ABSTRACTThe relative proportions of various lipid classes and the fatty acid composition of extramatrical structures (azygospores and auxiliary cells) ofGigaspora margaritaand intramatrical structures ofGlomus intraradices(spores),G. versiforme(vesicles) andG. vesiculiferum(vesicles) were measured. The most abundant lipid classes in all structures, except in auxiliary cells, were triacylglycerides followed by free fatty acids. In auxiliary cells ofG. margarita, free fatty acids were the principal lipid class followed by the triacylglycerides. Glycolipids were detected, in minor quantities, only in azygospores ofG. margaritaand intramatrical spores ofG. intraradices.There were qualitative and quantitative differences in the fatty acid composition among all VAM structures. The predominant fatty acids in extramatrical structures ofG. margaritawere 18:1 and 16:0, while in the threeGlomusspecies they were 16:1 and 16:0. Both isomers of linolenic acid (18:3Δ6, 9, 12and 18:3Δ9, 12, 15) and nonadecanoic acid (19:0) were present in all structures analysed. In addition, variousω3 andω6 polyunsaturates were found in different VAM structures. These patterns suggest that VAM fungi have closer links with protoctistan fungi than with Zygomycetes.