Armchair foraying

by Sarah Lloyd

Physarum sp.
Physarum species in moist chamber

Field surveys of myxomycetes (acellular slime moulds) are almost always augmented by the culturing of myxomycetes in the laboratory, a technique that in some instances can add 20-60% of species depending on the habitat. The technique was discovered inadvertently in 1933 when botany teachers set up moist chambers to demonstrate to their students the algae that grew on the bark of living trees. Much to their surprise they found numerous fruiting bodies of an undescribed myxomycete on the bark.

The process is simple and requires no specialist equipment except for a x20 or x40 microscope for searching for fruiting bodies. The method simply involves collecting organic material e.g. bryophytes, wood, leaf litter, bark, or dung. Wet material is placed on moistened tissue in a covered Petri dish or similar (shallow plastic supermarket containers are ideal). The material should be kept moist and the containers stored at room temperature out of direct sunlight. They should be checked regularly during the first few days and then once a week.

This is a particularly useful technique for certain groups of myxomycetes. For instance, species that live on the bark of living trees are usually extremely small and inconspicuous and have probably evolved to withstand the prolonged dry periods of tree trunk habitats and to respond rapidly when it rains. Numerous such species are reported to turn up in moist chambers within days.

In late November 2013 I set up six moist chambers and by 3 December several species appeared including the very common Physarum viride and Echinostelium minutum, a new addition to my Black Sugarloaf species list.

Pilobolus cristallinus
Pilobolus cristallinus

Herbivore dung can be productive for myxomycetes but it can take several months for them to appear. In the meantime Pilobolus cristallinus ('hat thrower' or dung cannon fungus), and a very small Coprinus species appeared on some pademelon dung.

In a US school students were asked to collect substrate for moist chamber cultures. They shared observations and compiled species lists that invariably included some rare or unusual species including some from their own backyards.

For a more extensive description of the method see David Mitchell’s paper.

References:
- Keller, HW and Everhart, SE 2010 'The importance of myxomycetes in biological research and teaching' Fungi Vol 3:1 Winter
- Mitchell, DW 1977 'The bark myxomycetes - their collection, culture and identification.' The Journal of the association for Science Education - The School Science Review Vol 58, No. 204.

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