tests of current hypotheses of mayfly (ephemeroptera) phylogeny using molecular (18s rdna) data

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Tests of Current Hypotheses of Mayfly (Ephemeroptera)Phylogeny Using Molecular (18s rDNA) DataAuthor(s) Lu SUN Aniko Sabo M D Meyer R P Randolph Luke MJacobus W P McCafferty and Virginia R FerrisSource Annals of the Entomological Society of America 99(2)241-252 2006Published By Entomological Society of AmericaDOI httpdxdoiorg1016030013-8746(2006)099[0241TOCHOM]20CO2URL httpwwwbiooneorgdoifull1016030013-8746282006290995B02413ATOCHOM5D20CO3B2

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SYSTEMATICS

Tests of Current Hypotheses of Mayfly (Ephemeroptera) PhylogenyUsing Molecular (18s rDNA) Data

LU SUN ANIKO SABO1 M D MEYER2 R P RANDOLPH3 LUKE M JACOBUSW P MCCAFFERTY AND VIRGINIA R FERRIS

Department of Entomology Purdue University West Lafayette IN 47907

Ann Entomol Soc Am 99(2) 241ETH252 (2006)

ABSTRACT Partial 18s rDNA sequences from 22 exemplar mayszligy species (Ephemeroptera) rep-resenting 20 families were analyzed to obtain a best phylogenetic tree for comparison to previousphylogenetic hypotheses With respect to relationships among the three major groupings our mo-lecular data support the hypothesis that Pisciforma and Setisura comprise a monophyletic sister groupto the Furcatergalia rather than the hypothesis that Setisura and Furcatergalia comprise a mono-phyletic group stemming from the Pisciforma Within Pisciforma acceptable trees show that Baetidaeseparates at the base of the Pisciforma clade The data suggest that Pisciforma is paraphyletic and donot support the grouping of all Southern hemisphere families as a monophyletic group An evolu-tionary sequence favored by the data suggests a grouping of Siphlonuridae Rallidentidae Nesame-letidae and Ameletidae and a grouping of Oniscigastridae Ameletopsidae and AcanthametropodidaeThe data support the monophyly of Setisura (Heptageniidae Arthropleidae Pseudironidae Oligo-neuriidae Isonychiidae and Coloburiscidae) Within Setisura a bootstrapjackknife test places thefamilies Heptageniidae Arthropleidae and Pseudironidae in one clade at 100 frequency Alsosupported are hypotheses that Pseudironidae is a sister group to a HeptageniidaeETHArthropleidae groupand that a sister relationship exists between the latter two families Hypotheses that Pseudironidaeseparated from other Setisura families at an earlier stage and comprises a sister group to a Heptage-niidaeETHOligonuriidae lineage or that Pseudironidae should be moved out of Setisura are not supported

KEY WORDS Ephemeroptera 18s rDNA phylogeny

EPHEMEROPTERA IS ONE OF the most archaic of extantwinged insect orders (Kukalova-Peck 1985) Thehigher classiTHORNcation of Ephemeroptera has evolvedconsiderably over the past 200 yr to include progres-sively more higher taxa However the use of strictphylogenetic classiTHORNcation is relatively recent (Mc-Cafferty 1991b) and cladistic data have been mostlymorphological in nature In this study we used mo-lecular data to test the various hypotheses outlinedbelow regarding certain aspects of the phylogeny ofEphemeropteraSuborder Level Classification of Ephemeroptera

At present four major groupings are generally recog-nized in Ephemeroptera under various names Wefollow a classiTHORNcation system (Table 1) taken fromMcCafferty (1991b) and its modiTHORNcations by Wangand McCafferty (1995) McCafferty (1997 2004) andMcCafferty and Wang (2000) In this classiTHORNcation of

four recent suborders Furcatergalia which was some-times previously referred to as Rectracheata (McCaf-ferty 1991b) includes Leptophlebiidae Behningiidaeall pannote families (Pannota) and all tusked bur-rower families (Scapphodonta) Setisura includes theszligat-headed mayszligies and their hypothesized minnow-like mayszligy ancestral groups including all forms thatpassively THORNlter food with their forelegs Pisciformaincludes all other minnowlike mayszligies and Carapaceaincludes Baetiscidae and ProsopistomatidaeRelationship between Carapacea and Other May-flies As a distinct monophyletic group supported byseries of synapomorphies (eg the presence of a larvalcarapace) the BaetiscidaeETHProsopistomatidae rela-tionship was suggested by various researchers (Ed-munds and Traver 1954) Kluge (1998) and McCaf-ferty and Wang (2000) showed the group to be basallyderived with its sister group represented by all otherextant mayszligies which share synapomorphic fore-wings with the tornus located between the ends ofveins CuA and CuP (CuP and A1 terminating in theanal margin rather than the outer margin of thewings) McCafferty (1997) THORNrst referred to the Baetis-cidaeETHProsopistomatidae grouping as the suborderCarapacea In our study using molecular data all trees

1 Human Genome Sequencing Center Baylor College of MedicineHouston TX 77030

2 Department of Biology Christopher Newport UniversityNewport News VA 23606

3 Section of Evolution and Ecology University of California DavisCA 95616

0013-8746060241ETH0252$04000 2006 Entomological Society of America

that we modiTHORNed and tested recognize the hypothesisthat Baetiscidae as a representative of Carapacea isthe most basal cladePhylogenetic Hypotheses Regarding FurcatergaliaSetisura and Pisciforma Among the suborders Fur-catergalia Setisura and Pisciforma which accommo-date the majority of mayszligy families Pisciforma andSetisura were considered to be derived togetherconstituting a sister clade to the Furcatergalia (Mc-Cafferty and Edmunds 1979 Landa and Soldan 1985McCafferty 1991b Tomka and Elpers 1991) Themonophyly of the Furcatergalia and the PisciformaETHSetisura groups were supported by anatomic synapo-morphies including the presence of the ventral anas-tomosis of tracheae in segments other than 8 and 9 ofthe abdomen and the absence of branches of a dorsaltrunk of tracheae formed in the head respectively(Tomka and Elpers 1991) Within the PisciformaETHSetisura clade no clear evidence has supported themonophyly of Pisciforma and McCafferty and Ed-munds (1979) indicated it was extremely paraphyleticMonophyly of Setisura however is clearly supported

