the distribution of selected diagnostic characters in the lecanorales

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The Distribution of Selected Diagnostic Characters in the Lecanorales

Gerhard Rambold and Gregor Hagedorn

The Lichenologist / Volume 30 / Issue 45 / July 1998, pp 473 487DOI: 10.1017/S002428299200046X, Published online: 14 January 2009

Link to this article: http://journals.cambridge.org/abstract_S0024282998001285

How to cite this article:Gerhard Rambold and Gregor Hagedorn (1998). The Distribution of Selected Diagnostic Characters in the Lecanorales. The Lichenologist, 30, pp 473487 doi:10.1017/S002428299200046X

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Lichenologist 30(4-5): 473-487 (1998)Article No. H980153

THE DISTRIBUTION OF SELECTED DIAGNOSTICCHARACTERS IN THE LECANORALES

Gerhard RAMBOLD* and Gregor HAGEDORNJ

Abstract: Traditional classification concepts in lichenology are often, but notalways, supported by molecular results. Molecular data should be compared andcorrelated with micro-morphological and ultrastructural information before system-atic rearrangements are undertaken. Visualization of the distribution of morpho-logical and other characters in specified groups is considered as a desirable resultper se, but it is also important to discover whether correlating characters aredependent on each other or not; and if not, whether their distribution in a groupmight support existing classification concepts. A data set for lecanoralean andother lichenized and lichenicolous genera, comprising 90—mostly multi-state—characters was used to store morphological, chemical and ecological data, and totest character correlations. Several examples of such analyses are presented. Thefollowing pairs of characters show some degree of dependence: ascospore septationand number per ascus, ascospore wall type and pigmentation, ascospore andepihymenium pigmentation. Several authors postulated that ascus types are goodphylogenetic markers. Ascus types have been widely used for classification conceptsof the Lecanorales. Two-dimensional correlation queries of ascus types with thefollowing morphologcal characters were made: substratum preference, thallusgrowth form and ascospore septation. These correlations supply characteristicprofiles for the various ascus types, which have to be compared with forthcomingphylogenetic hypotheses based on molecular data.

C 1998 The British Lichen Society

IntroductionNew possibilities opened up by the use of molecular techniques have initiatedfresh interest in the phylogeny of lichens. Several versions of 18S rDNA-basedpartial phylogenies have been proposed recently (e.g. DePriest et al. 1997;Wedin et al. 1998). These hypotheses of natural relationships proposed are,however, not yet fixed and are in need of comparison with morphological aswell as with non-18S molecular data, since the use of only a single geneactually produces a gene tree and not necessarily the desired species tree (e.g.O'Donnell & Cigelnik 1997).

The most profound changes in the systematic structure of the Lecanoralesduring the last two decades are due to the consideration of ascus characters.Meanwhile, these characters have been examined in more or less detail inrepresentatives of most lecanoralean genera (e.g. Hafellner 1984; Karnefelt &Thell 1992). It is a surprising fact that the attention of mycologists andlichenologists was drawn comparatively late to these usually well recognizable*Institut fur Systematische Botanik, Ludwig-Maximilians-Universitat Miinchen, MenzingerStrafie 67, D-80638 Miinchen, Germany.flnstitut fur Mikrobiologie, Biologische Bundesanstalt, Konigin-Luise-Strafie 19, D-14195Berlin, Germany.

0024-2829/98/040473+15 S30.00/0 © 1998 The British Lichen Society

474 THE LICHENOLOGIST Vol. 30

structures. Asci and ascogenous hyphae represent a distinct generation in thelife cycle of ascomycetes, but actually only ascus characters can be consideredas phylogenetically informative, although some infrageneric variation doesexist (e.g. Ekman 1996). In the Lecanorales, the ascus wall consists of fourdistinctive layers (in TEM), the inner two of which exhibit characteristic anddiagnostically important amyloid structures of different types. Several path-ways for ascus apex wall development within the Lecanorales were postulated(Bellemere & Letrouit-Galinou 1988).

