Absconditella amabilis is a species of lichen in the family Stictidaceae,[1] first found in inland rainforests of British Columbia. This tiny lichen grows hidden within the bark of western hemlock trees and produces minute, cream-coloured fruiting bodies that barely break through the surface. It was discovered in 2009 near a waterfall in Glacier National Park and is known only from that single location, where constant mist creates the humid conditions it requires.
The species was described in 2009 by Toby Spribille during a survey of old-growth inland rainforests in British Columbia. It belongs to the ostropalean genus Absconditella, a small group of lichens placed in the family Stictidaceae. Within the genus it is most closely compared with A.lignicola and A.trivialis, but it differs from the former in having markedly smaller fruit-bodies and narrower ascospores, and from the latter in its much shorter spores. The distinguishing combination of traits—a wax-coloured, flat-topped ascoma, a thin non-amyloid hymenium and three-celled spores no more than 15μm long—clearly separates it from all previously named members of the genus.[2]
Absconditella amabilis forms no visible crust on the bark. Instead, its fungal filaments grow within the outer corky layers of the host tree (an endosubstratal habit), and its green-algal partner appears only as scattered, jelly-sheathed cells about 6μm across. The fruit-bodies are minute, dome-shaped structures (technically perithecioid ascomata) that break through the bark surface. They are cream to pale yellow, 0.06–0.13mm in diameter and 60–90μm tall; a paler, flat to slightly cupped disc sits inside a persistent, waxy rim. Inside, the spore-bearing layer (hymenium) is around 50μm high and is not stained by iodine solutions, indicating a non-amyloid wall structure. Eight spores develop in each slender cylindrical ascus; the spores are usually three-celled, narrowly ellipsoid, 10–15μm long by 3–4.5μm wide, with delicate, colourless walls. No secondary metabolites were detected by spot tests or thin-layer chromatography, and no asexual reproductive bodies (pycnidia) have been observed.[2]
Habitat and distribution
Absconditella amabilis is currently known only from its type locality in the inland temperate rainforest of southeastern British Columbia. It grows on the bark of western hemlock (Tsuga heterophylla) 0.5–2 m above ground in a cool, moist gorge where spray from a nearby waterfall keeps the micro-climate perennially humid. The surrounding epiphytic community includes Parmeliopsis ambigua, a species of Lepraria, and members of the Micarea prasina group. The combination of a shaded canyon, constant water droplets and mature forest conditions suggests a requirement for very high humidity and minimal disturbance. Further searching of comparable old-growth habitats may reveal additional populations, but the lichen appears to be a local endemic restricted to a single British Columbian waterfall spray zone.[2]
1 2 3 4 Spribille, Toby; Björk, Curtis R.; Ekman, Stefan; Elix, John A.; Goward, Trevor; Printzen, Christian; Tønsberg, Tor; Wheeler, Tim (2009). "Contributions to an epiphytic lichen flora of northwest North America: I. Eight new species from British Columbia inland rain forests". The Bryologist. 112 (1): 109–137. doi:10.1639/0007-2745-112.1.109.
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