What is Lejeunea trigona (Studies on Lejeuneaceae subfam. Ptychanthoideae XXII)

5 Pages·1992·2.5 MB·English

by  S R Gradstein

Contr.Univ.Mich.Herb. 18:99-103.1992.
WHATIS LEJEUNEATRIGONA?
(StudiesonLejeuneaceaesubfam. PtychanthoideaeXXII)
S. RobGradstein
InstituteofSystematicBotany
3584CSUtrecht,TheNetherlands
Lejeunea trigona was described by Montagne and Nees (1836) based on a
liverwort specimen collected in Peru by the French traveller and palaeontologist
Alcided'Orbigny.Thematerialconsistsofonlyafewstems,whichaccordingtothe
original description were taken from a lichen ("in Parmelia speciosa parasita").
Although the material isfertile and hasboth antheridia andperianths, there has
beensomeconfusionabouttheidentityofLejeuneatrigona,presumablyduetothe
poor condition of the type specimen. The authors of the Synopsis Hepaticanim
(Gottsche, Lindenberg and Nees 1844-1847) considered the species to be most
closelyrelatedtoLejeuneachrysophylla(Lehm.)Gott.etal.,anAfricantaxonnow
placedintheg&nwiAcanthocoleus(Kruijt 1988).Stephani(1911),however,treated
LejeuneatrigonaasamemberofthegenusArchilejeunea. Morerecently,Lejeunea
trigona was studied by Kruijt (1985) who considered the species a synonym of
Lejeuneaphyllorhiza Nees 1833. The latter is a widespread neotropical species,
whichwasusuallyplacedinDicranolejeuneabutwastransferredtoBrachiolejeunea
byKruijtandGradstein(1986).
InthecourseofmyworkonneotropicalLejeuneaceaeforFloraNeotropica, I
have recently hadachance to reexamine the material ofLejeuneatrigona. It ap-
pears that the specieshasaffinity neithertoArchilejeuneanorto Brachiolejeunea
phyllorhiza. The rather flat leaves with reduced leaf lobules and the smooth
perianthswithoutorwithbroadlyroundedkeelsofLejeuneatrigonawouldruleout
B. phyllorhiza, which has concave and more or less squarrose leaves with large,
unreduced lobules, and sharply keeled, ciliate perianths surrounded by winged
femalebracts.AnotherimportantcharacteristicofLejeuneatrigonaisitsthinstem,
which hasadistincthyalodermandaventralmcrophytewhichismostlyonlytwo
cells across. Both Brachiolejeunea andArchilejeunea have broaderventral mero-
phytes, beingfourormorecellswide. InArchilejeunea, moreover,ahyalodermis
lacking.
Because of its narrow ventral mcrophyte and other morphological features,
Lejeuneatrigonaundoubtedlybearsclosest resemblancetomembersofthegenus
Acanthocoleus (subfam. Ptychanthoideae). This genus was recently segregated
from Dicranolejeunea by Schuster (1970) and wassubsequently monographed by
Kruijt (1985, 1988) whorecognized seven species, twoofwhich occurin tropical
America. Diagnostic characters of Acanthocoleus are its rather unspecializcd
stems, lacking a subepidermis and bulging epidermis characteristic of
Dicranolejeunea, itsuntoothedfemaleinvolucres,itscreepinghabitanditsbrown-
ish color. A comparison of Lejeunea trigona with the species recognized in
Acanthocoleusshowsthatitisdifferentfromallofthem.Itsmoststrikingfeatureis
the strongly inflated perianths which are barely keeled and completely smooth,
lackinganytraceofcilia. NoneofthespeciesofAcanthocoleushassuchperianths.
Furthermore,theantheridiaofL. trigonaarebornesinglyintheaxilsofleavesjust
99
100 CONIR.l!NI\FP^SI1^ Of MICHIGANHLiRBARIUM V01.UMI-;18
["IG. 1. AcanthoiolciisIrii^omi.s(NcesA:McMit.)Ciradst.
below the perianth, and the speeicsshould thus be considered paroieous. Within
Acaiuhocoleusaparoieoussexdistributionischaracteristicfor/i.juddiiKruijtfrom
theGreaterAntillesandMexico,andA. chrysophylla(Lehm.)KruijtfromAfrica.
