Ovstedal, D. O.

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Polarforschung 58 (213): 77-81. 19881.2 On the Variation of Ochrolechia parella inthe Western Antarctic and Subantarctic AreaBy Dag Olav 0vstedal*und Größenverteilung der Apothcticn untersucht. Das Materialläßtaufteilen: die' erste Grupp. 111iI vier Sporen. die zweite Gruppe mit acht etwas kleineren1. mit 1I11cl 3. einer Kombination DaskeineKorrelat ronm i[den an,Jen,,"n,HCTSnc hrcn Ch araktcrist iken.während antarctica (MÜll. Arg.) Darb. mit 0 ist. Aspekte derPhotosynthcsckapazuat durchdie Produktionvon Apothcuen werdenZusammenfassung: Es wurden Flechtensauren.sich in zwei Gruppenbezüglich Anzahl undSporen.Die elreiMaterial enthieltO. dceCfJtl",o~III;';'s:c;:I~:~~:O~'::I~;1sexuellen l{anrl sizc distribution 01' apothecia arc Thc material can be divided il110 two01' sporcs: Ollegroup with four sporcs und Olle group with somcwhat smallcr sporcs. Apothccium sizeolle wirh normal disuibuticn. Olle with a Ilat distnbuticn. and onc interprctcd as a combination bctwccnthc~~I:l;;';~;~cfi:c:~;i;~';:~,~a;ci~i,d,';'V~"i:r(i)olaricacid and alcctoronic but thcrc is no corrclation with thc other Cha["(IIC~,lt~e~r;Sul;~;;~~.\:~~~I;~; whilcO.ollfarcrica Arg.) Darb. is placed in svnonomv with (jproduction arc discusscd.I. INTRODUCTIONIn the western Antarctic and Subantarctic area, saxicolous speeimens of the liehen genus Ochrolechin appear tobe rather cornmon. Two species have been described from this area. ancl a third, described from Northern Europe,has been reported from the same arca, The species are closely rclated. anci this paper is mainly an allempt to clarifytheir taxonomy.2. MATERIAL AND METHODSThe material cornprises ca. 20 specimens, and secondary chcmistry, size distribution of apothecia,number ofspores and size of spores have been used in the treatrnent. The spore size was mcasured in a 10% KOH aqueoussolution. TLC analyses were performed in accordance with standard methods (CULBERSON 1972. MENLOVE1974).3. RESULTS3.1. Secondarv chetnistry.Three main compounds occurred: gyrophoric acid (found only in apotheeia). variolaric acid and aleetoronie acid.3.2. Spore number and si:e3.2.1. S p 0 ren u m b er.There were two groups in the material. One group had eight well-developed spores in the ase i. while the otherhad four well-developed and remains of four aborted spores in the asci.3.2.2. S p 0 res i z eLength of spores varied from about 60 to about 100 um (Fig. 1). Spores from asei with four well-developed sporeswere on average, larger than spores from asei with eight well-developed spores.Dr. Dag Olav Ovsredal. ARBOHA University of Bergen. P.O. Box 12. N-5027 Bergen. Norway773.3. Size distribution 0/apotheeiaMost specimens could be placed in either of two categories of size distribution of apothecia (Fig. 2). One categorycould be described as a bell-shaped distribution, while the other could be described as a flat distribution.4. DISCUSSIONOchrolechia parella (L.) Massai, is a fairly common species on maritime rocks in Northem Europa. It has a thick,white crustose thallus, and usually has abundant 2-4 mm broad apothecia with a broad thalline margin and 8spores in the asci. This taxon has been reported from the Antarctica area by LINDSAY (1971), and the specimenmatches weil with Northern European specimens. Two other closely related taxa have been described from theregion: O. deceptionis (Hue) Darb. frorn Deception Island, and O. antarctica (MÜll. Arg.) Darb. from SouthGeorgia. The holotypus of O. deeeptionis (PC) is almost completely covered by apothecia. Mean diameter sizeand standard deviation of apothecia (n= 12) are 1.8 ±0.3 mm. The apothecia are often angular due to crowding,the thalline margin is thin and about 0.2 mm in mature apothecia, and the disc is usually cracked and slightlymore brown than the margin which is similar in colour to the thallus. No mature spores were seen, but accordingto the protologue it is fourspored. The TLC-analysis showed gyrophoric and variolaric acids. The holotype of O.antarctica (M) has two unripe apothecia with ± pore-formed discs, and one mature apothecium with a flat,well-developed disc with a diameter of 1.7 mm. According to the protologue, it is four- to eight-spored, TheTLC-analysis showed variolaric acid (only thallus tested).In earlier treatments of these taxa, size and number of spores and size of apothecia were considered particulardiagnostic characters (VERSEGHY 