by a series of synapomorphies (McCafferty 1991aWang and McCafferty 1995 Kluge 1998) An alterna-tive hypothesis regarding the relationships among thethree major groupings was given by Kluge et al (1995)and Kluge (1998 2004) in which the Pisciformagroup (called Tridentiseta) and a Setisura-Furcater-galia group (called Bidentiseta) were considered sis-ter clades although Kluge admitted that Pisciformawas probably paraphyletic KlugeOtildes grouping of Seti-sura and Furcatergalia together was supported by apresumed initial presence of two dentisetae on larvalmaxillae Within this grouping Setisura (or Branchit-ergaliae) and Furcatergalia (or Furcatergaliae) alsowere considered monophyletic groups Soldan andPutz (2000) proposed another hypothesis based onkaryotype evidence that generally resembled KlugeOtildeshypothesis It differed from the latter in the arrange-ment of lineages within the hypothesized Furcater-galiaETHSetisura group by treating Scapphodonta Lep-tophlebiidae and Setisura as a monophyletic sistergroup to Pannota (Fig 3)

Table 1 McCafferty classification system of extant taxa followed in this study with families arranged alphabetically within theirgroupings

Suborder Infraorder Superfamily Family

Carapacea BaetiscidaeProsopistomatidae

Furcatergalia Lanceolata LeptophlebiidaePalpotarsa BehningiidaeScapphodonta Potamanthoidea Potamanthidae

Euthyplocioidea EuthyplociidaeEphemeroidea Ephemeridae

IchthybotidaePalingeniidaePolymitarcyidae

Pannota Caenoidea CaenidaeNeoephemeridae

Ephemerelloidea CoryphoridaeDicercomyzidaeEphemerellidaeEphemerythidaeLeptohyphidaeMachadorythidaeMelanemerellidaeTeloganellidaeTeloganodidaeTricorythidaeVietnamellidae

Pisciforma AcanthametropodidaeAmeletidaeAmeletopsidaeAmetropodidaeBaetidaeDipteromimidaeMetretopodidaeNesameletidaeOniscigastridaeRallidentidaeSiphlaenigmatidaeSiphlonuridaeSiphluriscidae

Setisura ArthropleidaeColoburiscidaeIsonychiidaeHeptageniidaeOligoneuriidaePseudironidae

242 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol 99 no 2

Phylogeny among Major Groups within Furcater-galia The suborder Furcatergalia is generally thoughtto be monophyletic with major clades Leptophlebi-idae Scapphodonta and Pannota containing 15 fam-ilies It has been generally recognized that within theFurcatergalia Leptophlebiidae is a basal lineage(Kluge 1998) and a sister group to a relatively derivedclade that includes a pair of sister groups Scapph-odonta and Pannota (McCafferty and Wang 2000) inaddition to a more basal lineage represented by theBehningiidae (McCafferty 2004) Scapphodonta andPannota are both monophyletic and are supported bya series of morphological synapomorphies (McCaf-ferty and Wang 2000 McCafferty 2004) In our studywe followed this arrangement of branches within Fur-catergalia in our construction of hypothesized phylo-genetic treesRelationships Regarding the PisciformandashSetisuraGroupingWhen Ulmer (1920) THORNrst introduced sub-order concepts to Ephemeroptera all minnowlikemayszligies (except Baetidae) and szligatheaded mayszligieswere placed in the suborder Heptagenioidea Ed-munds and Traver (1954) changed UlmerOtildes subordersinto superfamilies while adding Baetidae and Oligo-neuriidae to Heptagenioidea Edmunds et al (1963)considered Isonychiinae and Coloburiscinae as sub-families of Siphlonuridae (in Heptagenioidea) andRiek (1973) placed them in Oligoneuriidae which waslater followed by McCafferty and Edmunds (1979)Demoulin (1958) proposed Siphlonuroidea for Siph-lonuridae and Baetidae to recognize their hypothe-sized close relationship and he also separated themfrom the szligatheaded mayszligies (Heptageniidae andsome Oligoneuriidae) which he placed in Heptage-nioidea and Oligoneurioidea McCafferty and Ed-munds (1979) continued to include minnowlike andszligatheaded mayszligies together in one superfamily butchanged the name from Heptagenioidea to Baetoideahowever Landa and Soldan (1985) used Baetoidea foronly minnowlike mayszligy families and Heptagenioideafor Heptageniidae and Oligoneuriidae McCafferty(1990) THORNrst considered the Coloburiscidae Isonychi-idae Oligoneuriidae and Heptageniidae to constitutethe Heptagenioidea and later further elaborated cla-distic evidence for the monophyly of his groupingwith numerous synapomorphies (McCafferty 1991a)McCafferty (1991b) proposed suborders Setisura andPisciforma for Heptagenioidea and Baetoidea respec-tively in which a series of mayszligy subfamilies previ-ously placed under Siphlonuridae or Oligoneuriidaewere treated as families Later Wang and McCafferty(1995) moved Pseudironidae from Siphlonuroidea toHeptagenioidea However Kluge (2004) suggestedthat Pseudironidae should be moved out of Setisurabeing instead a pisciform groupRelationships among Families of Pisciforma The

evolution of the families of Pisciforma still remainslargely unclariTHORNed Edmunds (1975) Landa (1973)and Riek (1973) all presented various hypothesesof family evolution that included pisciform taxabased on phenetic interpretations Landa and Soldan(1985) discussed evolutionary trends of many lin-

eages which were deduced from a systematic studyof mayszligy anatomy Based on internal anatomical dataand other morphological evidence of Landa and Sol-dan (1985) Tomka and Elpers (1991) suggested anevolutionary tree for mayszligy families in which most ofthe clades were supported by presumed synapo-morphies Within the PisciformaETHSetisura groupingAmetropodidae was thought to branch THORNrst withother families sharing the nerve ganglion of abdominalsegment one merging with that of the metathoraxSiphlonuridae (Siphlonuridae and Dipteromimidaein Table 1) and Rallidentidae (Rallidentidae Nesa-meletidae and Ameletidae in Table 1) were thoughtto be sister groups that branched next with otherfamilies lacking a nerve ganglion in abdominal seg-ment 8 Acanthametropodidae and Ameletopsidaewere thought to branch next from the remainder thatincluded Baetidae Metretopodidae and Setisurawhich supposedly shared paired intercalaries in theforewings parallel with CuA and CuP Baetidae wastreated as a sister group to a MetretopodidaeETHHep-tagenioidea grouping that shared two-segmented la-bial palpi Metretopodidae was considered to be asister group to Heptagenioidea However the conclu-sions of Landa and Soldan (1985) and Tomka andElpers (1991) have been suspect because the char-acters used in their analyses have a propensity forconvergence and are inconsistent within the taxathey were said to represent as have been pointedout for example by Kluge et al (1995) and McCaf-ferty (2004)

