Catillaria nigroclavata is familiar to me these days on twigs and branches in my region. Will I learn any more about it if I attempt to make some drawings of it? 
At first sighting, C. nigroclavata (in lower part of image) is very similar to Amandinea punctata (above). With careful study differences in appearance of both thallus and apothecia become apparent.
The thallus of A. punctata consists of minute grey warts, its apothecia become somewhat convex with maturity. C. nigroclavata has a thin, scurfy, dark, dull green thallus; the apothecia have narrow margins and discs remain flatter with age.
Before attempting to draw a microscopic section, I hadn't realised that the apothecia contain three pigments, two shades of brown and blackish green.
The brown-capped paraphyses and colourless, 1-septate ascospores are well known Catillaria characters. Perhaps less well known are the distinct 'computer mouse' haustoria, which are also present in the genus Halecania.
The asci are typical of Catillaria after staining with iodine but the ascus tip seems elongated in C. nigroclavata. I ought to take note when I next examine C. chalybeia and see if these elongated ascus tips are particular to nigroclavata or not.
Back in 2015 I had just been studying the distinctive haustoria in C. nigroclavata and this helped me to identify the first British occurrence of C. fungoides as explained in this thread:
https://twitter.com/obfuscans3/status/1209217596165365761
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