The assumptions of these authors are in accordance with our own obser-vations due to the recognition of various transitional ascus apex or ' tholus 'types, resulting in a scenario of ascus evolution within the Lecanorales asstated below. The evolutionary lines assumed follow pathways of reductionand enlargement of the amyloid structural elements or areas in the apical wall.The occurrence of tube and cap structures in extra-lecanoralean orders, e.g.in the Leotiales (Baral 1997; Rambold et al. 1993), and the absence of suchtube structures in asci of lecanoralean families including taxa with a highlydifferentiated, mostly eucorticate thallus (e.g. Parmeliaceae, Physciaceae,Ramalinaceae and Teloschistaceae) may indicate, that the Porpidia- andPeltigera-type, asci with amyloid tubes (Fig. 1A) are to be considered asplesiomorphic within the Lecanorales. Transitions between asci with amyloidtube-like tholus structures and cap-like structures, e.g. within CecidoniaTriebel & Rambold, signalize that Lecidea- and Lobaria-typc asci withcap-shaped amyloid structures (Fig. IB) might be interpretable as reductiontypes of tube structures (Triebel & Rambold 1988). In several groups, as in thefamilies Micareaceae and Rimulariaceae, the development of a 'ring in thebourrelet' (Bellemere 1994) appears to be combined with an amyloid cap ora tube (Fig. 1C). A lateral enlargement of tube structures is observed inMicareaceae (Micarea FT.) as well (Hertel & Rambold 1988). In Scutula Tyl.,the axial structure is developed as a fuzzy amyloid plug, occupying most of thetholus space (Triebel et al. 1997). Continued broadening may have led to theBacidia- or Biatora-type, respectively, with a more or less narrow non-amyloid' axial body ' not reaching die tholus apex (Fig. ID). This structure is likely tobe homologous to the non-amyloid central part of amyloid tube structures inPorpidia- and Peltigera-type asci. Further lateral and apical enlargement of thenon-amyloid axial body, as realized in the Bacidia-type, leads to the Lecanora-type ascus (Fig. IE), which has no equivalence in other ascomycete orders. Itcould well be considered a synapomorphy within the Lecanorales, beingcharacteristic for parts of die core group of the order, including, for instance,Candelariaceae, Lecanoraceae, Parmeliaceae, and Physciaceae (Rambold &Triebel 1992; Tehler 1996). In recently presented 18S rDNA-based phylo-genetic trees of ascomycetes, tube-shaped tholus structures are present withinthe Lecanorales in three subclusters (Wedin et al. 1998) or even four (Stenroos& DePriest, handout distributed at the ABLS meeting in Montreal, 1997).This is consistent with the assumption, that die tube-shaped tholus structureis a plesiomorphic character persisting in various lecanoralean groups. How-ever, it is striking that Lecanora-type and Bacidia-typc asci appear in two orthree subclusters within the Lecanorales (Stenroos & DePriest loc. cit.). In onebranch, the family Physciaceae with Lecanora-type and Bacidia-type asci

1998 Lecanorales—Rambold & Hagedorn 475

FIG. 1. Major types of asci in the Lecanorales. A, Porpidia-xype {Porpidia crustulata); B,Lecidia-type {Cecidonia umbonella); C, Rimularia-type (Amylora cervinocuprea); D, Biatora-type{Buellia disciformis); E, Lecanora-type {Xanthoparmelia conspersa); F, Teloschistes-Type {Caloplaca

citrind).

(Rambold et al. 1994) appears as a sister group of suborder Teloschistineae(with Teloschistes-type asci). Provided that this tree topology remains stable,the Bacidia- or Biatora-type ascus (with non-amyloid axial body), as foundin the Physciaceae, can be considered the precursor type, having evolved viareduction of the axial body towards a Teloschistes-Xype (Fig. IF) and Catillaria-type ascus. Based on molecular data, Wedin & Tibell (1997) postulatemultiple events of a more or less total reduction of the tholus within theLecanorales by including the families Caliciaceae and Sphaerophoraceae into theorder. Asci with a well-developed, non-amyloid tholus occur in the Lecano-rales as well. These are, however, restricted to only few families of probablybasal phylogenetic position within the order, e.g., the Agyriaceae (p.p.),Acarosporaceae, Hymeneliaceae, Nephromataceae and Pannariaceae (p.p.).

Knowledge and quality of data with respect to a wide range of mor-phological and chemical characters of Lecanorales are rather good. Thisallows a first attempt at assessing the distribution of various characters in thisorder of lichens. It is the aim of this paper to point out the possibilities ofcharacter profiles and queries by two-dimensional cross-tabulation of data of


non-molecular (i.e., morphological, anatomical, chemical and ecological)characters for clarifying the distribution of characters in a group and fortracing character correlations under the aspect of dependence and indepen-dence, respectively. Several characters are correlated with the ascus type, acharacter that is considered as a major anatomical phylogenetic marker. Theresults are presented with the aim to be compared with forthcoming resultsfrom molecular analyses, to optimize tree topologies and to reach improvedphylogenetic concepts of the Lecanorales.

