Arthopyrenia
Mostly unlichenized fungi, but some species in regularly association with algae, some (coastal species) producing a well-lichenized thallus containing trebouxioid and/or trentepohlioid algae; perithecia black, mostly low-convex, some flat and nearly flush with the substrate, or high-convex in some species; paraphysis-like hyphae mostly branched and anastomosing, not embedded in gel; asci pear-shaped, elliptic, clavate, or cylindrical; spores 8 per ascus, always with transverse septae, many with a single primary septum and secondary constrictions or septae that divide the two primary cells, colourless, or turning brown with maturity.
References: Harris 1973; Purvis et al. 1992; Foucard 2001.
| 1a. | Spores 23-33 × 6.5-11 µ; thallus sometimes lichenized; growing on cottonwood or aspen (Populus); rare …Arthopyrenia populicola |
| 1b. | Spores up to 21 µ long; thallus not or scarcely lichenized; not growing on cottonwood or aspen …2 |
| 2a. | Spores lacking a gelatinous perispore in both water and K; perithecia 0.16-0.24 mm wide; uncommon …Arthopyrenia plumbaria |
| 2b. | Spores with a gelatinous perispore, at least in K; perithecia often larger than in 2a …3 |
| 3a. | Spores with the two primary cells divided partly or completely, at least in K, bipyriform (like two pears joined at their butt ends), 13-16 × 4-5.5 (‑7) µ …Arthopyrenia cf. cinereopruinosa |
| 3b. | Spores with only the main septum, the two cells not further divided, even in K, not bipyriform, more-or-less slipper-shaped, size various …4 |
| 4a. | Spores 15-21 × 7-8 µ (not including the perispore), strongly constricted at the septum; mature perithecia 0.2-0.5 mm wide …Arthopyrenia subalpina |
| 4b. | Spores 10-15 × 4-6 µ (not including the perispore), weakly or not constricted at the septum as seen in water mount or K; mature perithecia 0.15-0.35 mm wide …Arthopyrenia cf. analepta |
Arthopyrenia cf. analepta (Ach.) A. Massal.
Thallus poorly developed and scarcely observable, lacking algae; perithecia low-convex, 0.15-0.35 mm wide, with a black wall that is not continuous below the hypothecium; paraphyses about 1.2 µ wide, branched and anastomosing above the ascus tops; asci 60-70 µ long, narrowly elliptical or cylindrical; spores 1-septate, surrounded by a gelatinous perispore, weakly or not constricted at the septum as seen in water mount or K, 10-15 × 4-6 µ.
Reactions: Spot tests all negative.
Contents: No lichen substances known.
Habitat: On smooth bark of conifers and acidic-bark shrubs. Lower to middle elevations.
Similar Species: Numerous similar Arthopyrenia species occur in inland BC, but are yet to be found in the study area. Most of these have spores with 3 septae or 1 septum and secondary constrictions in the two primary cells.
Specimens: Björk 13200.
Local Status: Common.
Arthopyrenia cf. cinereopruinosa (Schaer.) A. Massal.
Thallus poorly formed, not or scarcely evident, lacking algae; perithecia low-convex, the wall not continuous below the hymenium; paraphyses 1.5-2 µ wide, straight (mostly), branched at the midpoint, or branching and anastomosing above the ascus tops; asci narrowly elliptical or cylindric-clavate, 55-80 µ high; spores with the two primary cells divided partly or completely, at least in K, bipyriform (like two pears joined at their butt ends), surrounded by a gelatinous perispore, 13-16 × 4-5.5 (‑7) µ.
Reactions: Spot tests all negative.
Contents: No known lichen substances.
Habitat: On smooth bark of conifer twigs. Lower to middle elevations.
Similar Species: Many similar Arthopyrenia species occur in inland BC, but have yet to be found in the study area. Further work is needed on Arthopyrenia in western Canada.
Specimens: Björk 12205, 13215, 14284.
Local Status: Common.
Arthopyrenia plumbaria (Stizenb.) R.C. Harris
Thallus weakly lichenized with Trebouxioid algae, appearing as a whitish or greenish haze around the perithecia; asci pear-shaped, much broadened toward the base; paraphyses often branched and anastomosed above the asci; spores with a gelatinous sheath 1-2 µ wide, 15-20 × 4-6.5 µ.
Reactions: All spot tests negative.
Contents: No known lichen substances.
Habitat: Bark of Alnus branches. Lower to middle elevations.
Similar Species: See notes under Arthopyrenia analepta.
Specimens: Björk 12292.
Local Status: Common.
Arthopyrenia populicola Björk ined.
Thallus with trebouxioid algae, thin and bright green, or poorly formed; perithecia high-convex, black, the wall not extending below the hypothecium; paraphyses straight, crowded; asci clavate; spores lacking a gelatinous sheath, but somewhat halonate, colourless, 23-33 × 6.5-11 µ.
Reactions: All spot tests negative.
Contents: No known lichen substances.
Habitat: Twigs and trunks of Populus tremuloides, especially on rough bark. Lower to middle elevations.
Similar Species: “Mycomicrothelia” conspicua is very similar, but has spores that turn brown and minutely warty with age.
Specimens: Björk 13864.
Local Status: Common.
Arthopyrenia subalpina Björk ined.
Thallus poorly developed and scarcely observable, lacking algae; perithecia low-convex, 0.15-0.35 mm wide, with a black wall that is not continuous below the hypothecium; paraphyses densely branched and anastomosing; asci cylindric-clavate or narrowly elliptical, 70-85 µ high; spores 1-septate, surrounded by a gelatinous perispore, weakly or not constricted at the septum as seen in water mount or K, 15-21 × 7-8 µ.
Reactions: Spot tests all negative.
Contents: No known lichen substances.
Habitat: On smooth bark of ericaceous shrubs in upper elevation forests and meadows.
Similar Species: Numerous Arthopyrenia species are known to occur in inland BC, but have yet to be found in the study area. Most of these have spores with 3 septae or 1 septum and secondary constrictions in the two primary cells.
Specimens: Björk 13777.
Local Status: Common.
Notes: Known only from inland BC and northern Idaho.