Enterographa aldabrensis

Enterographa aldabrensis is a species of corticolous (bark-dwelling), crustose lichen in the family Roccellaceae. It is only known to occur in Aldabra in the Seychelles.

Taxonomy
Enterographa aldabrensis was formally described as a new species by the Dutch lichenologist Laurens Benjamin Sparrius. The species is characterised by its that contain three septa and absence of norstictic acid, distinguishing it from closely related species such as Enterographa subserialis and E. elixii.

Description
The lichen has a up to 5 cm in diameter,  to, white to cream-coloured, and water-repellent, measuring 50–100 μm thick. It contains Trentepohlia ( a genus of green algae) as its partner. The is very thin, grey or absent. The upper algae-free medulla is about 10 μm thick, consisting of densely interwoven hyphae. The medulla is cream-coloured with abundant measuring 10–20 μm in diameter.

Ascomata are or slightly comma-shaped,, measuring 0.05 by 0.05–0.10 mm, with a  that is dark brown to black and. The thalline margin is approximately 0.1 mm wide and forms linear, frequently branched, which may become mixed with neighbouring pseudostromata. The is 5–10 μm wide, hyaline (translucent) in section but often brown near the. The is hyaline, 10–30 μm tall, and the hymenium is hyaline, 80–100 μm tall.

The is 10–12 μm tall, orange-brown, with crystals of about 0.5 μm in diameter, and reacts K+ (green). are cylindrical, 60–80 by 12–20 μm, and have eight spores. are, somewhat constricted around the middle, measuring 13–18 by 4.0–5.5 μm, 3-septate, with a perispore less than 2.0 μm thick. appear as dark brown dots along the thallus margin, and are rod-shaped, measuring 0.7 by 2.0–2.5 μm.

Chemistry
The thallus of Enterographa aldabrensis reacts C−, K+ (yellowish), P+ (yellow), UV+ (cream-coloured) to standard chemical spot tests. Thin-layer chromatography reveals the presence of psoromic acid. The and  show an  reaction, I+ and KI+ (dark blue), while the, , and  react I+ (red) and KI+ (dark blue).

Habitat and distribution
This species is known only from the type locality in Aldabra, Seychelles. It grows on the bark of coastal trees and shrubs.

Similar species
Enterographa aldabrensis is recognised by its thin, pale thallus with black, immersed ascomata arranged in lines. It is morphologically and chemically similar to E. subserialis but differs in having 3-septate and a K+ (green). It lacks trace amounts of norstictic acid found in the of similar species. This species is differentiated from E. compunctula, which also has 3-septate, by its chemical composition and the shape of its.