Storm Erik brings a surprise

I stopped by Woods Mill this lunchtime, after Storm Erik had passed through, and came upon a scene of devastation.

An old willow by the dipping pond had blown over and taken out a section of the new dipping platform. I couldn't resist going in for a closer look at this wet woody mess.

Halfway up the trunk, in an area where the surface of the trunk had started to rot, I noticed some little brown clusters growing on old knots of wood.

I'd never seen anything quite like this before, so popped back later that afternoon with a penknife and a collecting box, to get a specimen.

Under the stereomicroscope, I could see that the clusters were made up of tiny round cup-shaped fruit bodies: pale on the inside, tobacco-brown on the outside. I thought they must be an ascomycete of some kind.

With some difficulty, as the individual fruit bodies were so small, I managed to get a thin section of one of the cups under the microscope.

Cross-section through cup. Mounted in water 100x magnification.

The cups are super-hairy on the outside!

Looking more closely, the brown hairs appear to become more translucent (hyaline) towards the tips.

Hairs. Mounted in water 400x magnification.

And I'm thinking they perhaps look slightly encrusted? Not completely smooth anyway.

Hairs. Mounted in water 1000x magnification.

Once I'd got a good look at the hairs, I started looking for asci – the long thin bags full of spores which are a characteristic feature of ascomycetes – on the inside of the cup... but, er, couldn't find any.

I got confused.

But then a vague memory of a cyphelloid fungus flashed across my mind. It didn't take long to track down what I was remembering: a photo on a wikipedia page that I was reading a few weeks ago, after I found that weird cyphelloid fungus on Ulva Island.

This photo in fact:

The clustered Merismodes fasciculata, USA. This image was created by user damonbrunette ©2009 at Mushroom Observer, a source for mycological images. CC BY-SA 3.0, via Wikimedia Commons.

Reckon I'm onto a decent lead here...

The very clustered growth of my collection would be right for Crowded Cuplet Merismodes fasciculata (= confusa). But a quick search on the internet suggests that M. anomala can look pretty much the same. [Malcolm Storey has images of both M. fasciculata and M. anomala on his BioImages website, if you want to see what I mean.]

I see that some folks from the Chinese Academy of Sciences have published a simple key to Cyphellopsis (= Merismodes), in a paper on 'Two new species of cyphelloid fungi (Basidiomycota) from China'. This suggests spore size is a key feature when separating these two species.

I managed to find a few spores, by sitting my specimen upside-down on a glass slide for a while.

Two spores (top left and bottom right). Mounted in water at 400x magnification.

My measurements came out at 8-10 x 4.5-5 μm {based on measurements of 11 spores}. This is close to the quoted measurements for M. anomala (8-11 × 5-6.5 μm) in the paper I mentioned above; and I note that, like mine, Malcolm Storey's collection also came out a bit smaller on the width (8-9/4.5µm).

I think this is pointing towards my collection being Merismodes anomala.

For the record
Date: 09/02/2019
Location: Dipping pond, Woods Mill
Grid reference: TQ21781369