Slideshow image
Xanthoparmelia substenophylloides Hale
Family: Parmeliaceae
Xanthoparmelia substenophylloides image
Thallus: foliose to subcrustose, tightly adnate, 2-6 cm in diam., dichotomously lobate lobes: sublinear, elongate, plane to subconvex, separate and contiguous, 0.4-1 mm wide, becoming lobulate marginally with age; lobulae: dichotomously branched, 0.2-0.4 mm wide; main apices: subtruncate, black rimmed, smooth to crenate, eciliate upper surface: light yellow-green but darkening centrally, smooth, shiny, epruinose and emaculate, moderately isidiate isidia: cylindrical, mostly unbranched, 0.06-0.13 mm in diam., 0.1-0.3 mm tall; tips: syncorticate, brown; soralia and pustulae absent medulla: white, with continuous algal layer lower surface: black but dark brown peripherally, plane, shiny, moderately rhizinate; rhizines: black, simple, 0.1-0.2 mm long Apothecia: not observed Pycnidia: rare, sunken conidia: bifusiform, 5-6 x 0.5 ┬Ám Spot tests: upper cortex K+yellow to orange, C-, KC-, P+ orange; medulla K+ yellow becoming dark red, C-, KC-, P+ orange Secondary metabolites: upper cortex with usnic acid (major); medulla with stictic acid (major) and constictic, menegazziaic and norstictic acids (minor), cryptostictic and peristictic acids (trace). Substrate and ecology: on acidic rocks, often in open, arid to woodland habitats World distribution: frequent in tropical to subtropical regions of North and South America and also occurring in South Africa Sonoran distribution: occasional at intermediate elevations in Arizona, western Chihuahua and Sonora. Notes: Xanthoparmelia substenophylloides is characterized by its +subcrustose thallus, its elongate, separate, sparingly branched lobes, its delicate, pale-tipped cylindrical isidia, its black lower surface and the presence of the stictic acid chemosyndrome in the medulla. It is most likely to be confused with X. pseudocongensis, and the distinguishing features of these two species are discussed under the latter.