Based on molecular phylogenetic analyses, and also considering morphological characters, four new families are separated from the family Glomeraceae within the order Glomerales and the class Glomeromycetes. The revised family Glomeraceae comprises only four genera: the type genus Glomus, Complexispora, Sclerocarpum and Simiglomus. Septoglomeraceae fam. nov. comprises, besides Septoglomus, Funneliformis, Funneliglomus, Blaszkowskia and Viscospora. Sclerocystaceae fam. nov. is represented by the type genus Sclerocystis but also by Halonatospora, Oehlia, Parvocarpum, Rhizoglomus and Silvaspora. Kamienskiaceae fam. nov. encompasses Kamienskia, Microkamienskia and Epigeocarpum. Finally, Dominikiaceae fam. nov. includes the genera Dominikia, Macrodominikia gen. nov., Microdominikia, Nanoglomus and Orientoglomus. The genera Oehlia and Halonatospora form two other clades well separated from Silvaspora, Sclerocystis and Rhizoglomus and might represent two further families within Glomerales. This deeper separation is, in our opinion, fully supported by molecular phylogeny, but in view of the low numbers of taxa, the separation is not yet proposed at this stage of research progress.

The objective of the present study was to revise the recently described order Entrophosporales of the Glomeromycetes. The single family Entrophosporaceae had been divided into three genera, Entrophospora, Claroideoglomus and Albahypha, due to molecular phylogenetic or morphological analyses, but recently these three genera were combined within the type genus of the family, Entrophospora. Our new studies now suggest once more three genera, but Entrophospora and Claroideoglomus were not separated again. In the present study, we resurrected Albahypha with A. drummondii and A. furrazolae comb. nov. and established Alborhynchus gen. nov. with A. walkeri comb. nov. Morphologically, all glomoid morphs of the three genera have hyaline to white subtending hyphae with one spore wall continuous with the subtending hyphal wall. However, the genera can easily be differentiated from each other and from other glomoid species of the Glomeromycetes by the combination of the characteristics of the subtending hyphae, the staining reaction of the spore wall layers in Melzer’s reagent and phylogeny. In conclusion, the three AMF genera, currently recognized in the Entrophosporales, can unequivocally be identified by molecular phylogeny or by morphological characteristics of their spores and their subtending hyphae. An identification key distinguishes all AMF species currently attributed to Entrophosporales.

Increasing elevation affects many abiotic factors, such as a temperature decrease and an increase in radiation, as well as multiple biotic characteristics such as richness and composition of plant communities, both of which contribute to the formation of different habitats in mountainous landscapes. Both biotic and abiotic factors also affect belowground arbuscular mycorrhizal fungi (AMF) communities, but there is scarce information available from tropical mountain ecosystems. The objective of this study was to determine the diversity and distribution of AM fungi in different mountainous habitat types in the Chapada Diamantina mountain range in Bahia (NE Brazil). Soil samples were collected in five habitats types: high‐altitude cerrado savannas (HAC), natural grasslands (GRA), gallery forests (GAF), in natural rocky rupestrian fields (shrublands; CAR) and in rocky, rupestrian field in the regeneration stage (CRR). A total of 49 AMF species were identified, of which Glomeraceae and Acaulosporaceae species were the most representative families. The AMF communities did not follow the shifts in plant communities. The composition of the AMF communities differed only between CAR and HAC and between CRR and GAF, while the other habitats had similar AMF communities. Our conclusion is that the AMF community assemblages in tropical mountains are related to the heterogeneity of habitats of these ecosystems. In our study, silt and coarse sand contents were the main factors related to the community composition of AMF in the different habitats.

Tropical forests concentrate most of the world’s biodiversity. In the Northeast of Brazil it is possible to record mosaics of tropical dry and moist forests growing nearby but with completely different biotic and abiotic characteristics. These forests are constantly threatened by intense environmental devastation that affect not only above-ground communities but also those hidden below-ground, such as arbuscular mycorrhizal fungi (AMF), which act in maintaining ecosystem balance. This work aimed to determine the composition of native AMF communities in areas of humid forest (HF) and dry forest (DF) in northeastern Brazil. A total of 70 taxa of AMF were identified in the study areas, with Acaulospora (17) and Glomus (16) being the most representative genera. The sampling effort allowed the evaluation of 70%–73% of the species estimated for the areas. AMF communities differed between HF and DF areas. Species of the genus Glomus occurred predominantly in humid forest areas, whereas representatives of the order Gigasporales were associated more specifically with the dry forest area. Four soil attributes showed approximately 50% correlation with the composition of the AMF community (silt, clay, K, and CEC). Humid and dry forest areas presented a high diversity of AMF, and the soil properties were an important factor for the community composition of these fungi.