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Heterodermia obscurata (Nyl.) Trevisan
Family: Physciaceae
[Anaptychia heterochroa Vain.,  more]
Heterodermia obscurata image
Stephen Sharnoff  
Thallus: foliose, forming ± orbicular rosettes or irregularly spreading, robust, 2-4 (-10) cm diam., ± firmly adnate, dichotomously to irregularly lobate lobes: c. 1-2 mm, radiating, sparsely divided, ± discrete, flat to slightly convex, minutely notched, eciliate upper surface: gray-white to rarely dark gray in center, shiny, not or rarely pruinose, sorediate soredia: granular, often rusty brown, in labriform to capitate soralia on lateral and terminal lobes, sometimes confluent and forming marginal soralia upper cortex: prosoplectenchymatous medulla: white above, rusty brown below lower cortex: absent lower surface: felted with rust-colored or yellowish-brown pigment, K+ purple, not to be confused with the bluish-black underside present in H. japonica, arachnoid, rhizinate; rhizines: black, marginal, simple to squarrosely branched Apothecia: rare (not seen in Sonoran material), substipitate, 1-5 mm in diam., margin becoming sorediate; disc: blackish brown, epruinose asci: cylindrical to subclavate, 8-spored ascospores: brown, l-septate, ellipsoid, 29-35 x 15-19 Pycnidia: not seen Spot tests: cortex K+ yellow C-, KC-, P+ yellow; medulla K-, C-, KC-, P- Secondary metabolites: cortex with atranorin and chloroatranorin; medulla with atranorin, zeorin, an unidentified terpene and a rusty brown pigment. Substrate and ecology: growing on trunks of deciduous trees and mossy rocks in open but humid conditions World distribution: common and widespread in tropical and subtropical areas, extending to warm temperate region in Europe and SE North America Sonoran distribution: the mountains of SE Arizona, the Sierra Madre Occidental region of Chihuahua and mountains in the southern tip of Baja California Sur. Notes: It is characterized by its robust appearance, the distinct labiate soredia and the rusty-brown pigmented (K+ purple) lower surface. Similar species include H. japonica, which differs in having a K+ yellow-red medullary reaction and is not pigmented or with only sparse rusty brown pigment (K–) on its lower surface. Another similar species, H. speciosa, is distinguished by having a lower cortex and lacks any rusty brown pigmentation. Heterodermia obscurata is regarded as the sorediate counterpart of H. flabellata.
Heterodermia obscurata image
Troy McMullin  
Heterodermia obscurata image
Troy McMullin  
Heterodermia obscurata image
Troy McMullin  
Heterodermia obscurata image
Gary Perlmutter  
Heterodermia obscurata image
Stephen Sharnoff  
Heterodermia obscurata image
Stephen Sharnoff  
Heterodermia obscurata image
Stephen Sharnoff  
Heterodermia obscurata image
Stephen Sharnoff  
Heterodermia obscurata image
Stephen Sharnoff  
Heterodermia obscurata image
Stephen Sharnoff  
Heterodermia obscurata image
Stephen Sharnoff  
Heterodermia obscurata image
Heterodermia obscurata image
Heterodermia obscurata image
Heterodermia obscurata image
Heterodermia obscurata image
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Heterodermia obscurata image
Heterodermia obscurata image
Heterodermia obscurata image
Heterodermia obscurata image
Gary Perlmutter  
Heterodermia obscurata image
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Heterodermia obscurata image
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Heterodermia obscurata image
Roger Rittmaster  
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