Gigaspora erythropa, a New Species Forming Arbuscular Mycorrhizae

Gigaspora erythropa, a newly described species, occurs commonly in sand dunes of the Atlantic coast of the United States and the Bahamas and also in a silt-loam apple orchard in New York. The species is characterized by its dark orange- to red-brown, smooth-walled spores which possess a brittle outer wall group consisting of a thick, colored exterior wall and 1 or 2 thin, hyaline walls, and a flexible inner wall group composed of a thick, pale yellow laminated wall and a thin membranous innermost wall. Gigaspora erythropa formed mycorrhizae with arbuscules but not with vesicles in pot cultures with apple, onion, sorghum, and ryegrass. The species was also associated, but not proven mycorrhizal, with Ammophila breviligulata, Solidago sempervirens, and Lathyrus japonicus var. glaber.