Materials and Methods

Morphological, anatomical, chemical, and ecological data of 400 lecanoralean genera werecompiled in the LIAS generic database (Rambold 1997). They were analysed and compared withthose of a further 400 lichenized and lichenicolous non-lecanoralean genera of ascomycetes. Thedata set is based on 90 characters (mostly multi-state) scored for each genus (Rambold & Triebel1997). Almost 60 000 observations were coded in the DELTA (description language fortaxonomy) format (Dallwitz et al. 1995) and analysed using the database application DeltaAccess(Hagedorn 1997). DeltaAccess imports DELTA data sets into a relational database and providesediting and exporting functions, as well as a wide array of analysis functions.

The data of various morphological and anatomical characters were examined by two- ormore-dimensional character cross-tabulation queries. The resulting diagrams of character profilesand correlations supply information that may be of phylogenetic, morphogenetic, or ecologicalinterest. In comparison with external classification proposals, they are useful to interpretphylogenetic trees and provide clues for the confirmation or rejection of phylogenetic hypotheses.Conversely, such analyses can be enlightening as to the omission or erroneous recording of thecharacters analysed. However, any analysis at generic level implies a considerable degree ofuncertainty. The value of the results depends on the quality and availability of data and the correctand consistent delimitation of genera. A special handicap is that pairs of character states occurringin a genus do not have to co-occur in even a single species of this genus.

Some cross-tabulation profiles were further analysed in MS Excel. In order to test thecorrelation of various characters statistically, Fisher's Exact Test was applied using SAS 6.12, SASInstitute (1989).

Results and Discussion

Distribution of substratum, growth form, photobiont selection,chemistry and pigmentation

There are at least three major groups of ascus-substratum correlationsexisting in the Lecanorales (Fig. 2). The group of lecanoralean genera on soiland bryophytes possesses a high diversity of ascus types. As these substrata areused by a majority of non-lecanoralean, non-lichenized ascomycetes with adifferent nutritive behaviour as well, their selection is likely to be a plesiomor-phic trait in most groups of the Lecanorales. In genera with a preference togrow on rock and bark, Lecanora-type asci predominate. Thus, the selection ofrock and bark as substrata and the presence of Lecanora-type asci are positivelycorrelated and both characters can be interpreted as being apomorphic withinthe Lecanorales. Certainly, various taxa groups with Lecanora-type asci tend togrow on substrata like soil and bryophytes as well and it seems rather likelythey have acquired this feature secondarily, at least in several groups of folioseand fruticose growth habit. A third group of lecanoralean genera occurring on

1998

100%

80% -

Lecanorales—Rambold & Hagedorn 477

60% -

40% -

20% -

0%L

Ascus typeE3 Catillaria-Teloschistes-type• Bacidia-Lecanora-type• Porpidia-Lecidea-typeH Trapelia-Rimularia-type• Nephroma-Acarospora-type• Tholus reduced

rock leavessoil, bryophytes bark,detritus wood(n = 145) (n = 97) (n = 287) (n = 268) (n = 145)

Substratum

FIG. 2. Corrrelation between substratum selection and ascus main types in the Lecanorales.

living leaves, contains preferably the families Ectolechiaceae and Pilocarpaceaewhich have tube-shaped ascus structures (similar to the Porpidia-type). Theirsystematic position within the Lecanorales is completely unclear. On thewhole, the profile of substratum type selection of the Lecanorales resemblesvery much that of non-lecanoralean, lichenized groups.

The evolutionary level in the Lecanorales seems to be reflected well by thegrowth form to some extent (Fig. 3). Not surprisingly, genera with Porpidia-type asci predominate in the groups of indistinct or crustose to squamuloseand placodioid growth habit of the primary thallus. In this group, a generaltrend exists to develop stipitate apothecia and, in the extreme, a ' thallusverticalis ' (e.g., in Cladoniaceae and Stereocaulaceae), which has to be distin-guished from the ' fruticose ' organization of the primary, often eucorticatethallus, developed via the foliose growth habit, as existing in families of thesuborder Lecanorineae (e.g., in Parmeliaceae and Ramalinaceae). Genera ofthis suborder with Bacidia- and Lecarcora-type asci therefore dominate in thegroup with the highest differentiated and pronounced three-dimensionalthalli. However, the effect of some overrepresentation due to a comparativelynarrow genus concept in this group, for instance in the Parmeliaceae, must beconsidered when interpreting the diagram.

