Pyrrhospora palmicola

Pyrrhospora palmicola is a species of corticolous (bark-dwelling), crustose lichen in the family Lecanoraceae. It has a yellow thallus with rounded to irregular (fruiting bodies) with pale brown or black. The lichen is found in Mato Grosso, Brazil, and the Seychelles.

Taxonomy
Pyrrhospora palmicola was described as a new species in 2009 by the lichenologists André Aptroot and Mark Seaward. The type specimen was collected in 1974 from Anse Mais, Aldabra (Seychelles), where it was found growing on Cocos nucifera. This lichen is noted for its yellow and the presence of a xanthone, most likely thiophanic acid, a characteristic distinguishing it from related species.

Description
The lichen has a bright citrine-yellow to greenish-yellow or straw-coloured, with a diameter of up to 1 cm. are and round to irregular in outline, measuring 0.2–0.4 mm in diameter. The is pale brown to usually fuscous brown to black, flat to convex, dull, and sometimes covered with a thin layer of white. The margin of the is hardly prominent to  and is about 0.1 mm wide, often becoming excluded. The is largely orange-brown in section and pale brown inside.

The is orange-brown, approximately 20 μm high. The is infrequently anastomosing, not, and about 50–70 μm high. The is orange-brown, with numerous relatively large crystals, about 5 μm high, with the crystals in potassium hydroxide solution dissolving to reveal slightly swollen  tips with the upper 1–2 cells grey-tinted. are, 14–16 by 5–6 μm, with a wall nearly 1 μm wide.

This species is the first Pyrrhospora with a yellow, C+ (orange) but without. The authors suggest that it is probably closely related to P. quernea, sharing xanthones and small, pale to dark.

Chemistry
The species contains a xanthone, most probably thiophanic acid. In terms of standard spot tests, the thallus reacts UV+ (pink) and C+ (orange).

Habitat and distribution
Pyrrhospora palmicola was originally known to occur only in the type locality in Aldabra, Seychelles. It grows on coastal trees and shrubs. It has since ben reported from the Chapada dos Guimarães, Mato Grosso, Brazil.