From: Battaglia B., Valencia J. & D.W.H' Walton (eds.)' Anlarctic Communities. Species, Structure and Survival ' Camtridge University hess: 15-21, 1997. 2 Diversity of lichens in Antarctica MIRIS CASTELLO AND PIER LUIGI NIMIS Depa ment of Biolo$', Uni'ersity oJ nieste, Vio Oiotgi?ti 10, I 34127 Triask, Ilaly ABSTRACT fora of Antat.ticz, Mt of C WDodge, Published in 1973. of nhich vere described b1' Dodge os nex to science. We 152 r ofa total of 186) species des<ribed b1'Dodge the typesof haw recentll, exttnittet! ( and accept onll' 3l species 2O/,) as ralid. All of Dodge's species rere des$ibed os endemic to Antarctica: aflet rc\ision A larctica has lost l2l endernic lichens. On the other hand, recent lichenologicol rcseorch it Antarclica hos added nany lichen species The onl1, extont li<hen includes 415 species, 44.6'% lichenfora. This papet summari:es the results of the last 20 years of lichenolog' ical explorution of Anlordica, and co,tsidef lhe main fotitlic-Phltogeographic elemen$ in the fora. The knolrn lichen foru of Antarc ca is reduced from 415 to 260 species, the percentage of endemic species falls lron 9l'%' to 3B%, and that of bipolar to its and cosmopoliton species increases fron 2.4j1' to 41,5%', Although these figutes are likely ,o change in the neor futu,'e as a consequence of lhe presenl intensive lichenologthey suggest that the lichen fora of lhe continent, and espe- ical research in cially of 'lntarctica, continental Antarctica, is a )oung one' n'hich motuly originated br- long4istance dispersal in lhe Qu4ternqt| periodKey rvords: Antarctica, biodivcrsity, fl ora. lichens, phyrogcography. INTRODU CTION Although lichcng one of the most conspicuous elemen$ of Antarctic terrcstrial ecosyslems, havc bcen investigated sinc€ the early Antarctic expeditionq theit taxonomy is still vcry confused, and knowledge of the Anlarctic lichen flora is incompletc. According to some authors (c.g. Dodgc 1973), Antarctica hosts mor€ than 400 lichen species, while orhers (c.g. Hcrtcl 1988, Galloway l99l) givc much lower estimalcs of 160-200 spccies Dodge (1973) ard several carlier author claimed that most Aniarctic lichens are narrow-ranging cndcmics according to I tcrtel (I whercas, 98E), thc endemic clement does not cxcced of thc total. Such a confused situation is due to sevcral rcasons. Most collectors wcrc not lichenologist+ which resultcd in incomplctcly rcprcs€ntative collections The idcntification of Antarctic material was oftcn csrried out by people who did not study the 20% material in the ficld, with a consequent underestimation of phcnotypic variation. Most of thc early taxonomists working with Antarctic matcrial started from the prcmis€ that thc lichen ffora of Antarctica, becausc of its isolation, had a very high dcgrcc of endemism, and rarcly tricd to compar€ their lichens with thos€ alr€ady known from other pans of the world. Thuq many 'cndcmic' species were described, which latcr proved to be citha morphorypes of thc samc species induced by differcnt environmental conditions or even synonyms of widespread specics with a more-or-less cosmopolitan, or bipolar distribu- tion (Smith 1984, Hertel 19E78, 19E8, Nimis 1990). Finally' the type specimens of many specic* and esprcially those of thc two authors who were most prolific in describing new taxa from ADtar€tica, i.