Graphidaceae of Central French Guiana

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Sarcographa sp. Harris 33911

Thallus corticolous, epiphloeodal, unevenly raised and rugose, cracked, patchily cartilaginous and corticate (where green), pale greenish-light gray with large patches dispersed throughout, still covered by thin even corticate layer (perhaps grazed and medulla showing through with only slow regrowth?). K+ yellow. Ascomata of discrete raised small (up to 1 mm) whitish stroma of loosely woven whitish hyphae and thick algal layer and often crowded on ridges of thallus and developing over last years grazed stroma, lirellae short, crowded, often densely packed, mostly short (up to 0.4 mm) and few-branched, and so appearing contorted, branches short, mot confluent, not radiating. Disks blackish brown widely exposed (0.06 - 0.08mm) with broadly rounded ends. Exciple carbonized throughout and thickened and continuous below, joining nearby lirellae below stroma, thin laterally, whitish margins ± convergent, narrow (up to 0.06 mm). Hymenium rounded below and at sides, strongly inspersed, epihymenium dark brown-black. Paraphyses less than 2 u wide, simple, slightly tapering and wider above, anastomosing rarely. Spores 8/ascus, brown, 6-locular, thick walled, oblong with broadly rounded ends, I-, 5-7.5x17.5-20µ. Stictic acid.

This is somewhat similar to S. meduselina (Nyl.)Müll-Arg., the type of which (Nyl. 7135) has 4-6 celled spores and short, broadly rounded lirellae, but differs in having somewhat larger spores, having well developed stroma and sticitc acid (versus spores 7x15-18µ, not very conspicuous stroma and no lichen substances in the type specimen). The description of G. impressopunctata Vainio (1921) from the Phillipines is also apparently a good fit for this taxon, although the type was not seen