Graphidaceae of Central French Guiana

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Graphis cf. glaucocaesia Müll-Arg. H 33281

Thallus thin, ± farinose, matte splitting along with bark below, otherwise continuous and ± uniform in thickness, glaucescent greenish to bluish, paler where thickest, lacking a cortex, K+ sordid yellowish, P?. Ascomata ± fissurine, immersed, lirelline, quite irregularly developed, from .3-5 mm long irregularly several branched, sometimes radiately so, more often elongate with several small lateral branches, disks narrowly exposed to .14 mm, brown, with brownish erect labia, usually well-separated from thalline margin, thalline margin often partially covering disks, disks brown pruinose. Exciple ± wanting, no carbonization. Spores oblong, not fusiform, 5-8(10)x14-20µ, 6-8 locular, I+ blue. No lichen substances.

Also examined: B 18302. (Thalline corticolous, very thin, tightly appressed to substrate, extensive, probably > 10 cm across, continuous to slightly cracked, ± uniform, greenish gray with hints of blue, ecorticate and farinose, K+ yellow, P-. Apothecia immersed, broadly exposed and brownish with distinct and slightly protruding margins, up to 1 cm long and sparingly branched, not radiate, but undulate, with ascomata running parallel to grain of the bark, evenly ca. 0.09 mm exposed, brown pruinose, apices acuminate appearing as fissurine cracks, evenly distributed and abundant, exciple darkened at the apices only or about halfway up from base to top, widely open below, Spores 5x18µ, 6-8 locular, 8/ascus, I+ blue, ± oblong to slightly tapered. )