These two species are very different from Lejeunea trigoiia. however, by their
keeled perianthswith ciliate margins and theirapiculate leaves. Lejeuneatrii^ona
thusappearstobeadistinctspeciesoiAcanlhocoleusandthefollowingnewcombi-
nationmaybeproposed:
1992 GRADSTEIN:LEJEUNEA 101
Acanthocoleustrigonus(Nees&Mont.)Gradst.,comb.nov.
LejeimeatrigonaNees&Mont,inMontagnc&Nees,Ann.Sci.Nat.Bot.,Ser.
2,5:61. 1836;Archilejeimeatrigona(Nees&Mont.)Steph.,Spec.Hep.4:
721. 1911. Fig. 1.
DISTRIBUTION
ThedistributionoiAcanthocoleustrigonushasbeenremarkablypoorlyknown
andfor more than a hundred yearsonlythe scanty typespecimen fromPeru has
been available. As a happy coincidence, however, I have recently been able to
rediscoverthe species in southern Bolivia (Dept. Tarija), during a collecting trip
madeinthecompanyofmywifeandthebryologistMarkoLewis,acuratoratthe
National Herbarium of Bolivia in La Paz. Acanthocoleus trigonus proved to be
quitecommon inhumidPodocarpusforestremnantsinmountainvalleys,inareas
withaprolongeddryseason and atelevationsbetweenabout 16()()-260()m. (Fig.
2).Thespecieswasalwaysgrowinginthinmatsonbouldersalongstreams. Inthe
field, the species could be easily recognized with a handlens by its peculiar
perianths, which were often completely terete and devoid of keels. Searching
throughthe unidentified liverwort materialsofthe herbarium in La Paz, I subse-
quentlyfound furtherspecimens oiA. trigonus collected by Marko Lewis in the
samegeneralarea. Inaddition,twofurthercollectionsoiA. trigonushaverecently
becomeavailable: onefromsouthernBrazil,collectedbyAlfonsSchafer-Verwimp
and his wife, and an older collection from northern Argentina (leg. Hosseus),
described by Herzog as Archilejeunea argentinica Herz. (Feddes Repert. 55: 12.
1952).ThelattershouldbeconsideredasynonymoiAcanthocoleustrigonus.
FIG. 2. RemnantsofPodocarpusforestinmountainvalleysatabout2()()()mnearEntreRios.
Dept.larija,southernBolivia.Acanthocoleustrigonusoceursonroeksalongstreamsintheseforests.
102 CONTR.UNIVFiRSITYOFMICHIGANHERBARIUM VOLUME18
ItthusappearsthatAcanthocoleustrii^onusoccursinrehitivelydry,subtropical
mountainareasofSouthAmerica(Peru,Bohvia,southernBrazil,northernArgen-
tina), in regions with a seasonally dry climate. The Lejeuneaceae flora of this
region is ratherpoorand most ofthe taxa reported arc widespread, neotropical
species. Among the Ptychanthoideae, Acanthocoleus trigoiiu.s is the only species
endemictothisregion.AnexplanationforthepoorLejeuneaceaefloraofsubtropi-
calSouthAmericaisprobablytherarityintheseareasofwell-developedevergreen
rainforests, which are themain habitatforthespeciesofthisfamily. Supportfor
thisassumptioncomesfromacomparisonbetweentheLejeuneaceaefloraofSouth
AmericaandAustralia(Thiers 1990,Gradstein 1991).AsdemonstratedbyThiers,
thesubtropicaleastcoastofQueenslandhasarichLejeuneaceaellorawithseveral
endemicspecies. Thishighdiversityisduetotheoccurrencein thisregionofrain
forests,distributedinpatchesfromnorthtosouthalongthecoastsofQueensland
andNewSouthWalesandrangingwellintothetemperatezone.Theseforestsoffer
agreat varietyofhabitatsfor inhabitation by Lejeuneaceae. Asimilarlatitudinal
gradient ofrain forest is lackingin the NewWorld, however, and this, then, may
well acctnint for the povertyofLejeuneaceae in the subtropical regionsofSouth
America.
Key ro rHi;Ni;otropicai,Sf^i-xie-sorAc\\nthoc()i.i:us
I. Lobulelarge, i/2-%x lobelength,rarelyreduced,firsttoothofthelobule
3-6cellslong; leavesorbicular;paroicous; GreaterAntilles, Mexico,ca.
