Carbacanthographis is a genus of corticolous (bark-dwelling) lichens in the family Graphidaceae. The genus was circumscribed by German lichenologists Bettina Staiger and Klaus Kalb in 2002. An updated worldwide key to the genus was published in 2022 that added 17 new species. This revision allowed for further identification of undescribed species from other collections, and subsequently, 14 species were added in 2023 from the Amazonian lowland forests of Brazil and the Guianas.
Genus Carbacanthographis bears a strong resemblance to the genera Allographa and Graphis, with which it shares several characteristics, such as Trentepohlia-like, a typically (blackened) excipulum, and colourless, transversely septate or ascospores.
One of the main distinguishing features of Carbacanthographis is its unique apical structure of the . Unlike in Allographa and Graphis, where the excipulum's two lips close and the extends into the fissure, in Carbacanthographis, the excipulum extends above the hamathecium, leaving an open fissure. This fissure's walls are covered at the tips by warty, which are challenging to observe and rarely seen. Additionally, the excipulum may have somewhat radiating and apically emergent, smooth hyphae.
The growth pattern of the carbonised excipulum in Carbacanthographis results in less evident striate lirellae compared to many species of Graphis and Allographa. Clearly striate lirellae in Carbacanthographis are typically visible only when the excipulum is abraded, as seen in species like C. latispora.
The in Carbacanthographis also show notable differences. While in Allographa and Graphis, the spore become rounded to with a strong I+ blue-violet reaction due to deposition, in Carbacanthographis, some species have rounded to lentiform lumina without a positive I-reaction. In other species, there is little or no endospore formation, and the septa remain thin, with ascospores that may or may not exhibit a positive I-reaction.
The hamathecium's inspersion in Carbacanthographis consists of minute droplets approximately 0.5–1 μm wide, in contrast to the larger, unevenly sized oil-like droplets found in Graphis and Allographa. This difference in inspersion further aids in distinguishing Carbacanthographis from its close relatives.
, Species Fungorum (in the Catalogue of Life) accept 43 species in Carbacanthographis.
Former species;[1]