Scutellospora ArenicolaandGlomus Trimurales: Two New Species in the Endogonaceae

Abstract

San Miguel Island is the westernmost member ofthe Channel Islands and is situated 42 km off the coast of southern California. This small is? land (37 km2) is transversed by three major sand dune fields (Johnson, 1980) that account for ca 15% ofthe habitable island surface. Examination of soil samples collected from around the roots of plants growing in the dunes revealed two undescribed species, one each in Scutellospora and Glomus. Spores ofthe latter previously had been found in sand dunes ofthe eastern United States seaboard (Koske, 1987). Spores were recovered from soil by sucrose centrifugation (Walker et al, 1982). Descriptions and observations reported in this study are from specimens mounted in a poly vinyl alcohol/lactic acid/glycerol (PVLG) mounting medium (Koske and Tessier, 1983) or in Melzer's reagent. Wall descriptions and terminology follow those sug? gested by Walker (1983,1986) and Morton (1986). Except where noted, all stated dimensions are based on analysis of ca 150 spores of each species. Holotypes have been deposited in the herbarium at Oregon State University (OSC), and isotypes have been deposited at the Farlow Herbarium (FH) and at Kew (K).