Summary ²

Chrysothrix is a lichenized genus of fungi in the family Chrysothricaceae. They are commonly called gold dust lichens or sulfur dust lichens because they are bright yellow to greenish-yellow, sometimes flecked with orange, and composed entirely of powdery soredia. Apothecia are never present in North American specimens.

Description ³

 Life habit: lichenized; Thallus: crustose, leprose or byssaceous, in rounded patches or irregularly spreading, indeterminate to determinate, unstratified or stratified; prothallus: not evident; surface: bright yellow to vivid yellowish green, entirely composed of soredia and/or anastomosing hyphae; soredia: spherical, fine (up to c. 50 µm in diam.) to coarse (mostly more than c. 50 µm in diam.), loosely constructed and easily becoming disintegrated in squash preparations; photobiont: primary one a Chlorophyceaen coccoid (up to 22 µm in diam.), secondary one absent; Ascomata: apothecioid, rare, immersed or superficial, up to 2 mm in diam., round; disc: green, yellow, pale orange or brownish; concave to spherical; margin: poorly developed and ecorticate, or absent; exciple: poorly developed, composed of anastomosing hyphae; epihymenium: distinct, composed of the upper parts of the paraphysoids; hymenium: up to 75 µm tall; hamathecium: composed of paraphysoids richly anastomosing in epihymenium, without or with only slightly swollen apical cell; hypothecium: hyaline, poorly developed; asci: clavate, the inner wall extends to form a K/I+ blue papilla, 8-spored; ascospores: hyaline, 3-septate, narrowly obovate to narrowly ellipsoid, 9-15 x 2.5-5 µm; Conidiomata: unknown; Secondary metabolites: pulvinic acid derivatives, terpenes, depsides, and diagnostic unknowns; Geography: world-wide on all continents; Substrate: on trees, wood, rock, and plant remnants.; Note: Prior to the discovery of ascomata (Laundon 1981), species of Chrysothrix were placed in Lepraria, a genus for which no ascomata are known. 

Sources and Credits

1. (c) CALS, some rights reserved (CC BY-NC-ND), uploaded by CALS
2. (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Chrysothrix
3. (c) Lichen Unlimited: Arizona State University, Tempe., some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/10548000

More Info

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