Taxonomy and palaeobiogeography of charophytes from the Upper Eocene-Lower Oligocene of the Eastern Ebro Basin (Catalonia, NE Spain)

摘要

EighteencharophytespeciesaredocumentedfromtheUpperEocene-LowerOligocenetransitionalandterrestrialfaciesontheeasternEbroBasin.ThecharophyteassemblageiscomposedofoneEurasianspecies,Lychnothamnusstockmansii(Grambast,1957),fourteenspeciesdistributedthroughoutEurope(Harrisicharavasiformisformvasiformis-tuberculataFeist-Castel,1977,HarrisicharalineataGrambast,1957,Harrisicharatuberculata(Lyell,1826),Nitellopsis(Tectochara)merianii(Al.BraunexUnger,1852),Lychnothamnusvectensis(Groves,1926),L.grambastii(Feist-Castel,1971),L.major(Grambastamp;Paul,1965),Gyrogonacaelata(Reidamp;Groves,1921),Psilocharaaff.acutaGrambastamp;Paul,1965,Charaaff.antennataGrambast,1958,C.rhenanaSchwarzamp;Griessemer,1994,C.microceraGrambastamp;Paul,1965,SphaerocharalabellataFeistamp;Ringeade,1977,Lamprothamniumsp.)andthreespeciesrestrictedtotheEbroBasinduringtheintervalconsidered(NodosocharajorbaeChoi,1989,LychnothamnuslongusChoi,1989andCharaartesican.sp.,anewspeciesdefinedbyverysmallgyrogonitesandshowingareducednumberofconvolutions.AbiogeographicanalysisoftheassemblagestudiedsuggeststhatduringLateEoceneandEarlyOligocene,EuroperepresentedabioprovincecharacterisedbytheregularandabundantoccurrenceofspeciesbelongingtothelineagesofHarrisicharavasiformis-tuberculataandLychnothamnusstockmansii-major,alongwithNitellopsis(Tectochara)merianiiandCharamicrocerainallEuropeanbasins.Charophytedistributioninthisbioprovincedisplaysanorthtosouthpolaritywithareductioninthenumberofspecies.EcologicalfeaturesrelatedtothedynamicsoftheEbrobasin,suchasthehighterrigenousinputinfreshwaterwetlandsduringtheUpperEocene-Oligocene,areincontrasttothesea-connectedandcarbonaticsystemsoftheParis,HampshireandRhinebasins.ThisresultedinlowspeciesrichnessintheEbroBasin.ThesebiogeographicpatternshaveimplicationsintheuseofsomeEuropeanbiozones,whichshouldbeofuseonlyataregionalscale.