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The objective of this study was to describe the morphological and anatomical features of five unidentified ectomycorrhizal types of Alnus acuminataand to complement their identification based on ITS-rDNA sequence analysis. The combined approach of morphotyping and sequence analysis based on ITS sequence comparison with sequences contained in GenBank and the UNITE database let us assign three of the five field-collected ectomycorrhiza morphotypes to the tomentella-thelephora lineage that closely matched European and North American species. The sequencing results within Tomentellapoint toward alder specific clades within T. sublilacina, T. ellisiiand T. stuposasensu lato. The two other EcM morphotypes matched Lactarius omphaliiformisand a Russulasp. Better focused, concomitant fruit body surveys are needed for accurate identification of South American ectomycorrhizal fungi because of the evidence of cryptic speciation in both agaricoid and resupinate mycobionts.

Ectomycorrhizae (ECM) of Lactarius aff. omphaliformisRomagn., Russula alnijorullensis(Sing.) Sing. and Cortinarius tucumanensisMos. on Andean alder (Alnus acuminataKunth) were characterized and identified. The identification of the fungal symbionts was achieved by morpho-anatomical observations of mycorrhizae and by comparison of ITS-RFLP patterns obtained from ECM and fruitbodies. L. aff. omphaliformisECM differed in some morphological details such as ramification and mantle type from ECM of the same species on A. glutinosa. L. aff. omphaliformisECM show an orange to ochre mantle containing latex cells, which stain with sulpho-vanillin, emanating hyphae without clamps. R. alnijorullensisECM represent a typical Russula-type-ECM, light yellow to pinkish, the outer mantle being composed of triangular latex-filled cells staining with sulpho-vanillin, emanating hyphae without clamps. C. tucumanensisECM exhibit a white (silvery) to yellowish brown mantle covered with soil particles, emanating hyphae with clamps.

Field studies in Argentina’s Yunga District revealed Alpova austroalnicolasp. nov., a hypogeous fungus associated with Alnus acuminatassp. acuminata.Morphological and molecular studies based on amplification and sequencing of the nuclear LSU rDNA gene showed its unique identity within Alpova.Related genera included in the analyses were Boletus edulis, Rhizopogonspp., Suillus luteusand Truncocolumella citrina.Additional observations of animal diggings around the sites and microscopic examination of fecal pellets of the nine-banded armadillo (Dasypus novemcinctus novemcinctus) indicate A. austroalnicolais consumed and its spores dispersed by animals.