Micarea ternaria  

Like M. lignaria in anatomy, but the apothecia are smaller and less convex with a more well-defined true exciple in section, and ascospores 13-22 × 3.5-5 μm, never more than 3-septate and no lichen products detected by TLC. M. erratica is similar in external appearance but with aseptate ascospores and brown pigment in the exciple.