A SECOND SPECIES OF ORITROPHIUM (ASTERACEAE: ASTEREAE) FROM MEXICO

4 Pages·1998·1.7 MB·English

by  Guy L Nesom

ASECOND SPECIES OF ORITROPHIUM
(ASTERACEAE:ASTEREAE) FROMMEXICO
GUYL.NESOM
BONAP-NCBG
CokerHallCB3280
UniversityofNorthCarolina,
ChapelHill,NC27599-3280, U.S.A.
ABSTRACT
OritrophiumdurangenseNesom,sp.nov.,isdescribedfromtheSierraMadreofsoutfi-
ernDurango,Mexico.ItisthesecondspeciesofthegenusknownfromMexico,following
anotherrecentlydescribedfromthenortheasternslopesofPicodeOrizabainVeracruz,
about1000kilometersnorthwestoftheDurangolocality.Theremainderofthespeciesof
OritrophiumoccurinmontanehabitatsofnorthernSouthAmerica.
RESUMEN
SedescribeOritrophiumdurangense^esom,sp.nov.,delaSierraMadredelsurdeDurango,
Mexico.EslasegundaespeciedelgeneroqueseconoceenMexico,despuesdeotrarecientemente
descritadelasladerasnorestedelPicodeOrizabaenVeracruz,unos1000kilometrosal
noroestedelalocalidaddeDurango.LasotrasespeciesdeOritrophiumsedanenhabitats
delnortcdeAmericadelSur.
IdentificationandreviewofspecimensofAsteraceaetribeAstereaein
LL,TEXhavebroughttolightacollectionofthegenusOritrophium(Kunth)
Cuatrec.fromnearthecrestoftheSierraMadreinsouthernDurango,Mexico.
Theseplantsdonotcorrespondtothesinglepreviouslydescribedspecies
oi^OritrophiuminMexico(Nesom1992)oranyotherspeciesofthegenus
fromitscenterofdiversityinSouthAmerica(Aristeguieta1964;Cuatrecasas
1961, 1969, 1997).TheplantsfromDurangoaredescribedhereasanew
species.
OritrophiumdurangenseNesom,sp.nov.(Fig.1).Type:MEXICO.Duran(;;o:
Mpio.ElSalto,4kmdeladesv.haciaSanMigueldeCruces,bosquedepino-encino
principalmente,sueloprofundo,conpiedrasuelto,2200m;herbaceade15-25cm
dealto,floresamarillas,encabezuela,abundante;6Jul1982,R.Hernandez7676
conP.Tenorio(noi.OTYPE:TEX!).Thespecimenwasidentified(onthedistributed
label)as''Pionocarpus[=lostephane]af.madrensis(Wats.)Blake."
AOritrophioorizabenseNesomdiffertcaudicetenuifoliisbasalibuspaucis,foliisintegris,
foliisbasalibuscaulinislongioribus,etfloribusradiipaucioribuslimbismultobrcvioribus.
Perennialherbsfromashort,thick(ca.8mm)fibrous-rootedrhizome,
producinganerect,unbranchedstemandaclusteroferect-ascendingbasal
SiDA18(2):523-526.1998
524 SiDA18(.
.'^^J''.<>
I'ld. 1.IlabitilluMiationofOritropljiurutluvdrigeiisc,fioniihctypecollection.
NesOiM,asecondspeciesofOritrophium 525
leaves.Stems12—16(—25)cmtall,purplish,minutelypubescentwithamixture
ofTypeBandTypeCtrichomes(seeNesom1976forillustrations),most
denselysoneartheheads. Leavesbasal (largest) andcauline (reducedin
size);basalleaveslinear, 1-nerved,entire,flat,somewhatsucculent,7—14
cmlong,3-6mmwide,graduallytaperedtoalong,sharppoint,glabrous
exceptnearthebase,wherelong,thin,cobwebbyhairs (TypeB) become
copiousandconspicuousneartheleafinsertion;caulineleavesreducedin
sizefromthebasal,linear-lanceolate, 10—14mmlong,2—2.5mmwideat
thebase,subclaspingbutnotatallauriculate,7—11perstem,relativelyeven-
sizedupthestem,with internodes 1-3cmlong, mostcloselyspaced to-
wardthebase. Headsradiate, turbinate, theinvolucres 10—14mmwide;
phyllariesthin-herbaceous,withoutconspicuousvenation,purpleonthe
marginsandapex,nearlyflat,oblong-lanceolate,mostlywithacuteapices,
slightlylacerate-fringed onthedistalmargins, in 3(—4) graduatedseries,
theinnermost8—10mmlong,ca.2mmwide,theoutermost 1/2—2/3as
longastheinner;receptaclesflat,epaleate. Rayflowerspistillate,ca. 10—
15inasingleseries,thecorollas6—7mmlong,thelimbs3—5 mmlong,
mm
barelyexsertedfromthehead,whiteorcreamy,1.8 wide,apicallycoiling,
denselyinvestedwithviscid,unicellularhairsaroundthetube-limbjunc-
mm
tion,thetubeca2 long;discflowersfunctionallystaminate,withregular
mm
corollas,5 long,yellow,narrowlytubular-funnelform,thelobestrian-
mm mm
gular,1 long,thestylebrancheslinear-lanceolate,1.8 long,densely