1962, LINDSAY 1971). In the present material, the specimens showed a highconstancy in spore number, and only in one specimen (from South Georgia) was any variation in spore numberfound. In the closely related genus Pertusaria, Dibben (1980) found no constancy in spore number in three of 66investigated North American species. In this case the absence of constancy may weil be genotypically determined,but other cases are reported where it appears that absence of stability is phenotypically detennined (cf J0RGEN-SEN et al. 1983).The spore size of the specimens investigated here is fairly closely correlated with the number of spores in asci(Fig. I), simply because when the number of spores is reduced, there is more room for the remaining, ripe sporesin asci of the same size. Figure I also shows that there is no discontinuity in the spore size material, even if themean size of spores from four-spored specimens is Iarger than that from eight-spored specimens.~o L-1.-------r----,---.----.----,-- flmLength of sporespm70t1l 60GI...00.Vl'Y 500.c+J'0 40•.j~307'<'.60 70 80 90 100L, 1A 2o 3+ 4• 5• 6+ 7o 8o 9Fig. 1: Spore size of8 spccimens of Ochrolechianarclla from the western Antarctic and Suban-tarctic areaand Falkland islands. and one speci-mcn from Norway. One apothecium was investi-gated front each specimen. Each score representu spore froman individualascus. Fullline: eight-spored specirnens: broken line: four-spored spe-cimens.I: Falklandislands, Op. Tabarin 110 2995 (BM)2: Falklandislands, Op. Tabarinno. 2869 (BM)3: Sourh Shetland Islands, Livinaston island,Lindsay 00. 349 (AAS) ~4: South Shetland Islands. Greenwich island,Lindsay 00. 700a (AAS)5: South Orkney Islands. Signy island, R. I. L.Smith 00. 431 (AAS)6: Sourh Sherland Islands. Deccption island, R. I.L. Smith 00. 3661 (AAS)7: South Shetland Islands, Livinzston island.Lindsay 00. 513 (AAS) ~X:Falkland islands, Lindsay no. 1668 (AAS)9: Norway, Hordaland, Stord, Gullberget. Havaasleg (s.n.) (BG)The largest apothecium of each of the types of O. deceptionis and O. antarctica have, respectively, a diameter of2.5 and 1.7 mm. In neither case is the material sufficient for statistical analysis. The apothecia of NorthernEuropean O. parella may have a diameter up to 4 mm (own observations). To get a more sound basis for theinterpretation of apothecium size, a number of size distributions were studied. Three selected distributions arepresented in Figure 2. In the case A, a bell-shaped distribution is found, statistically reminiscent of anormaldistribution. The strategy behind this may be explained as folIows: a mature thallus starts development of allapothecia at the same time. Among these apothecia, some will grow weil, and others less weil, and they willproduce sizes following a normal distribution. Such a strategy may be advantageous when the specimen lives ina harsh environment, with short speils of better conditions, which the specimen can take advantage of for itsapothecium production. The distribution B (Fig. 2) has about the same number of apothecia in each size class.This may happen when new apothecia are produced continously, and may be called a "safety-first" strategy. Athird type of distribution, C, may be described as an inverted J. This is a kind of age/size distribution often foundin higher plants, but in that case it is usually explained as a result of high mortality rate. In these lichens, I couldnot observe any mortality among the apothecia, so its cause has to have some other reason. It may be explainedas a combination of the two already mentioned strategies; a constant, safety first strategy with the addition of arecent outburst of apothecium production. But it is obvious that apothecium initiation and growth are complexand cannot be used in taxonomic treatments without thorough field investigations.There was no discontinuity in the distribution of the size of the largest apothecia.As to the secondary chemical compounds, two groups were found. One group had gyrophoric and variolaric acids,while the other had alectoronic acid in addition. This is in accordance with what is found in European specimens(HANKO et al. 1985). However, no correspondance with these two groups and spore number or geographicaldistribution was found.No.15105oA5o105o0-1.0 1.1-1.5 1.6-2D 2.1~5 2.6-303.1-35 3.6·4.0 > 4 m mDiameter of apotheciaFig. 