Diaplan

Live and slightly squeezed animals as well as histological sections were observed and documented using a Leitz Diaplan or a Leica DM 5000 B light microscope equipped with a Motic Moticam 1080 camera or a Leica DFC 490 camera, respectively. Confocal stacks of fluorescently stained animals were made with a Leica TCS SP5 II confocal microscope. Images were analyzed and processed with the open‐source software Fiji v. 1.52j (Schindelin et al., 2012). The look‐up tables “Ice”, “ICA 3”, “physics” and “mpl plasma”, included in Fiji, were used to create depth‐color‐coded images. Schemes were drawn with the open‐source software Inkscape v. 0.92 (https://inkscape.org) and picture editing was done using the open‐source software GIMP v. 2.10.8 (https://gimp.org).

The majority of studied materials are dried specimen collections stored in herbarium H (Helsinki). Type material and reference specimens from herbaria BPI, H, L, O and PDD were also studied. Herbarium acronyms are given according to Thiers (2017) .
Pore measurements (12 per specimen) were done under a stereomicroscope (Wild M54) by counting the number of pores per 1 mm; only pores aligned in straight rows were selected for this purpose. Microscopic structures were studied and measured with Leitz Diaplan and Leica DMBL microscopes (×1250 magnification). Microscopic routines used in this study follow Miettinen et al. (2006 , 2012 (link)). Measurements were made and illustrations were drawn in Cotton Blue using phase contrast illumination and oil immersion (with a subjective accuracy of 0.1 μm; Miettinen et al. 2006 ).
In microscopic descriptions, the following abbreviations are used: L – mean spore length; W – mean spore width; Q – mean L/W ratio; n – pore counts, spores or hyphae measured / number of specimens. For presenting a variation of basidiospores and hyphae, 5% of measurements were excluded from each end of the range and are given in parentheses. The respective cut-off for reported pore measures is 20%.