Interesting, why so few deer in Wales historically? Much discussion about proper grazing levels for bryophytes/lichens in Welsh Atlantic woods...I have visited some where overshading by bracken/bramble is a serious issue, others where the effects of past overgrazing are stark

I've only ever seen it as a saxicole too. Some amazing photos on iNaturalist of it covering tree trunks and branches in places like Madeira and the Azores

Yes, for a lot of the woodland sites I have visited here in N Wales, NRW's site management statements note that deer are spreading in the region as their numbers increase and may become an issue for woodland regen

Here is what the leaves look like under the microscope. The nerve is less stout than in H. tenax and longer than in H. humile. It is often "kinked" in the upper half.

Characteristic down-turned margins with strongly curved hairs separate it from similar Metzgeria conjugata - plus the "fan-like" growth habit visible in some of the colonies photographed above.