How to arrange the diversity of a tropical lichen family? : Systematics and generic concepts in the lichen family Graphidaceae Autor(en): Staiger, Bettina Objekttyp: Article Zeitschrift: Archives des sciences [2004-ff.] Band (Jahr): 58 (2005) Heft 1 PDF erstellt am: 23.09.2021 Persistenter Link: http://doi.org/10.5169/seals-738389 Nutzungsbedingungen Die ETH-Bibliothek ist Anbieterin der digitalisierten Zeitschriften. Sie besitzt keine Urheberrechte an den Inhalten der Zeitschriften. Die Rechte liegen in der Regel bei den Herausgebern. Die auf der Plattform e-periodica veröffentlichten Dokumente stehen für nicht-kommerzielle Zwecke in Lehre und Forschung sowie für die private Nutzung frei zur Verfügung. Einzelne Dateien oder Ausdrucke aus diesem Angebot können zusammen mit diesen Nutzungsbedingungen und den korrekten Herkunftsbezeichnungen weitergegeben werden. 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Systematics and generic concepts in the lichen family Graphidaceae Bettina STAIGER^ Short introduction to lichens in general The famous botan/'st Car/ von L/'nné considered the //'cbens to be /ust «rust/ci pauperr/m/"» - tbe poor frasb of vegetation - anc/ be d/'d not even d/st/'ngulsb fam/7/'es or genera of //'cbens but c/ass/f/'ed tbem a// /'n one genus - «//eben», Jldm/'ffed/y, most //'cbens bave ratber Inconspicuous grey/sb or green/sb fba///' but some are producing ye//ow, orange or red p/gments, and tbe var/'ab/7/'fy of tbe/'r growth forms fcrustose, fo//'ose, sbrub-//'/re or even barbe-//'/ce) and tbe/'r fruiting bodies ("round or e/ongafe, open or c/osed, exposed on podef/'a or b/'dden In tbe fba//us) /'s fascinating. /n tbe 79fb century many bofan/'sts became Interested /"n tb/'s group of organisms and started fo /'nvesf/'gate tbem In more defa/7 - sucb as tbe two famous bofan/'sts of Geneva Augusf/'n Pyramus de Cando//e and Jean /Wü//er J\rgov/ens/s. But /'f foo/r gu/'fe a /of of time unt/7 tbe/'r rea/ nature was revea/ed: /t was /'n 7869 wben S/'mon Scbwendener d/'scovered tbat //'cbens are not one organ/'sm but composed of two - a fungus and an a/gae //'v/'ng together /"n a we// organ/'sed symb/'os/"s. However severa/ decades bad fo pass before fh/'s new d/scovery was accepted by most //"cbeno/og/"sfs. The mycob/'onf ("the funga/ partner,/ /s the more dom/'nanf part of fh/s symb/'os/'s, be/'ng respons/'b/e for the growth form and be/'ng ab/e fo reproduce sexua//y wb/'/e the a/ga/ partner (pbofob/ontj /'s /ess spec/'f/'c and resfr/'efed fo vegefaf/'ve reproducf/'on. Therefore systemat/c and c/ass/'f/'cat/'on of//"cbens a/ways refer fo the funga/ partner. Lichen systematics important characters for the lichen systematic changed considerably from time to time. Very often It was an important aim of lichenology not only to the development of new techniques lead to the dis- describe new species but also to «put in order» this covery of new characters which were considered to great variability and diversity - i. e. to develop a hier- be essential for a «modern» system. archical system. This system should reflect similari- ties and possible relationships between taxa. But The first lichen systems were mostly based on the soon the question arose on which characters the sys- growth form of the thallus: Crustose thalli were con- tern should be based on. If we look back in the history sidered to be less evolved («primitive»); foliose and of lichenology we see that the point of view what are shrub like thalli high evolved. ' /nsf/ftvfe of ßofaey (Jn/Ve/s/ty of Äegensburg I ARCHIVES DES SCIENCESI Arch.Sei. (2005) 58: 53-621 I 54 I Bettina STAIGER How fo arrange rte d/Vers/'ty of a rtop/ca/ //'crten fam/'/y? I However some time later the fruiting body (the asco- the bark of trees as substrate, only very few are grow- carp) thus the reproductive part of the lichen came ing on rock or soil. The family Graphidaceae com- into the focus of the lichenological research. While prises more than 1000 species and the great majority first the texture or character of the margins (black, of them occur in tropical rain forests or subtropical round, with or without algae) were observed, later forests. So the tropics are the centre of diversity for also microscopic features were investigated in detail this family - and we find there a great diversity and - and for a long time spore characters were most variability of ascocarp morphology and shape: There important for the systematic of lichens. are species with fissure-like fruiting