8()()-25()()m A.jiuhliiKruijt
1. Lobule smaller, V-i-V^x lobe length, often reduced, first tooth 0-2 cells
long;leavesovate;autoicousorparoicous.
2. Paroicous; perianth terete orvery bluntly keeled, smooth; leafapex
rounded, entire; S Brazil, Peru, Bolivia, northern Argentina, ca.
1000-2600m A. ingoniis(Nees&Mont.)Gradst.
2. Autoicous; perianth sharply keeled,ciliatc; leafapexpointed, rarely
rounded, toothed orentire; throughoutthe neotropics, L'^()-26()0m.
A.ahernuis(Lindenb.&Gott.) Kruijt
A full description ofAcanthocoleus trigonus will appear in my forthcoming
monographoftheneotropicalPtychanthoideaeinfloraNeotropica.
Specnncnscxtunincd Vvkv.LACiUNA:SantaCiu/,,'inParnicliuspcciosa".D'Orhitifivs.n..ivpcof
dLeojeCuoiriveaoiBriiiainocnoa,Nereoasdt*tcJMrii)inbitc.i-(CSrTaoR,P^ahroak.itjuyspte;beIl'oCw-Mtohnet.p.assi,sotDyepce).19B9r0a.zSici/i.iSiafcnri-aVeCrawiimapriLnUa9(;-)S(ehnba.
Sehafcr-Verwimp,U). Bolivia.Chuqui.saca: Rio.latumMayu14kmN\VofZudanez.Lewis^4-()4S9
(l.PB,U). Tarua:alongroadTarija-Bcrmejo.ca.10kmNofLaMarmora,GnicLsiein7720.7721(LPB.
U);headwatersofRioLosPinos21)kmNWofPadcaya,Lewisf<4-29l()(LPB);headwatersRioPosta
alongroad Larija-EntreRios 1950m,(Iradslein 7648(LPB,U);headwatersRi'oHuaycoalongroad
8N4a^r2v6a7e5z-(SLaPnB)J.ose(ciirtaod,sl(eIirniit7l(sil5elin(7L6P(SB7.(LUP);B,CeUr)r;oalSoanrgzoR.f4oTkammbNoWcao.f.5CaknmalSetoafsN.arLveaweizs.<SL4e-w2i5s1084(-L2P6B3)L.
AKCii-NTiNA.C(')RIX)ba:Ongamira,Hosseiiss.n..typeoiA/ehilejeiiiieti(iri^eninudiHerz.(.Hi.holotvpe),
ACKNOWLEDGMENTS
IexpressmygratitudetoMarietteAptrool-TeeuuenforpreparingthedrawingofAenntlioeoleus
irii^oniisandtothecuratorsoftheherbariacitedfortheloano(si^ecimens.
1992 GRADSTEIN:LEJEUNEA 103
LITERATURECITED
Gottsche,C.M.,J.B.LindenbergandC.G.NeesvonEsenbeck.1844-1847.SynopsisHepaficarum.
Hamburg.
Gradstein,S. R. 1991. DiversityanddistributionolAsianLejeuneaceaesubfamilyPtychanthoideae.
Trop.Bryoi.4:1-16.
Kruijt, R. 1985. ApreliminaryrevisionofthegenusDicranolejeunea(Spruce) Schiffn. Beih. Nova
HedwigiaSO:155-163.
1988.AmonographofthegeneraDicranolejeuneaandAcanthocoleus.Bryophyt.Biblioth.36:
1-135.
andS.R.Gradstein. 1986.OnBrachiolejeuneaphyllorhiza(Nees)Kruijt&Gradsteincomb.
nov.NovaHedwigia43:299-309.
Montague,J.P.F.C.andC.G.NeesvonEsenbeck. 1836.JungermanniearumherbariiMontagncani
Species.Ann.Sci.Nat.Bot.,Ser.2,5:52-72.
Schuster, R. M. 1970.StudiesonHepaticaeXLIX-LIII.NewLejeuneaceaefromDominicaandJa-
maica.Bull.TorreyBot.Club97:336-352.
Stephani,F.1911.Archilejeimea.In:SpeciesHepadcarum4:703-736.Geneva.
Thiers,B.1990.AnoverviewoftheLejeuneaceaeinAustralia.Trop.Bryol.2:273-283.