Halecania viridescens Coppins & P. James

     Thallus thin and poorly defined, a little areolate and warty, fragile if fresh (scratchable with the nail and easily eroded), pale gray-green, greenish, green, covered with fine punctiforme soralia 0.1-0.3 mm of diameter which give it a finely grainy or leprous aspect, concolorous to the thallus or greener if moist. Apothecia rare and often absent, 0.2-0.5 mm in diameter, disc flat or slightly convex, hyaline and greyish at the beginning then pale yellowish-brown and finally brownish at the end, soredate margin or bordered by a hyaline gel at the early then quickly naked. Spores hyaline, fusiform to elliptical, 1-septate with sometimes upper cell slightly wider, 12-17 x 4-6 µm with a perispore of 3-5 µm according to the literature; 13-15 x 4-5 (6) µm with a perispore of 3-6 µm according to our measurements. Thallus and soralia: C-, K-, KC-,P+ red (Sometimes red-orange on herbarium samples), UV-, Pd/UV+ orange. Rare (or neglected) species occurring on the bark of twigs or branches, the small trunks of trees or shrubs (Salix, ...) of damp forests.

N.B. The great rarity of this species may be relative because it is very difficult to identify in the field if it is sterile (which is very common!) in the absence of a P test (especially under UV).