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When: 2018-11-27

Collection location: Chorro Park, San Luis Obispo Co., California, USA [Click for map]

Who: J-Dar

Specimen available
Collection number: Jason Dart 1128

On sandstone bedrock in coastal grassland setting. The site is a large somewhat flat bedrock outcrop with Indian grinding holes. It is along a popular trail and gets people walking on the lichens regularly, hence this specimen had somewhat depressed apothecial margins. A flake of the sandstone had been dislodged by hikers, so I picked it up and decided to give the lichen a future home in the herbarium.

Thallus white, thick, rimose, with convex or irregularly angular areoles. Cortex K+Y. Thalline margin persistent, white. Disk black, epruinose, shiny. Epihymenium strongly green, with a 10-15µm thick epinecral layer. POL+ small crystals in center where disk was deeply concave and epihymenium brown, but otherwise POL- where normal and green. Hymenium hyaline, about 80µm tall, amyloid (IKI+blue). Amphithecium with large POL+ crystals insoluble in K, and cortex POL+ white like the medulla below the apothecia. Algae interrupted below the apothecia. Large POL+ crystals occasional in medulla below apothecia.

Spores 8 per ascus, simple, hyaline, broadly ellipsoid, about 12-13 × 7-8µm.


100x in water
100x polarized (POL)
Amyloid hymenium
400x in Lugol’s (IKI)
100x polarized
400x in water, detail of hymenium, asci, and epihymenium
100x in water
100x polarized showing large crystals in amphithecium

Proposed Names

92% (2)
Based on microscopic features: Green epihymenium, spore size
Based on chemical features: K+Y

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= Observer’s choice
= Current consensus


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