€. M. A. Hue and C. W Dodgq wcl€ not available to spocialistq either because they wcre lost (as was apparently th€ case for many of Hue! ryp€s), or becaus€ the auihor did not makc them available for loan (as in the cas€ of Dodge's types). The most complete lichen flora of Antarctica, that of Dodge (1973), was reviewcd with the following words by Almborn (1974):'This author [f)odge] has causcd untold damage to taxonomic lichenology- His publications unfortunately cannot be M. Castello und P L. Nitnis l6 simply igno.ed. Futrrrc serious licheno!ogi\15 will hate to sp€nd much time and trouble in cvaluatingand identifyingall his many worthless taxa'(see also commcnts by Lindsay. l9?4). \4e also becam€ convinced that this flora was the major obslacle to any serious study of Antarctic lichens as we tried to identify the frtst coltections from the surroundiugs of the ltalian research starion at Terra Nova Bay (victoria Land). It was clear that little could of the many species described by Dodge and collaborators Thc taxonomic criteria adopted by Dodge were hcavily criticized by many lichcnologistr but no scrious rcvision ofhis species wascarried out, mainly becauseof be done wiihout a rcvision unavailability of the types The lichcn hcrbarium of C. W Dodge was donated, before his dcath, to thc Farlow Herbarium (FH, Cambridge MA). Thanks ro the curators of FH. $e were rrcently able to carry out a critical revision of the types trf 152 (ofa total of 186) sp€cies dcscribed by Dodge (Castello & Nimis 1995). Thc main purpose of this papcr is lo giv€ a brief account of the rcsults of this revision, and to deduce the floristicand phytogeographic elements of this flora from 20 years of post-Dodge lt ,groa/.dl a o.hr tt ho| Fig. 2.1. Hithcrlo known distribution ol Ac.ltosPotu ga'ynnii and of threc synonymous taxa in Antarctica The four 'cndcmic'taxa proved to b€ a single circum-Antarctic specics in Pleopsidiun; Pleopsidiun is rcpresented in Antarctica by onc species, P chlorophanun (Wahlenb.) Zopf' genus belongs lichenological research in Antarctica by various authors THE REVISTON OF C. W. DODGE'S aL which was trcated under different generic and spccific namcs by earlier aulhors Altogether, the number of species of ycllow T'Oi,{ his Lichen Floru of the Anturctic Continent Dodge ( 1973) listcd 415 spocies (excluding dubious rccor<is and infraspccific taxa); of thcsc, nearly half (45%) were describcd by Dodge (alon€, or with collaborators), 22% by Huc,9/o by Vainio. and 5% by Darbishire. In our revision (Castcllo & Nimis 1995) wc ccnsidered only spccies described by Dodg€, Dodge & Rudolph and Dodge & Bakcr which are reported in Dodge's F/ora (Dodge Acarosporaccae known from Antarctica was r€duccd from len lwo gerlft, Acotospora znd Pleopsidiwtt. to rhrce. disttibuted il The rwo species of ,/ carospora are, so far as is known' cndemic chlorophanwt is a widespread bipolar-subcosmopolitan lichen. The case of I gwynnii is particularly pertincnt, and repres€ntativc of the status of many to Antarctica, while P of other lichenologisrs who Species dcscribed by Dodge Dodge's types analysed some from subAntarctic areaq and not cited in thc flora. were not Antarctic 'endcmic' taxa: this sp€cics was dcscribed four timeq as A. gfynnii Dodge & Rudolph, A. enetgens Dodge' A. knovlesii Dodge zll,d A. petalina Golubk. & Savicz; the four species wcre endemic to particular, more'orless wide arcas of ircludcd. Whcn wE started rcvising Dodge's material we discovercd the Antarctic continent. Thc recognition of their consp€cificity shows that ,,1. gwyzzfi is a widcspread circum'Antarctic species that some typcs were merely fragmcnts of indeterminable sterilc crusts the samc sp€cies was somctimes described scvcral timcs (Fig. 2.1). Its status as an Antarctic cndemic may be provisional, as,r. gx?rr still has to be compared with the numcrous similar undcr widcly diffcr€nt gcncric namcs, the original dcscriptions do not comply with the characters of the typeg and thc cbaractcrs givcn for somc sp€cics arc a mixtur€ of thos€ of dilfcrcnt lichens growing togcther on the typ€ sample. To givc an examplc of