Rhizoglomus dalpeae, R. maiae, and R. silesianum, new species

ABSTRACT

We examined three arbuscular mycorrhizal fungi (AMF; phylum Glomeromycota) producing glomoid spores. The mode of formation and morphology of these spores suggested that they represent undescribed species in the genus Rhizoglomus of the family Glomeraceae. Subsequent morphological studies of the spores and molecular phylogenetic analyses of sequences of the nuc rDNA small subunit (18S), internal transcribed spacer (ITS1-5.8S-ITS2 = ITS), and large subunit (28S) region (= 18S-ITS-28S) confirmed the suggestion and indicated that the fungi strongly differ from all previously described Rhizoglomus species with known DNA barcodes. Consequently, the fungi were described here as new species: R. dalpeae, R. maiae, and R. silesianum. Two of these species lived hypogeously in the field in habitats subjected to strong environmental stresses. Rhizoglomus dalpeae originated from an inselberg located within Guineo-Sudanian transition savanna zone in Benin, West Africa, where the temperature of the inselberg rock during a 5-mo drought ranges from 40 to 60 C. Rhizoglomus silesianum originated from a coal mine spoil heap in Poland, whose substrate is extremely poor in nutrients, has unfavorable texture, and may heat up to 50 C. By contrast, R. maiae was found in more favorable habitat conditions. It produced an epigeous cluster of spores among shrubs growing in a tropical humid reserve in Brazil. Moreover, the compatibility of phylogenies of species of the family Glomeraceae reconstructed from analyses of sequences of 18S-ITS-28S and the largest subunit of RNA polymerase II (RPB1) gene was discussed.

KEYWORDS:

• Arbuscular mycorrhizal fungi
• Glomeromycota
• molecular phylogeny
• morphology
• RPB1
• 18S-ITS-28S nuc rDNA
• 3 new taxa

ACKNOWLEDGMENTS

We thank Dr. Crossay, Université de Nouvelle-Calédonie, for providing spores of R. neocaledonicum for analyses.

Additional information

Funding

This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), which provided research grants to B. T. Goto and financial support in the project “Sporocarpic species of arbuscular mycorrhizal fungi (Glomeromycota): taxonomy, systematic and evolution” (proc. 408011-2016-5). We also thank Universidade Federal do Rio Grande do Norte for covering the costs of J. Błaszkowski’s stay as visiting professor (internationalization incentive program PPg/UFRN/2017). We thank Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for providing PhD scholarships to K. Jobim and J. M. R. Lima and CONACYT–Mexico for providing PhD scholarship to X. M. Vista in Brazil. The research was funded, in part, by the Institute of Botany at the Jagiellonian University (project nos. K/ZDS/007340 and K/ZDS/008054). The travel of N. S. Yorou to the sampling sites was supported by the German Research Foundation (DFG; grant no. YO 174/2-1).