Chrysothrix
Crustose lichens containing a trebouxioid alga; thallus leprose or with weakly corticate portions, sometimes with a woven hypothecium that supports microfoliose growth of the soredia; apothecia very rare or absent in most species, rim absent or thin and quickly receding, formed of densely branching and anastomosing hyphae loosely bound in weak gel; hymenium formed of gnarled paraphyses that branch and anastomose mostly in their upper portions, upper parts of the hymenium with crystals; hypothecium colourless; asci broadly clavate, with a shallow IKI+ blue tholus having a broad ocular chamber; spores 8 per ascus, colourless, 3-septate, clavate or elliptical.
References: Tønsberg 2004a.
| 1a. | Thallus stratified, with a continuous white hypothalline layer below a dense layer of soredia, sometimes becoming placodioid or lifting from the substrate in small sheets; with calycin and diffractaic acid; rare …Chrysothrix granulosa |
| 1b. | Thallus usually not stratified, only with loosely piled soredia, any hypothallus inconspicuous, never lifting the soredia up off the substrate; with calycin and/or pinastric acid, but not diffractaic acid; very common and widespread …2 |
| 2a. | Soredia averaging 10-100 µ wide, thallus mostly brilliant yellow …Chrysothrix candelaris |
| 2b. | Soredia averaging 100-200 µ wide, thallus yellowish green …Chrysothrix chlorina |
Chrysothrix candelaris (L.) J.R. Laundon
Thallus entirely sorediate, brilliant canary-yellow, often with an orangish tinge, covering areas as large as a meter, but in higher elevation forests usually limited to patches less than 5 cm wide; soredia 10-30 µ wide, often in clusters up to 100 µ wide; apothecia extremely rare, not found in specimens from BC.
Reactions: K- or K+ slighly reddish, PD- or PD+ orange, KC- or KC+ orange turning blackish, UV+ orangish.
Contents: Calycin or pinastric acid.
Habitat: Rain-sheltered bark or wood, above the winter snowpack. All forested elevations.
Similar Species: Chrysothrix chlorina may also be found in upper elevation forests, where it normally occurs on rock but sometimes also on bark or wood; it differs in having a greener colour and larger soredia.
Specimens: Björk 8462, 9468.
Local Status: Common.
Chrysothrix chlorina (Ach.) J. R. Laundon
Thallus with an inconspicuous greyish hypothallus, sorediate, the soredia yellowish green, 100-200 µ wide, granular, usually thin piled or diffuse, but sometimes thickly piled up and forming a cracked-leprose crust; apothecia unknown.
Reactions: K- or + orangish, C-, PD-, sometimes KC+ reddish.
Contents: Calycin and vulpinic acid.
Habitat: On rough bark of conifers in humid places, also on rock, lower to middle elevations.
Similar Species: Psilolechia lucida may be similarly coloured, but usually contains the rod-shaped alga Stichococcus, and has soredia less than 100 µ wide.
Specimens: Björk 13952.
Local Status: Occasional as a saxicole, rare as an epiphyte.
Chrysothrix granulosa G. Thor
Thallus with a white hypothallus that gives rise to thickly piled brilliant yellow soredia, the soredia 25-45 µ wide; apothecia very rare, not seen in BC specimens, with a constricted base, 0.2-1 mm wide, nearly lacking any exciple, and lacking any thalline rim; hymenium 60-70 µ high, topped in yellowish crystals; spores colourless, 3-septate, narrowly ovate, 11-15 × 3 µ.
Reactions: K+ orange, C-, KC-, PD+ orange, UV+ dull orange.
Contents: Calycin and diffractaic acid.
Habitat: On a thin exposed root at shoreline along a whitewater stretch of the Clearwater River, sheltered from rain-drip, but very humid and cool.
Similar Species: Chrysothrix candelaris lacks the cottony white hypothallus, and lacks the K+ and PD+ reactions.
Specimens: Björk 14996.
Local Status: Rare.
Notes: This is the only record of this coastal species from inland North America.