the taxonomic miasma crcatcd by spccies dcs€ribed from othcr parts 1973), also including the results of of thc world. a sludy on thc gcnus & Nimis 1994b). This gcnus was trcatcd by Dodge (1973) undcr sevcral genera-Blastenia, Biatorella, Eklundia, Protoblattenia' of b€longing to familics which arc quite unr€latcd to the Dodgc we summarizc her€ thc results of a reccnt revision Antarctic ycllow Acarosporaocae (Castcllo & Nimis 19944). Four gcncra (Acarospora, Biatorella, Bialorellopsis {td E(rudiia) and tcn spocies, all of them dcscriM as cndemic to Anrarctica, wrrc r€portcd by Dodge (1973)' Our revision shou/cd that in Antarctica Acarospota s.s. includes only two ycllow sp€cies, l. gttlnnii Dodge & Rudolph and A. favocordia Castcllo & Nimis; Biotorello docs not ocsur in Antarctica, the specics described by Dodge bclonging instead does in Condelariella: of Candelatiella; Biatorellopsis not occur in Antarctica eithcr, and the type species of the the genus Etrutrdia is a synonym Similar rcsults wcre obtaincd in Condelariella in Antarctica (Caltello Candclariaceae. The two species of Cand€ lariells rcpottcd from Antarctica by Dodge (1973'), C. albovirens Dodge & Bakcr and C. rudolphi Dodgebelong instead in lzcanora and Xantho a. rcspectivcly. The six spccies examined by Castcllo & Nimis (I 994b), all purported to be endemic to Antarctica, were found to be synoryms of thrce spocies, Candelaiella aarello (Hofim.\ Zatrlbt., C. virel/ra (HofIm.) Mtll. Arg. and C./ova (Dodge & Baker) Castello & Nimis, two of them cosmopolitan and the lattcrcndemic. In the light of rhese results, it is not surprising that aftcr the Dh,ctsit) oJ lihens in Antd(ti(u t7 rcvision of Dodge' typei only 3l Peninsula to acccpted ar valid (Cisrcllo South Sarrdwich lslands. out of 151 (2OZ) wcrc 'pecies & l.limis i995). 'fhis confirnrs the hypothesis by Hertel(1986) that c.80'% of rhe species crcated by Dodge would be reduced tc synonyr,rs. All of these spccics were considercd by Dodge (1973) as endcmic to Antarctica. Thus, Antarctica has losl l2l 'cndcmic' lichcns This considerably alters thc phytogeographic imagc of Antarctica as a refugial r.63'S, plus Sourh Sherland. Soulh Orkne] irnd Thc thr€e datasets provide the basis for determining strnre main phytogeographic groups of lichcns in continenral Antarctica, maritime Antarctica and in thc whole Antarcric rcgion. The following main phytogeographic clements are distinguished: Endenrrc: subdivided into endemic to continenral centre for old, Gcndwanaland species as postulated by Dodge Antarctica. endemic to maritime Antarctica and cndemic ro the (r973). Antarctic region (occurring both in contincntal and in maririme Antarctica). Suh-Antatli<', specics occurring in rhe subAntarctic and Antarctic regions. Cool-tenperote'. sp.cies of the cool-tcmperate areas of southem South America (Fuegia and Falkland Islands). also occurring in Antarctica.,{t/-fl/.r/: spccies described from othcr southcrn continentr outside the rropical and subropical zonel and also found in Antarcrica. 8?()/.rr: species distributed in the boreal and in the austral zones but absent from tropical lowlands, with or without intermediate populations in tropical mountain aicas (Du Rierz l9{0). DATA AND METHODS This paper is based on three species lists, covering the whole of Antarctic Region. the (a) The 415 species included in The Lichen Floru of the W Dodge ( l9?3). The same as (a). after the revision by Castello & Nimis (1995), and including synonymies proposed by sevcral other authors which cxamined t)p€s of Antarctic species described by various authors (e.g. Lamb 1964, 1968, Brodo & Hawksworth 1977. Ovstedal 1983. Filson 1984, 1987, Hertel 1984. Redon 1985, Walkcr 1985, Filson 1987, Hale 