Mycoblastus
Crust lichens containing a trebouxioid alga; thallus smooth, areolate, granular, or sorediate; sometimes very thick and glossy, with a dense cortex over a spongy, fragile medulla; apothecia with a non-algal rim that is like the disc in colour and texture, receding with maturity and the apothecium becoming rimless, sometimes also with the thallus forming an outer ring; disc jet black, usually very glossy; hymenium streaky dark blue-green, formed of densely branched and anastomosing paraphyses embedded in firm gel; hypothecium colourless, red-brown or bright red; asci balloon-shaped, thick-walled, without a distinctly thickened tholus; spores 1 or 2 per ascus, simple, colourless, very thick-walled, oblong or broadly elliptical.
References: Purvis et al. 1992; Spribille 2006.
| 1a. | Thallus sorediate, becoming almost leprose; apothecia absent …Mycoblastus alpinus |
| 1b. | Thallus lacking soredia; apothecia ever-present …2 |
| 2a. | Apothecia usually with a bright red band between the dark upper portions and the white medullary lower portions; almost all asci with 1 large spore; spores 65-100 × 32-50 µ …Mycoblastus sanguinarius |
| 2b. | Apothecia lacking any bright red pigments; almost all asci with 2 spores; spores 40-70 (‑100) × (25‑) 30-42 µ …Mycoblastus affinis |
Mycoblastus affinis (Schaerer) Schauer
Thallus smooth or verrucose, greenish white or pale grey, sometimes with white soredia; apothecia 0.5-1.5 mm wide, rimless, jet-black, glossy, essentially rimless; hymenium streaky dark blue-green; hypothecium colourless or pale brown; spores usually 2 per ascus, 40-70 (‑100) × (25‑) 30-42 µ.
Reactions: K+ yellow.
Contents: Atranorin, chloratranorin, and planaic acid.
Habitat: On acidic bark or wood in humid forest, lower to middle elevations.
Similar Species: Easily confused with Mycoblastus sanguinarius, and the two may not be distinct in our area.
Specimens: Björk 9041, 10923; Goward 94-911.
Local Status: Common.
Notes: This and M. sanguinarius are often not reliably distinct in inland BC.
Mycoblastus alpinus (Fr.) Kernst
Thallus of thin whitish or pale grey-green areoles on a white hypothallus, often outlined by a grey to blackish prothallus, the areoles giving rise to mounded soralia, the soredia 15-25 µ, often tightly clustered into groups 50-100 µ wide, creamy yellow-green, mature thalli becoming entirely covered in soredia; apothecia rare, 0.5-0.8 (‑1.5) mm wide, jet black, essentially rimless; hymenium streaky dark blue-green; hypothecium colourless to light brown; spores 1 or 2 per ascus, elliptical, 60-100 × 30-50 µ.
Reactions: K- or + yellow, KC+ yellow-orange.
Contents: Atranorin, chloratranorin and planaic acid, and usnic acid only in the soredia.
Habitat: On acidic or basic bark, where sheltered from rain-drip, especially directly below a Picea canopy. Lower elevation forests.
Similar Species: Lecanora hygrophoba ined. appears similar, but lacks the dark prothallus and its soredia lack the distinct greenish tone of those of M. alpinus.
Specimens: Björk 13667.
Local Status: Common.
Notes: Typically, M. alpinus grows on moss and detritus in alpine habitats. In the study area, it is known only as an epiphyte in lower elevation forests in microhabitats sheltered from rain drip. Alpine specimens are more corticate and more apt to produce apothecia, while corticolous specimens become leprose and do not produce apothecia.
Mycoblastus sanguinarius (L.) Norman
Thallus pale greenish or bluish white, usually with a pearly lustre, usually thick, continuous and lumpy, rarely immersed or sorediate; apothecia black, glossy, high-convex, usually adnate (not constricted at the base), in section with dark upper layers above and a white spongy medulla below that often has regions pigmented brilliant red; hymenium and hypothecium dark blotchy blue-green throughout; asci 1.3-1.5 × long as wide, with walls equally thick throughout; spores 1 or 2 per ascus, elliptical, with walls 4-7 µ thick.
Reactions: K+ yellow, PD- or PD+ yellow.
Contents: Atranorin, chloratranorin, and rhodocladonic and caperatic acids are reported.
Habitat: On branches and trunks above the winter snowpack, more often on bark than wood. All forested elevations.
Similar Species: No other species in our area has similar apothecia.
Specimens: Björk 10782; Goward 96-595.
Local Status: Common.
Notes: Local material sometimes lacks the red pigment in the apothecia. Forms having this trait and 2-spored asci with smaller, thinner walled spores with rounded rather than truncate ends have been called Mycoblastus affinis, but in our area, presence/abence of the red pigment is not correlated with spore number, spore wall thickness or spore shape.