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 Physarum nucleatum
BiostatusPresent in region - Indigenous. Non endemic
Article: Stephenson, S.L. (2003). Myxomycetes of New Zealand. Fungi of New Zealand. Ngā Harore o Aotearoa 3: xiv + 238 p. Hong Kong: Fungal Diversity Press.
Description: Fruiting body a stalked sporangium (or rarely plasmodiocarpous), gregarious to crowded, up to 1.8 mm tall. Sporotheca globose, erect or nodding, 0.3–0.5 mm in diameter. Stalk slender, subulate, yellowish white, rugose, not calcareous, 0.5–1.5 mm long. Hypothallus membranous, discoid to irregular, colourless to light brown. Peridium consisting of a single layer, membranous, studded with rounded, white calcareous nodules, the lime sometimes scanty and then appearing metallic, the lower portion thicker and remaining as a collar on the stalk after the upper portion has disappeared. Columella usually lacking, small and inconspicuous when present. Capillitium dense, consisting of small, white, rounded lime nodes and slender, hyaline filaments, the lime nodes usually aggregated in the centre to form a conspicuous white, globose or somewhat irregular ball of lime, the latter free from the stalk and thus not representing a true pseudocolumella, albeit resembling such a structure. Spores black in mass, clear lilaceous by transmitted light, minutely warted, 6.0–7.5 µm in diameter. Plasmodium grey.
Habitat: Decaying wood and bark.
Distribution: Reported from widely scattered localities in the Northern Hemisphere and also South America (Martin & Alexopoulos 1969) but apparently most common in warm temperate to tropical regions of the world. Reported from New Zealand by Rawson (1937), based on a specimen collected in Dunedin.
Notes: This species is rather similar in appearance to Physarum globuliferum but lacks a columella and the stalk is not calcareous. The central lime ball is a useful diagnostic feature but is sometimes not present.
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