The Lichenologist 46(4): 489–513 (2014) doi:10.1017/S0024282914000139
6 British Lichen Society, 2014
A revision of the epiphytic species of the Lecanora subfusca group (Lecanoraceae, Ascomycota) in the Czech Republic ˇ EK Jirˇı´ MALI´C Abstract: During a revision of epiphytic species of the Lecanora subfusca group in the Czech Republic, nine taxa were recorded. Lecanora cinereofusca, although reported for the first time from the country here, is considered to be extinct, as is L. horiza. Lecanora circumborealis has been excluded from the list of Czech lichens. Lecanora rugosella and L. subrugosa respectively are regarded as extreme morphological forms of L. chlarotera and L. argentata, ecologically derived through nutrient enrichment (eutrophication). Lecanora laevis is regarded as a morphotype of L. horiza. An identification key is provided. The importance of the amphithecium and cortex type as taxonomic characters is discussed in detail. Several new secondary metabolites belonging to the terpenoids, discovered during an investigation of lichen compounds, proved to be taxonomically important. The abundance of L. allophana and L. chlarotera has decreased during the second half of the 20th century, but L. pulicaris has expanded. The main reasons for these changes are air pollution and acidification of substrata; L. pulicaris, for example, formerly a predominant lichen on acid-barked trees, today grows mainly on trees with slightly acidic or subneutral bark. Key words: chemotaxonomy, extreme morphological forms, Lecanora laevis, lichens, substratum acidification, terpenoids Accepted for publication 22 January 2014
Introduction Lecanora, one of the most diversified and taxonomically complicated lichen genera, comprises 75 species in the Czech Republic (Lisˇka et al. 2008). One of the most poorly understood groups is the L. subfusca group. It is characterized by apothecia with generally reddish brown discs, the presence of calcium oxalate crystals in the apothecial margin, and the presence of atranorin in the greyish white to grey thallus; almost all species have ellipsoid to broadly ellipsoid spores c. 10–20 6–9 mm (Brodo 1984). This group is considered here in a narrow sense (sensu Brodo 1984), but some authors (e.g. Magnusson 1932; Poelt 1952; Iba´n˜ez & Burgaz 1998; Edwards et al. 2009) also include the L. albella group, which is characterized by the absence of an apothecial cortex (exJ. Malı´cˇek: Department of Botany, Faculty of Sciences, Charles University in Prague, Bena´tska´ 2, CZ-128 01, Prague 2, Czech Republic. Email:
[email protected]
cept L. carpinea), strongly pruinose discs, and contains some species with xanthones (Kofler 1956; Imshaug & Brodo 1966). The name of the group is derived from the taxon described by Linnaeus, Lichen subfuscus L.; Acharius (1810) created the genus Lecanora and established the combination Lecanora subfusca (L.) Ach. with eight varieties, most of which are now regarded as species (Brodo & Vitikainen 1984). Taxonomic revisions of the L. subfusca group were undertaken by Stizenberger (1868) and Hue (1903). A further revision by Magnusson (1932) has proved useful in the present study, as he described several taxa and studied the anatomy with emphasis on the epihymenial granules, amphithecial crystals, and cortex characters. Another important work by Kofler (1956) used polarized light to study crystals in the apothecia. Contributions by Poelt (1952), Clauzade (1953), Makarevich (1971) and Motyka (1977) added to our regional knowledge. The typification of many collections, mainly from the Acharius Herbarium in
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Helsinki, was made by Brodo & Vitikainen (1984). In a very valuable and critical monograph of North American species, Brodo (1984) revised in detail the morphology, anatomy and chemistry of all taxa. His work was followed by several other monographs from Japan (Miyawaki 1988), Australasia (Lumbsch 1994), India (Upreti 1997), South and Central America (Guderley 1999), and Thailand (Papong & Lumbsch 2011). In Europe, Estonian taxa were investigated by Ju¨riado (1998), Iberian species by Iba´n˜ez & Burgaz (1998), and Lecanora growing on Rhododendron in the Alps by Hinteregger (1994). Two new epiphytic species (L. barkmaniana, L. sinuosa) from Western Europe have been described (Aptroot & van Herk 1999; van Herk & Aptroot 1999). Guderley & Lumbsch (1999) studied taxa with polysporous asci. Useful data on the groups selected are present in several determination keys (Poelt & Veˇzda 1981; Clauzade & Roux 1985; Tønsberg 1992; Nimis & Bolognini 1993; Wirth 1995; Ryan et al. 2004; Edwards et al. 2009; Wirth et al. 2013), and important chemical data are