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The other night I was looking for spiders in tiny tree holes formed by now missing branchlets. These holes were around 1 cm in diameter on Cypress Trees. To my surprise I began to notice that each little tree hole had rows of tiny fungal discs or cups, most circling the edges of the holes. These little fungi were not to be found anywhere else on the trees. They are yellow to orange in color with striped borders, flat to slightly cupped in shape. They varied in diameter from 0.2 to 1 mm in size. I suspect that these are specifically adapted to grow in small tree holes. All the row of trees I was looking at had these fungi only around the edges of the holes. We have all heard of the specialized fauna that live in our navel cavities, this is something similar for trees. Pictures 1 to 4 show close-ups of the fungi and their position within the hole. Picture shows a hole farther away, but the tiny discs are visible. Picture 6 shows a tree trunk with 3 holes, when expanded, all have the fungi inside.
Cypress trees, semi-rural residential area, San Cristobal de Las Casas, Chiapas, Mexico 2,200 meters.
Tree holes are more likely to contain minute amounts of leaf litter and other organic residue that can provide a food source for the tiny fungi.
Awesome find Lauren! You've definitely come across a fungus with a unique habitat. I will start looking at tree holes more that's for sure. I like to study old scars on trees as these can have a variety of fungi and lichens that would not be there otherwise.
Brian, Hi, would you have a look at some of the minute tree holes in your forests to see if these kinds of micro fungi are growing there?