Fissurina tuckermaniana

The thallus forms a crust on bark, typically 1–2 cm across and about 30–50 μm (micrometers) thick. It forms a continuous crust with a smooth surface that is yellowish-brown to olive-brown and contains a trentepohlioid photobiont (Trentepohlia-type alga). In cross-section, the thallus has a prosoplectenchymatous upper cortex, an irregular algal layer, and scattered clusters of crystals. The lirellae are straight to curved and usually unbranched (sometimes sparsely branched), ranging from immersed to slightly erumpent. Individual lirellae are about 1–3 mm long and 0.3–0.5 mm wide, with a complete thalline margin; the disk is concealed. The labia are conspicuous but not thickened, appearing greyish black to brown-black beneath the corticate thalline margin. The excipulum is also darkened (brown-black). Microscopically, the asci are fusiform and contain 2–4 ellipsoid ascospores. The spores are 3-septate (divided by three internal walls), about 25–40 × 11–14 μm, and amyloid (I+ violet-blue). Paraphyses and periphysoids are present, with spinulose (spiny) tips. No lichen substances were detected by thin-layer chromatography.

Fissurina tuckermaniana is known from two collections from Fakahatchee Strand Preserve State Park in southwestern Florida. It was found on the bark of hardwood trees in second-growth habitat along the park's Scenic Drive near gate 14.

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