Hunting for Cetrelia chicitae (Lichenized Ascomycetes) in the Eastern European Alps : (Including an Attempt for a Morphological Characterization of All Taxa of the Genus Cetrelia in Central Europe)

Six hundred and eighty one specimens of the lichen genus Cetrelia W.L. CULB. & C.F. CULB. (Parmeliaceae, lichenized Ascomycetes), collected mainly in the eastern European Alps (as well as some specimens from North America), have been studied by means of TLC (thin-layer chromatography). As many specimens were found to be heterogeneous, they were re-studied several times, resulting in a total of more than 1400 chemical analyses. Considering the collections from the south-eastern part of Central Europe (642 packets in total, 91 of which contained more than one taxon), 2 % (i.e. 15 specimens) were identified as Cetrelia chicitae (W.L.CULB.) W.L. CULB & C.F. CULB. (alectoronic acid / a-collatolic acid syndrome), 13 % as Cetrelia olivetorum (NYL.) W.L. CULB. & C.F. CULB s.str. (olivetoric acid syndrome), 30 % as C. cetrarioides (DELISE ex DUBY) W.L. CULB. & C.F. CULB s.str. (perlatolic acid syndrome; + traces of imbricaric acid) and 55 % as C. monachorum (ZAHLBR.) W.L. CULB. & C.F. CULB. (imbricaric acid syndrome [major] and perlatolic acid [minor]). No thalli were found to contain mixed or intermediate chemosyndromes. Beside listing all diagnostic TLC characters, useful morphological features for separating the taxa have been evaluated and discussed. Densely developed, conspicuous pseudocyphellae on the lower surface of sterile thalli were found to be the most reliable morphological character for the delimitation of Cetrelia cetrarioides s.str. Three main types of pseudocyphellae could be distinguished on the upper side of the thallus. 'Type I' pseudocyphellae are rather large (when mature), with a homogeneously smooth and flat (not raised) surface, whereas the 'type II' pseudocyphellae comprise slightly convex structures, which may become agglomerated to form rather large, often elongated ridges with an heterogeneous punctuate centre. 'Type III' pseudocyphellae are rather small (difficult to see with the naked eye), flat or even slightly immersed in the thallus surface, and are commonly cracked in the centre. The latter type is frequently observed in Cetrelia olivetorum and C. cetrarioides. The rather large and usually well developed pseudocyphellae of 'type I' are typical for Cetrelia chicitae, where they commonly occur both at the margins and at the central parts of the thalli. Convex pseudocyphellae of 'type II' are characteristic of the most frequent morphotype of C. monachorum, but can also be found in other Cetrelia species. In addition, the size and shape of soredia and soralia respectively, are found to be helpful for separating the Cetrelia taxa. Freshly developed soredia of Cetrelia cetrarioides s.str. are in general smaller (25-35[40] μm) than in all other taxa treated ([35-]40-55 μm). Smooth, labriform (strongly convex) soralia are typical for C. olivetorum and (at least in part) for C. cetrarioides, whilst C. monachorum and C. chicitae have rather coarse soredia, exposed on more irregularly shaped soralia which - especially in C. chicitae - are developed on markedly undulate, contorted lobe margins, giving the lobe apices a somewhat nibbled appearance. - The slightly dumbbell-shaped (= weakly bifusiform) pycnospores (spermatia) of Cetrelia chicitae, the perforate apothecia of C. cetrarioides as well as the imperforate apothecia of both C. cetrarioides and C. monachorum are illustrated.