A worldwide key to species of Carbacanthographis (Graphidaceae), with 17 species new to science.

We provide an updated, worldwide key to species of the genus Carbacanthographis, which is characterized by lirellate ascomata, a carbonized excipulum, warty periphysoids, and mostly non-amyloid ascospores. New collections and revision of herbarium material revealed 17 species new to science: Carbacanthographis acanthoamicta, with a thinly corticate thallus, a completely carbonized excipulum, apically warty paraphyses, small and (sub-)muriform ascospores, and salazinic acid; C. acanthoparaphysata, with a completely carbonized excipulum, apically warty paraphyses, small and submuriform, amyloid ascospores, and protocetraric acid; C. aggregata, with aggregated lirellae, a completely carbonized excipulum, small and submuriform ascospores, and salazinic acid; C. amazonica, with a completely carbonized excipulum, small and transversely septate ascospores, and stictic acid; C. aptrootii, with a completely carbonized excipulum, apically warty paraphyses, small to medium-sized and transversely septate, amyloid ascospores, and norstictic acid; C. brasiliensis, with a completely carbonized excipulum, apically warty paraphyses, medium-sized and transversely septate, amyloid ascospores, and no substances; C. chionophoroides, with a completely carbonized excipulum, small and transversely septate ascospores, and protocetraric acid; C. halei, with a corticate thallus, a completely carbonized excipulum, small and transversely septate ascospores, and stictic acid; C. latispora, with a completely carbonized excipulum, very large and transversely septate ascospores, and stictic acid; C. megalospora, with a corticate thallus, a completely carbonized excipulum, very large muriform ascospores, and stictic acid; C. multiseptata, with a completely carbonized excipulum, very large and transversely septate ascospores, and protocetraric acid; C. novoguineensis, with a completely carbonized excipulum, small and submuriform ascospores, and salazinic acid; C. pseudorustica, with a corticate thallus, a completely carbonized excipulum, medium-sized and transversely septate, amyloid ascospores, and stictic acid; C. salazinicoides, with a corticate thallus, a completely carbonized excipulum, medium-sized and muriform ascospores, and salazinic acid; C. sipmaniana, with a completely carbonized excipulum, apically warty paraphyses, small and transversely septate, weakly amyloid ascospores, and norstictic acid; C. spongiosa, with a completely carbonized excipulum, inspersed hymenium, small, transversely septate ascospores, and stictic acid; and C. subchionophora, with a completely carbonized excipulum, small and transversely septate ascospores, and protocetraric acid. New molecular data confirm the position of C. megalospora in the genus. In addition, we propose one new combination, Carbacanthographis nematoides. The known world distribution of four species is expanded: C. amicta is reported from Papua New Guinea; C. induta from Thailand; C. marcescens from French Guyana and Papua New Guinea; and C. stictica from Colombia, French Guyana, Venezuela and Suriname. For all species, short descriptions and distribution notes are given, and most species are illustrated. [ABSTRACT FROM AUTHOR]