Diversity in crystal production by some bird's nest fungi (Nidulariaceae) in culture

Hyphae of many species of bird's nest fungi (Nidulariaceae) were examined for the presence of crystals. Scanning electron microscopy revealed crystals typical of calcium oxalate associated with hyphae. Crystal depositions included complete hyphal encrustation, organized druses, randomly arranged groups, single crystals, and relatively "clean" hyphae. The majority of crystals could be morphologically classified as styloid, raphide, or bipyramidal type. Energy-dispersive X-ray microanalyses confirmed that all crystal types were rich in calcium, and X-ray diffraction identified both the dihydrate (weddellite) and monohydrate (whewellite) forms of calcium oxalate. Morphological variation of crystals was species and medium specific, with generally more crystals being produced on relatively calcium-rich V8 juice agar than on PDA. No association was found between crystal types and geographic and habitat distribution of species. Keywords: wood rotting fungus, decomposition, calcium oxalate.