1987. Botnen & ovstedal 1988. Sdchting & ovstedal 199 i . Smith & Ovstcdal 1991. etc.), wirh a lotal of 241 spccies. A 'post-Dodge' checklist of Antarctic lichcns including the re{ords given by most authors who worked on Antarctic A,Ior.'tic Continpnt (b) (c) by C. lichens after the publication of Dodgel flora (1973-1994), with a total of 260 species This list, which is not includcd herq is available from the authors upon request, The lisrs Cb) and (c). although with a similar number of species, are widely different. The reason is thar Dodge acccptcd, besides Coatrcpolitan: widespread species. occurring in both hemi- spheres. in more than one vegetation zone. The comparison between the percentage occurrence of these phytogeographic groups in thc lhrec species lists indicares the drastic changes in the floristic-phytogeographic imagc of Antarctica brought about by the progrcss of lichenological rescarch since l9?3. THE NEW FLORISTIC IMAGE OF ANTARCTICA Table 2.1 prescnts the p€rcenlage occurrence of lichen species in the thrce species lists, subdivided into phytogcographic ele- mentE in continental Antarctica, in maritimc Antarctica and in post-Dodge aurhors, for two main reasons; (a) b€caus€ his flola Antarctic region. Thc data for continental Antarctica are shown in Fig. 2.2. The critical re-appraisal of many taxa reported in Dodge! Eora lcd to a drastic decrease in the numb€r of speci€s, from 201 (Dodge 1973) to 8l; thc post-Dodgc chccklist includes 90 *as largely unworkablc, (b) because the dcscriptions of Hue, as species The present authoff consider the lichen flora those of Dodgc, rarely give a clear idea of the species. Howcver, nental Antarctica to b€ of approximately 100 specier i.c. half these oamcs cannot be simply ignorcd. They wcre validly published, and they could prove to ha\€ priority with rcspoct to specics described later. Many taxa described by Darbishire the number given by Dodge Vainio, Zahlbruckncr, and especially b) Hue saill await revision. regional floras are undcr completion by diffcrenr authors. The and on these w€ are currcntly working. Until tbis rcvision is complct€d it would b€ prematurc to compile a general checklist 9V/'(Dodge the many sp€cics described by him. also many othcr poorly known taxa described by earlicr authors, and especially those described by Hue Many of thesc taxa wcre not considered by ofAntarctic Iichens For the subdivision of Antarctica into regions wc follou/cd Smith (I 984), who recognizcs three main biological regions: sub Antarctic, maritimc Antarctic and continental Antarctic. In the prescnt paper, thc sub-Antarctic region is not considercd. Continental Anlorctica includes the coastal fringe of Grcater Antarctica and lrss€r Antarctica south of 70" S, and the cast of the Antarctic Peninsula, south of c. 63" S. Maitime Antqrcli(a includcs the west coast of Antarctic Peninsula and offshorc islands to ?0" S. and also the northeast coast of thc coast the wholc ( 1973). of conti- of lt should beadded, however, that thisestimate is bas€d on the hitherto available data. and rhat thc numb€r of spocics is likely to increase in the future. as ser€ral incidence of endcmics in continental Antarctica reduces from 1973), to 65% (Dodge 1973 afier revision). to 30% (post-Dodge checklist). This last 6gure is probably closer ro r€ality, sinc€ in the flora of Dodge (19?3) s€veral poorly known, 'endemic'taxa describcd by otherauthors are accepted, many of which will c€rtainly prove to b€ synonyms of other more widespread species. Thc decrcase of continental endemics is paralleled by an incrcase in endemics forall of Antarctica (from 9 to 2V/o), mainly because many specics known only from thc rype collection, and hence considered