At least once a year slime moulds make the news. On December 21 2016 the headline in Science Daily was ‘Giant cell blob can learn and teach’. The article explained how the plasmodial stage of a slime mould—essentially a moving feeding giant brainless cell—can transmit what it has learned to a fellow slime mould when the two combine.
Acellular or plasmodial slime moulds, also known as myxomycetes or myxogastrids, are ubiquitous opportunistic organisms. They are most abundant in temperate forests but they also occur in tropical forests, alpine areas, heathlands, grasslands, deserts, and arctic and sub‑Antarctic regions. In short, wherever there is organic material.
Myxomycetes were once included with plants when all living things were placed in just two kingdoms – plants and animals. When more kingdoms were created to encompass a vastly more complex world than was originally imagined, slime moulds were moved to the kingdom fungi. Indeed, they are often described as fungus‑like organisms and, like most fungi, they make only a relatively brief appearance at their fruiting body stage. However, they do not have any structures analogous to fungal hyphae, so when their pulsating feeding plasmodial stage was discovered they were moved to the animal kingdom. Then their single‑celled amoeboid feeding stage was observed and they were moved again, this time to the kingdom protozoa. However, this kingdom does not encompass organisms that have an amoeboid, plasmodial AND spore-bearing stage. They are now considered to be Amoebozoans but whether Amoebozoa is a supergroup or a kingdom is matter of some debate.
My research is about another stage in the lives of these intriguing organisms. The reproductive or spore-bearing stage comprises fruiting bodies that range in size from large amorphous blobs to tiny delicate structures little more than 2 mm high. (Background to the study and descriptions of the study site can be found on the Slime Mould Log.)
In 2010 I started collecting myxomycetes in a tall wet eucalypt forest at Black Sugarloaf Birralee, central north Tasmania. I have several regular walking tracks which take me through different forest types including Melaleuca ericifolia (paperbark) swamp forest; ferny gullies dominated by Dicksonia antarctica (treeferns); wet eucalypt forest with several different Eucalyptus species, Acacia melanoxylon (blackwood), Banksia marginata (banksia), lots of ground ferns, copious quantities of fallen logs in various stages of decay, and other ‘coarse woody debris’, i.e. fallen branches, twigs and leaf litter. In short, fantastic slime mould habitat.
In the years since starting my research I have amassed over 1500 collections representing approximately 110 different species. This seems extraordinary given that all specimens have been collected within two kilometers of our house, and only 42 species had hitherto been officially recorded for Tasmania.
There are several conspicuous and easily recognisable myxomycetes including Lycogala epidendrum, Ceratiomyxa fruticulosa and Fuligo septica (also known as dog’s vomit slime, demon droppings, caca de luna (i.e. moon shit), or if you live in Tasmania, dog poo), but most species require examination of their spores, capillitium, columella, peridium and other microscopic features to confirm their identity (see glossary). With a stereo and a compound microscope, both with cameras attached, I take photos of and describe these features. All information is collated in colour plates which are compared with published texts. With the help of several reference books, scientific papers, and the microscopic examination of numerous collections, I have slowly made progress with their identification. Links to PDFs of colour plates of the species are arranged taxonomically under the heading Myxomycete Orders: Liceales, Echinosteliales, Trichiales, Physarales and Stemonitales. (Links to PDFs of the colour plates are arranged in alphabetical order on the disjunctnaturalist website.)
References used for identification include Martin and Alexopoulos (1969); Poulain et al. (2011); Neubert et al. (1993-2000); Stephenson & Stempen (1994); Stephenson (2003); Nannenga-Bremekamp (1991); and various scientific papers and websites. However, many Australian myxomycetes ‘don’t quite fit published descriptions‘ (S.L. Stephenson pers. com.) and species in some genera (e.g. Cribraria) are notoriously difficult to identify.
Duplicates of most collections have been lodged at the National Herbarium of Victoria (MEL). These may be requested for study by researchers.