ANUPDATEDPHYLOGENYOFTHECONCHOSTRACA— CLADOCERA CLADE(BRANCHIOPODA, DIPLOSTRACA)
BY
JØRGEN OLESEN 1) HumboldtUniversitä t zuBerlin,Institut f ürBiologie,V ergleichendeZoologie, Philippstrasse13, D-10115 Berlin, Germany and ZoologicalMuseum, University of Copenhagen,Universitetsparken 15, DK-2100 Copenhagen, Denmark
ABSTRACT
Anupdated phylogenetic analysis of the Conchostraca and Cladocera (Branchiopoda, Diplo- straca)is presented in responseto arecentlypublished critique of Olesen (1998). Some errors are correctedand some scorings are modi ed. Practically all earlier conclusions are supported. Among theseare (1) monophyletic Diplostraca and Cladocera; (2) an uncertainstatus of the Conchostraca andSpinicaudata, probably they are both paraphyletic with respect to theCladocera; (3) uncertain relationshipsbetween the four distinct taxa within the Cladocera, though some support was found forthe Gymnomera (Haplopoda and Onychopoda).
ZUSAMMENFASSUNG
AlsAntwort auf eine j üngstpublizierte Kritik an Olesen (1998) wird eine aktualisierte phylo- genetischeAnalyse der Conchostraca und Cladocera (Branchiopoda, Diplostraca) prä sentiert. Einige Fehlerder fr üherenAnalyse werden korrigiert, einige Merkmals-Kodierungen modi ziert. Prak- tischalle Schluß folgerungen werden erneut unterst ützt,so 1. dieMonophylie der Diplostraca und derCladocera, 2. der unsichere Status der Conchostraca und der Spinicaudata, beide Taxa sind wahrscheinlichparaphyletisch, und 3. die unsicheren V erwandtschaftsbeziehungender vier h öheren Taxainnerhalb der Cladocera, obwohl insbesondere die Gymnomera(Haplopoda und Onychopoda) einigeUnterst ützungerfahren.
INTRODUCTION
Twoyears agoI presentedthe rst cladistic analysis ofa widespectrum of cladoceransand conchostracans (Branchiopoda, Diplostraca) (Olesen,1998). The
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c KoninklijkeBrill NV ,Leiden,2000 Crustaceana 73(7):869-886 ® 870 JØRGEN OLESEN informationused was takenfrom the literature andfrom morphological studies conductedin relation to that studyand analysed using the parsimonyprogram PAUP(Swofford, 1993). The result was onlypartly successful, since some parts ofthe selected cladogramwere not convincingly resolved. However, I decided to publishthe result becauseearlier efforts to applythe cladistic approachto branchiopodphylogeny had included only the major taxa orjust afewcharacters (e.g.,Wingstrand, 1978; W alossek, 1993;Martin &Cash-Clark,1995). A testable workinghypothesis of the intrinsic phylogenyof the Conchostracaand Cladocera (Diplostraca) was therebyprovided. Afurtherreason for making a phylogeneticanalysis ofcertain branchiopodtaxa concernedthe openstate in whichthe branchiopodtaxonomy was left byFryer (1987a,b). He elevated twodistinctly different subgroupsof the Conchostraca (Spinicaudataand Laevicaudata) and four ditto ofthe Cladocera(Ctenopoda, Haplopoda,Anomopoda, and Onychopoda) to ordinalstatus which,together with the Anostracaand Notostraca, yielded the total numberof eight extant branchiopod orders,arranged in a ‘at’structure with nosupra-ordinallevels indicated.At the same time, anumberof more or less well-established taxa,like the Phyllopoda (sensu Preuss, 1956),Diplostraca, Conchostraca,and Cladocera were suggested to beabandoned.The eight extant orderswere then, together with twoextinct orders, “dened in moredetail thanhitherto as aworkingbase forfuture investigation” , as said byFryer (1987b). And, indeed, this paperhas beena veryuseful working base fora numberof workers (e.g., Martin, 1992;Walossek, 1993; Olesen, 1998).Seen from a phylogeneticperspective, it cansometimes bea useful and meaningfulapproach to split upa taxonwith anuncertain intrinsic phylogeny(like the Branchiopoda)into the smaller taxa,which are each,with ahighdegree of certainty,monophyletic.Thereby ,anyfuture attempts at groupingthem are given abetter starting point,as has beendone for the Branchiopodaby Fryer (1987b). Fromthe diversity pointof view,there are also goodreasons forside-ranking the highertaxa ofthe Cladoceraand Conchostraca with the Anostracaand Notostraca, since, forexample, the fourmajor cladocerangroups truly “are as distinctive as are otherorders of the Branchiopoda”, as it is beingsaid byFryer (1987b), even thoughsuch reasoning always will containan amount of subjectivity, as will any otherattempt at usingthe Linneanhierarchical system. A‘at’taxonomic scheme, as the oneproposed by Fryer (1987b), can only beconsidered a starting pointfor future attempts torecombine the component taxa in high-leveltaxonomic categories. Suchan attempt was madeon a phylo- genetic basis byOlesen (1998)who found support for a numberof the supra- ordinalcategories suchas Diplostraca, Cladocera,and Gymnomera, whereas the Conchostracaturned out to beunsupported as didone of the ordersin the scheme