Another Fluke: Sarea resinae

I wrote about the fluke of finding Lachnellula resinaria var. resinaria in my last post—fluke because they were so incredibly tiny. I found those first ones on a dead spruce. When I went back out into the snow to look for more, I discovered an even nicer cluster growing from a large resinous canker on a dead balsam fir. It was while using my loupe at home to inspect that second batch that something else caught my eye. Something just as minute as the Lachnellula, but discoid and reddish brown. Another fluke ascomycete! 

Sarea resinae are .5-1.5 mm in size.

Fungi that tiny and dry are hard to get any information from, so I plopped the chunk of resin into a bowl of water and waited. Within an hour the dried discs had swollen and had brightened from dull red-brown to orange. Since there weren't very many, I didn't want to poke at them until I'd given them a chance to come back to life, so I stuck them in a ziplock bag overnight. The next day they'd become active enough that, with the help of the microscope, it wasn't too hard to give them a name, first Biatorella resinae, from Fungi of Switzerland (Volume I), and then, after searching around on the internet, Sarea resinae, their current name. 

Fruiting bodies are tiny, stemless discs.

Ascomycetes produce asci (plural of ascus) which contain ascospores. As a group, Ascomycetes average eight ascospores per ascus. Sarea resinae have asci that contain more than eight—way more. I didn't count them, but there were obviously several hundred tiny round ascospores in each—pretty startling when you're used to seeing fewer than ten.

A Sarea resinae ascus holds numerous ascospores.

Its ascospores are small (2-3 µm) and globose.

Sarea resinae isn't rare, just rarely found, mostly because of its tiny size. Though it usually has an association with diseased coniferous trees, there's apparently no firm evidence that it's a pathogen. Its preferred habitat just happens to be the resin exudates from cankers and other wounds. Which is where you should look if you want to find them.

Reference:

Hawksworth, D.L. 1980. Sarea resinae. CMI Descriptions of Pathogenic Fungi and Bacteria. 677 (Mycobank)