Worldwide phylogeny of Lactarius section Deliciosi inferred from ITS and glyceraldehyde-3-phosphate dehydrogenase gene sequences

Abstract

A phylogenetic analysis of Lactarius sect. Deliciosi was performed based on collections of all known species. Several samples of each species were included, originating from a wide geographic range. The two DNA regions we used (ITS and a part of the gene encoding glyceraldehyde-3-phosphate dehydrogenase) showed an incongruent phylogenetic signal. Much attention was paid to carefully observed macro-and micromorphological characters to draw taxonomic conclusions. We currently accept 38 taxa (31 species and seven varieties) in Lactarius sect. Deliciosi worldwide; four species are new to science. More sampling is needed to resolve the status of the North American varieties. Our knowledge of the Asian species in this section remains fragmentary. The monophyly of the section and its position within Lactarius subgenus Piperites, as proposed in recent morphology-based classification schemes, is confirmed. The intrasectional relationships however do not coincide with the color of the latex (as previously supposed). Intercontinental conspecificity is low in general. The name L. deliciosus is wrongfully applied in North and Central America and only two species seem to occur in both Asia and Europe.

• Dapetes
• L. deliciosus
• L. porninsis
• Russulales

The authors thank the curators of the herbaria and all collectors mentioned (Table I) for providing herbarium collections. We acknowledge Dr Saisamorn Lumyong (Chiang Mai University) for providing us with a material transfer agreement for the Thai specimens. The department of Plant Systems Biology, Prof Dr G. Borgonie, the Centre for Molecular Phylogeny and Evolution (Ghent University) and Terry McClean and the Nucleic Acid Exploration Facility (University of Wyoming) are thanked for making available their infrastructure for molecular work and for their help in sequencing and analysis of the data. The research of the first author is financed by the Institute for the Promotion of Innovation by Science and Technology in Flanders (IWT), Belgium. Contributions by Miller were financed by NSF Biotic Surveys DEB-0315607 and USDA CREES 2003-01542.