Phylogenetic implications of the mesofurca and mesopostnotum in Hymenoptera

37 Pages·1994·12.7 MB·English

by  J M Heraty

HYM. RES.
J.
Vol. 3, 1994, pp. 241-277
Phylogenetic Implications of the Mesofurca
and Mesopostnotum in Hymenoptera
John M. Heraty, James B. Woolley and D. Christopher Darling
(JMH)Biological Resourcesdivision,CLBRR,AgricultureCanada,C.E.F.,Ottawa,Ontario,Canada KlA0C6
(prese(nJtBaWd)drDeespsa:rDtempeanrttomfenEtntoofmEonltoogmyo,lToegxya,sUAni&veMrsUintiyvoefrsCiatlyi,foCronlilae,gReivSteartsiiodne,,TCeaxlaisf,ornUiSa,AU7S78A439;2521);
(DCD) DepartmentofEntomology, RoyalOntarioMuseum,Toronto,Ontario,CanadaM5S2C6
—
Abstract. Theskeleto-musculatureofthemesofurcaand themesopostnotumisexamined in Hymenoptera.Character
systemsbasedoninternalstructureofthemesothoraxsupportrecenthypothesesthatsuggestsawfliesareparaphyleticwith
respect to Apocrita. Unique character states for Hymenoptera include the presence of two mesofurcal-laterophragmal
muscles, a mesofurcal-third basalare muscle, and a scutellar-metanotal muscle. Other possible apomorphies include the
medialemarginationofthemesopostnotumandtheformationofanteriorfurcalarms.Thearrangementofmesofurcalmuscles
that attach totheprofurcaand thelaterophragmaaredescribed and interpreted in lightofrecentphylogenetichypotheses.
Changesinattachmentsites, fusionorlossoftheanteriorarmsofthemesofurcaand featuresofthelaterophragmaprovide
charactersthatareconsistentwiththemonophylyofTenthredinoidea +(Cephoidea+(Siricoidea(includingAnaxyelidae) +
(Xiphydriidae + Orussoidea + Apocrita))). Groundplan states for the Apocrita are proposed that include retention of a
mesofurcal bridge, retention of an anterior process on the bridge that supports the interfurcal muscles, reduction of the
mesofurcal-laterophragmal muscles from two to one, retention of the mesotergal-laterophragmal muscle, loss of the
mesofurcal-thirdbasalaremuscle,andlossofthemetafurcal-spinamuscle.WithinApocritathedistributionofcharacterstate
changesislessinformativethaninSymphyta,butprovideevidenceforrelationshipsofsometaxa.Themesofurcalbridgeis
lostconvergentlyinCeraphronoidea,Pelecinidae,Platygastroidea,Mymarommatoidea,MymandaeandsomeChalcidoidea.
The tergal-laterophragmal muscle and associated posterior lobe of the laterophragma are postulated to have been lost
independentlyinninelineagesofApocrita.Thedevelopmentofthelaterophragmaintoanaxillaryleverisasynapomorphy
forVespoideaandApoidea,andinApiformestheleverisanindependentsclerite.Thedistributionofstatesfor12characters
isdiscussed for62 families ofHymenoptera. Parsimonyanalysisofthesedata result intrees thatgenerally agreewith the
current hypotheses forSymphytabutnotforApocrita.
INTRODUCTION
1969,1980,Matsuda1970,Shcherbakov1980,1981,
Gibson 1985,Johnson 1988, Whitfield et al. 1989).
"Students of these [hymenopteran] parasites discover that Thedeterminationofhomologousstructuresand
latahncedktcholfoarsrasexilfipiarcbaeltseieosnnttuosdfvisaeplseucoainbelste,hbcehusattrtrahuccettyeurarsreefoohrfattnhhdeeidctehatoperpraemxdi"nbaytitohne fproorlaurnitdy>erosftcahnard_a•icntgerpsh,yi,nloHgyemneent.io•cptreeliraat.•iaorneshicirpusc,iaal
Snodgrass 1910p 37 toPlc recently addressed by various authors
(Rasnitsyn 1969, 1980, 1988, Brothers 1975,
Since Snodgrass (1910) first attempted to ex- Konigsma^ndn 1977, 1978a 1978b, Carpenter 1986,
pand our knowledge of the structure of the hy- Brothers Carpenter 1993).