long-papillate,withoutstigmaticlines.Rayachenesfertile,denselysericeous,
mm
eglandular, 5-nerved, ca. 5 long(notcompletelymature), narrowly
oblong,withpappusofnumerousbarbellatebristles4-5mmlongin 1—2
series;discovariessterile,withpappusbristlesnearlysmooth,equallingthe
disccorollalength.
Thenewspeciesisknownonlyfromthetypecollection.Thetypesheet
apparentlybearstwoplants(onewithouttheroot/caudexsystem)andfour
basalleavesdisconnectedfromaplant.Theillustration"attaches"several
oftheseleavestothemorecompleteplant. Itislikelythatasingleplant
mayproduceseveralfloweringstems,asischaracteristicofotherspeciesof
thegenus.
Theplantso^Oritrophiumdurangensearesimpleinhabitbutdistinctin
appearance,producingafew,linear,basalleaves,asingle,monocephalous
stemwithafew,small,nearlybracteatecaulineleaves,andarelativelysmall
head.Theraycorollasarewhiteandapparentlybarelyexsertedfromthe
involucre,perhapsaccountingforwhythecollectorsdescribedtheflowers
asyellow (thecolorofthedisccorollas). Still, itseems unusual thatthe
speciesiscurrentlyknownonlyfromasinglecollection,sincenumerous
botanistshavepassedthroughtheareaandmadecollections.Thecollec-
torsofO.durangensenotedthatitwas"abundante."
526 SinAl8(2)
TheseplantsareunequivocallyidentifiedasthegenusOritrophiumbya
distinctivesetoffeatures:monocephalousherbsproducingabasalrosette
ofelongateleaves,whiterays,functionallystaminatediscflowers(withsterile
ovariesandassociatedfeaturesofthestylebranches), phyllarieswith in-
conspicuousvenation,copiouslyelaborated,thin,nearlyfloccosewhitehairs
(TypeBtrichomes)intheaxilsofthebasalleaves,andalackoflong,uniseriate,
thick-walledtrichomes(TypeAtrichomes).Thenewspeciesisperhapsrelated
to O. orizabenseandasmallgroupofVenezuelanspecies (Nesom 1992),
butthisisspeculative.ThetwoMexicanspeciesaredifferentenoughfrom
eachotherthatevenahypothesisofsisterrelationshipbetweenthemisobscure.
ThenewspeciesdiffersfromOritrophiumorizabenseinitsrelativelythin
caudex/rhizome(8mmvs.7-15mm)withfewbasalleaves(vs.denseclus-
terofbasalleaves),entire(vs.serrate)leaves,longerleaves(basal7—14cm
v1s51vs..5—241.-03c7m),wciatuhlimnuec1h0—sh1o4rtmermlivsm.b4s-(63-m5mm),mavnsd.f7e-w1e0rmramy)f.loWwheirsle(1t0h-e
habitatofO.orizabenseisacliffface,thatofO.durangenseisinsoil("stielo
profundo"),probablyinarelativelyflatarea,withlooserocks("conpiedra
suelto").ThehabitatofO. orizabenseapparentlyismorelikethatofmost
oftheSouthAmericanspecies,whichgenerallygrow"inwetplaces, the
marshyandswampygroundoftheparamos, locationsthatarevisitedby
birdslookingforwaterandseeds"(Cuatrecasas 1997,p.289).
Oritrophiumorizabense'isdisjunctfromthemainpartofthegenus(from
theclosestpointofdistributioninVenezuela) byabout 1500kilometers.
TheseparationbetweenO.durangenseds\dO.orizabensehabout1000kilometers,
withthelatterthemidpointinmoreorlessastraightline,makingthedis-
tancebetweentheDurangolocalityandthoseinSouthAmericaabout2500
kilometers.
ACKNOWLl'DGMEN'l'S
IamgratefultothestaffofLL,TEXforaccomodatingarecentvisitthere,
HaroldRobinsonforprovidingacopyoftherecentsynopsisbyCuatrecasas,
andJohnPruskiandTimLowreyforcommentsonthemanuscript.
RHI-ERHNCI-:S
Arisikcliifia,L. 1964.Cxnnpositae.FloradcVenezut-hi10:1-483.
CuA'rRiiCASAS,J. 1961.NocassobreAstereasAndinas.C'.iencia[Mexico]21:21-32.
CuAiRi-CASAS,J. 1969.PrimafloraColombiaiia.3.Compositae-Astcreac.Webbia24:1-
335.
C]UA'rRlx;ASA,s,J.1997.Synopsi.softheneotropicalgenusOritrophium(Astcraceae:Asrereae).
BioLlania,EdicionEspecial6:287-303.
Ni-:soM,G.L.1976.AnewspeciesofErigeroii(Astcraceae)anditsrelativesinsouthwest-
ernUtah.Brittonia28:263-272.
Nf.som,G.L. 1992.Oritrophiumorizabense(Astcraceae:Asiereae),anewspeciesantithe
firstreportofthegenusfromNorthAmerica.Phytologia73:338—344.