Wednesday, 25 February 2015

Clumsiness Pays Off: Lachnellula subtilissima and Podospora appendiculata

Podospora appendiculata on rabbit dung
Podospora appendiculata on rabbit dung

It was the first collecting morning of the Mycological Society of Toronto's annual Cain Foray. As usual, I didn't get very far from where we parked our cars. That's what happens when you're looking for the small stuff—for ascomycetes and slime moulds. But even when you're specifically looking for tiny things, help is sometimes needed. In this case, help was my own clumsiness—I skidded along the length of a slippery branch and went down.

This sort of thing seems to be happening to me with some frequency these days. Fortunately I haven't yet speared my liver with a broken branch or snapped a bone, though I've often enough ended up lying prone—which turns out to be a terrific position from which to spot the incredibly tiny things I'm looking for, things I'd never be able to see from a normal person's upright stance. 

Lachnellula subtilissima measure
Lachnellula subtilissima is a tiny species.

This time, the first thing I saw was a conifer twiglet sporting a couple of white dots. My loupe exposed a grand total of three minute egg-yolk yellow disks rimmed with white fur—a Lachnellula of some sort.  

I wasn't ready to get to my feet yet, so I poked around in the duff and found a rabbit pellet. At first I thought it was a dud since none of the tiny coloured disks or hairy cups I've come to expect on dung jumped out at me. Magnification, however, revealed several minute black oddities that I thought at first might be undigested seeds—except they were hairy, and they were all oriented pointing outwards. Weird little characters. 

Podospora appendiculata bristles
Podospora appendiculata are ornamented with short bristles.

Lachnellula subtilissima

It wasn't until I got home a couple of days later that I was able to spend enough time with my finds to identify them. Once I'd given the Lachnellula a couple of days of warmth and moisture, which prompted it to produce spores, it was clear that it was L. subtilissima

Lachnellula subtilissima spores
Lachnellula subtilissima spores

Lachnellula subtilissima asci and paraphyses
Lachnellula subtilissima asci and paraphyses
Lachnellula subtilissima hairs
Lachnellula subtilissima hairs are septet and covered with fine granules.

Podospora appendiculata

The pear-shaped coprophilous guys on the rabbit dropping were a bit more tricky to nail down, but once I'd plucked one off with tweezers and took a closer look I realized it was a flask fungus, some kind of pyromycete (now taxonomically Sordariomycetes), so that was a start. But it wasn't until I'd isolated some mature spores and found their crazy colourless tails that I was able to find the genus and species—Podospora appendiculata. Until this point, the only ascomycetes I'd found on dung had been Pezizales, or cup fungi, so it was exciting to have found something from a class that I'd only found on wood before. The length of the gelatinous appendages, or caudae, on the spores, as well as the character of the hairs, pointed to P. appendiculata, which is apparently not uncommon, just uncommonly noticed, and is frequently found on rabbit dung. 

Podospora appendiculata size
Podospora appendiculata are barely a millimetre tall.
spores and asci of Podospora appendiculata
Podospora appendiculata spores and asci at different stages of maturity.
septate hairs of Podospora appendiculata and spore appendages
Podospora appendiculata have 1-2 septate hairs with hyaline
ends and spores with gelatinous appendages.
Podospora appendiculata showing caudate
The cauda at the base of the spore is attached to a hyaline pedicel. 

References and Resources:

H.O. Baral's Worldwide Key to Lachnellula (pdf)

IMI Descriptions of Fungi and Bacteria No. 1649: Lachnellula subtilissima
Dung Fungi: an illustrated guide to coprophilous fungi in New Zealand, by Ann Bell. Victoria University Press, Wellington; pp. 88, 1983

Podospora on Ascofrance
Mycological Society of Toronto
See also my post on Lachnellula resinaria var. resinaria