155 rhizosphere soil and root mixtures were collected from under <em>Ammophila arenaria </em>colonizing maritime dunes of the island Bornholm (Denmark) to determine arbuscular mycorrhizal fungi (AMF) of the phylum Glomeromycota co-existing with this plant. In the laboratory, each mixture was divided into two parts. One part was used to establish a pot culture with <em>Plantago lanceolata</em> as the host plant to initiate sporulation of fungi that had not produced spores in field conditions. In the second part, the numerical and species composition of the spore populations of AMF sporulating in the field was determined. Spores of AMF were found in 70 field-collected samples and 134 trap cultures. They represented 26 species and six undescribed morphotypes in six genera of the Glomeromycota. Of them, 20 species and three morphotypes in five genera occurred in the field, and 16 species and three morphotypes in five genera were found in trap cultures. The fungi most frequently revealed were members of the genus <em>Glomus</em>; a total of 17 species and six morphotypes of this genus were recognized. Considering the occurrence of spores in both field samples and trap cultures, the fungi most frequently co-occurring with roots of <em>A. arenaria </em>growing in the dunes of Bornholm were <em>G. irregulare </em>(present in 73.6% of samples), followed by <em>Scutellospora dipurpurescens </em>(19.4%) and <em>Archaeospora trappei </em>(10.3%). However, <em>Glomus irregulare </em>mainly sporulated in trap cultures; spores of this fungus were found in only 0.6% of field samples. Other relatively frequently found species were <em>G. aggregatum </em>(9.0%), <em>G. eburneum </em>(7.1%), <em>Paraglomus laccatum </em>(5.2%), and <em>S. armeniaca </em>(6.5%). The species most abundantly sporulating in the field were <em>G. aggregatum </em>(produced 28.36% of all spores isolated), <em>G. badium</em> (11.00%), and <em>S. dipurpurescens </em>(21.55%).