Tapellaria forms a thin, paint-like crust (a
crustose thallus) that sits flush against its leaf or bark
substrate and never develops an outer skin (it is ). A separate —an early growth fringe visible in some lichens—is absent. Microscopic examination reveals a partner alga with spherical green cells 6–18
μm across; these cells supply the lichen's
photosynthetic energy. The
sexual reproductive bodies are small, black
apothecia that rest on the thallus surface, pinched slightly at the base. Their flattened remain plane for most of their life and may carry a faint grey or white dusting (). Surrounding each disc is a low rim (the ) that is the same colour as the disc itself; in cross-section it resembles a shallow cup whose walls are built from dark-pigmented, brick-like cells. Inside, the clear (
hyaline)
hymenium stains blue with iodine (KI+), indicating the presence of starch-like compounds, and remains firmly gelatinous when treated with
potassium hydroxide solution. Slender threads called
paraphyses weave through this layer, repeatedly branching and re-joining without swollen tips. The
asci are broad and club-shaped and conform to the
Ectolechiaceae type: their walls
stain a vivid blue in iodine, and the upper cap () is thickened and deeply
amyloid, pierced by a narrow axial column. Each ascus contains one to eight colourless
ascospores, either with several cross-walls (transversely
septate) or with both cross- and longitudinal walls forming a brick-like () pattern; the spores are
ellipsoid to cylindrical and lack any gelatinous envelope.
Asexual propagation occurs in distinctive, hood-shaped outgrowths called . These tiny, erect structures sport in-rolled flaps that protect the spore-producing surface. They release long, thread-like ()
conidia divided by three to seven septa; the spores are often slightly curved and may detach with small algal cells attached, allowing the lichen to disperse as a ready-made symbiotic unit. No characteristic
secondary metabolites have been detected in the genus. ==Ecology==