This species produces smooth, yellowish‑brown crusts several centimeters across. The
thallus is about 50–100
μm thick and lies mostly inside the bark, with only a thin, approximately 25 μm-thick cortical layer exposed. Its
perithecia (fruiting bodies) are dark brown to black and conical, standing on the thallus surface. They measure 0.7–1.0 mm across and have heavily walls roughly 300 μm thick on the sides but much thinner at the base. There are no red,
potassium hydroxide (KOH)‑reactive crystals in the walls. The pores are depressed and pale brown. The is clear, with unbranched filaments about 1 μm wide. The
asci are around 80 μm long and 10 μm wide and produce eight
ascospores, usually in a single row. Each spore has three cross‑walls (
septa) and measures 17–18 μm long by 6.5–7.5 μm wide. The spores are pale reddish brown with thin septa; the end chambers are rounded or triangular and the central chamber is elongated. A thickened inner wall is present at the tips. No
asexual reproductive structures or diagnostic
secondary metabolites are known to occur in
Pyrenula mattickiana. ==Habitat and distribution==