as 'narrow ranging endcmic', proved to be identical with sp€cies occurring also in maritime Antarctica (see Fig. 2.1). Altogethcr. the endcmic tl. !8 (b) L Nimis lil lichekforos of conlinenlal Dodge (i973)' ,ogion, according ro three ntain sources: ( a ) Eforuof msiirfune ,rrrrarcrica ond of the ,*ol" intir"ii, Tioie2.l. Perceange Antarcrica, Ccstello and P rhe satne, oc.urrerice of tfu ,nnin phltogeographic elemcnts cnd totdl nnmbet of tpedes in fecent aulhols, posl.Dodge ,,ulho',l1 ( c ) o checklisr of oll lichen records by after rcvision or ,nun\, Anlarctic taxa by excludiltg Dodge Contincnisl Maritime Antarctic cndcrnic cndcrnic cndcmic no. Co tinental /ntatalko 180 Dodge (1973) 5l Dodgc (1973) aftcr .svisiots Rcccttt au$ors .xcluding Ngc 89.5 u3 -30.0 - Marilime Antarclico - Dodgc (19?3) Dodgc (1973) aftcr Evisions Rlccnt authors cxcluding Mgr Yo Dodgc (1973) aftcr rcvisions Rrccnt authors cxciuding Dodgp no, vo 178 76.3 71 45.6 19 20 l t.8 54 23.9 l8 8.0 t80 41.4 178 42.9 t9 4.6 54 22.4 77 31.9 26 10.7 27 10.4 v 20.8 l8 6.9 20 26 of thc post-Dodge checklist. Austral and sub-Antarctic spccies' postpractically abscnt in Dodge's flora, makc uP ?% of the Dodge checktist. For thc maritimc Antarctic (Fig' 2 3), the trend is analogous to that of contincntal Antarctica, cxcept for lhe number of reduction Dodgc spccics, which docs not show such a drastic (iszf) [st d 233 spccies from maritimc Antarctica; aftcr ltvi' 20 years sion thc numb€r of spocics drops to 169, but in thc last this from spccics many authors reponcd many ncw or additional rcgiin, so that the post-Mge checktist includes 226 spccier only a fex, lcss than in Dodge's ffora The phytogeographic maritime Antarctie' howcvcr, shows dramatic (1973) from maritime changcs Of atl species listed by Dodge rcgion' Aftcr Antarctica, 76% wrtr dcscribad as cndcmic to tbis thc numbcr of cndcmics is reduccd ro 45%' while the r,evision, post-Dodgc checklist iocludes only 24% of cndcmics' Sub-Antarctic specics, a category not PEscDt in Dodge's is likcly to fiora, arr now c. I l-lyo of thc total, a numbcr which incrcasc in the futurc. Wide-ranging specics (including lcss cosmopolitan, bipolar, austral and cool'tcmperatc)' arc post' thc in 50/o than than 15% in Dodgc's flora, and more Dodge chccklist. The previous information is surnmarized, for thc cntire given Antarctic r€gion, io Fig. 2.4. Thc total number of specics rcvision by Dodge (1973) for Antarctica as a whole was 415; the of many taxa rcduced it to 241; the post'Dodgc chccklist gflo in includes 260 spccies The endemic elem€nt is morc than l'j I1.3 l1.5 8.3 10.0 o/o Bipolar Cosrnopolit.n Toial no. no. l.l 22 9.3 4 19 ll.2 5 15 6.6 ll 1.6 8 oA 3.4 12.2 3l.l ll g-2 t 3.0 3 l.l I1.8 9 5.3 6i 2?.9 38 16.8 7 3.0 ?0 21 5.5 5 l.l t9 1.96 6 2.4 t5 5.7 12 4.5 Yo !lo. 201 0.5 1.0 5-5 19 26 43% Dodgc! flora, but makc up l3% of its revised vcrsion' and of t.2 8.6 (Dodg€ 1973) to clcmcnt shows a substantial decreasq from 99% from all rccords dcduccd as 85% (Dodgc after rcvision), to 50/o of post-Dodge authors. Thc oppositc trend characterizcs cos' in mopolitan and bipolar spocics; thcsc arc not repres€ntcd structurr no. Yo no Yo 9.4 -| - 19 20.2 -17l8 20.0 5 - lnlarclico Dodsp (1973) no, CoolSub-Ant rctic tempcratc Auslral 1 27 6 8l 90 233 169 226 1.7 1 0.7 415 lt.2 12 4.9 241 26.5 39 15.0 2& in the Dodge's flora, 65% in its reviscd \.ersion, and only 38% a post-Dodgc chccklist. Widc-ranging sp€cics, which constitute of thc sflo than morc up make very minor pan of Dodgc's flora, post-Dodge checklist. Thc figures discussed abovc are not dcfrnitive' Most collccby tions, espccially from continental Antarctica, werc made most thc collcct to tended non-lichenologists, who obviously