Arbuscular mycorrhizal and dark septate fungi are not common in roots of epiphytic pteridophytes of a transitional forest area in South Brazil

Arbuscular mycorrhizal fungi (AMF) and dark septate fungi (DSF) are symbionts that are associated with the roots of plants, including epiphytic lycophytes and ferns. Paris-type mycorrhiza and glomoid structures are the most common forms of colonization in these plants. This work aimed to evaluate the occurrence of these symbionts in the roots of epiphytic lycophytes and ferns as well as the diversity of AMF spores recovered from substrate associated with the roots of eleven species. Roots of Asplenium gastonis, Campyloneurum aglaolepis, C. nitidum, Niphidium crassifolium, Pecluma pectinatiformis, Phlegmariurus mandiocanus, Pleopeltis hirsutissima, P. pleopeltifolia and Selaginella microphylla had hyphae and vesicles typical of AMF colonization, but not arbuscules. Campyloneurum nitidum, Pecluma pectinatiformis, Phlegmariurus mandiocanus, Pleopeltis pleopeltifolia and Selaginella microphylla had melanized hyphae and microsclerotia typical of DSF. All species colonized by DSF were also colonized by AMF. Seventeen spore morphotypes of AMF were identified, of which six were acaulosporoid and eleven glomoid. Glomus aff. formosanum and Acaulospora aff. lacunosa were the most abundant and frequent species. Epiphytic lycophytes and ferns host concurrently AMF and DSF but colonization is scanty in their roots. For the first time, acaulosporoid spores and intraradical vesicles are reported for this group of plants.