2: Distribution of apothecium diameters from threc selected speci-rnens of Ochrolechia parella.A: Falklands islands, Op. Tabarin 2869 (specimen I) (BM)B: Falkland islands, Op. Tabarin no. 2998 (BM)C: Falkland islands, Op. Tabann no. 2869 (specirnen II) (BM)79The conclusion is that thcre appears to be no discoutinuity in the material cxcept for olle main characrer: numberof spores. Tbc specimens with four-spored asci are all found in the South Orkney and South Shetlancl area (Fig.3). O. deceptionis is based on such a specimen. but wirh a difference in only one main characrer from O. parella,ir cannot be maintainecl as a species and it is reducecl to a variety of thar species: O. parella var. deccptionis (Huc)0vst. comb.nov (basionym Lecanora dcceptionis Hue 1915: 93). O. antarctica must be recluced to a synonum ofO. parclla.Two aspects of liehen biology should be mentioned; the photosyntheric part lost by apothecium production, andreproduction by means of spores. The thallus of Ochrolechia parel la has algae 70 to I00 um below the cortex.but also in the thalline margin of the apothecia and below the hymenium. However. the algal layer below thehymenium is thinner than that in the medulla, anel preliminary results show that the replacement of thallus withapothecia reduces the pbotosyntetic tissue by about 30%. This may be an important, but not an extreme. reductionin photosynthetic tissuc.Ochrolechia parella is mosr probably able to rcproduce sexually, as it apparently produces ripe spores. Usuallyit has been assumed that liehen spores must germinate and meet a specific algal partner very soon afterwards toproduee the syrnbiosis. The algae of O. parclla are trebouxoid. probably belonging to the genus Trcbouxia. andiftbese algae cxist in a free-living state on rock under such harsh enviroments as in the Antarctic, thcy are probably?BouveL Is.Tkrra del Ri'rJ0I/Ii·f.sauMSandwich Is.Fig, J: (;C"~I"l'h,ddl"lrJhllllol1llj (Ji ilr"ft'( lUd Ihlrd/u 111 lhl' \\ L"ILTIl .\IlI~l)l·IIL .md Sub.uu.ucnc .11'-'<1. anc! Oll thc l-nlktund 1.,1'1I1l1". Stur: clglll-"porcdpopulutions. four-spored populuuons80rare. However. thcre is the possibility that small. loose thallus parts or diaspores from the sarnc or other liehenspecies may be thc source for the rclichenization (HALE 1974. OTT 1987). Anothcr possibility, wh ich has justreeently been proposecl is that the fungus associates with other algae and eventually re lichenizes with the corrcctliehen partner (OTT 1987). In a reproductive context. it is interesting to note that thc only major clifference in thepresent material is spore size, a character whieh must be important for spore germination ancl carly dcvelopmcntof the hyphae.5. ACKNOWLEDGEMENTSI am greatly indeptecl to Mr.T. Tonsberg. Bergen. for comments on the manuscript ancl help with TLC analyses,to Prof. P. M. Jorgcnscn, Bergen, for commcnts on the manuscript. ancl to Dr, R. I. L. Smith, Cambridge, for accessto the British Antarctic Survey collections. Mrs, S. Herlancl skilfully made the illusrrations. Dr. H. J. B. Birks,Bergen, kindly revised the language.k c rc rcn c c sC II 1b c r S 0 11 . C F lmprovcd condition and ncw data for the identification 01' liehen prcducts by a standardizccl thin-lnycrchromatographicrncthod. J. 72: 113-125.D i b b C Tl. M. 1. ('19fW): The chemcsystcmatics 01' the liehen gcnus Pertusaria in North Amcrica nonh of Mc xico. Milwaukcc Public Hause publ.5.HaI e. lVI. (1984): Thc biology of lichens. 2. cd. - E. Amcld. London.Ha Tl k o . B. L e uc k e r I. C. A 11 ti . T. (198)): Beiträge zur Chcmotaxonornie der Gattung Ochrolechia (Lichenes) in Europn. - NovaHcdwigia zlS: 165-199.H u c , A. lVI. (1915): Lichenes. Dcuxicmc Expedition Antarctiquc Francaisc 1908- I91 O. Massen et Cic. Paris.J 0 r g cn s en . P. M. V c z da. A. Bot n c n. A. Clathroporinu calcurcu. a misunderstood liehen spccics. and a notc Oll thc gcnusClathroporina in Europe. --- Lichenclogist (15) 1:Li Tl d s a y . D. C. (1971): Notcs on antarctic lichcns: V. Thc genus Ochrolcchia Massul. - Brit. Aruarct. Survcy Bull 26: 77---'k?>.lvi e 1110 v c . J. (1974): Thin-lnyer chrornarogrnphy Ior thc idcntification 01' liehen substanccs. - Bull British Lichen Sec. ?>4: 3-5.o t t . S. (1987): Sexual rcproduction and devclopmcnt adnptations in Xnnthona parictina. - Nordic J. Bot. 7(2): 219-228.Ver s c g h ) K. (1962): Die Gattung Ochrolcchia. _. Bcih. Nova Hedwigia I.81

1.2 On the Variation of Ochrolechia parella in the Western Antarctic and Subantarctic Area

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