menopteran thorax, additional studies have de- The mesofurca is an invagination of the ster-
scribed the skeleto-musculature of single species num mto the thorax that forms a central Point of
orsinglefamilies(Weber1925,1927, Tulloch1935, attachment f°r the ventral longitudinal muscles,
Maki 1938, Duncan 1939, Michener 1944, Bucher thesterno-pleuralmuscles,thecoxalandtrochant-
1948, Alam 1951, Saini et al. 1982, Daly 1964, eral muscles' and the mesopostnotal muscles
Gthiobrsaocnic198s6t,r1u9c9t3u)r.eFsewaemrosntugdiefsamhialvieescomofpaHrye-d c(KoemlsPenYse1d95o7f< aMabatssauld™pala1t9e70()d.isTchreimemneaslofluarmeclalai)s
menoptera(Snodgrass1942,Daly1963,Rasnitsyn that rises vertically f the discrimen, slopes
posteriorlytothefurcalbase,anddividesdorsally
242 Journalof Hymenoptera Research
into two lateralarms, termed thesternal apophy- MATERIA! S AND METHODS
ses (Snodgrass 1927, Chapman 1992, Lawrenceet
al. 1992). The mesopostnotum is one of the pri- Terms for structures and muscles generally
mary dorsal sclerites involved in flight through followSnodgrass(1910,1942),Daly(1963),Gibson
the posterior inflection of the antecosta (second (1985, 1986, 1993) and Ronquist and Nordlander
phragma) which forms the posterior attachment (1989). Muscleswereidentified usingthesystems
ofthe longitudinal flight muscles. Recent studies proposedbyKelsey(1957)andDaly(1963)(Table
involving skeleto-musculature of the hy- 1). Figures 1 and 2 are used to place the skeleto-
menopteran thorax have focused on the pleural musculature within thecontextof the mesosoma.
attachments(Shcherbakov1980,1981,Gibson1985, Muscles and stuctures are extensively labeled in
1993), the extrinsic musculature of the mesocoxa Figs. 3and4.TheKelseysystemusesafixedsetof
(Johnson 1988), and the development of the numbers and isusefulforcomparisonsacross the
metapostnotum (Whitfield et al. 1992). Rasnitsyn Endopterygota.Daly'ssystemispreferredforclar-
(1969, figs. 187-194) was the first person to com- itybecausetheinsertion-originofattachmentsites
pare the different skeletal structures for the are readily identified and new muscles can be
mesofurca of8 familiesofSymphyta. Hisillustra- added tothesystem;forexample,thenewmuscle
tionsshowthetransformationseriesforSymphyta fu,-ba was given the abbreviation fbl for the
3
that are discussed in this paper. Rasnitsyn (1988) Kelsey system as it could not be assigned a nu-
refers to the furca for features supporting mericvaluethatwouldsignifyitsrelativeposition
TenthredinoideaandforCephoidea+Siricoidea+ to other muscles in the mesothorax. Terms pro-
Apocrita. Similarly,Snodgrass (1942) presented a posed by Matsuda (1970) are comprehensiveand
pictorialevolutionary historyfordevelopmentof may be referenced across orders of insects; how-
theaxillary lever ofApoidea. This workexpands everhisabbreviated system isdifficult touseand
upon these initial studies and extends the com- is not followed here.
parative aspects of these works to include most Several new classifications of families within
families of Apocrita. Hymenoptera have been proposed recently that
This study of the mesofurca and differ largely in placement of certain families as
mesopostnotum began as an attempt to under- separate superfamilies, families, or subfamilies.
stand the polarity and homology of mesofurcal We follow the classification of Huber and Goulet
structures and muscles of Aphelinidae (1993), as it represents the mostcurrent synthesis
(Chalcidoidea)and thephylogeneticimplications of information across the order.
