Sirenophila sp. A  

Description
Thallus effuse, areolate, cream to pale yellow but with numerous deep orange apothecial initials or pycnidia, c. 0,2 mm thick but becoming thinner towards margins; areoles angular 0.3–0.6(–1.0) mm across; medulla I–. Photobiont trebouxioid, cells 10–15 µm diam.
Apothecia numerous, sessile, lecanorine, 0.4–0.6(– 0.8) mm diam.; disc flat red-orange; thalline margin present in young apothecia, pale yellow, 0.05 mm wide, becoming irregular and mostly excluded; proper margin persistent and slightly raised, 0.05 mm wide. Proper exciple cupular, hyaline, 25 µm wide composed of narrow vertically aligned hyphae. Hypothecium hyaline c. 100 µm deep composed of randomly orientated hyphae, underlain by 25 µm deep horizonally aligned hyphae of the proper exciple. Hymenium 65–75 µm high, paraphyses simple, c 1×1.5 µm wide, swelling towards the apex and upper 3–4 cells monilliform, apical cell 4 µm wide; epihymenium c 10 µm deep, orange (K+ crimson); epipsamma medium coarse. Asci cylindrical, Teloschistes-type, 55–65 ×10×12 µm; ascospores polarilocular, narrowly ellipsoid with a narrow septum, (13–)15.25±1.288(–18) × (3.5–)4.46±0.582(–5.0) µm ( measured in water, swelling to 8–10 µm wide in K), l/b ratio (2.89–)3.68±0.618(–4.57), septum (1.0–)1.167±0.326(–2.0), (n=12). Conidiomata deep orange, hemispherical, 0.7–1.0 mm diam; conidia short bacilliform, 2.5–3.0× 0.8 µm.
Chemistry. Undetermined anthraquinones.

Ecology and Distribution:
Reported only from ornithocopriohilous rocks, on coastal cliffs on the Falkland Islands.

Comments.
Characterized by the long and narrow ascospores with a very thin septum. The generic placement is provisional, being based on an ITS sequence from a collection with an identical thallus morphology but lacking apothecia.