Kluge et al (1995) recognized two superfamiliesin Pisciforma Baetoidea (including Baetidae andSiphlaenigmatidae) and Siphlonuroidea (includingthe rest of the Pisciforma families) These authorsalso divided Siphlonuroidea into a Northern hemi-sphere group of families that included Siphlon-uridae Dipteromimidae Ameletidae Metretopodi-dae Acanthametropodidae and Ametropodidae anda Southern hemisphere group of families that includedOniscigastridae Nesameletidae Rallidentidae andAmeletopsidae and suggested that the Southern hemi-sphere group was possibly monophyleticRelationships among Families of Setisura Various

researchers have believed that Setisura representedan evolutionary branch derived from Pisciformamayszligies that became adapted to szligowing water habi-tats by way of passive THORNlter feeding (Sinitshenkova1984 Edmunds and McCafferty 1988 McCafferty1991a) The determination of which families repre-sent the intermediate evolutionary links is most im-portant for establishing a phylogenetic classiTHORNcationWithin Setisura McCafferty (1990 1991a) hypothe-sized an evolutionary sequence from the primitiveforms including Coloburiscidae Isonychiidae andOligoneuriidae to the more derived Heptageniidaebased on morphological evidence from fossil and ex-tant mayszligies Wang and McCafferty (1995) also hy-pothesized that Pseudironidae was relatively highlyderived within Setisura representing a sister groupto the HeptageniidaeETHArthropleidae group all ofwhich represented the most apotypic clade in the

March 2006 SUN ET AL MAYFLY PHYLOGENY 243

suborder Alternative evolutionary relationships ofPseudironidae and other Setisura families were sug-gested by Tomka and Elpers (1991) in which Pseud-ironidae was thought to separate from other Setisuraat an earlier stage and was a sister taxon to a hypoth-esized HeptageniidaeETHOligoneuriidae lineage Also asmentioned above Kluge (2004) did not considerPseudironidae to be a member of Setisura

Materials and Methods

SpecimensWe sequenced partial 18s rDNA from 22mayszligy species belonging to 20 families as shown inTable 2 Specimens were collected between 1982 and2002 preserved in 70 ethanol and deposited in thePurdue Entomological Research Collection (PERC)The homologous sequence of one species of Ralliden-tidae Rallidens mcfarlanei Penniket (GenBank acces-sion no AY338696) was incorporated into our anal-yses Therefore all Pisciforma and Setisura familieswere included in this study except SiphlaenigmatidaeSiphluriscidae and Dipteromimidae These three fam-ilies are thought to have close relationships with Baeti-dae Acanthametropodidae (or possibly Nesameleti-dae) and Siphlonuridae respectively based onmorphological evidence (Edmunds and Koss 1972Edmunds 1973 Meyer et al 2003 Zhou and Peters2003)WeusedonespeciesofThysanura(Lepisma spGenBank accession no AF005458) to serve as thenon-Ephemeroptera outgroup in our molecular anal-ysesMethods forObtaining andManipulatingDNAWe

dissected and rinsed in Tris-EDTA buffer (TE pH 75)pieces of muscle from the thorax or abdomen of asingle specimen of each mayszligy species We used aKontes grinder (Kontes Glass Vineland NJ) to grindthe tissue in 25 l of Molecular Grinding Resin (Geno-tech St Louis MO) in a 15-ml microcentrifuge tubewhich was immediately used or frozen at 20C for

later use Total genomic DNA was extracted usingInstaGene Matrix (Bio-Rad Hercules CA) accordingto manufacturerOtildes recommendations The mixtureswere incubated overnight at 56C and then wereboiled and centrifuged as directed by the manufac-turer The supernatant was stored at 4C for use astemplates for polymerase chain reaction (PCR) Prim-ers (Ferris et al 2004) for the 620-bp fragment of the18s rDNA were (forward) 5-AGGGCAAGTCTGGT-GCCAGC-3 and (reverse) 5-TTTCAGCTTTGCA-ACCATAC-3 The ampliTHORNed fragment was clonedinto the pGEM-T vector (Promega Madison WI)and transformed into Escherichia coli strain JM109(Promega) Colony cultures containing inserts of theexpected size as determined by PCR were used tomake Wizard Plus plasmid preparations (Promega)Automatic sequencing of the plasmid preparationswas done at the Purdue Genomics Facility Bothstrands of DNA from two to four clones were se-quenced for each insect isolateMethods for Phylogenetic Analysis Tree Buildingand Testing Sequences were aligned using Clustal X(Thompson et al 1997) with default parameters (gapopen 15 gap extend 666) Phylogenetic analysiswas performed with PAUP 40b10 (Swofford 2002)under Parsimony criteria by using the heuristic searchwith Lepisma sp assigned as an outgroup We usedMacClade 401 (Maddison and Maddison 2000) tocreate trees reszligective of hypotheses for the phylogenyof Ephemeroptera based on morphological data dis-cussed above Hypotheses were compared individu-ally to the best tree based on molecular data by usingthe ShimodairaETHHasegawa (SH) test as implementedin PAUP In this test when P 005 trees wereconsidered not signiTHORNcantly different from the originalbest tree and the hypotheses represented by thesetrees were not rejected WhenP 005 the trees wererejected In addition we manipulated these trees inPAUP and MacClade to obtain additional shorter trees

Table 2 Mayfly taxa sequenced for this study

Family Species Collection locale

Acanthametropodidae Analetris eximia Edmunds Canada SaskatchewanAmeletidae Ameletus celer McDunnough USA MontanaAmeletopsidae Chiloporter sp Chile Region IXAmetropodidae Ametropus neavei McDunnough Canada SaskatchewanArthropleidae Arthroplea bipunctata (McDunnough) USA MichiganBaetidae Baetis bicaudatus Dodds USA Montana

Callibaetis ferrugineus (Walsh) USA MontanaBaetiscidae Baetisca lacustris McDunnough USA MontanaCaenidae Caenis youngi Roemhild USA MontanaColoburiscidae Coloburiscoides giganteus Tillyard Australia Australian Capital TerritoryEphemeridae Ephemera simulansWalker USA IndianaHeptageniidae Epeorus grandis (McDunnough) USA Montana