oftheseattributeswithin theChalcidoidea. Even- Dissections were based on specimens pre-
tually the entire Hymenoptera needed to be sur- servedin70%ethanolorinitiallyfixedinDietrich's
veyed to resolve what we initially thought were or Kahle's solution and then transferred to etha-
relatively simple questions. In this study, all nol. All specimens werecritical point-dried prior
muscles attaching to the mesofurca and to dissection. The mesosoma of Monomachns
mesopostnotum are identified and compared to (Monomachidae) was rehydrated using Barber's
homologous muscle groups in Neuropterida and solution, transferred through increasing concen-
Mecopterida (sensu Kristensen 1992), as they are trations ofethanol to 98% and then critical point-
considered to be phylogenetically close to Hy- dried. For each dissection, the mesosoma was
menoptera(Kristensen1992),andhaveamesotho- anchoredontoastandardSEMstub usingchloro-
rax which is structured similar to the Symphyta. form-based silver paint. Dissections were made
Within Hymenoptera, we have concentrated our usinghooked minutenpins orfragmentsofrazor
analysisontheskeletalstructureofthemesofurca blades. Dried haemolymph and extraneous tis-
and mesopostnotum, and on the muscles attach- sues were removed from dissections using small
ing between the thoracic furcae and the amounts of glue obtained by dragging a hooked
laterophragma of the mesopostnotum. The evi- minutenpinacrossclearstickytape(Gibson1985).
dence provided by the mesofurca and Exemplar taxa were chosen to represent the
mesopostnotum for relationships within the maximum variation within taxa. In some groups
Chalcidoidea will be discussed in a subsequent (e.g. Apoidea), there was virtually no variation;
paper. whereas within some taxa (e.g. Diapriidae) both
Volume 3. 1994 243
structureandpresenceofmusclesvariedandmore + remaining Hymenoptera), the anterior furcal
genera were dissected to characterize this varia- armsareeitherabsent,short,orelongateandwell
tion. Our primary concern was for establishing separated along their entire length. The anterior
groundplan states for higher taxa, although arms, ortheequivalentregion on the lateral arms
autapomorphies are discussed. The taxa exam- of the mesofurca, form the posterior attachment
ined for internal characters are listed in Table 2. sitesfortheventralintersegmentalmuscles(muscle
Numerous Chalcidoidea were also dissected as 124,fiij-fUj,andmuscle 127,fu-rsps,). Withfusion
partofacomprehensivestudyofthemesofurcain oftheanteriorarms,thefurcaseparatesthegastric
that superfamily. Representative dissections are and nervous systems and the ventral nerve cord
housed at the Canadian National Collection passes through the foramen bounded by the
(CNCI),RoyalOntarioMuseum(ROM)andTexas mesofurcal bridge and the lateral arms of the
A&M University (TAMU). When possible, con- mesofurca.
specific adults of the dissected specimens are de- In most Neuropterida and Mecopterida, the
positedasvoucherspecimensintheabovecollec- interfurcal muscles attach directly to the anterior
tions. The majority of specimens were obtained faceofthelateralarmsofthemesofurca(state0,no
from the CNCI alcohol collection. arms)(Snodgrass1927,Kelsey1957,Matsuda1970).
The mesofurcal-mesopostnotal complex was InXyelidae(Fig. 3)and Pamphiliidae(Fig. 6)(and
broken up into 12 characters with a total of 36 probably Megalodontidae, cf. fig. 187, Rasnitsyn
characterstates.Seventyhymenopterantaxawere 1969), the interfurcal muscles attach to anterior
scored (Appendix2)based on theexaminationof projections(af,anteriorfurcalarms) thatarelong,
internal characters for 119 species (Table 2). A robust, and separated along their entire length
singleoutgrouptaxonwasscoredbasedondissec- (state 1). Of the outgroup taxa examined, only
tions of5 families ofNeuropterida and 3 families Brachynemurus (Myrmeleontidae) have anterior
of Mecopterida. Characters 1, 3 and 9 are postu- arms (state 1) similar to Xyelidae, and thus their
lated as unique characters for Hymenoptera; in presence could be plesiomorphic or apomorphic
each of these cases, the outgroup is coded as a for Hymenoptera. Because anterior arms are
uniquecharacterstate(state0).Thestatevalue"?" presentonlyinaderivedmemberoftheoutgroup,
wasusedtodenoteuncertainhomology,notmiss- weconsider the presenceoflonganteriorarms in
ing data. XyeloideaandMegalodontoideatobeapomorphic
Illustrationsweremadewithacameralucida. for Hymenoptera.
