Dimidiographa

Dimidiographa is a genus of lichen-forming fungi in the family Roccellographaceae. It has three species of crustose lichens, with Dimidiographa loandensis serving as the type species.

Taxonomy
Following a molecular phylogenetic-based reorganization of the order Arthoniales, lichenologists Damien Ertz and Anders Tehler circumscribed Dimidiographa in 2011, with D. loandensis assigned as the type species. The genus name is derived from the distinctive dimidiate. Dimidiographa is reminiscent of the genus Opegrapha, but it can be distinguished mainly by its unique dimidiate excipulum (where the lateral parts of the excipulum are, meaning they are dark brown to black and hardened, while the , which is the layer beneath the excipulum, remains pale) and the septation pattern. Among the other genera in the Roccellographaceae, Dimidiographa stands out due to its carbonized excipulum. All three species of Dimidiographa were originally described in the genus Opegrapha.

Description
The thallus of Dimidiographa is crustose and lacks a, and it features a belonging to the green algal genus Trentepohlia. The ascomata are, ranging from semi-immersed to sessile, often , and measure 0.5–6.5 by 0.15–0.4 mm. The hymenial appears slit-like or narrowly exposed, with little to no white. The is dark brown to, reacts olivaceous with a solution of potassium hydroxide, and is broadly discontinuous below the. The hypothecium is pale, while the is brown. are richly branched and anastomosing.

Asci are cylindrical to, 8-spored, and measure 50–85 by 12–18 μm. are hyaline, more or less oblong to fusiform, straight or slightly curved, and measure 14–35 by 3.5–6.5 μm. They have between 4 and 9 septa and follow a macrocephalic ascospore septation pattern. The ascospores become dark brown and when over-mature. may be absent or present, with hyaline that are slightly to strongly curved, measuring 12–28 by 0.75–1 μm.

Species
, Species Fungorum (in the Catalogue of Life) accept 3 species of Dimidiographa.
 * Dimidiographa graphidiza
 * Dimidiographa loandensis
 * Dimidiographa longissima