Photobiont selection traditionally has been used for the circumscription oforders of ascomycetes, but at a lower systematic level, for example within theLecanorales, the diagnostic value of this character has been largely neglected.Beck et al. (1998) found that photobiont selection can be highly specific, and


100%

60%

I

20%

Ascus type0 Catillaria-Teloschistes-type• Bacidia-Lecanora-typeB Porpidia-Lecidea-typeM Trapelia-Rimularia-typeM Nephroma-Acarospora-typeD Tholus reduced

TOII

c

a s8-

13

II

o>CO

3m3

||

i3S

1OIIc

•a

sJ3"P.

00TO

II

Thallus growth form §

FIG. 3. Correlation between thallus growth form and ascus main type in the Lecanorales.

does not have simply to be a function of neighbouring occurrence within alichen population. Photobiont selection therefore may be an importantcharacter also in the classification of lecanoralean lichens. The order Lecano-rales contains the majority of lichenized ascomycetes, and chlorococcoid greenalgae represent the majority of photobionts in lichenized associations. Withinlecanoralean lichens, green algae constitute the majority of primary photo-bionts as well (for figure, see Rambold et al. in press). Going on theassumption that Acarospora A. Massal. (suborder Acarosporineae) has to beexcluded from the Lecanorales (DePriest et al. 1997) and given that the generaHymenelia Kremp. and Ionaspis Th. Fr. belong into this suborder (Rambold& Triebel 1992), the filamentous green algal genus Trentepohlia Puymaly{Ulvophyceae) is exclusively associated with non-lecanoralean mycobionts, forexample, of the orders Arthoniales, Dothideales, Gyalectales, Pyrenulales,Ostropales (incl. Graphidales), and various families incertae sedis. Ramboldet al. (in press) points out that the recently redefined photobiont genusAsterochloris Tscherm.-Woess and Trebouxia s. str. occurs in the majority oflecanoralean lichens. Within the two suborders Cladoniineae and Lecanori-neae, the distribution of the two genera shows significant differences. Astero-chloris occurs mainly in genera with amyloid tube-structure in the ascus apex(suborder Cladoniineae) and Trebouxia mainly in genera with a non-amyloidaxial body in the apex (suborder Lecanorineae).


In the Lecanorales, more than 400 multi-biont symbioses with two or morelecanoralean mycobionts, so-called ' inter-lecanoralean associations', areknown (Rambold & Triebel 1992). Also, numerous multi-biont symbioseswith more than one photobiont occur in the Lecanorales, for example,accessory cyanobacteria that are mostly organized in cephalodia. Thesestructures are found in 7% of the lecanoralean genera. The majority of theselichens colonize substratum types such as detritus and soil, which they sharewith non-lichenized fungi. Bark and rock, which are mostly colonized bylichenized fungi (beside free-living algae), are used by cephalodiate lichens lessfrequently (for figure, see Rambold et al. in press). Except for Lasioloma R.Sant., cephalodia are lacking in foliicolous lichens. In addition, the presenceof cephalodia in the Lecanorales may also reflect a natural relationship.Cephalodia mostly occur in lecanoralean groups having Porpidia- and Lecidea-type asci (subord. Cladoniineae and Peltigerineae) and almost lack taxa withBacidia- and Lecawora-type asci (subord. Lecanorineae). In pluri-specificgenera with cephalodiate species, accessory photobionts are normally not onlyfound in a single species, but occur in the majority or in all species (e.g., inAmygdalaria Norman, Coccotrema Mull. Arg., Lepolichen Trevis., PilophorusTh. Fr., Psoroma Michx., Solorina Ach., and Stereocaulon Hoffm.). The generaof Peltigeraceae and Lobariaceae are special in so far as they include speciesforming pairs of photosymbiodemes, beside others having chlorococcoidprimary photobionts and accessory cyanobacteria in cephalodia. A conse-quence of these facts is that in lecanoralean groups with mainly cephalodiatespecies (e.g. in Amygdalaria and Stereocaulon), the presence of accessoryphotobionts is probably a plesiomorphism and that the order Lecanoralesmight have originated from precursors with gloeocapsoid or scytonemoidmajor (or minor) photobionts.