conspicuous spccies. fierc might still bc scveral uncollccted tbem might spocics, cvcn in contincntal Antarctica, and sonc of p-u" lo be cndemic to this rcgion Furthcr wcrk by ""ro of this lichenologists will continuc ro change our undcntandinS it is as flora. Thc new phytogeographic image of Antarctica, is very cmerging ftom thc dccp fog of past uncritical rrsearch, diltcrcnt from what is still found in many tcxtbooks' 8nd is wonhy of brief discussion. DISCUSSION - THE NEW PHYTOGEOGRAPHTC IMACE OF ANTARCTICA Early hypothcscs on rhe origin of thc Ant'rctic lichcn flora' bascd on the assumption of a high dcgee of cndcmism' relied hcavily on thc theory of the migrarion of oontincnts, which later dweloped into platc tcctonics. According to somc views the flora lichcn flora of Antarctica should baYc bccn an old, rclict with Gondwanaland afnnities Dodgc (19?3) claimcd that conti- ncntal Antarctica, with its many narrow-ranging cndemicg hosts an ancient lichen flora' which sunivcd on nunataks during the l8st glacial pcriod: the flora of thc Antarctic Pcninsula' on thc contrary, should be somcwhat lcss wcll characterized, and might have dffived from Ticrra del Fuego. It is now clear that thc endemic clcment is lJsE important in Antarctica than was suppos€d and that the percentagc of .i Dirctsit t, of li.hens in.4n tarc t ica c..td tl &ardL. - Ito.lt oddnird !*Ic!o Cqrdr-t l ^nlr!{- - . Dcd!.llat:r) 5.lltr.'r (ie?r) iE:r,c . ItodForr:) .rir dard bnlr R.ad .lrhor .r.!drE D..lg. Fig. 2.2. Pcrr.[tagc occurrcncc of thc main ph]togcographic .lcmcnts in thc lichcn iora of Contincntal Antarctic! acording to thrcc main sourcc!: (a) lhc flora of Dodgc (1973), (b) th. sam.. aftcr rcvision of many Aotarctic t.Ia by post-Dodgc autho.s (c) a checklist of all lichcn Ecords by Eccol authors, cxcluding Dodgr. cndemics is likcly to decrcasc even funher in the futurg as a Ad.Eoc - i...d rrrl5|t .r.rr4l9 D.d!. Fig. 2.1- Pcrc€ntagc occunencc of thc main phytogcoFaphic clcmcnts in thr lichcn flora of Maritime Antarctica according to thrca main sourcas: (a) the nom of Dodgc (1973), (b) thc samq aftcr nvision of many Antarctic tara by post-Dodgc auihors, (c) a chccklist of all lichen rccords by ,cccnt authors, cxcluding Dodga conscqu€nc€ of the rcvision of thc t}?es described by prc-Dodge lcsscr degrcc, to maritime Antarctica, wh€reas there is cvidcnc€ that thc subAntarctic rcgion is rclativcly rich in cndemics (also authors (cspocially by M. A. Hue), and of thc comparison of Antarctic cDdcmic spocies with taxa from orher parts of thc at gencric lcvel), and thcrcforg contrary to Dodg€'s (1973) thcory hosts an oldcr flora (Hcrtel l9E7a, b, 1988, Galloway world, particularly from moDtanc at€as of southem contincnts l99r). Scvcral Anbrctic cndcmics havc closely r€lated taxa in the Nonhcm Hemisphere. c.g. Caloplaca athallina Darb. (Antarctica) and C. tyroliensis Zahlbr. (Antarctica and N Hcmisphcrc), Carborca copsulata (Dodgc & Bakcr) Halg and C vorricosa (Fl6rke) Hcrtc;l, lzcanoro ,a.oru-nir'r Darb. and L hagenii s-1., Izcanoru luscobrunnea Dodge & Bzket ar,d L poly,rcpa s.1., RhimcarponfavumDodge &B^ker and Rh. geogoph- icun s.l-, Xanthorit nal,.ronii Dodge and X. borealir R.Sant, & Poclt. Th€s€ taxa are only rcakly dilferentiatcd, somc ar€ sympatric in Antarctica, and in many cases it of thcm is dubious whcth€r they really deserve to b€ scparatcd at sp€ci* rank. These considerations apply to contincntal Antarctica and, to a The prcsence of widespread and bipolar spocies in the Antarctic lichen flora has been explaincd by three main thcories The 6nt is the 'migration hypothesis' of Stcbbins (1950) and Dodge (1964). lt postulatcs that bipol spccies reached Antarctica from thc north through the morc-or-lcss unintcrruptcd mountain chains of North, C€ntral and South Amcrica. Such a theory howcvct is quite dimcult to defcnd as many bipolar spccics arc South America, rot known from the northern Andes in or from thc southcm Cordillera in North Amerie. The sccond is the'persistence theory'(s€€ Lindsay 1977, Sheard 197?, Kernefelt 1979), which postulates that bipolar l'l 20 Custrlh u'd P !