Biatora subduplex
This crustose lichen is common on plant debris, stumps, and tree bases in alpine and subarctic habitats, but has probably gone largely overlooked throughout much of its range since it is small, subtle, and easily confused with similar looking species. It has a pale, crustose thallus and produces orange- to red-brown, biatorine (with soft, non-carbonized, true margins) apothecia. The phylogeny of this species was elucidated in 2023 using genetics, but the morphological analysis showed an overlap between most morphological characteristics between the most difficult to differentiate taxa. Sometimes, that's just how the lichen crumbles, I guess. The authors suggest that greater sampling or inclusion of more morphological characters could help, but that for now, the best morphological character used to differentiate these species is the number of hyphae and paraphyses (sterile filaments in the apothecia structurally supporting the spore-producing structures) and densely packed into the apothecial margin and hymenium (area of the apothecia where spores are produced). As this requires careful dissection of the tiny apothecia and counting the number of microscopic filaments within a 50 µm area, you get why folks might avoid identifying these specimens down to the species level. That's just the joy of lichenology, I guess.
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