2011-06-23

The new fungus from Bikini Bottom | Science | guardian.co.uk

The new fungus from Bikini Bottom

There's a newly discovered fungus amongus and its name is SpongeBob SquarePants


Fruit bodies of the bolete fungus Spongiforma squarepantsii Desjardin, Peay & Bruns. Specimens collected in Lambir Hills National Park, Borneo, Sarawak, Malaysia. [NOTE: this image has been altered from the original: it has been cropped.]

Original image: Tom Bruns.

What's round, bright orange, full of holes and resembles a sponge? A newly-discovered fungus that was named SpongeBob SquarePants, Spongiforma squarepantsii (pictured above). But instead of living in a pineapple on the seafloor at Bikini Bottom, the real-life SpongeBob is a terrestrial fungus that lives in rainforests on the tropical island of Borneo.

"It's really like a rubbery sponge with big hollow holes," said Dennis Desjardin, a professor of ecology and evolution at the San Francisco State University. Dr Desjardin and his colleagues, Kabir Peay, an assistant professor of plant pathology at the University of Minnesota, and Thomas Bruns, a professor of ecology and evolution at the University of California at Berkeley, co-discovered the new species.

The genus name, Spongiforma, refers to the close resemblance of the spherical fruit body to a sea sponge, whilst the specific name, squarepantsii, is the Latinisation of SpongeBob's SquarePants (pictured).

The formal description has already been published online in the research journal Mycologia by Dr Desjardin and his colleagues. (The print version is in press.)

Dr Desjardin mentioned that the editors of Mycologia initially rejected the cartoon name as "too frivolous."

"But we insisted that although the science might be their business, we could name it whatever we liked," said Dr Desjardin. "We need a little frivolity in this stodgy old science we love."

But the name of this new mushroom species isn't all that's unusual about it.

"When it's wet and moist and fresh, you can wring water out of it and it will spring back to its original size," Dr Desjardin said. Almost like a sponge. "Most mushrooms don't do that."

The surface of the fungus has deep ridges and folds resembling a brain. Further, when viewed with scanning electron microscopy, the convoluted spore-bearing surface in the mushroom's interior resembles a "seafloor covered with tube sponges, reminiscent of the fictitious home of SpongeBob".

As if its brilliant orange colour isn't flamboyant enough, the mushroom turns purple when sprinkled with a 3% potassium hydroxide solution.

The formal description also states that SpongeBob SquarePants has a "pleasant fruity-musty odor". (Alas, no mention was made of whether it's poisonous).

Despite its unusual appearance, close physical examination and DNA analysis revealed that SpongeBob SquarePants has a close relative. Its congener, Spongiforma thailandica, is very different from SpongeBob SquarePants: it ranges in colour from pale brownish-grey to reddish-brown and smells strongly of coal-tar. (No word as to whether that mushroom is poisonous, either, although its description doesn't make it seem very tasty.)

Curiously, even though SpongeBob SquarePants was discovered in the Lambir Hills National Park in Sarawak, Malaysia, S. thailandica lives thousands of miles away in the forests of central Thailand. This suggests there are many more Spongiforma species located in-between that have yet to be discovered.

"[P]erhaps we haven't seen it in more places because we haven't collected it yet in some of the under-explored forests of the region," said Dr Desjardin, who discovered S. thailandica one year earlier, in 2009.

"We expect that [Spongiforma] has a wider range than these two areas."

DNA work reveals that the spherical Spongiforma are related to a group of mushrooms that includes the tasty porcini mushrooms, which have a cap and stem like most mushrooms. According to Dr Desjardin, ancestral Spongiforma had a cap and stem too, but lost them over time -- a common occurrence in fungi.

Mushrooms' familiar cap-and-stem design is an elegant evolutionary solution to a fungal problem, explained Dr Desjardin. The stem lifts the fungus' reproductive spores off the ground so they can be dispersed more easily by wind and passing animals, whilst the cap protects the spores from drying out.

But rainforests are humid places, so the cap-and-stem design was not necessary for Spongiforma.

"It's become gelatinous or rubbery," Dr Desjardin said. "[Spongiforma's] adaptation is to revive very quickly if it dries out, by absorbing very small amounts of moisture from the air."


Scanning electron micrograph of basidiospores of Spongiforma squarepantsii (Holotype). Scale bar: 10 μm

For globe-trotting citizen-scientists and those who wish to discover new species, fungi are a rewarding group of organisms to focus on.

"We go to under-explored forests around the world, and we spend months at a time collecting all the mushrooms and focusing on various groups," Dr Desjardin said. "And when we do that type of work, on average, anywhere from 25 percent to 30 percent of the species are new to science."

Researchers estimate that there are somewhere between 1.5 and 3 million fungal species in the world, but only five percent have been formally described.

"Most of these are very cryptic, molds and little things, most of them are not mushrooms," Dr Desjardin explained. But even mushrooms -- which are like the big game of the fungal world -- are mostly unknown.

This astonishing number of undiscovered fungal species indicates that ecosystems are even more complex than most people realise.

"We don't know what's there, and that keeps us from truly understanding how these habitats function," Dr Desjardin said. "But we think that all this diversity is necessary to make the forests work the way they're supposed to work."

Sources:

Dennis E. Desjardin, Kabir G. Peay, & Thomas D. Bruns (10 May 2011). Spongiforma squarepantsii, a new species of gasteroid bolete from Borneo. Mycologia, 103 doi:10.3852/10-433 PMID: 21558499

San Francisco State University press release [quotes]

Many thanks to my twitter pal, Mason Kulbaba, for sending me this paper.

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