Coccocarpia lichens are usually
foliose (leaf-like), though some species form small, scale-like squamules. Thalli are thin (to about 0.23 mm), typically forming rosettes 1–8(–15) cm across that sit tightly to loosely on the
substrate. Lobes are fan-shaped, wedge-shaped, or narrow and radiating; tips are commonly slightly thickened and bent downwards.
Soredia and
pseudocyphellae are absent. Some species produce minute surface outgrowths used for vegetative spread (
isidia) or small . The upper surface is usually dull blue-grey, but can be greenish or brownish, and only rarely yellow. It ranges from smooth to finely roughened or wrinkled, often with concentric ridges and faint radiating striations; a light, frosted bloom () is occasional. A thin, pore-bearing skin () is usually present. The lower surface has a cortex (skin-like outer layer), is pale cream to brown or black, and is anchored by dense, simple
rhizines—fine, root-like holdfasts—that may project beyond the margin and can be dense enough to form a hypothallus. The
photosynthetic partner is a
cyanobacterium of the genus
Rhizonema; its cells are roughly spherical to
ellipsoid (roughly spherical to oval), 6–14 μm wide, occurring in clusters or as short filaments aligned parallel to the thallus surface. Older literature reported the partner as
Scytonema, but many of those records have since been re-interpreted as
Rhizonema based on newer work. Sexual
fruiting bodies are apothecia that lack a (). They sit broadly attached to the surface, often appearing rimless, and may show a few scattered white hairs protruding from beneath. The is flat to slightly convex and reddish-brown, sometimes darkening towards black. The (the apothecial rim tissue) is extremely reduced—at most a thin, pale border—and in section is
hyaline (colourless), cup-shaped, and built of robust, radiating, brick-like tissue () with cells to about 5 μm wide. The layer beneath () is usually pale yellowish and poorly set off from the exciple. The
hymenium (spore-bearing layer) is hyaline or faintly pigmented at the top and gives an amyloid reaction in iodine (I+ blue; KI+ blue).
Paraphyses are mostly simple and stout, 2–5 μm wide; their tips can be slightly swollen, with a pigmented cap and a subtly beaded outline.
Asci are club-shaped to cylindrical, eight-spored, with
amyloid walls, a strongly amyloid apical cap, and a well-developed but only weakly amyloid that contains an intensely amyloid, roughly horseshoe-shaped ring; a small ocular chamber is usually visible.
Ascospores are simple (non-septate), hyaline, broadly ellipsoid to (spindle-shaped), thin-walled, and lack a clear ; oil droplets are often visible.
Asexual structures (
pycnidia) are immersed in the thallus surface or margin, producing short, rod-shaped
conidia that are only a few micrometres long (typically about 2–4 × 1 μm, though longer ranges have been reported in some regional accounts). Most species lack detectable
secondary metabolites; where present, compounds such as
fallacinal or
lichexanthone are occasional and geographically patchy. ==Habitat and distribution==