Outlinesofmusclespresentbutnotillustratedare InTenthredinoidea,theanteriorarms(af)can
represented by dashed lines. Some muscles not be reduced in size (Cimbicidae Fig. 8,
centraltothisstudywerenotconsistentlyfigured Blasticotomidae Fig. 20, and Nematus
(e.g.muscle180forSymphyta)andcautionshould (Tenthredinidae) Fig. 21), modified into support-
beexercised inderivingadditional interpretation ingcup-likestructures(Diprionidae,Fig.7),orlost
from the illustrations. Abbreviations referring to entirely so that the interfurcal muscles attach to
muscles are circled in all figures, skeletal charac- theanteriorfaceofthelateralfurcalarms(Argidae,
ters are not. The mesofurcal-mesopostnotal com- Pergidae Fig. 5, and most Tenthredinidae).
plex is abbreviated as MF-MPN complex. Rasnitsyn (1988) treated "fore arm short" as a
character state (his 2-3d) supporting
Tenthredinoidea and "fore arm reduced" (his 6-
RESULTS AND DISCUSSION 8a) for Argidae + Pergidae. Short arms, as in
Blasticotomidae (Fig. 20), are probably
Character Analysis plesiomorphic for Tenthredinoidea, and further
modifications of the arms or complete loss are
Character 1. Mesofurcal bridge derived within Tenthredinidae. It is possible to
The most significant modification of the code for several different character states within
mesofurca in Hymenoptera is the fusion of the Tenthredinoidea(small,absent,cup-shaped,etc.),
elongateanteriorarms(af)intoamesofurcalbridge but this would only introduce unnecessary ho-
(fb) that characterizes virtually all Apocrita. In moplasyintotheanalysis(i.e."absence"derived2
basal groups ofSymphyta (excludingCephoidea ormore times)ora seriesofautapomorphicchar-
244 Journalof Hymenoptera Research
Table 1.HomologyandtermsformusclesofthemesopostnotumandmesofurcaexaminedinNeuropteraandHymenoptera
Lettermadded todistinguish metathoracic muscles. Muscle fbl described intext.
—
Kelsey 1957 Con/dalus Hymenoptera
No Name Matsuda Daly Johnson Present Notes
1970 1964 1988 designation
Mesothoracicdorsal indirectmuscles
112 internal(ventral]longitudinal tl4 lph-2ph lph-2ph longitudinal flightmuscle Kelsey(1957)recognizedboth
ventral(internal, 112)anddorsal(external, 113)muscles
RecognitionofthetwomusclesinHymenopteraisunnecessary
112m metathoraciclongitudinal tl4 2ph-3ph 2ph-3ph reducedandattached laterallyinmostHymenoptera
114 scutellar-metanotal tl3 t,-t, t,-t, inHymenoptera,pairedmedialmusclespassingfrommeta-
notum(t,)toscutellumovermesopostnotum(PN,),externalin
somesawflies FromPN inNeuroptera
;
116 seconddorsaldiagonal t,-2ph t,-pn, dorsomedialattachmentonmesoscutumtoanteriorfaceof
laterophragma(pn,),attachmenttodorsalaxillarsurfacewhere
transscutalarhculahonpresent
Mesothoracicventral muscles
124 mesothoracicinterfurcal sl3 fu,-fu, fu,-fu, fromlateralfaceoffu, toanteriorfaceorarmsoffu, Kelsey
(1957)treatsasthreemuscles(124-126)andMatsuda(1970)as
bundlesofthesamemuscle Hymenopterahavemaximumof
twobundlesandhomologyofeachisuncertain
127 mesofurcal-spina sl4 fu,-lsps fu,-sps, spinaofprofurcatoapexoflateralarmoffu,.