Heptagenia diabasia Burks USA NebraskaIsonychiidae Isonychia rufa McDunnough USA IndianaLeptophlebiidae Paraleptophlebia memorialis (Eaton) USA MontanaMetretopodidae Metretopus borealis (Eaton) Canada Northwest TerritoryNesameletidae Ameletoides lacusalbinae Tillyard Australia New South WalesOligoneuriidae Lachlania talea Allen amp Cohen Honduras OlanchoOniscigastridae Tasmanophlebia sp Australia New South WalesPolymitarcyidae Tortopus primus (McDunnough) USA IndianaPseudironidae Pseudiron centralis McDunnough USA WisconsinSiphlonuridae Siphlonurus columbianus McDunnough USA Montana


with better SH scores if possible for the hypothesisbeing tested For example we frequently searchedpartial trees containing only some of the groups toobtain optimal arrangements for them

Results and Discussion

Relationships among Setisura Pisciforma and Fur-catergalia The THORNrst hypothesis with respect to rela-tionships among the three major groupings is thatPisciforma and Setisura comprise a monophyletic sis-ter group to Furcatergalia In the test of this hypoth-esis the best tree was modiTHORNed in the following waysBaetiscidae was moved to the base of the clade thatrepresented all extant Ephemeroptera Above theBaetiscidae branch all Furcatergalia taxa were placedat the base of the three major lineages to form oneclade which was a sister group to a hypothesizedPisciformaETHSetisura clade Within Furcatergalia ar-rangements of families followed hypotheses thatwere described above Letophlebiidae separated at anearlier stage at the base of the lineage the sistergroups Pannota (represented by Caenidae) and Scap-phodonta (represented by Ephemeridae and Poly-mitarcyidae) were placed at the top In the Pisci-formaETHSetisura clade Setisura was considered to bemonophyletic To obtain the tree with the highestpossible score a partial tree that included only dataof the Pisciforma taxa plus Coloburiscidae was in-ferred using the Heuristic Search under Parsimony in

PAUP with Thysanura as the outgroup The familyColoburiscidae hypothesized as the most primitiveSetisura mayszligy form (McCafferty 1991a) served as apositional indicator of the origin of the Setisura sub-order within Pisciforma Taxa of Pisciforma were ar-ranged in MacClade according to this partial tree Theremaining lineages of Setisura were added on theColoburiscidae branch and were placed in the searchfor the shortest total length function in MacCladeWhen the THORNrst hypothesis and other assumptions de-scribed above were followed the tree with the highestpossible score is shown in Fig 1 This tree was notsigniTHORNcantly different from the best molecular treebased on the SH test score Therefore our data sup-ported the THORNrst hypothesis regarding the relationshipsamong the three major groupings of mayszligies repre-sented by the framework of McCafferty (1991b)

The alternative hypothesis is that the subordersSetisura and Furcatergalia comprise a monophyleticsister group However the ancestral nature of thisgroup has not been clearly inferred in this hypothesisTherefore we assumed that there are two possibilitiesthe hypothesized ancestor could be either a Setisura-like form or a Furcatergalia-like form To obtain thebest tree score the above-mentioned possibilitieswere examined separately in two trees In the THORNrst treethe ancestor of the hypothesized grouping of Setisuraand Furcatergalia was represented by Coloburiscidaewhich was considered to be the most primitive formin Setisura whereas in the second tree it was repre-

Fig 1 Tree 1 an acceptable tree that supports the hypothesis of relationships among the three major groupings ofmayszligies in which Pisciforma and Setisura comprise a monophyletic sister group to Furcatergalia


sented by Leptophlebiidae which was considered tobe the most primitive form in Furcatergalia Afterplacing Baetiscidae at the base of the entire Ephemer-optera clade we inferred using the Heuristic Searchunder Parsimony a partial tree that included only dataof Pisciforma taxa plus Coloburiscidae with Thysa-nura as the outgroup Next taxa of Pisciforma werearranged above Baetiscidae in MacClade as indicatedby the partial tree The rest of the lineages of Setisuraand Furcatergalia were then added on the Colo-buriscidae branch Taxa of these two suborders wereplaced in two respective clades as sister groups Ineach of the clades families and genera were arrangedin the same way as for tree 1 (Fig 1) The tree createdis shown in Fig 2 (tree 2) Second a partial treeincluding only data of all Pisciforma taxa plus Lepto-phlebiidae was inferred using the Heuristic Searchunder Parsimony with Thysanura as the outgroupAnother complete tree was constructed based ondata from this partial tree in the same way as thatdescribed above except that the hypothesized Fur-catergaliaETHSetisura clade was added on the Leptophle-biidae branch instead of the Coloburiscidae branch(Fig 2 tree 3) Trees two and three were comparedwith the best tree based on molecular data (using theSH test as implemented in PAUP) and both treeswere signiTHORNcantly different from the best tree As afurther test of the possibility that Furcatergalia andSetisura comprise a monophyletic group we made

further searches for the shortest total length in Mac-Clade by using the taxa of the FurtcatergaliaETHSetisuragroup of trees 2 and 3 However all trees generatedusing this method were rejected by the SH testsTherefore our molecular data did not support thesecond hypothesis represented by the framework ofKluge (1998 2004)

We also examined the hypothesis given by Soldanand Putz (2000) based on karyotype evidenceTrees 2 and 3 (Fig 2) were modiTHORNed by moving Eph-emeridae Polymitarcyidae and Leptophlebiidae fromFurcatergalia to Setisura as suggested by Soldan andPutz (2000) The SH test showed these trees to besigniTHORNcantly different from the best tree We alsoperformed the Heuristic Search under Parsimony cri-teria and obtained a best tree based on the moleculardata for only the families studied by Soldan and Putz(2000) (except Potamanthidae and Ephemerellidae)with Thysanura as the outgroup We used MacCladeto create another tree that included the same may-szligy families (Baetidae Siphlonuridae HeptageniidaeOligoneuriidae Leptophlebiidae Ephemeridae andCaenidae) following the arrangement of Soldan andPutz (2000) (Fig 3) The SH test indicated a signif-icant difference between this tree and the best treebased on molecular data Therefore the frameworksuggested by Soldan and Putz (2000) was not sup-ported by our molecular data

