Prof Steve Stephenson, of the University of Arkansas, is one of 45 enthusiasts from the United States, Australia, New Zealand, the United Kingdom, Sweden and Japan working at the Waiora Scout Camp for the 22nd New Zealand Fungal Foray this week.
The fungi fans will take daily field trips to 16 sites around the Dunedin area.
The Landcare Research-backed forum will identify and display each day's finds for a national database and hold a mycology symposium today.
Prof Stephenson was seeking one particular sample: "There's a new species that was first discovered in New Zealand and it hasn't been published. That species is only known in the southern part of the South Island."
He began studying the distribution of slime moulds and their role in the detritus food chain in 1977. He is one of fewer than 100 experts in the field.
"There's a lot of overlap with the northern hemisphere but there are slime moulds unique to New Zealand and this is probably my favourite place to research."
Like fungi, slime moulds reproduce via microscopic spores, but the big difference comes when the spores germinate.
Fungi develop threadlike structures but slime moulds develop a gooey structure.
Prof Stephenson has visited New Zealand 13 times and has written a book on the subject - Myxomycetes of New Zealand.
"There are 185 colourful and intricate slime mould species in this country with more waiting to be discovered," he said.