provided by Lumbsch & Feige (1992, 1994, 1996), Elix et al. (1994), and Elix & Lumbsch (1996). Several other papers on the L. subfusca group deal mainly with saxicolous species (e.g. Brodo et al. 1994) or non-European species (e.g. Lumbsch 1995; Lu¨ et al. 2011; Papong et al. 2011, 2012). Members of the Lecanora subfusca group were usually overlooked or misidentified in the Czech Republic, and many published records are dubious. This study provides detailed observations of the ecology and distribution of all epiphytic species in the Czech Republic, a critical revision of secondary metabolites, and numerous taxonomic notes, including comments on some traditionally used and problematic characters. Several synonymizations are proposed. Material and Methods Observations are based on material collected by the author from the Czech Republic and on specimens housed in BRNM, BRNU, CBFS, HOMP, OLM, PL, PRA, PRC, PRM and the personal herbaria of F. Bouda, J. P. Halda, J. Kocourkova´, A. Mu¨ller, Z. Palice, O.
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Peksa, D. Svoboda and L. Syrova´tkova´. All specimens collected by the author are retained in his personal herbarium (abbreviation hb. JM). Type and comparative specimens were studied from GZU, H, L, PRM and UPS. Microscopic descriptions are based on observations made on hand-cut sections mounted in water. The solubility of epihymenial crystals was studied in 50% HNO3. The amphithecium and apothecial cortex were observed in KOH. Crystals and granules in apothecia were observed in polarized light (using two polarized filters). For the terminology of anatomical characters, the work of Brodo (1984) was followed. The presence of fumarprotocetraric acid or pannarin was primarily detected by a fresh ethanol solution of paraphenylenediamine (Pd), which was applied to the apothecial margin. Thin-layer chromatography (TLC), with a few minor modifications, followed the methods of Orange et al. (2001). Lichen compounds were applied on a set of three glass plates and placed into solvents A, B and C. A distance between starting and finishing line was usually c. 100 mm. A volume of added acetone into the test tube was two or three drops (according the quantity of testing material). Fatty acids were detected by dipping each of these into water tanks. Chloratranorin was not distinguished from atranorin. Selected samples were analyzed by HPLC following the methods of Feige et al. (1993). In the description of species, only total numbers of samples analyzed from the Czech Republic are mentioned. Specimens of rare or floristically interesting species are presented as ‘Selected specimens examined’. Statistical analyses were carried out in R. 2.9.2. using the application R Commander. Rare species were excluded since they were data deficient. Only L. argentata, L. chlarotera and L. pulicaris were used for analyses. For graphs, L. allophana was also included. Altitude and bark pH preferences were tested according to the negative binomial linear model of Haldane (1945) with interaction. This technique was used instead of the model with a Poisson structure of errors due to a high overdispersion (Crawley 2007). The normality of resulting residuals was verified by the Shapiro-Wilk test (Shapiro & Wilk 1965). A dispersed parameter theta for altitude was 77517, and for bark pH 676. Altitude data were acquired from herbarium labels or subsequently found via a map. Average bark pH values for all common phorophytes, determined from several sources (Barkman 1958; Bibinger 1967; Bates & Brown 1981; Wirth 1995; Marmor & Randlane 2007), were as follows: Acer platanoides (575), A. pseudoplatanus (61), Alnus sp. (45), Betula pendula (43), Carpinus betulus (56), Fagus sylvatica (53), Fraxinus excelsior (53), Picea abies (365), Pinus sylvestris (34), Populus tremula (59), Quercus sp. (45), Sorbus aucuparia (49), Tilia sp. (51), etc. This procedure was employed for the following reasons: 1) to prevent destruction of the herbarium material during the measurements, 2) pH of old samples could change over time, and 3) for a comparison of historical and recent preferred substrata, it is better to use standardized values from more independent sources. Distribution maps were created in ArcGIS, with recent (black circles) and historical (white circles) records
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indicated; 1990 was selected as the boundary since it is the period 1) after the strong impact of acid rain, 2) with a stabilized system of agricultural farming, and 3) with a high probability that the record still exists. Photographs of species including type specimens and apothecial sections are available on www.jjh.cz/foto.