Soluble and insoluble secondary compounds and pigments are diagnosti-cally useful at species and genus level in most groups of lecanoralean lichens(Elix 1992; Huneck & Yoshimura 1996). Secondary metabolites are known tooccur in c. 80% of the 335 chlorophycophilous lecanoralean genera. Mostmajor groups of substances that occur in the Lecanorales can be found in thelichenized non-lecanoralean ascomycetes as well (Fig. 4), but the ability toproduce a-orcinol depsidones appears to be a synapomorphic feature ofLecanorales s. lat. (including subord. Pertusariineae with Pertusaria DC, andOchrolechia A. Massal.). The sterile genus Leprocaulon Nyl. also fits into theorder due to its ability to produce a-orcinol depsidones (in addition to(3-orcinol depsidones, depsides, triterpenoids, fatty acids, dibenzofurans andphloroglucinol derivatives). In the Lecanorales, the production of xanthonesis restricted to genera with green algal photobionts. Xanthones have notbeen observed in cyanophycophilous genera or in genera that form photo-symbiodemes, although a few are found in Micarea, a genus that includesM. assimilata (Nyl.) Coppins and related species with accessory cyanobacterialphotobionts as well. However, it is highly probable that the M. assimilatagroup is not congeneric with the xanthones-containing species, M. lignaria(Ach.) Hedl. (Coppins 1983) and Al. isabellina Coppins & Kantvilas (Coppins& Kantvilas 1990). Thus, in the Lecanorales, the presence of primary oraccessory cyanobacterial photobionts and the production of xanthones (and


35%

30%o.3

25%

g 20% ha0)bo

13 15%

I 10%

5%

0%

B LecanoralesD Non-Lecanorales

1**yv

Secondary metabolite groups

FIG. 4. Correlative distribution of the major secondary metabolites in the Lecanorales (« = 398)and non-lecanoralean, lichenized and lichenicolous Ascomycetes (n = 398).

secalonic acids and benzyl esters) appear to be mutually exclusive. Onlyrelatively few cyanophycophilous lichen genera produce secondary com-pounds. They belong to the lecanoralean families Pannariaceae {FuscopannariaP. M. Jorg.: aliphatic acids; Pannaria Delise in Bory: e.g., (3-orcinol depsi-dones), Peltigeraceae (Hydrothyria J. L. Russell: orcinol depsides) or are ofuncertain systematic position [Fuscoderma (D. J. Galloway & P. M. Jorg.)P. M. Jorg. & D. J. Galloway: P-orcinol depsidones; Leioderma Nyl.: terpe-noids]. With respect to ascus type groups, secondary compounds are more orless equally distributed. An interesting fact is that the small genus group withTrapelia-Rimularia type asci has a rather simple chemistry and lacks pulvinicacid derivatives, dibenzofurans, triterpenoids, and xanthones. Xanthones arealso absent in genera with Nephroma-Acarospora and Teloschistes-Catillariatype asci.

Apothecial and thallus pigmentation in Lecanorales is rather diverse anddiagnostically relevant only at a lower systematic level. In several genera, theepihymenium is rather poorly pigmented. Strikingly, this is strictly correlated


160 r-

c

_ Q

| I hyaline

• pale brown

H dark brown

Epihymenium pigmentation

FIG. 5. Correlation between epihymenium pigmentation and ascospore pigmentation in dieLecanorales.

with hyaline ascospores, and pigmented spore walls never occur there (Fig. 5).The significance of this correlation could be confirmed by Fisher's Exact Test(Table 1). A possible explanation for this phenomenon is, that lecanoraleanlichens with a pale epihymenium may have lost their capability to producedark pigments in general. This is an example of two seemingly independentcharacters (or character states) being in fact dependent. Since most statisticalmethods of testing phylogentic hypothesis, including parsimony methods,assume strict independence of characters, this type of problem must be takenparticularly seriously.