181 metathoracicinterfurcal sl3 fuj-fu, • fu,-fu, ptohsrteeermiuorscflaecseo(f18l1a-te1r8a3l)arHmysmeonfofpu;tteorfau,haKveelsmeyax(1i9m57u)mtroefattswaos
180 metafurcal-spina sl4 fUj-spSj spinaofmesofurcatoapexoflateralarmoffu,
Tergopleural muscles
137 laterophragmal-basalare t-p87 t-ba, posteriorfaceoflaterophragma(=t,)toapodemeofbasalare
(ba,) Synonomywitht-p8isquestionable
Furcal muscles
150a posteriorfurcal-laterophragmal t-sl fu,-2ph fu,-pn, posteriorattachmentonlateralarmoffu,toanteriorprocessof
laterophragma(ap)
150b anteriorfurcal-laterophragmal t-sl fu,-pn, attachmentanteriorto 150aonanteriororlateralarmoffu,to
posteriorlobeoflaterophragma (pn,)
151 furcal-pleuralarm p-sl pl,-fu, pl,-fu,_ lateralsurfaceoffu,topleuralridge
170 coxalarhculation-furcal s-cx2 pl,-fu,t lateralsurfaceoffu2tocoxalprocessonpleuron
fbl furcal-basalare p-s3? fu2-pl37 fu,-ba, apexoflateralarmoffu2tobasalare(ba,),maybehomologous
withpupalmuscleofApis(Daly 1964),welldeveloped with
dorsalcapandapodemeinDipnon(onepreparationwhereba,
dissectedwithfu;-ba,andpl,-ba,bothattached). Possibly
homologouswithMatsuda'sp-s3fromfurcatoanteriormargin
ofsucceedingepisternum
Walkingand indirectflightmuscles
169 anteriorfurcal-coxal s-cx6 fu,-cx fu-cx fu,-cx anteriorbaseoffu tomediannmofcoxa.
;
173 posteriorfurcal-coxal s-cx3 fu2-cx fu-cx fu2-cx. attachmentonfu,posteriortomuscle169toposteromesalrimof
174 furcaldepressoroftrochanter s-trl hyh", fu,-tr, anteriorbaseoffu;(orarms)totrochanteralapodeme
Volume 3, 1994 245
Table2. Taxadissected forstudyofthemesofurcal-mesopostnotalcomplex.
Section: NEUROPTERIDA Trigonalyoidea
Mantispidae Mantispasp. Trigonalyidae Orthogonalyspulchella (Cresson)
Chrysopidae Chrysopasp.
Corydalidae Corydalussp. Ceraphronoidea
Myrmeleontidae Brachynemurussp. Megaspilidae Megaspilusfuscipennis (Ashmead),
Rhaphidiidae Rhaphidia sp. Trichosteresissp.
Ceraphronidae Ceraphron sp.
MECOPTERIDA
Section:
Bittacidae Bittacussp. Evanoidea
Meropeidae MeropetuberNewman Aulacidae Prislaulacusstrangahae(Rohwer)
Panorpidae Panorpa sp. Evaniidae Hyptw thoracica (Blanchard), Evaniasp.
Gasteruptiidae Gasteruptwn sp.
HYMENOPTERA
Order:
SYMPHYTA Ichneumonoidea
Xyeloidea Braconidae Alysiinae: Coelwiussp.; Hybrizontinae:
Xyelidae Macroxyelinae: Macroxyelaferruginea Hybrizon sp.; Macrocentnnae:
(Say); Xyelinae: Pleuroneurasp.,Xyela Macrocentrussp.; Miscogastennae:
minorNorton Apantelessp.; Rogadinae: genus?.
Ichneumonidae Ephialtinae: genus ?, Scambussp.,
Megalodontoidea Megarhyssa sp.;Ophioninae: Enicospilus
Pamphilndae Cephalciinae:Acantholydasp., sp.
Pamphiliinae: Pamphiliussp. Chrysidoidea
Plumarndae Plumana
sp.
Tenthredinoidea
Sclerogibbidae Probethylussp.
Blasticotomidae Blasticotomasp. Embolemidae Etnbolemus nearcticus (Brues)
Tenthredinidae Heteranthinae: Profenusacanadensis Dryinidae Anteoninae(female),Gonatopodinae
(Marlatt);Nematinae: Nematussp.; (male)
Selandriinae:Aneugmenusflavipes
(Norton), Strongylogasterfflcirn(Norton); Bethylidae Anisepyrissp., Epyrissp.
Tenthredininae: Filacussp.,Macrophya Chrysididae Amiseginae:Adelpheanisomorphae
sp. Krombein;Chrysidinae: Chrysissp.,
Dipnonidae Dipnoninae: Diprionsimilis (Hartig) Parnopesp.;Cleptinae: Cleptessp.
Cimbicidae Cimbicinae: Cimbexamericana Leach;
Ambnnae: ZaraeaamericanaCresson Vespoidea
Pergidae Acordulecerinae:Acordulecerasp., Tiphiidae Myzinumsp.
Syzygoninae: Lagideus ImexicanaSmith Sapygidae Sapyga sp.
