuous flowers and large,
drupaceous fruits, given that these morphological characters are
distributed across a grade of lineages (Icacinaceae, Oncothecaceae,
Metteniusaceae) subtending the core lamiid clade (Boraginales,
Gentianales, Lamiales, Solanales, Vahlia). Furthermore, the presence of
similar morphological features among members of Aquifoliales suggests
these characters might be ancestral for the Gentianidae (euasterids) as a
whole.