Thallus fuscous- to green-brown, minutely squamulose-granulose, granules 0.1–0.2 mm diam. (Fig. 1); effuse, up to 2 cm across in a mosaic with other crustose lichens, prothallus not observed; cortical cells dilute red-brown, 5–8 mm diam. Photobiont green; cells thick-walled, ca (8.5–)10–15 µm diam. Apotheciafrequent, lecideine, 0.4–0.6(–0.8) mm diam., sessile, flat with red-brown disc and thin (0.05 mm across), barely raised, dark brown proper margin when young, becoming adnate, darker brown, convex, and immarginate when old.Hymenium50–60 µm high, hyaline, I+ blue becoming yellow-brown; epihymenium dilute red-brown, 5–8 µm high; paraphyses thick (2.0–2.5 µm), simple, rarely branching above, septate, appearing moniliform in Lugol’s iodine, apices scarcely swollen (to 3.0 µm) and only lightly pigmented. Ascicylindric 40–50 X 10–12 µm, with amyloid apical sheets (I+ blue). Ascospores hyaline, simple, subglobose 8.5–10.0 X 7.0–9.0 µm, usually with single large oil droplet, mostly uniseriate in ascus. Hypothecium hyaline, 120–150 µm high, composed of randomly orientated hyphae. Excipulumcupular, although poorly developed below hypothecium, composed of orbicular cells 0.5–0.8(–1.0) µm diam., outer cells with dark red-brown pigmented walls, inner cells mostly hyaline although some with pigmented walls resulting in ‘streaked’ appearance. Conidiomatanot observed.
Chemistry.Thallus C-, K-, KC-, Pd-, UV-. Not tested by TLC.
The presence of amyloid sheets in the asci of this new species clearly places it in subgenus Micropannaria (Jørgensen 1994). Fuscopannaria globigera appears most closely related to F. leucophaea (Vahl) P. M. Jørg. and is not closely related to F.viridescens P. M. Jørg., the only other species of the genus so far described that has a green photobiont (Jørgensen & Zhurbenko 2002).
It is surprising that the only two described species of Fuscopannaria with a green photobiont are known only from the Arctic, because it is generally believed that the presence of cyanobacteria as the photobiont would be advantageous in nitrogen-poor communities, such as that of alpine-arctic terrestrial ecosystems. There are, however, other factors to be considered, especially pH because cyanobacteria operate more efficiently at high pH levels (e.g., Fogg et al. 1973). The tundra generally has a low pH (Everett 1980), and this is most probably the reason why F. globigera and F. viridescens occur only in these habitats. A similar situation occurs in Nephroma, with N. arcticum (L.) Torss., which has a green photobiont (although cyanobacteria are present in cephalodia), being confined to the Arctic, whereas most other species of the genus have a cyanobacterium as photobiont and occur outside the Arctic.
The new species is known only from the type locality—a damp, low, west-facing bank on the north coast of Alaska (Fig. 2) where it grows over soil and bryophytes and is associated with Salix rotundifolia Trautv. Lichen species associated with the three collections are Fuscopannaria praetermissa, Lecanora epibryon, Lecidella wulfenii, Physconiamuscorum, and Schadonia fecunda. Although the area is generally acidic, the presence of species such as Gyalecta foveolaris and Solorina saccata elsewhere on the same bank, suggest that, at least,pockets of isolated base-enrichment do occur.