Fig 2 Trees 2 and 3 best trees following the second hypothesis regarding relationships among the three major groupingsof mayszligies in which Furcatergalia and Setisura comprise a monophyletic group stemming from Pisciforma Tree 2 a tree builton the assumption that the ancestor of the hypothesized FurcatergaliaETHSetisura lineage is a Setisura-like form Tree 3 a treebuilt on the assumption that the ancestor of the hypothesized FurcatergaliaETHSetisura lineage is a Furcatergalia-like form Bothtrees were rejected by the SH test


According to our results Setisura evolved indepen-dently from a siphlonurid-like ancestor within Pisci-forma and did not share a direct common ancestorwith Furcatergalia which originated independentlywithin Ephemeroptera Because the PisciformaETHSeti-sura (PisciformaETHHeptagenioidea) clade is monophy-letic subordinal status could be assigned to this entiregroup As such Setisura would be subsumed underPisciforma as per McCafferty (1997)Status of Pisciforma Additional trees were gen-

erated in MacClade to examine the status of Pisci-forma sensu stricto These trees were modiTHORNed fromtree 1 (Fig 1) by adjusting the positions of Pisci-forma families which included Acanthametropo-didae Ameletidae Ameletopsidae AmetropodidaeBaetidae Metretopodidae Nesameletidae Onis-cigastridae Rallidentidae Siphlaenigmatidae andSiphlonuridae

We THORNrst explored the possibility that Pisciforma ismonophyletic A partial tree was obtained by includ-ing data of all Pisciforma taxa (with Thysanura asoutgroup) by using the Heuristic Search under Par-simony We then selected the partial tree with the bestscore and modiTHORNed tree 1 (Fig 1) by placing all taxaof Pisciforma in one clade that followed the arrange-ment indicated by the best partial tree Baetidae is atthe base of the Pisciforma clade as in tree 1 (Fig 1)whereas all other families (Siphlonuridae-like forms)form a sister clade (Fig 4 tree 5) The SH testindicated that the new tree was signiTHORNcantly differentfrom the best tree based on molecular data We alsoexplored the possibility that all Siphlonuridae-likefamilies comprised a monophyletic group (Siphlonu-roidea) when a paraphyletic Pisciforma was dividedinto two superfamilies Baetoidea (represented in ourtest by Baetidae) and Siphlonuroidea (represented byall other Pisciforma families) Another tree was con-structed based on tree 5 in which all Pisciforma (ex-cluding Baetidae) were placed in one clade as a sistergroup to Setisura This tree (Fig 4 tree 6) also wasrejected by the SH test and therefore our moleculardata suggest that Pisciforma is paraphyletic If it isdivided into two superfamilies Siphlonuroidea in it-self is also a paraphyletic group

We then examined the possibility that Siphlonuri-oidea included a monophyletic Southern hemispheregroup comprised of Oniscigastridae NesameletidaeRallidentidae and Ameletopsidae as suggested byKluge et al (1995) Tree 1 was modiTHORNed so that thefour families comprised one clade We used MacCladeto THORNnd an arrangement with the shortest total lengthwithin this clade and tentatively added it at the orig-inal position of each of these families to explore allpossibilities (eg Fig 4 tree 7) However all suchtrees were rejected by the SH test and our moleculardata suggest that all Southern hemisphere Siphlonu-roidea families are not likely to be derived from asingle common ancestor

Following the assumption that Pisciforma is para-phyletic a series of trees was constructed to test thephylogeny of this group as hypothesized by Tomkaand Elpers (1991) as shown in tree 8 (Fig 4) Becausethe family Oniscigastridae was not included in theTomka and Elpers study we obtained another treethat included molecular data for all our taxa exceptOniscigastridae by using the Heuristic Search underParsimony This best molecular tree was comparedwith a series of trees created to examine the variousaspects of the hypothesis As suggested by Tomka andElpers (1991) we THORNrst treated Metretopodidae as asister group to Setisura A partial tree was obtained byincluding data of all Pisciforma taxa (with Thysanuraas outgroup) based on molecular data using the Heu-ristic Search under Parsimony in PAUP Tree 1 (Fig 1)was modiTHORNed in MacClade with the families of Pisci-forma arranged as indicated by the partial tree ob-tained previously whereas Setisura was added on theMetretopodidae branch as a sister group to the latterThe SH test showed the resulting tree to be signiTHORN-cantly different from the best tree

Next we examined the possibility that SetisuraBaetidae and Metretopodidae comprise a monophy-letic group Another partial tree that included allPisciforma taxa except Metretopodidae was obtainedbased on molecular data using PAUP Arrangementsof these families in tree 1 (Fig 1) were modiTHORNed asindicated in this new partial tree and Metretopodidaeand Setisura were added on the Baetidae branch The

Fig 3 Tree 4 a tree created including limited families following the hypothesis given by Soldan and Putz (2000) in whichSetisura tusked burrowers and Leptophlebiidae were considered to form a monophyletic group This tree was rejected bythe SH test when compared with the best tree based on our molecular data of the same families


clade comprised by these three groups also was placedin the search-above-branch function to obtain thehighest possible score This tree also was rejected bythe SH test

We then constructed another tree to examine thepossibility that Setisura Baetidae MetretopodidaeAcanthametropodidae and Ameletopsidae comprisea monophyletic group as suggested by Tomka andElpers (1991) Because they suggested that Acan-thametropodidae and Ameletopsidae were a sistergroup and formed a most primitive clade in this groupwe placed each of two families at the base of thishypothesized group The THORNrst partial tree includedonly Acanthametropodidae plus the rest of the Pisci-forma taxa The arrangements of these families weremodiTHORNed in tree 1 following this partial tree and thena group of taxa including Ameletopsidae BaetidaeMetretopodidae and Setisura was added to the Acan-thametropodidae branch as a monophyletic groupand placed in the search for the shortest total length

function in MacClade The second partial tree in-cluded the same taxa as in the THORNrst partial tree exceptthat Acanthametropodidae was replaced by Amele-topsidae Accordingly the group of interest was addedon the Ameletopsidae branch in MacClade Both thesetrees were shown by the SH test to be signiTHORNcantlydifferent from the best tree

