Cresponea flavosorediata

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 prothallus). 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.^[2]

Apothecia (sexual fruiting bodies) are sessile, round to slightly lobed, usually few in number, 0.5–1.6 mm across. Their discs are flat and densely coated with vivid greenish-yellow pruina; 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 paraphysoids 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 epihymenium turns red with K (indicating an anthraquinone pigment). Thin-layer chromatography shows zeorin in the thallus along with a non-anthraquinone pigment.^[2]

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.^[2]

The species grows on smooth bark of trees in primary rainforest. It was originally known only from Brazil, with collections from the type locality in Rondônia.^[2] It has since been recorded in the Brazilian states Amazonas and Sergipe.^[3]