The thallus (lichen body) is
corticolous (growing on bark) and typically 1–2 cm across and about 30–50 micrometers (
μm) thick. It forms a continuous crust with an uneven surface that is white to pale gray, and it contains a photobiont (a
green alga that provides
photosynthesis). The apothecia are (sitting directly on the thallus, without a stalk) and rounded, about 0.3–0.7 mm in diameter and 170–270 μm high. The disk (the exposed spore-bearing surface) is black, concave when young, and becomes flat to slightly convex with age. The margin is thick and prominent and is typically covered with a gray layer (often strongest in younger apothecia) that may wear away with age. Under the microscope, the (the rim tissue around the apothecium) is dark purplish brown, and the (tissue beneath the
hymenium) is also dark purplish brown; the
K test is positive (K+), giving a purplish reaction. The hymenium (spore-producing layer) is about 100–120 μm high and is colorless to faintly purplish toward the top. It has branched, net-like
paraphyses (anastomosing filaments), and the
asci (spore sacs) are about 90–110 × 18–25 μm. The
ascospores are
ellipsoid and (divided into many small compartments), produced 4–8 per ascus, and measure about 20–25 × 9–12 μm; no
lichen substances were detected by
thin-layer chromatography. The species also produces (
asexual spore-producing structures) that are sessile and hood-shaped, with a black lobe, and it forms filiform, curved conidia that are multiseptate (reported as 7–13 septa). In
Tapellaria, species are mainly separated by ascospore size and septation (number and pattern of internal divisions) and by whether pruina is present on the apothecial margin; this is the main feature used to distinguish
T. floridensis from similar
taxa.
Tapellaria floridensis is morphologically similar to
Tapellaria parvimuriformis and can be confused with it. It is separated by its white to pale grey thallus, black campylidia (gray with a whitish base in
T. parvimuriformis), and longer conidia (80–90 μm rather than 45–50 μm). ==Habitat and distribution==