Coniocarpon
Coniocarpon is a small genus of four recognized species at world level. Three species are known from boreo-nemoral rainforests in Norway. Coniocarpon is lichenized with a trentepohlioid photobiont.
- Innhold
- Description
- Ecology
- Remarks
Description
Thallus
Coniocarpon species have a thin but extensive thallus that can be immersed in the bark substrate to superficial. The thallus color varies from pale grey with a weak greenish tint when fresh to fawn. The surface is smooth to minutely felty. A thin brownish line delimiting the thallus is often present when in contact with other lichens.
Fruitbodies
The apothecia of Coniocarpon are well-delimited and typically raised over the thallus surface. Characteristic for most species is an orange to red pruina covering the apothecial margin and partly the otherwise white pruinose disc. Coniocarpon cuspidans is the only species lacking visible pruina. The apothecia of Coniocarpon are roundish to lirellate, often lobed to shortly branched, or aggregated in irregular star-shaped clusters up to 2 mm in size.
Orange, red and purplish pigment granules together with a weak, amorphous, red to purplish pigmentation of the gelatinous matrix are present in the apothecia of all species. This pigmentation is concentrated in the apothecial margin and the epithecium, but a weak and patchily distributed pigmentation is often also present in the hymenium and in the hypothecium.
The apothecial margin is formed of compacted branched and netted hyphae with patchily distributed brown pigment in the cell walls. It contains unpigmented crystals in addition to the granular pigment. The hyphae of the apothecial margin often form short hair-like extensions at the outer edge.
The hymenium is mostly unpigmented.
The epithecium is formed of the densely intertwined tips of the paraphysoids that extent horizontally above the asci and form short hair-like extensions at the outer surface. Like the apothecial margin, the epithecium includes unpigmented crystals, and patchily distributed brown pigment is deposited along the cell walls.
The hypothecium is colorless to pale brownish.
Asci are of the Arthonia-type and contain 8 spores.
The spores are oblong-ovoid and divided by 3–5(–8) transverse septa. They are colorless or have a pale brown pigmentation with granular ornamentation when old. The apical cell is enlarged.
Anamorph
Pycnidia are reported for Coniocarpon cinnabarinum. They are 50–70 μm in size, immersed in the thallus and have a red-brown wall. The conidia are rod-shaped and 3.5–5.5 × 0.7–0.8 μm in size.
Chemistry
Four quinoid pigments, A1 to A4, have been identified from the apothecia of Coniocarpon in Norway. With reference to the available literature (Yamamoto et al. 2002), these pigments include bostrycoidin, 8-O-methyl bostrycoidin, and arthoniafurone A and B. The hymenial gels react I+ red or blue, and KI+ blue. A KI+ blue ring structure is present in the tholus of the asci.
The brown pigment in the wall of the pycnidia turns olive-grey in K solution.
Spore drawings, from left to right: Naevia punctiformis, Coniocarpon fallax, Reichlingia anombrophila and Bryostigma muscigenum. The spores of Bryostigma muscigenum are 10 µm long.
Ecology
Coniocarpon is widely distributed in humid forest communities from the tropics to temperate regions. In Norway, the genus is confined to the boreo-nemoral rainforests and oceanic woodlands from Vest-Agder to Møre og Romsdal. Coniocarpon species typically occur on tree species with smooth bark. Common hazel (Corylus avellana) and European ash (Fraxinus excelsior) and are the most common host trees in Norway, but Coniocarpon species have also been found on other trees including holly (Ilex aquifolium), oak (Quercus spp.), and rowan (Sorbus aucuparia).
Remarks
The species of Coniocarpon are readily recognized by the crystalline orange, red and purple pigments in the apothecia. In C. cinnabarinum and C. fallax these pigments form a distinct pruina on the apothecial margin and partly on the otherwise white pruinose apothecial disc. The transversely septate spores have an enlarged apical cell and turn brownish with granular ornamentation with age. All species can be locally common in suitable habitats. They are, however, threatened by their restricted habitat size in Norway and habitat destruction.
Several species of Arthonia s.lat. in Norway produce reddish, K+ purple pigments in the apothecia. These can be distinguished from Coniocarpon by only 1-septate spores and reddish quinoid pigments that are diffusely staining the gelatinous matrix and hyphal walls in the apothecia. Pigment granules and a distinct orange red pruina are lacking.
Literature
Frisch A, Moen VS, Grube M and Bendiksby M (2020). Integrative taxonomy confirms three species of Coniocarpon (Arthoniaceae) in Norway. MycoKeys 62: 27–51.
Yamamoto Y, Kinoshita Y, Thor G, Hasumi M, Kinoshita K, Koyama K, Takahasi K and Yoshimura I (2002). Isofuranonaphthoquinone derivatives from cultures of the lichen Arthonia cinnabarina (DC.) Wallr. Phytochemistry 60: 741–745.