We examined whether Ametropodidae could be themost primitive form of the PisciformaETHSetisura lin-eage as suggested by Tomka and Elpers (1991) byplacing the family at the base of the clade that in-cluded all PisciformaETHSetisura families in tree 1(Fig 1) and using the search for the shortest totallength function in MacClade on all taxa above theAmetropodidae branch The tree generated was re-jected according to the SH test Therefore we con-clude that several characteristics treated as synapo-morphies by Tomka and Elpers (1991) in theirhypothesized phylogeny of the SetisuraETHPisciformagroup are the result of homoplasy These character-

Fig 4 Trees 5ETH8 Tree 5 the best tree following the assumption that Pisciforma is a monophyletic group Tree 6 the besttree following the assumption that Pisciforma could be divided into two separate monophyletic groups Baetoidea andSiphlonuroidea Tree 7 an example of trees following the assumption that Pisciforma included a monophyletic Southernhemisphere family group Tree 8 a hypothesized tree in which the arrangement of Pisciforma families follows the hypothesisgiven by Tomka and Elpers (1991) where Nesameletidae and Ameletidae were genera under Rallidentidae All of these treeswere rejected by the SH test


istics include the presence of two-segmented labialpalps thepresenceofpaired intercalariesparallelwithCuA and CuP on forewings the absence of a nerveganglion in abdominal segment 8 and the merging ofthe nerve ganglion of abdominal segment 1 and that ofthe metathorax

We tested two additional aspects of the Tomkaand Elpers (1991) hypothesis In their study Siph-lonuridae and Rallidentidae (Rallidentidae Nesame-letidae and Ameletidae in Table 1) were thought tocomprise a monophyletic group although no synapo-morphy was provided They also suggested that Acan-thametropodidae and Ameletopsidae are sister groupssupported by anatomic evidence The trees that wecreated that reszligected these hypotheses could not berejected based on the SH tests We further addedOniscigastridae back to this tree Because the familywas not included in the Tomka and Elpers (1991)study we followed the hypothesis given by Landa andSoldan (1985) in which Ameletopsidae and Onis-cigastridae were considered to be sister groups Thusin our tree Acanthametropodidae was placed at thebase of a clade comprised by the two families (Fig 5tree 9) The SH test indicated that this new tree wasnot signiTHORNcantly different from the best tree There-fore these particular aspects of the Tomka and Elpers(1991) hypothesis are acceptable

On the best phylogenetic tree based on moleculardata of the families of the SetisuraETHPisciforma group

(with Thysanura as the outgroup) placement ofBaetidae at the base of this clade was supported by a100 bootstrap score This suggested that Baetidae(the superfamily Baetoidea including Baetidae andpossibly Siphlaenigmatidae) separated at a very earlystage from other lineages of Pisciforma leaving aparaphyletic superfamily Siphlonuroidea The combi-nation of the rest of the Pisciforma families plus allthe Setisura families into one monophyletic group hada bootstrap support of 52 as did the arrangement ofRallidentidae and Ameletidae as a sister group inPisciformaEvolution of SetisuraAt the outset of our study the

suborder Setisura was considered by many to be amonophyletic group that included the families Hep-tageniidae Arthropleidae Pseudironidae Oligoneuri-idae Coloburiscidae and Isonychiidae (Wang andMcCafferty 1995 Kluge 1998) Our data strongly sup-ported the hypothesis that Heptageniidae Arthro-pleidae and Pseudironidae form a monophyleticgroup These three families (represented by four se-quences) were exclusively placed in one clade at 100bootstrap frequency on the best tree based on mo-lecular data that included all our mayszligy sequences Asdiscussed above our SH test results indicated that itwas acceptable to include the families OligoneuriidaeColoburiscidae and Isonychiidae in Setisura thus sup-porting the monophyly of this suborder that was based

Fig 5 Tree 9 an acceptable tree based on tree 1 following one hypothesis given by Landa and Soldan (1985) in whichAmeletopsidae and Oniscigastridae are sister groups and two hypotheses given by Tomka and Elpers (1991) 1) PresentSiphlonuridae Rallidentidae Nesameletidae and Ameletidae (of Table 1) comprise a monophyletic group and 2) Amele-topsidae and Acanthametropodidae are sister groups (when Oniscigastridae was absent)


on morphological evidence as per the framework ofWang and McCafferty (1995)

The sequence of evolution of the Setisura lineagesshown in tree 1 (Fig 1) and tree 9 (Fig 5) was a resultof the search for the shortest total length function inMacClade and favored the hypothesis given by Mc-Cafferty (1991a) based on morphological evidenceregarding the origins of Setisura and relationshipsamong Coloburiscidae Isonychiidae Oligoneuriidaeand Heptageniidae McCafferty (1991a) also had ob-served that two of the 36 apomorphies he studiedoccurred exclusively in the families ColoburiscidaeIsonychiidae and Oligoneuriidae all possessing apo-morphic maxillary gills and THORNltering setae on the fore-legs McCafferty (1991a) hypothesized that thesewere gained synapomorphies at the base of Setisurathat were subsequently lost in the apotypic familyHeptageniidae Nonetheless an alternative arrange-ment of lineages in a phylogeny might be to placethese three families exclusively in a single clade torepresent a primitive lineage of Setisura We con-structed a tree modiTHORNed from our tree 1 (Fig 1) inwhich such a clade was recognized (Fig 6 tree 10)The rest of the Setisura families Pseudironidae Ar-thropleidae and Heptageniidae were placed in an-other clade as a sister group to the former This group-ing of the three lineages was supported with the 100bootstrap frequency and also was supported by mor-phological synapomorphies noted by McCafferty(1991a) and Wang and McCafferty (1995) Each ofthese clades was then placed in the search for the

shortest total length function in MacClade The SHtest indicated that this tree was signiTHORNcantly differentfrom the best tree and therefore not acceptable basedon our molecular data Thus our molecular evidencesuggested that Coloburiscidae Isonychiidae and Oli-goneuriidae separated from the rest of Setisura atdifferent times and do not comprise a monophyleticgroup and the explanation for the two incongruentcharacters as given by McCafferty (1991a) is highlyprobable which also was supported by data from ecol-ogy and behavior (McCafferty 1991a)

