Chemotypes of Dimelaena oreina (Ascomycotina, Physciaceae) in the Iberian Peninsula

Abstract

Four chemotypes of Dimelaena oreina are reported from the analysis of 140 specimens from the Iberian Peninsula. Chemotypes II (usnic and gyrophoric acids) and V (usnic and stictic acids) were previously known from this area, but chemotype I (usnic and fumarprotocetraric acids) is new to the region, and chemotype VII (usnic, stictic, and gyrophoric acids) is new for the species. Chemical and phytogeographical evidence suggests that chemotypes V and VII are closely related. In addition to geographic distributions, phytogeographic affinities and minor morphological trends, some lichens and lichenicolous fungi growing on Dimelaena oreina chemotypes are reported. Among all the species of Dimelaena hitherto known (e.g., Mayrhofer et al. 1996; Sheard 1974; Sheard & Mayrhofer 1984), Dimelaena oreina (Ach.) Norman is well characterized by its yellowgreen thallus containing usnic acid in the cortex, lecanorine apothecia, and an hyaline hypothecium. It is widespread in Temperate and Boreal regions of the northern hemisphere and is also known in the southern hemisphere (Mayrhofer et al. 1996). In Europe, its distribution is from Scandinavia to the Mediterranean. Dimelaena oreina is one of the best studied lichens from a chemical point of view. It is chemically variable, with six chemotypes recognized worldwide (Culberson et al. 1984; Leuckert & Poelt 1978; Leuckert et al. 1975, 1981, 1987; Mayrhofer et al. 1996; Sheard 1974, 1977; Sheard & Ahti 1975). According to the terminology of Sheard (1974, 1977) and Culberson et al. (1984), each chemotype is designated with a number, and is characterized by the content of the main substances (see Table 1). Except for the chemotype with sphaerophorin, described from California (Culberson et al. 1984) all chemotypes occur in Europe. They are distributed following a north to south gradient, with northern Europe having fewer and less complex chemotypes than southern territories (Leuckert & Poelt 1978). Chemotype III is predominant in northern Scandinavia, chemotype I is the most frequent in some mountainous regions of central Europe (with chemotype IV often associated), and chemotype V becomes the predominant chemotype in other parts of central Europe and in the Mediterranean region. A good correlation between chemistry and elevation has been also demonstrated in a study from South Tyrol (Leuckert et al. 1981). Chemotype V dominated at lower elevations, whereas at higher elevations chemotype I was the most frequent. The overall distribution of the chemotypes is summarized in Table 1. The main aim of this paper is to study the chemical variability of D. oreina in the Iberian Peninsula (Andorra, Portugal and Spain), a particularly interesting territory considering its great climatic and biological diversity, as well as the above mentioned chemical richness and complexity in southern Europe. In the Iberian Peninsula, D. oreina is a widespread lichen, extending from regions close to the coast to the highest mountains, mostly associated with hard siliceous rocks. Sporadic analysis of Spanish and Portuguese specimens by Leuckert et al. (1975), Sheard (1977), and Culberson et al. (1984) reported two chemotypes (II and V) for this territory. A rare occurrence of chemotype III (Sheard 1977) in Spain is here excluded, and needs confirmation because of the low elevation and typical Mediterranean character of the locality. Also, a few samples from the Canary Islands and Morocco have been analyzed; this complementary information is included in representative specimens studied. MATERIALS AND METHODS The study is based on material kept at BCC, LEB, LISU, MA, MAF, VAB, and Etayo priv. herb. The main morphological and anatomical characters were studied by means of standard light microscopic techniques. A total of 142 samples, 140 from the Iberian Peninsula, one from the Canary Islands and one from Morocco, were analyzed by Thin-Layer Chromatography (TLC) and 12 selected specimens by High-Performance Liquid Chromatography 0007-2745199139-44$O.7510 This content downloaded from 157.55.39.129 on Thu, 28 Jul 2016 04:05:12 UTC All use subject to http://about.jstor.org/terms 40 THE BRYOLOGIST [VOL. 102 TABLE 1. Lichen substances content and distribution of the chemotypes of Dimelaena oreina, excluding rare occurrences FU = fumarprotocetraric acid, GY = gyrophoric acid, ST = stictic acid and SPH = sphaerophorin. Usnic acid present in all the chemotypes. Greenland Eastern Western Southern ChemoRussia FennoscanCentral Southern and North North Hemitype Substances and Asia dia Europe Europe N. Canada America America sphere