bodies having inconspicuous, pale, uncarbonised margins (Fig. 2A) At the beginning of the 20® century the chemical or species with very prominent ascocarps and black, exploration of the lichens started: The so called carbonised margins (Fig. 2B). The fruiting bodies of lichen acids and their chemical constitution were dis- other species have uncarbonised but well developed covered and had a great impact on the systematic and margins with striation (Fig. 2C), or the ascocarps are taxonomy of lichens. At the end of the last century clustering together and are located in special parts of another new character, the ascus type, came into the the thallus (so called «stromata», Fig. 2D, E, F). We focus of fungal (and lichenological) research while also find species with conspicuous red or orange during the last 5-10 years molecular genetics pro- coloured ascocarps (Fig. 2H, J) or species with more vided new tools for lichen systematic studies. or less round fruiting bodies (Fig. 21, K), a feature that Nowadays differences of DNA sequences are used to is quite uncommon within the family Graphidaceae. investigate the relationships of lichens and to recon- struct phylogenetic trees. And the question was how to arrange this great vari- ability in a systematic order. What is a suitable natu- Each new approach led to a better understanding of ral system that reflects phylogenetic relationships the relationships between taxa and improved the cur- between taxa and how can we distinguish genera? rent phylogenetic system. Yet the perfect system still does not exist. Generic concepts in the family Graphidaceae Special part - The lichen family Graphidaceae If we look back on the early 19® century several com- peting, parallel generic concepts existed. However With this history of lichen systematic in mind I want these concepts were not very clear or concise and to focus now on my special subject, the family many lichenologists did not follow any of these but Graphidaceae. placed all species with elongate ascocarps in the Typical members of the Graphidaceae are charac- genus Grap/ris. It was finally Jean Müller Argoviensis terised by whitish to greyish crustose thalli with black, (1880, 1882) who developed a «modern» system «carbonised», elongate fruiting bodies («lirellae») based on spore characters for the Graphidaceae. This (Fig. 1). The Graphidaceae are also called «script- system was widely accepted by most lichenologists lichens» and the probably best known species is and also adopted by Zahlbruckner (1926) in Engler & GrapMs scripta. Most species of the family favour Prantls important oeuvre «Die natürlichen Pflanzenfamilien». Müller Argoviensis (loc. cit.) con- sidered the spore colour and the spore septation as most important characters for the delimitation of genera. He distinguished species with hyaline (colourless) or brown spores, having transverse septa only or transverse and longitudinal septa (muriform spores). Based on these differences Müller Arg. described four main genera: Grap/ws, Grap/iiM, Ptoeograpte and PMeoprap/ima (Fig. 3). His system allows a quite easy determination of the genera but it has several drawbacks and does not fulfil the criteria for a natural system, as the fol- lowing examples will show 11. Hyaline spores may become brown when degenerating Fig. 7: Graphis duplicata, a typical member o/rte lic/ien/amily and several species have (wrongly) been placed in brown Graphidaceae, icit/i folacfc fcarbcmisedJ elowgale/mifmg bod- spored genera as degenerated spores were present in the ies, bar i mm. type specimen. I ARCHIVES DES SCIENCES I Arch.Sei. (2005) 58: 53-621 I How fo arrange fbe d/Vers/fy of a frop/ca/ //'eben fam/'/y? Bettina STAIGER I 55 I ranxt. Fig. It Ascocarp i/ariabliitg M/i/fern t/ie/amiig Grap/wdaceae. A; Fissurina dumastii; F; Platygramme australiensis; C: Acanthothecis subclavulifera; I): Sarcographa cinchonarum; F; Glyphis cicatri- cosa,- F: Sarcographa difformis; G: Platythecium dimorphodes; F.- Thecaria montagnei; /: Phaeographis lobata; J: Graphis chrysocarpa; F Graphis muscicola; bar 7 mm. I 2. The presence of one additional longitudinal septum Therefore I started to study the species of the family changes the generic affiliation of species. Therefore many Graphidaceae (with main focus on the old generic species with similar or corresponding morphological names and their types) in order to develop a new, characters (but different spore septation) have been placed more natural generic system.