Distribution of ascosporal and conidial charactersNo general correlation between major types of asci and ascospore septation

types can be detected in the Lecanorales (Fig. 6). The majority of genera inthe order have one-celled ascospores and only few groups develop muriformspores. Aseptate and transversally septate spores are equally distributedamong the different major types of asci. In some groups of Lecanorales, theevolutionary pathway seems to go from transversally septate towards aseptateascospores. For instance, septate spores occur in ' basal' groups of the


TABLE 1. Cross-tabulation of epihymenium and ascospore pigmentation groups *

Epihymenium

DarkPaleLight

Dark

62130

Ascospore

Pale

3590

Hyaline

1928461

•Showing the number of lecanoralean genera after the epihymenium colourswere grouped into three pigmentation groups: ' dark'=black, brown,olivaceous, green, or violet, ' pale '=grey, ochraceous, or red, and ' light ' =orange, rose, yellow or hyaline.Fischer's exact test was significant with P=3-5 x 10 ~ 8. A second test, wherethe ' pale ' and ' hyaline ' groups of both epihymenium and ascosporepigmentation were combined, was significant with P= 1 -2 x 10 ~ 4. The lattertest should be conservative regarding possible misinterpretations of pigmen-tation type.

100%

Ascus type£2 Catillaria-Teloschistes-type• Bacidia-Lecanora-type• Porpidia-Lecidea-type• Trapelia-Rimularia-type• Nephroma-Acarospora-type• Tholus reduced

aseptate (incl.polarilocular)

(n = 299)

transversallyseptate

(n = 139)

(sub-)murifom

(n = 224)

Ascospore septation

FIG. 6. Correlation between ascospore septation and ascus main type in the Lecanorales.

Lecanoraceae s. lat. with Biatora-type asci and mostly non-trebouxioidphycobionts, whereas one-celled spores occur in ' advanced' groups withLecanora-typc asci and trebouxioid phycobionts. Ascospore septation is evi-dently independent from the ascomatal attachment; a similar spectrum ofseptation types (ascospores aseptate monoblastic, aseptate polar-diblastic,

1998

100%

80% -

Lecanorales—Rambold & Hagedorn 483

60% -Ascosporeseptation type

^ (sub-)muriformL~] transversally septate• diblastic-aseptateH monoblastic-aseptate

S 40%

20% -

c. 1-2 c. 4 c. 8 12-16 16-32 >32(n = 123) (n = 194) (n = 833) (n = 55) (n = 36) (n = 55)

Spore number per ascus

FIG. 7. Correlation between ascospore number per ascus and ascospore septation type inlichenized and lichenicolous Ascomycetes.

transversally septate, muriform) appears in all three groups of ascomataattachment (ascomata immersed, sessile, stipitate). A clear, but rather trivialrelationship exists between spore number per ascus and ascospore septationtype, as shown in Fig. 7 for lichenized and lichenicolous ascomycetes ingeneral. Genera including species with oligospored asci show a high percent-age of muriform ascospores. On the other hand, polysporous asci mainlycontain monoblastic-aseptate spores. For most genera, smooth ascosporesurfaces are reported. An ornamented surface occurs in 10% and a halonatespore surface in about 20% of the genera. The highest percentage ofpigmented spores (more than 50%) is found in spores with an ornamentedsurface (Fig. 8). This relationship should be interpreted with care, since wallornamentation of hyaline spores may not always be easily recognizable. Like inother orders of the Ascomycetes, bacilliform to fusiform conidia occur in themajority of lecanoralean taxa. They occur in all groups of ascus types. Noindication exists about the apomorphic or plesiomorphic status of conidialtypes in the Lecanorales.

Several poorly studied anatomical characters such as the variation ofsepta types in the medullary hyphae, may be diagnostically valuable as well.For instance, both Physciaceae and Teloschistineae comprise genera with

THE LICHENOLOGIST Vol. 30

Ascosporepigmentation

D hyalineI pale brownish, greyish• dark brownish, blackish

smooth halonate/ ornamentedmultilayered

(re = 376) (n = 76) (n = 40)

Ascospore wall structure

FIG. 8. Correlation between ascospore wall surface structure and ascospore pigmentation in theLecanorales.

multi-perforate septa in the medullary hyphae. At least with respect to theTeloschistaceae, it seems obvious that the type of septa depends on thallusorganization: crustose taxa have uniperforate septa, while foliose and fruticosetaxa exhibit more or less multi-perforate ones (Rambold 1995). A comparisonbetween groups must therefore be focused on representatives at comparablelevels of thallus organization. Striking differences of septal pore numbers inthe medullary hyphae were indeed found within the foliose and fruticoserepresentatives of the Ramalinaceae with uniperforate septa and Parmeliaceaewith multi-perforate septa.

