Molecular delimitations in the Ehretiaceae (Boraginales)

Area of Science:

• Botany
• Molecular Phylogenetics
• Plant Taxonomy

Background:

• Previous molecular phylogenetic analyses have not fully encompassed major taxa of Ehretiaceae, including parasitic Lennoaceae.
• This omission has led to unresolved generic limits and circumscriptions within the family, impacting floristic studies.

Purpose of the Study:

• To resolve the generic limits and phylogenetic relationships within the Ehretiaceae family.
• To identify monophyletic groups within Ehretiaceae using molecular data.

Main Methods:

• Phylogenetic analyses were conducted using DNA sequences from one nuclear (ITS) and three plastid loci (rps16, trnL-trnF, trnS-trnG).
• Data were obtained from 67 accessions of Ehretiaceae, including 91 new GenBank entries, covering the group's known diversity.

Main Results:

• Ehretiaceae were found to be monophyletic when Lennoaceae were included.
• The analyses identified nine distinct monophyletic lineages within Ehretiaceae: Bourreria, Cortesia, Ehretia, Halgania, Lennoa, Lepidocordia, Pholisma, Rochefortia, and Tiquilia.
• The study revealed distinct biogeographical patterns, with some genera found in both Old and New Worlds, while others are restricted to the Americas or Australia.

Conclusions:

• The inclusion of Lennoaceae resolves Ehretiaceae as a monophyletic group with nine well-defined lineages.
• The findings provide a clearer taxonomic framework for Ehretiaceae, supporting distinct generic circumscriptions.
• Historical biogeography suggests limited colonization events shaped the distribution of Ehretiaceae, and fruit evolution shows independent instances of endocarp fusion.