Our data favored the hypothesis by Wang and Mc-Cafferty (1995) regarding the relationship betweenPseudironidae and the HeptageniidaeETHArthropleidaegrouping (Figs 1 and 4) To examine the accept-ability of alternative hypotheses regarding sequenceof evolution of these families we created additionaltrees Tree 1 (Fig 1) was modiTHORNed by moving Pseud-ironidae to the base of the clade comprised of Hep-tageniidae Arthropleidae and Oligoneuriidae (Fig 6tree 11) as suggested by Tomka and Elpers (1991) Toexamine the hypothesis given by Kluge (2004) whosuggested that Pseudironidae should be moved out ofSetisura a partial tree that included only Pseud-ironidae Coloburiscidae and all the Pisciforma fam-ilies was inferred using the Heuristic Search underParsimony in PAUP with Thysanura as the outgroupThe complete tree was constructed by modifying tree1 (Fig 1) in which the Pseudironidae and Pisciformataxa were arranged as indicated by the new partialtree the Setisura taxa (except Pseudironidae) were

Fig 6 Trees 10ETH12 Tree 10 an alternative hypothesis regarding the evolution of Setisura lineages in which Coloburisci-dae Isonychiidae and Oligoneuriidae were placed in one clade Tree 11 an alternative evolutionary hypothesis of Setisurain which Pseudironidae is a sister group to a hypothesized OligonuriidaeETHHeptageniidaeETHArthropleidae lineage Tree 12 aparsimonious arrangement of Pisciforma and Setisura lineages based on the hypothesis that Pseudironidae is a part ofPisciforma not Setisura All of these trees were rejected by the SH test


added on the Coloburiscidae branch and placed inanother search for the shortest total length in Mac-Clade (Fig 6 tree 12) Both tree 11 and tree 12 (Fig 6)were rejected by the SH tests Therefore our mo-lecular data support the hypothesis that Heptageni-idae Arthropleidae and Pseudironidae comprise aclade separate from Oligoneuriidae within the Hep-tagenioidea

Wang and McCafferty (1995) discussed the sistergroup relationship between Heptageniidae and Ar-thropleidae which was supported by morphologicalsynapomorphies We tested this hypothesis by mod-ifying tree 9 (Fig 5) to make another tree in whichHeptageniidae genera Heptagenia and Epeorus wereplaced in one clade to represent the family Arthro-pleidae was treated as a sister group to the Heptage-niidae clade (Fig 7 tree 13) The SH test indicatedno signiTHORNcant difference from the best tree Thereforeour data support a sister group relationship betweenHeptageniidae and Arthropleidae

Our molecular data support tree 13 (Fig 7) regard-ing the phylogeny of Ephemeroptera Other trees areprobably also acceptable especially with respect toevolution among Pisciforma families Uncertainty inthe reconstruction of a phylogenetic tree for mayszligiesprobably stems from their long evolutionary historybeing an ancient group of winged insects Despite theoften-demonstrated highly conserved nature of 18Sribosomal DNA (Ferris et al 2004) variations in ratesof molecular change in the rRNA gene may occur over

very long time spans These variations can lead toerrors in estimates of phylogenetic relationships in thesame way that long time spans may obscure pathwaysof changes in morphological characters To furtherclarify the phylogeny of Ephemeroptera more re-search with both morphological and molecular datasets is needed

Acknowledgments

We thank J Webb (Purdue University West LafayetteIN) for collecting part of the mayszligy specimens We alsothank J S Yaninek (Purdue University) and the Departmentof Entomology for supporting this project which was initi-ated during a Molecular Systematics course in which weparticipated

References Cited

Demoulin G 1958 Nouveau schema de classiTHORNcation desArchodonates et des Ephemeropteres Bull Inst R SciNat Belg 39 1ETH18

Edmunds G F Jr 1973 Some critical problems of familyrelationships in the Ephemeroptera pp 145ETH154 InW LPeters and J G Peters [eds] Proceedings of the FirstInternational Conference on Ephemeroptera E J BrillLeiden The Netherlands

Edmunds G F Jr 1975 Phylogenetic biogeography ofmayszligies Ann Mo Bot Gard 62 251ETH263

Edmunds G F Jr and R W Koss 1972 A review of theAcanthametropodinae with a description of a new genus

Fig 7 Tree 13 a tree modiTHORNed from tree 9 with Arthropleidae a sister group to Heptageniidae This tree was acceptedby the SH test


(Ephemeroptera Siphlonuridae) Pan-Pac Entomol 48136ETH144

EdmundsGF Jr andWPMcCafferty 1988 The mayszligysubimago Annu Rev Entomol 33 509ETH529

Edmunds G F Jr and J R Traver 1954 An outline of areclassiTHORNcation of the Ephemeroptera Proc EntomolSoc Wash 56 236ETH240

Edmunds G F Jr R K Allen andW L Peters 1963 Anannotated key to the nymphs of the families and subfam-ilies of mayszligies (Ephemeroptera) Univ Utah Biol Ser13 1ETH49

Ferris V R A Sabo J G Baldwin M Mundo-OcampoR N Inserraa and S Sharma 2004 Phylogenetic rela-tionships among selected Heteroderoidea based on 18Sand ITS ribosomal DNA J Nematol 36 202ETH206

Kluge N J 1998 Phylogeny and higher classiTHORNcation ofEphemeroptera Zoosyst Ross 7 255ETH269

Kluge N J 2004 The phylogenetic system of Ephemerop-tera Kluwer Academic Publishers Dordrecht The Neth-erlands

Kluge N J D Studemann P Landolt and T Gonser 1995A reclassiTHORNcation of Siphlonuroidea (Ephemeroptera)Bull Soc Entomol Suisse 68 103ETH132

Kukalova-Peck J 1985 Ephemeroid wing venation basedupon new gigantic Carboniferous mayszligies and basic mor-phology phylogeny and metamorphosis of pterygote in-sects (Insecta Ephemerida) Can J Zool 63 933ETH955

Landa V 1973 A contribution to the evolution of the orderEphemeroptera based on comparative anatomy pp 155ETH159 InW L Peters and J G Peters [eds] Proceedingsof the First International Conference on EphemeropteraE J Brill Leiden The Netherlands

Landa V and T Soldan 1985 Phylogeny and higher clas-siTHORNcation of the order Ephemeroptera a discussion fromthe comparative anatomical point of view AcademiaCesk Akad Ved Praha Czech Republic

Maddison D R and W P Maddison 2000 MacClade 4analysis of phylogeny and character evolution version40 Sinauer Sunderland MA

McCaffertyW P 1990 Chapter 2 Ephemeroptera pp 20ETH50 In D A Grimaldi [ed] Insects from the SantanaFormation Lower Cretaceous of Brazil Bull Am MusNat Hist 195