SummarySpecific structures in the ascus apex are commonly accepted as phylo-genetically highly relevant characters. A range of basic ascus types can bedistinguished within the Lecanorales (Fig. 1), but it could not be determinedwhether they are monophyletic or not. Nevertheless, the examples of characterprofiles for ascus type groups with respect to substratum selection, typesof growth form, and ascospore septation supply useful insight into the


relationships of the genera studied and the dependency of characters. Visual-ization of the distribution of morphological and other characters is considereda desirable result per se. Correlations of independent and dependent characterscan include combinations of monophyletic pairs of characters as well asparallel adaptations by independent phylogenetic events. In Figs 2, 3 and 6,the ascus types are correlated with three ecological and two morphologicalcharacters. There is no indication that the characters used are dependent oneach other. The resulting profiles can therefore be considered group-specificand relevant. This is also true for Fig. 4, which supplies a profile of theoccurrence of major chemical substance groups in the Lecanorales in compari-son with non-lecanoralean, lichenized (and lichenicolous) ascomycetes.

The micro-morphological ascomatal characters as used for Figs 5, 7 and 8are often applied as key characters at a lower systematic level. However, thecross-tabulation diagrams indicate possible dependencies between these pairsof characters. They are worth being considered, especially in the context ofcharacter weighting in morphology-based matrices for cladistics, for example,spore number per ascus and ascospore septation, ascospore ornamentationand pigmentation, ascospore and epihymenium pigmentation. Some of theseresults may have been expected by experienced students of the Lecanorales,but they are now supported by the analysis of a large data set.

Many groups of the Lecanorales have been studied relatively well, but stillmany give rise to questions that exist in respect to the definition andhomologization of characters. A critical revision of the LIAS character matrixused for the examples in this paper shows that the definitions of somecharacters and character states are still unsatisfactory. They suffer from theproblem, that non-homologous characters were combined into a singlecharacter. For instance, isidia-like, lichenized propagules (isidia, blastidia,branchlets, papillae, tubercules, etc.) of different kinds are included in a singlecharacter state. To overcome these limitations, a considerable number ofexperts should co-operate in elaborating a refined, consistent, and stablereference list of characters for ascomycetes (Rambold 1997). In order toobtain more complete and reliable generic data sets of ascomycetes, moredetailed alpha-taxonomic studies with respect to morphological, chemicaland ecological data are indispensable. Based on such improved data, the kindof data analysis presented here can inspire the phylogenetic concepts ofascomycetes and other taxonomic groups.

Thanks are due to M. Wedin and O. W. Purvis (both London), organisers of the ' Symposium onTaxonomy, Evolution and Classification of Lichens and Related Fungi', for an invitation to thesymposium held during the Annual Meeting of The British Lichen Society in association with TheLinnean Society of London and The Systematics Association. M. Wedin is thanked for helpfuldiscussion and constructive criticism on the manuscript. We also thank the numerous revisers ofthe LIAS generic data (URL: http://wzvw.botanik.biologie.uni-muenchen.de/botsamml/lias/genrev/html), B. J. Coppins (Edinburgh) for supplying us with data and J. A. Elix (Canberra) for revisingthe section on chemistry. Financial support from the Deutsche Forschungsgemeinschaft (grantno. Ra 731/1) is acknowledged.

REFERENCES

Baral, H. O. (1987) Der Apikalapparat der Helotiales. Zeitschrift fur Mykologie S3: 119-135.


Beck, A., Friedl, T. & Rambold, G. (1998) Selectivity of photobiont choice in a lichencommunity: inferences from cultural and molecular studies. New Phytologist 139(4).

Bellemere, A. (1994) Asci and ascospores in ascomycete systematics. In Ascomycetes Systematic!.Problems and Perspectives in the Nineties (D. L. Hawksworth, ed.). NATO ASI Series A, 269:111-126.

Bellemere, A. & Letrouit-Galinou, M. A. (1988) Asci, ascospores and ascomata. In CRCHandbook of Lichenology (M. Galun, Ed.) 1: 161-179. Florida: CRC Press.

Coppins, B. J. (1983) A taxonomic study of the lichen genus Micarea in Europe. Bulletin of theBritish Museum (Natural History), Botany 11(2): 17-214.

Coppins, B. J. & Kantvilas, G. (1990) Studies on Micarea in Australasia I. Four new species fromTasmania. Lichenologist 22: 277-288.

Dallwitz, M. J., Paine, T. A. & Zurcher, E. J. (1995) User's Guide to the DELTA System: A GeneralSystem for Processing Taxonomic Descriptions. Ed. 4.02 (May). Canberra: CSIRO Division ofEntomology.

