Resolving basal lamiid phylogeny and the circumscription of Icacinaceae with a plastome-scale data set.
OBJECTIVE
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.


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.
Department of Biology, University of Florida, Gainesville, Florida 32611-8525 USA Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611-7800 USA gwstull@gmail.com.
Gregory W
GW
Stull
Herbario CICY, Centro de Investigación Científicas de Yucatán A. C., Mérida, Yucatán 97200 Mexico.
Rodrigo
R
Duno de Stefano
Department of Biology, University of Florida, Gainesville, Florida 32611-8525 USA Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611-7800 USA.
Douglas E
DE
Soltis
Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611-7800 USA.
Pamela S
PS
Soltis
D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D054627:Genome, Plastid / Q000235:genetics*; D019684:Magnoliopsida / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D018087:Plastids / Q000235:genetics
D018744:DNA, Plant
Garryales; Icacinaceae; Lamiidae; Metteniusaceae; Oncothecaceae; phylogenetic nomenclature; phylogenomics; plastid genome