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Inoderma byssaceum (Weigel) Gray

Forrige Opp Neste
Eikeflekklav.
Creative Commons Attribution Share-alike | Andreas Frisch

Inoderma byssaceum collected from Quercus sp. at Vemannsås north of Larvik (O-L-20016).

Inoderma byssaceum is a rare southern species of old oak trees. The adnate apothecia and raised pycnidia are covered in a thick white pruina. The extensive thallus is felty to subgranular with trentepohlioid photobiont. The colorless spores are 2–5-transversely septate and have a slightly enlarged apical cell.

Description

Thallus

The thallus is off-white or pale fawn in color and has a matt, rough, felty or subgranulose surface. It is up to 50 µm thick, continuous or cracked, and immersed in the bark to partly superficial. The margin is not determinate. The photobiont is a species of the family Trentepohliaceae.

Fruitbodies

The apothecia are adnate, rounded to slightly wavy in outline, and pale brown beneath a thick white pruina. They are 0.1–0.2 mm in size and 110–200 μm tall. The disc is slightly convex.

The epithecium is 10–25 μm tall, greyish to brown, and densely inspersed with pale granular crystals 1–3 μm in size.

The hymenium is colorless or a pale yellowish brown, and it is 45–65 μm tall.

The hypothecium is dark brown and 50–120 μm tall.

The paraphysoids are 1–1.5 μm wide. Their tips are slightly widened to 2 µm, with sparse dark brown pigment on the outer wall.

The asci are clavate, with stipe, 30–43 × 13–21 μm in size, and 8-spored.

The spores are unpigmented, narrowly obovoid, 11–19 × 4–6 μm in size, and divided by 2–5 transverse septa. The apical cell is slightly enlarged.

Anamorph

The pycnidia are raised above the thallus. They are covered by a dense white pruina and are 0.15–0.4 mm in size. The pore is 0.1–0.35 mm wide. The rim of the pore is entire or rugged and often weakly recurved. The pycnidial wall is dark brown to black. Pale fawn conidial masses are often protruding from the pore. The central cavity of the pycnidia is bowl-shaped to weakly cerebriform (brain-like), 100–250 μm in diameter and typically divided by thin septa. The conidia are rod-shaped and 4–6 × 1–1.5 µm in size.

Chemistry

The thallus does not react with C, K, KC, Pd or UV (C–, K–, KC–, Pd–, UV–). Two compounds named the byssaceum unknowns have been detected by TLC. These may represent 2'-O-methylperlatolic acid and an accessory compound.

The hymenium reacts I+ and KI+ deep blue, or I+ red mottled with blue and KI+ deep blue. KI+ blue ring structures in the asci have not been observed.

The brown pigment in the epithecium changes to greenish in K solution.

Eikeflekklav.
Creative Commons Attribution Share-alike | Andreas Frisch

Inoderma byssaceum collected from Quercus sp. near Götlunda in Närke, Sweden in 1864 (O-L-202392).

Ecology

Inoderma byssaceum is a temperate, suboceanic species that preferably grows on dry, rain-shaded bark of old oak (Quercus spp.) trees in humid forests and woodlands. The species has become increasingly rare and appears to be sensitive to air-pollution and eutrophication.

In Norway, it has been found on oak (Quercus spp.) trees in Quercus dominated deciduous forests.

Distribution in Norway and the Nordic countries

Inoderma byssaceum is known from three localities near Skien in Telemark og Vestfold. In the Nordic countries, it is further known from Denmark and southern Sweden.

Global distribution

Inoderma byssaceum is widespread in temperate Europe and has been found in eastern North America, central Asia, the Russian Far East, and Japan.  

Eikeflekklav.
Creative Commons Attribution Share-alike | Andreas Frisch

Inoderma byssaceum collected from Quercus sp. at Vemannsås north of Larvik (O-L-202392).

Similar species

Fruiting individuals of Inoderma byssaceum cannot easily be confused with any other species in Norway.

Without apothecia, Lecanactis abietina can be separated from I. byssaceum by longer conidia (12–17 × l.5–3 µm) and the C+ red pruina of the pycnidia.

Kart. Utbredelse i Norge.
Lecanactis abietina (Ach.) Körber

Literature

Frisch A, Ohmura Y, Ertz D and Thor G (2015). Inoderma and related genera in Arthoniaceae with elevated white pruinose pycnidia or sporodochia. Lichenologist 47:  233–256.

Frisch A, Klepsland J, Palice Z, Bendiksby M, Tønsberg T and Holien H (2020). New and noteworthy lichens and lichenicolous fungi from Norway. Graphis Scripta 32(1): 1–47.

Sundin R (1999). Phylogenetic and taxonomic studies within Arthonia Ach. (Ascomycetes, Arthoniales). Botaniska institutionen, Stockholms universitet, Stockholm.