Figs S1-S3 & Tables S1-S2

Fig. S1. Rhizophagus intraradices: culturing history of the type and successful ex-type culture attempts (ATT 4) and a new isolate (ATT 1102) from the type location established approx. 30 years later. Both pot cultures (PC) and root organ cultures (ROC) are shown with dates of establishment and voucher numbers for samples that yielded specimens for preservation in herbaria. Sun bags are item B7062, Sigma Aldrich (https://www.sigmaaldrich.com). Location of cultures: Forestry Commission Northern Research Station or other localities in UK; Université catholique de Louvain (UCL); Ludwig Maximilian University of Munich (LMU). Gel refers to a small portion of substrate from a parent ROC, with a single spore, several spores, or root fragments (usually with attached mycelium).Fig. S2. Phylogenetic maximum likelihood phylogenetic tree of Rhizophagus species and isolates characterised for the SSU-ITS-LSU rDNA region, with Sclerocystis as outgroup. Bootstrap (BS) values below 60 % and BS values of terminal sister relations are not shown. “Rhizoglomus venetianum” (= R. irregularis) sequences are marked in red, sequence variants characterised in a Rhizophagus irregularis genome project are marked in blue. Sequences of Rhizophagus intraradices cultures derived from the ex-type culture FL 208, including the epitype (voucher W 5719 from MUCL 52327 = ATT 4-83), are shown in green and sequences of the new isolate collected from the type locality (MUCL 49410 = ATT 1102-12) in brown.Table S1. Rhizophagus intraradices: lengths and widths (µm) of extra- and intraradical spores from two strains, ATT 4 and ATT 1102 spores with inferential statistics (number of spores observed (n), minimum value (Min), first quartile of the data (Q1), median, third quartile of data (Q3), maximum value (Max), mean, standard deviation (SD) and % coefficient of variation (CV %)). Table S2. Rhizophagus intraradices: spore colours from two strains (ATT 4 – type and ex-type) and ATT 1102 (new culture from type locality) from pot cultures (PC) and root organ cultures (ROC). Where possible, colours were matched with charts from Royal Botanic Garden Edinburgh, Munsell, or Methuen Handbook of Colour.