Fossil and Extant Western Hemisphere Boragineae, and the Polyphyly of “Trigonotideae” Riedl (Boraginaceae: Boraginoideae)
Boraginaceae tribe Trigonotideae comprises a heterogenous assemblage of taxa, many of which have been shown to belong to widely divergent lineages in Boraginaceae in the recent past, with some taxa now assigned to three of the four currently recognized tribes of the Boraginaceae s. s., namely the Cynoglosseae, Echiochileae, and Lithospermeae. The systematics of Moritzia and Thaumatocaryon, the only endemic South American genera of Boraginaceae, have been controversially discussed in the past, and their most recent placement was in Trigonotideae. The present study investigates the phylogenetic relationships of “Trigonotideae” based on micromorphology and molecular data (ITS including 5.8S rRNA, and the trnL-trnF spacer). Molecular data show that “Trigonotideae” are polyphyletic, and none of its members is at all closely related to Trigonotis itself. Moritzia and Thaumatocaryon are closely allied to each other and are the sister group of the Old World Boragineae. Flowers, pollen, and fruit morphology strongly support this systematic placement. Extant (native) Boragineae are absent from North America and had not previously been reported from South America, whereas members of the Cynoglosseae, Echiochileae, and Lithospermeae have been reported from both continents. Moritzia and Thaumatocaryon are thus the only native representatives of Boragineae in the Americas and represent an unexpected western Eurasian/South American disjunction. However, several (widespread and abundant) fossil taxa from the Cenozoic of North America (especially species of †Prolithospermum) can be confidently placed into Boragineae. Extant Moritzia/Thaumatocaryon likely go back to a lineage which reached North America from Europe and then migrated into South America, with subsequent extinction in North America.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
Document Type: Regular Paper
Publication date: 2010-04-01
More about this publication?
- Systematic Botany is the scientific journal of the American Society of Plant Taxonomists and publishes four issues per year.
2011 Impact Factor: 1.517
2011 ISI Journal Citation Reports® Rankings: 87/190 - Plant Sciences
34/45 - Evolutionary Biology
- Editorial Board
- Information for Authors
- Submit a Paper
- Subscribe to this Title
- Membership Information
- Ingenta Connect is not responsible for the content or availability of external websites