Morphology and phylogeny of Acaulospora foveata (Glomeromycetes) from Mexico

Dora Trejo, Gastón Guzmán, Liliana Lara, Ramón Zulueta, Javier Palenzuela, Iván Sánchez-Castro, Gladstone Alves da Silva, Ewald Sieverding & Fritz Oehl

Sydowia 67: 119-126

Acaulospora foveata, a glomeromycete fungus with pitted ornamentation on the outer spore surface, was originally isolated from a sugar cane field close to the city Orizaba, Veracruz, Mexico, in 1982. At that time, the concepts of morphological spore descriptions were less evolved, and only two wall layers are mentioned in the protologue, an outer pigmented layer and an inner hyaline layer. In recent years, several Acaulospora spp. with pitted ornamented spore surfaces were described. In order to mini­mize errors on the identification of A. foveata and similar fungal species, we studied the holotype, isotype and newly collected epitype material from the type location and morphologically re-described the fungus from these types, and we performed mo­lecular phylogenetic analyses of sequences obtained from the ribosomal gene gained from single spores collected at the type loca­tion. Acaulospora foveata has - like many other species in the genus - three spore walls, including an inner, ‘beaded’ wall, and at least eight spore wall layers. Phylogenetically, the fungus clusters in a clade well separated from all other known Acaulospora spp., and it is most closely related to A. lacunosa. We conclude that with this new information A. foveata can now be correctly identified also by molecular analyses.

Keywords: Arbuscular mycorrhizal fungus, Glomeromycota, Acaulosporaceae.

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