McCafferty W P 1991a The cladistics classiTHORNcation andevolution of the Heptagenioidea pp 87ETH101 In J Alba-Tercedor and A Sanchez-Ortega [eds] Overview andstrategies of Ephemeroptera and Plecoptera The San-dhill Crane Press Inc Gainesville FL

McCafferty W P 1991b Toward a phylogenetic classiTHORNca-tion of the Ephemeroptera (Insecta) a commentary onsystematics Ann Entomol Soc Am 84 343ETH360

McCafferty W P 1997 Ephemeroptera pp 89ETH117 InR W Poole and P Gentili [eds] Nomina Insecta Nearc-tica a check list of the Insects of North America vol 4

non-holometabolous orders Entomological InformationServices Rockville MD

McCafferty W P 2004 Higher classiTHORNcation of theburrowing mayszligies (Ephemeroptera Scapphodonta)Entomol News 115 84ETH92

McCaffertyW P and G F Edmunds Jr 1979 The higherclassiTHORNcation of the Ephemeroptera and its evolutionarybasis Ann Entomol Soc Am 72 5ETH12

McCaffertyW P and T-QWang 2000 Phylogenetic sys-tematics of the major lineages of pannote mayszligies(Ephemeroptera Pannota) Trans Am Entomol Soc126 9ETH101

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Sinitshenkova N D 1984 The Mesozoic mayszligies(Ephemeroptera)with special reference to theirecologypp 61ETH66 In V Landa T Soldan and M Toner [eds]Proceedings of the Fourth International Conference onEphemeroptera Czechoslovak Academy of SciencesPrague Czech Republic

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Received 24 March 2005 accepted 6 December 2005


SYSTEMATICS

Tests of Current Hypotheses of Mayfly (Ephemeroptera) PhylogenyUsing Molecular (18s rDNA) Data

LU SUN ANIKO SABO1 M D MEYER2 R P RANDOLPH3 LUKE M JACOBUSW P MCCAFFERTY AND VIRGINIA R FERRIS

Department of Entomology Purdue University West Lafayette IN 47907

Ann Entomol Soc Am 99(2) 241ETH252 (2006)

ABSTRACT Partial 18s rDNA sequences from 22 exemplar mayszligy species (Ephemeroptera) rep-resenting 20 families were analyzed to obtain a best phylogenetic tree for comparison to previousphylogenetic hypotheses With respect to relationships among the three major groupings our mo-lecular data support the hypothesis that Pisciforma and Setisura comprise a monophyletic sister groupto the Furcatergalia rather than the hypothesis that Setisura and Furcatergalia comprise a mono-phyletic group stemming from the Pisciforma Within Pisciforma acceptable trees show that Baetidaeseparates at the base of the Pisciforma clade The data suggest that Pisciforma is paraphyletic and donot support the grouping of all Southern hemisphere families as a monophyletic group An evolu-tionary sequence favored by the data suggests a grouping of Siphlonuridae Rallidentidae Nesame-letidae and Ameletidae and a grouping of Oniscigastridae Ameletopsidae and AcanthametropodidaeThe data support the monophyly of Setisura (Heptageniidae Arthropleidae Pseudironidae Oligo-neuriidae Isonychiidae and Coloburiscidae) Within Setisura a bootstrapjackknife test places thefamilies Heptageniidae Arthropleidae and Pseudironidae in one clade at 100 frequency Alsosupported are hypotheses that Pseudironidae is a sister group to a HeptageniidaeETHArthropleidae groupand that a sister relationship exists between the latter two families Hypotheses that Pseudironidaeseparated from other Setisura families at an earlier stage and comprises a sister group to a Heptage-niidaeETHOligonuriidae lineage or that Pseudironidae should be moved out of Setisura are not supported

KEY WORDS Ephemeroptera 18s rDNA phylogeny

EPHEMEROPTERA IS ONE OF the most archaic of extantwinged insect orders (Kukalova-Peck 1985) Thehigher classiTHORNcation of Ephemeroptera has evolvedconsiderably over the past 200 yr to include progres-sively more higher taxa However the use of strictphylogenetic classiTHORNcation is relatively recent (Mc-Cafferty 1991b) and cladistic data have been mostlymorphological in nature In this study we used mo-lecular data to test the various hypotheses outlinedbelow regarding certain aspects of the phylogeny ofEphemeropteraSuborder Level Classification of Ephemeroptera

At present four major groupings are generally recog-nized in Ephemeroptera under various names Wefollow a classiTHORNcation system (Table 1) taken fromMcCafferty (1991b) and its modiTHORNcations by Wangand McCafferty (1995) McCafferty (1997 2004) andMcCafferty and Wang (2000) In this classiTHORNcation of

four recent suborders Furcatergalia which was some-times previously referred to as Rectracheata (McCaf-ferty 1991b) includes Leptophlebiidae Behningiidaeall pannote families (Pannota) and all tusked bur-rower families (Scapphodonta) Setisura includes theszligat-headed mayszligies and their hypothesized minnow-like mayszligy ancestral groups including all forms thatpassively THORNlter food with their forelegs Pisciformaincludes all other minnowlike mayszligies and Carapaceaincludes Baetiscidae and ProsopistomatidaeRelationship between Carapacea and Other May-flies As a distinct monophyletic group supported byseries of synapomorphies (eg the presence of a larvalcarapace) the BaetiscidaeETHProsopistomatidae rela-tionship was suggested by various researchers (Ed-munds and Traver 1954) Kluge (1998) and McCaf-ferty and Wang (2000) showed the group to be basallyderived with its sister group represented by all otherextant mayszligies which share synapomorphic fore-wings with the tornus located between the ends ofveins CuA and CuP (CuP and A1 terminating in theanal margin rather than the outer margin of thewings) McCafferty (1997) THORNrst referred to the Baetis-cidaeETHProsopistomatidae grouping as the suborderCarapacea In our study using molecular data all trees

1 Human Genome Sequencing Center Baylor College of MedicineHouston TX 77030

2 Department of Biology Christopher Newport UniversityNewport News VA 23606

3 Section of Evolution and Ecology University of California DavisCA 95616

0013-8746060241ETH0252$04000 2006 Entomological Society of America










































































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Acknowledgments


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tests of current hypotheses of mayfly (ephemeroptera) phylogeny using molecular (18s rdna) data

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