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P>In the present study, we used PCR-Single-Stranded Conformation Polymorphism (SSCP) techniques to analyse arbuscular mycorrhizal fungi (AMF) communities in four sites within a 10 km2 gypsum area in Southern Spain. Four common plant species from these ecosystems were selected. The AM fungal small-subunit (SSU) rRNA genes were subjected to PCR, cloning, SSCP analysis, sequencing and phylogenetic analyses. A total of 1443 SSU rRNA sequences were analysed, for 21 AM fungal types: 19 belonged to the genus Glomus, 1 to the genus Diversispora and 1 to the Scutellospora. Four sequence groups were identified, which showed high similarity to sequences of known glomalean species or isolates: Glo G18 to Glomus constrictum, Glo G1 to Glomus intraradices, Glo G16 to Glomus clarum, Scut to Scutellospora dipurpurescens and Div to one new genus in the family Diversisporaceae identified recently as Otospora bareai. There were three sequence groups that received strong support in the phylogenetic analysis, and did not seem to be related to any sequences of AM fungi in culture or previously found in the database; thus, they could be novel taxa within the genus Glomus: Glo G4, Glo G2 and Glo G14. We have detected the presence of both generalist and potential specialist AMF in gypsum ecosystems. The AMF communities were different in the plant studied suggesting some degree of preference in the interactions between these symbionts.