Phylogenetic relationships of Clerodendrum s.l. (Lamiaceae) inferred from chloroplast DNA
Steane DA., Scotland RW., Mabberley DJ., Wagstaff SJ., Reeves PA., Olmstead RG.
Seventy-nine accessions representing forty-seven taxa of Clerodendrum s.l. (Lamiaceae) and seven putative outgroup genera are included in an analysis of chloroplast DNA restriction sites for ten enzymes. Parsimony analysis of 456 potentially informative characters identifies four large discrete clades (Clades I-IV) within Clerodendrum s.l. and shows that Clerodendrum s.l. is polyphyletic. Clades I and II comprise Asian and African taxa respectively. Clade III comprises coastal species from Africa, Asia and central America and presents an hypothesis of relationship within Clerodendrum that has not previously been explicit in classifications of the genus. Clade IV, comprising subg. Cyclonema and sect. Konocalyx (subg. Clerodendrum pro parte) emerges as a lineage distinct from the rest of Clerodendrum. Traditional sections Squamata, Odontocalyx (subg. Clerodendrum), Cyclonema and Stacheocymosa (subg. Cyclonema) are well-supported monophyletic groups. Subgenus Clerodendrum and sections Clerodendrum and Axilliflora (subg. Clerodendrum pro parte) are shown to be polyphyletic. The polyphyly of Clerodendrum s.l. is also supported by a separate analysis of chloroplast ndhF sequences, in which a smaller sampling of Clerodendrum is included in a broader sample of labiate genera. The ndhF sequence data suggest that Tetraclea belongs in Clade I of Clerodendrum and support the monophyly of the recently circumscribed subfamily Teucriodeae.