Hysterium pulicare Persoon : Fr.
Ascomycota, unlichenized and potentially confused with lichens ((Graphina, Graphis,...).
Thallus absent. The fruiting bodies are hysterotheca, blackish, ellipsoid or wheat seed-shaped, rather short, 0.5-1.5-0.3-0.5 mm, with a marked deep slit on top and several longitudinal furrows. Spores cylindrical, a little shuttle-shaped, straight to weakly arched, smooth, 3- (5)-septate, colorless then brown but the cells at the ends remaining paler (like poles), 28-38 x 8-10 µm depending on the literature, 27-36 x 8-10 (12) according to our measurements. Common, on bark of branches and twigs of deciduous trees. Many similar species do exist, notably: Hysterium angustatum Alb. & Schw. ex Mérat on bare dead wood of Fagus and Fraxinus of which the ascospores smaller and homogeneously coloured ; Hysterographium elongatum (Fr.) Corda on branches of Salix and Populus, Hysterographium fraxinii (Pers. : Fr.) de Not., on Fraxinus. In case of different ascospores morphology, see Gloniopsis praelonga.*