Glomus segmentatum, rediscovery of a rare epigeous sporocarpic fungus to Cuba

Abstract

Cuba has shown in several studies a high diversity of arbuscular mycorrhizal fungi, related with its high plant endemism. During diversity studies of the epigeous mycota an rare sporocarpic arbuscular mycorrhizal fungi species was found in San Andrés, western Cuba associated to Quercus cubana in a holm-oak wood. The fungus identified as Glomus segmentatum forms large sporocarps (3.5 × 6 mm) over soil surface and 8–16 polyhedral segments interconnected by basal hypha. Its globose to subglobose glomerospores (55–)65(–82) µm have three spore wall layers: an outer (swl1) evanescent, hyaline up to 1 µm layer, a second laminate layer (swl2), dull white to yellowish white 3.6–7.5 µm thick and yellowish white 0.5–1.0 µm inner layer (swl3). Subtending hypha is hyaline to white, 7.5– 16.8 µm at spore base, continuous with spore wall layers (swl1–swl2), 2.8–4 µm thick, at the point of attachment, from this point gradually thins up to 0.5 µm thick. This study provides additional taxonomic information of a rare fungus and represents a new occurrence data for Cuba and the second global record for the species.