The lichen has a dull grey crustose thallus comprising irregular, gnarled areoles that are 0.1–0.3 mm wide. There are numerous apothecia measuring 0.3–0.8 mm in diameter, which occur either singly or sometimes fused in clusters of two or three. Ascospores are hyaline, broadly ellipsoid to ovate in shape, and typically 6–13 by 4–6 μm. There are two types of conidia present. The macroconidia are ellipsoid, measuring 8–12 by 3.5–4 μm, and usually contain two vacuoles; the microconidia are bacilliform to fusiform with blunt tips and measure 5–7.5 by 1.5 μm. What most distinguishes Hertelidea wankaensis from another member of the genus Hertelidea is its chemistry: it contains fatty acids that comprise the constipatic acid chemosyndrome (a set of major and minor natural metabolic products produced by a species), including constipatic acid (major constituent), dehydroconstipatic acid, subdecipienic acid A, and subdecipienic acid B, the latter three all as minor constituents. In contrast, other members of the genus have perlatolic acid or homosekikaic acid.[2]