Results and Discussion Morphology – extreme forms The main problem in the identification of single species within the L. subfusca group is the large morphological variability, especially in the size and shape of apothecia. The morphologies of thallus and apothecia are the main characters differentiating L. rugosella and L. subrugosa from L. chlarotera and L. argentata, respectively. In Europe, I regard the first taxa as extreme morphological forms of L. chlarotera and L. argentata following Lumbsch & Feige (1994, 1996). The extreme morphotypes are characterized by 1) a thick, coarse and verrucose thallus, 2) constricted base of apothecia, 3) a thick, coarse, frequently flexuose, crenulate or verrucose apothecial margin, and 4) slightly larger ascospores with thick walls (more than 1 mm). Such morphotypes are conditioned ecologically, in most cases, dependent upon the availability of nutrients. Typical habitats for them are eutrophicated sites along roads and fields, dusty places, dying trees, subneutral and decaying bark. The occurrence of the typical form together with the extreme one was frequently observed in the field; for example, typical L. argentata gradually develops into ‘L. subrugosa’, which was growing on old or partly decaying bark of the same tree. On roadside trees, L. chlarotera and L. pulicaris frequently develop into extreme morphotypes on the bark of trees facing the road due to their exposure to nitrogen compounds derived from vehicle emissions, whereas bark on the reverse sides of such trees supports typical forms. The large morphological variability of L. argentata has been confirmed by ITS molecular data, where several samples with different morphology including typical ‘L. subrugosa’ have formed one well-supported
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clade ( J. Malı´cˇek, unpublished data). The lectotype of L. subrugosa is a typical extreme form of L. argentata with all characters (see above), which is relatively common in, for example, the Alps, but rare in the Czech Republic. In the case of L. rugosella, the type material is quite poor and represents an atypical form of L. chlarotera with a very thick apothecial margin and constricted bases of apothecia. Separation of L. rugosella, L. subrugosa or both former species is traditionally kept by many authors, such as Poelt & Veˇzda (1981), Nimis & Bolognini (1993), Wirth (1995), Thomson (1997), Ju¨riado (1998), Diederich & Se´rusiaux (2000), Ryan et al. (2004), Santesson et al. (2004), Lisˇka et al. (2008), Roux (2012) and Wirth et al. (2013). An ecologically derived morphology of L. argentata was studied in more detail by Lumbsch & Feige (1996), who emphasized the influence of the substratum in the creation of extreme forms and regarded L. subrugosa as a synonym of L. argentata.
Anatomy Taxa known from the Czech Republic are characterized by the well-developed thalline margin, colourless hymenium and hypothecium, orange, red-brown to brown epihymenium, presence of apothecial cortex, and 8spored asci of Lecanora s. str. type. Pycnidia were rarely found and no differences in the conidium size were observed. As an important taxonomic character, three types of epihymenia sensu Brodo (1984) were distinguished. The chlarotera-type epihymenium is usually brown due to the mass of coarse (slowly soluble in HNO3) granules [10– 25(–40) mm], which are concentrated at the tips of paraphyses. The red-brown pigment is absent or present. The pulicaris-type is mostly reddish brown with fine (insoluble in HNO3) granules of 05–10 mm, which are dispersed in the upper part of the hymenium. In the glabrata-type, the granules are absent and the pigment is orange to orangered. Oil droplets are rarely present. In contrast to the former types, the pigment usually
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persists in KOH or changes to (reddish) brown. The second important character is the type of amphithecium. The pulicaris-type has large crystals (>10 mm) and the allophana/ campestris-type has small crystals (
