Spore wall traits of ectomycorrhizal and saprotrophic agarics may mirror their distinct lifestyles

• Spore characteristics differ considerably between fungal trophic guilds.
• Our phylogenetically informed analysis suggested that the differences persist beyond phylogenetic noise.
• Spore traits seem to mirror guild-specific trophic behaviour.

Although fungal spores are tiny compared to plant seeds, their morphological variability is enormous, which points toward selective forces. We investigated the frequency of ornamentation, thick walls, pigmentation and germ pores of spores of ectomycorrhizal and saprotrophic agarics. We hypothesised that these traits are shaped by the needs of these distinct lifestyles. All traits showed a strong phylogenetic signal; we therefore applied a phylogenetically informed statistical analysis. There was a significantly higher occurrence of spore ornamentation in ectomycorrhizal agarics and a higher occurrence of thick-walled spores in saprotrophic agarics. The interplay between thick-walled and pigmented spores and the occurrence of germ pores was only significant for saprotrophs. We argue that ornamentation is probably important to ectomycorrhizal fungi for dispersal by soil invertebrates, whereas pigmented thick walls and germ pores would be more advantageous for predominantly r-selected saprotrophic agarics exposed to hazardous environments and in need of quick germination success.