Argidae Arginae:Argesp.,Durgoa matogrossensis Mutillidae Sphaeropthalminae(males,3genera)
Mai. Sierolomorphidae Sierolomorphacanadensis Provancher
Pompilidae Pepsinae: Calicurgushyalinatus Fabr.;
Cephoidea Pompilinae: Aporinellagalapagensis
Cephidae Cqjhuscinctus Norton, Rohwer,Aporussp.
Hartigia trimaculata (Say) RhopalosomatidaeRhopalosomasp.
Bradynobaenidae Bradynobaenus sp.
Siricoidea Formicidae Myrmicinae: Solenopsis invicta Buren
Anaxyehdae Syntexislibocedrii Rohwer (queen &worker);Formicinae:
Siricidae Siricinae: Urocerusalbicornis (Fabricius); Camponotusplanus F. Smith(queen),
Tremicinae: Tremexcolumba (Linnaeus) Paratrechinasp. (queen)
Scoliidae Scoliasp.
Xiphydrioidea Vespidae Eumeninae: Odynerussp.,
Xiphydriidae XipiudriaabdommalisSay Parancistrocerus sp.;Vespinae:
Dolichovespulasp., Vespulasp.
Orussoidea
Orussidae Orussus terminalisNewman Apoidea
Crabronidae Ectetnniussp.,Larrasp.
APOCRITA
Heterogynaeidae Heterogynasp.
Stephanoidea
Stephanidae Megischusbicolor(Westwood)
continued on nextpage
246 Journalof Hymenoptera Research
Table2 continued arm are joined (state 3). The anterior arms are
considered to be homologous with those of
Andrenidae Andrena sp. Xyeloidea and Megalodontoidea; therefore, state
AHAapnlitidhcaoteipdhaoendae NAApgoinmspaomdsealtlesimpf.oe,rnaCseLp.r.,,aBtLmoaamsbwsugps.lossps.,umTrsipg.onasp. 3hiisspcrhoabraabcltyedrer1i9vbe)dfirnocmlusdtaetse1C.eRpashnoiitdseyan(1w9i8t8h;
Megachilidae Megachilesp. Siricoidea + Vespina based on having the fore-
arms of the mesofurca long and fused for some
Proctotrupoidca distance. Although true forSiricoidea + Vespina,
Diaprndae AABenmlebyoutsriirntyarnei:cnhAaucesl:isspDt.ia,sssOpox.xy,yllAaacbbriiosspissepps..,t;asp., the aIrnmAsnaarxeyeolnilydaaepi(cFailgl.y1f0u)seadndinSCierpihciiddaaee.(Fig.
Diaprunae: Copterasp., Paramenia sp. 11),theanteriorarmsareelongateandfusedalong
Spilomicrus sp., Trichopna sp. mostoftheirlength (state4). Theanteriorarmsof
VMaonnhoomrancihidiadeae MVoannhoomrancihauesucsnp.emidarum Crawford Siricidae are laterally flattened (Fig. lib) and in
HReolpornodnahedae HReolporroursuasps.p. ditosrseanltivreielwenegatchh a(Frigm.c1a1na)b.eAdniasxtyiengluiidsaheedhaavloenga
Proctotrupidae Exallonyxsp.,Mwtavera (Fouts) similarstructure, including anteriorplacementof
Pelecimdae Pelecinuspolyturator (Drury) muscle 150b, but fusion of the arms is morecom-
plete (Fig. 10a). Posteriorly, the anterior furcal
Cynipoidea armsofAnaxyelidaeareconnectedby a thinhori-
Ihalndae Jbfl/ifl sp.
Eucoihdae genus 7 zontal plate ofcuticle.
AUoxvstidae Alloxystasp. InXiphydrndae(Fig.12),theanteriorarmsare
completelyfusedandformatransversemesofurcal
SPclealtiyognaisdtareoidea SMOacecmerahcsotfenlomebaiaeae:uabsy4snos/pnc.ar,iMsGurseyp.so,enbCsaeplc.okt(,ewlieSnapgaslrpea.s,ssi)o,n bs1ur24ri.fdagDceiess(psfltoaatrceme5mt)e,hneatpnoodsftmtehuresicoerlnetaistrte1a5dc0oharmsaeannldta1fno5rd0bmluatstoectrlhaeel
sp., Teleasinae: Tnmorussp. lateral arms suggests that fusion of the arms in
Platygastndae Inostemmatinae: hocybus sp., Inoslemma Xiphydriidaemaybeindependentofthefusionin
sP. Siricidae and Anaxyelidae.
