Die Entstehung einer Strauchflechte aus einem Formenkreis krustiger Verwandter

Abstract

The taxa included in the lichen complex of Lecanora swartzii are a sorediate species as well as several richly fruiting, non-sorediate taxa. Although the latter show considerable diversity in thallus form, from crustose in Lecanora swartzii ssp. swartzii to fruticose in ssp. caulescens , nevertheless both taxa are closely related, not only in their chemistry, but also in other aspects. The thalline excipulum of both has a true cortex except for an annular zone surrounding the hymenium., which is here called a pseudocyphellum. The thallus of ssp. swartzii is not corticate, the so-called cortex being no more than a necrotic layer, composed of dead hyphal walls of the mycobiont and the compressed empty walls of old phycobionts. In ssp. caulescens the podetia-like structures are not corticate in juvenile stages, but subsequently they do develop a true cortex from the base upwards, which is identical to that of the thalline exciple of an apothecium. The non-corticate area above corresponds to the pseudocyphellum in ssp. swartzii . New “podetia” arise from the non-corticate, pseudocyphellate zone and are themselves non-corticate during an early state in their development. Thus the fruticose thallus corresponds to an apothecium in the crustose ssp. swartzii with the early differentiation of a cortex and late formation of fruiting bodies.