Cetraspora helvetica, a new ornamented species in the Glomeromycetes from Swiss agricultural fields

Author： Oehl Fritz Jansa Jan de Souza Francisco Adriano da Silva Gladstone Alves

ISSN： 2154-8889

Source： Mycotaxon, Vol.114, Iss.1, 2010-10, pp. : 71-84

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Abstract

A new arbuscular mycorrhizal fungus, Cetraspora helvetica, was found in three Swiss agricultural soils: a no-till crop production system and two temporary grasslands. It forms white spores, 210–270 μm diam, on dark yellow sporogenous cells. The spores have three walls: a triple-layered outer, a bi-layered middle and a triplelayered inner wall. The spore surface is crowded with convex warts, 5–12 μm diam at the base and 1.5–5.0 μm high. The germination shield is hyaline with multiple (6–10) lobes. Glomerospores of two other Gigasporineae spp. have also three walls, multiple-lobed hyaline germination shields, and projections on the outer spore surface: C. spinosissima and C. striata. However, spores of these fungi are substantially pigmented (ochraceous yellow to rust) and crowded with short, thin spines or fingerprint-like processes, respectively. Partial sequences of the 28S ribosomal gene place the new species adjacent to C. spinosissima, C. pellucida, and C. gilmorei. Phylogenetic analyses demonstrate the monophyly of the two genera Racocetra and Cetraspora within the Racocetraceae.