Slideshow image
Arthonia varians (Davies) Nyl.
Family: Arthoniaceae
[Celidium varians (Davies) Arnold,  more]
Arthonia varians image
Life habit: lichenicolous, on apothecial discs of Lecanora rupicola coll. Thallus: inapparent photobiont: absent disc: black, more or less plane epihymenium: olive-brown, 10-20 µm thick, hyphal tips olivaceous brown, 3-4 µm wide hymenium: hyaline, 30-40 µm tall; paraphysoids branched and anastomosed, c. 2 µm wide; subhymenium: hyaline, 10-20 µm thick asci: clavate, 30-35 x 12-14 µm, with thin lateral walls, 8-spored ascospores: persistently hyaline, 3-septate, isolocular, narrowly obovate, 13-18 x 4-7 µm Pycnidia: ± round conidia: bacilliform, 4-6 x 1 µm Chemical reactions: ascomatal gels I+ red, KI+ blue, with minute KI+ blue ring-structure in tholus. Substrate and ecology: see host lichen World distribution: apparently distributed throughout the subcosmopolitan range of its host lichen Sonoran distribution: Arizona (Gila, Santa Cruz, and Coconino Counties) and Baja California (Guadalupe Island). Note: Navarro-Rosines and Hladun (1990: 78) mentioned this species as also occurring on Lecanora marginata. The basionym Lichen varians Davies is based on a mixed description of the host and the parasite, but the black discs, representative of the parasitic component, were seen as the typical character. The required typification will be done elsewhere (Hafellner pers comm.).