The
thallus (lichen body) forms extensive, dull to slightly glossy crusts that can blanket large areas of bark; it is olivaceous green to olivaceous brown and lacks a contrasting border (no ).
Soralia are small, rounded, powdery patches that shed
soredia (tiny clumps of algal cells wrapped in fungal threads for asexual spread); in
C. flavosorediata they are always present; they are yellow-olive, mostly circular, 0.5–2.5 mm across, and may become numerous enough to merge and cover much of the surface. The
photosynthetic partner is a
Trentepohlia-type
green alga.
Apothecia (sexual fruiting bodies) are , round to slightly lobed, usually few in number, 0.5–1.6 mm across. Their are flat and densely coated with vivid greenish-yellow ; the margin is black and slightly higher than the disc, with yellow pruina on the inner face. Internally, the outer wall is blackened and rough; the
hymenium is
hyaline and
stains blue with iodine (IKI+); the are branched with brown, heavily pruinose tips.
Asci contain eight
ascospores that are hyaline, narrowly club-shaped, 7–9-septate, and typically 26–38(–50) × 50–65 μm, often slightly curved. No
pycnidia (
asexual fruiting bodies) were seen. In
spot tests, the thallus and apothecia are UV–, C–, P–, and K–; the turns red with K (indicating an
anthraquinone pigment).
Thin-layer chromatography shows
zeorin in the thallus along with a non-anthraquinone pigment.
Similar species Cresponea flavosorediata can be distinguished from other sorediate members of the genus by its yellow-olive soralia, apothecia dusted with bright yellow pruina, and 7–9-septate ascospores that are moderately long. It can be distinguished from lookalikes:
C. leprieurioides has whitish soredia and contains
lecanoric acid;
C. sorediata is a
subarctic species known only in a sterile state;
C. leprieurii and
C. proximata lack soredia and differ in spore size and in the iodine reaction of the
hymenium. ==Habitat and distribution==