-' N'mi\ Islandr and by Engelskjon & Jdrgensen (1986) for Bouvetdya' thcir lichen These islands were s'Jtject to hcavy Slacialiorr' anC long-distancc the floras have featurcs which strcngli support wide-ranging dispersal hypothcsit such as a prepondetance of numberof high a cndcmics' of number and bipola..pecies, a low of many absence the and genera comparcd with that of sp€cies. sub'Antarctic other specics which arc othcrwise common in lhc (1979) for the zone. Similar results were obtained by Schuster hepatics of South Shetland lslands. ln conclusion, the hithedo available information rl-dra - lLda. flf'1 tn Lr.nt suggests that the lichen nora of Antarctic+ and especially of continental the Antarctica, is a young onc, which mainly oriSinated during dispersal Quatemary period by long-distance ACK NOWLEDGEMENTS for This study was financed by the ltalian National Programme Antarctic Rescarch (PN RA). REFERENCES Itf.u.ib. rsll. R*iew of Dodge' C. w Lichen flor"a of thc Antarctic Co tircnl. Botatiska Notber,ln' 45455' /!irrL.. i-d rtlt llt{rlllgO.a!p and oth'r Botncn. A. & 6vstcdal, D. O 1988. Muscicolous Leprario leprarioid lichcns in thc l\ntatclic Polat Research' 6' I29-I33' allied Scnera in Brodo: I. M. & Hawtsx,o nh, D. L.lg7'l ' Atectoria and North America. OP".d 8o unica,12' l'164 ' Antarctic ycllow Castcllo. M. & Nimi\ P L. l99ila. Critical notes on AcarosDomc.a.. Lr'clen ologitt,26,283 -294 ' thc gcnus Casrelto. tri. & Nimis P. L. I99lb. critical noles on Candzla etta (Lichcn6) in Antarctica' '4crt 8o tonica Fennica' l5[. 5-10. lichcns Castcllo, M. & Nimii P. L. 195. A oitical rcvision of Antarctic l-92' Lichenologico'i1 ge. Bibliotheca V{ Dod d.scribed by C. '1 ooagc C. w. r9,6a. E"ology and gcographical distribution of Antarctic -- ph) logrographic clcm€nlsin Fiq. 2.4. Prrc.ntaSc occurtrnc. of th. main thrcc main sourccs: (a) the to ac.ording oi,lnr"rclicg no. ihi ti"h.u nora of poag" ffSz:1, (b) rhc ssmq aftcr rcvision of many Antarclic r'ccnt lara by pGt-aodgp authors' (c) a ch.ckli$ of all lichcn Ecords by suthors, dcluding Ngc' spccics, or closcly rclarcd anccstorg wcre widespr€ad alrrady bcfoE the fragm€ntstion of Pangca. Thc populations brought pcrsisting in into the Arctic zonc by contincntal drift, and thosc Antarctica, unde cnt only slight or no diffcrcntiation' duc to which rhc vcry slow cvolutionary ratcs of lichcns This theory prcviwas ffora' rclict vcry old, a implies that Antarctica hosts of eodcmic incidence ously supponed by thc prcsumcd high to bc taxa, but cannot bc maintained now that cndemics appcar much less numqous than hithcrto assumcd' Finally, thc third tbcory implies a rcccnt, probably post' glacial r€colonizrtion by lichens through longdistance disp€rsal mcchanisms Contrary lo the fi$t two thcories, which cannot bc falsified, thc longdistanc. dispcrsal hypothesis can be are corroborated by field studies, ss in thc Antarctic region thcr€ thcrcforc' which' areas which wer€ complctcly glaciated, and werc werc only recently colonized by lichcns Informativc results obtained by Hertel ( I984' 198?a) for Marion and Prince Edward ii"i"n" In Canick, R., Hotdgsre M. & Pr'vost, J, cds Antarctique, Psi,s: Hcfiann, 165-17l' 'iolo8ie Dodcc C. w. l9?3 ll.r?rrt ion of he Antarctic continen' ond adiocent -rlaals. 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