DePriest, P. T., Stenroos, S., Ivanova, N. & Gargas, A. (1997) Polyphyletic origins of the lichenassociation in the fungi: phylogenetic analyses of nuclear small subunit ribosomal DNAsequences. American Journal of Botany 84(Suppl.): 9.

Ekman, S. (1996) The corticolous and lignicolous species of Bacidia and Bacidina in NorthAmerica. Opera Botanica 127: 1-148.

Elix, J. A. (1992) Lichen chemistry. Flora of Australia 54: 23-29.Hafellner, J. (1984) Studien in Richtung einer naturlicheren Gliederung der Sammelfamilien

Lecanoraceae und Lecideaceae. Beiheft zur Nova Hedwigia 79: 241-371.Hagedorn, G. (1997) DeltaAccess—an SQL interface to DELTA (" Description Language for

Taxonomy"), implemented in Microsoft Access. URL: http:llwww.bgbm.fu-berlinldelprojects!DeltaAccess/.

Hertel, H. & Rambold, G. (1988) Cephalodiate Arten der Gattung Lecidea sensu lato (Asco-mycetes lichenisati). Plant Systematics and Evolution 158: 289-312.

Huneck, S. & Yoshimura, I. (1996) Identification of Lichen Substances. Berlin: Springer Verlag.Karnefeldt, I. & Thell, A. (1992) The evaluation of characters in lichenized families, exemplified

with the alectorioid and some parmelioid genera. Plant Systematics and Evolution 180:181-204.

O'Donnell, K. & Cigelnik, E. (1997) Two divergent intragenomic rDNA ITS2 types within amonophyletic lineage of the fungus Fusarium are nonorthologous. Molecular Phylogenetics andEvolution 7: 103-116.

Rambold, G. (1995) Observations on hyphal, ascus and spore wall characters in Lecanorales s.l.Cryptogamic Botany 5: 111-119.

Rambold, G. (1997) LIAS—the concept of an identification system for lichenized and licheni-colous Ascomycetes. Bibliotheca Lichenologica 68: 67-72.

Rambold, G. & Triebel, D. (1992) The inter-lecanoralean associations. Bibliotheca Lichenologica48: 1-201.

Rambold, G. & Triebel, D. (1997) Genera of Lichenized and Lichenicolous Ascomycetes.-URL:httpn'Iwwwlbotaniklbiologie. uni-muenchen. delbotsammllliaslgenform. html.

Rambold, G., Triebel, D. & Hertel, H. (1993) Icmadophilaceae, a new family in the Leotiales.Bibliotheca Lichenologica 53: 217-240.

Rambold, G., Mayrhofer, H. & Matzer, M. (1994) Correlations of ascus and spore characters inthe Physciaceae (Lecanorales). Plant Systematics and Evolution 192: 31-40.

Rambold, G., Friedl, T. & Beck, A. (in press) Photobionts in lichens: possible indicators ofphylogenetic relationships? Bryologist.

SAS Institute Inc. (1989) SAS/STAT User's Guide. Version 6, 4th edn. Vol. 1-2. Cary, NC: SASInstitute Inc.

Tehler, A. (1996) Systematics, phylogeny and classification. In Lichen Biology (T. H. Nash, ed.).Cambridge: University Press.

Triebel, D. & Rambold, G. (1988) Cecidonia and Phacopsis (Lecanorales), zwei lichenicolePilzgattungen mit cecidogenen Arten. Nova Hedwigia 47: 279-309.

Triebel, D., Wedin, M. & Rambold, G. (1997) The genus Scutula (lichenicolous ascomycetes,Lecanorales): species on the Peltigera canina and P. horizontalis groups. Acta UniversitatisUpsaliensis Symbolae Botanicae Upsalienses 32(1): 323-337.


Wedin, M. & Tibell, L. (1997) Phytogeny and evolution of Caliciaceae, Mycocaliciaceae, andSphinctrinaceae (Ascomycota), with notes on the evolution of the prototunicate ascus.Canadian Journal of Botany 75: 1236-1242.

Wedin, M., Tehler, A. & Gargas, A. (1998) Phylogenetic relationships of Sphaerophoraceae(Ascomycetes) inferred from SSU rDNA sequences. Plant Systematic^ and Evolution 209:75-83.

Accepted for publication 24 May 1998

the distribution of selected diagnostic characters in the lecanorales

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