Trichothelium angustisporum has a continuous
thallus that is pale greenish to yellowish-grey in colour, and can grow up to across. The is
Trentepohlia (a genus of
green algae), with cells forming short, irregular threads. are more or less spherical and black, measuring 0.25 to 0.40 mm in diameter. The lichen is characterized by its numerous perithecial , which can be as short as 0.05 mm or as long as 0.15 mm, and are usually arranged in several layers around the
ostiole. The
asci of
Trichothelium angustisporum are obclavate to
fusiform in shape, with dimensions of 170–210 by 20–28
μm. are narrowly fusiform to almost cylindrical, contains between 21 and 29
septa, colourless, and typically measure 100–170 by 5–7 μm. (structures bearing ) have not been observed in this species. ==Distribution==