Mymarommatoidea Orussidae(Fig. 13)exhibitcompletefusionof
MymarommatidaePalaeomymarsp the anterior arms into a smooth and bowed
mesofurcal bridge (state 6) with a strong median
Chalcidoidea (additionaldissections forworkin progress anterior process that is the attachment site for
not listed) muscles150and 124,asoccursinAnaxyelidaeand
Mymandae Gonafoccrus sp.
Siricidae.
Pteromalidae Cleonvminae: Cleonymussp., Ooderasp.
The groundplan states for the mesofurca of
Apocrita consists of 1) a complete mesofurcal
acterstates.Codingofcharacterstatesmustinpart bridge (as in Xiphydriidae and Orussidae), 2) an
reflectthelevelofanalysis. Atadifferentlevel,for anteriormedial projectionsupporting muscle 124
example in an analysis of the relationships of (fu^-fUj) (as in Xiphydriidae and Orussidae), and
Tenthredinoidea that is associated with a more 3) lateral displacement of muscle 150a (fu,-pn, )
extensivesurveyoftaxa,itmightbeappropriateto (asinXiphydriidae).NoApocritahavemuscle150
further partition thevarious shapes. Thesemodi- originating on the anterior projection of the
fications are difficult to characterize and here we mesofurca as in Orussidae. Because of the lateral
have combined them into one apomorphic state, displacement of muscle 150a, which is similar to
thereductionofwell-separatedanteriorarms(state Xiphydriidae (see character 2), Apocrita with a
2). mesofurcalbridge are coded as character state4.
A clear transformation series leading to the The mesofurcal bridge is absent (state 7) in
development of the mesofurcal bridge is found Ceraphronoidea (Fig. 25), Pelecinidae (Fig. 31),
withintheSymphytabeginningwiththeCephidae. some Chalcidoidea (including all Mymaridae),
InCephidae (Fig. 9), theanteriorarmsarenarrow Mymarommatidae, and Platygastridae (Fig. 28).
and elongate and only theextreme apices ofeach We consider that absence of the bridge is an
Volume 3, 1994 247
apomorphic loss of the type of bridge found in muscles150and 116,andthelossofeitherofthese
Xiphydriidae (state5), whichissimilar tothe type musclesisassociatedwithacorrespondingchange
found in most Apocrita. Assuming that presence instructureofthelaterophragma.Toavoiddupli-
of a bridge is a groundplan state for Apocrita cationofcharactercoding,thepresenceorabsence
(whether states 4, 5 or 6), losses within each of of certain structures of the laterophragma are
these taxa are considered irreversible (unlikely treated under other characters. For example, the
thatabridgecanberegained) and probably inde- anteriorapodeme is lacking in Neuropterida and
pendent. In Ceraphronidae, Pelecinidae, Mecopteridabutthiswasnotcoded as adifferent
Mymarommatidae, Platygastridae, and some stateforthischaracterbecauseitisreflectedinthe
Mymaridae,themesofurcaislyre-shapedwiththe differentiation of muscle 150a in Hymenoptera,
lateral arm terminating in a cup-shaped process which is dealt with as Character 3. A broad
thatsupportsmuscle150a.Whenthefurcalbridge laterophragma with a small anterior apodeme
is lost in Chalcidoidea (Aphelinidae, Encyrtidae, (state 0) occurs in Xyelidae, Pamphiliidae (and
Rotoitidae, Signiphoridae and Tricho- probably Megalodontidae), Blasticotomidae,
grammatidae), the shape of the mesofurca and Tenthredinidae, Argidae, Diprionidae, and
attachmentofmuscle150aareconsiderablydiffer- Cephidae.
ent. ThelaterophragmaofCimbicidae(Fig.8)pos-
sesses an exaggerated apodeme (ap) and an en-
Synonymy for mesofurcal bridge: largedposteriorlobe(pn,),whichisfusedwiththe
Siricidae & Vespidae: mesofurcal ring second phragma (2ph). The laterophragma is
(Tenthredinidae, Vespa,Weber 1925). Ichneu- unique in form and apparently autapomorphic.
monoidea: mesofurcal bridge (Stenobracon, InXiphydriidae(Fig.12),Monomachidae(Fig.
Alaml951).Aculeata:mesofurcalbridge(ArF2) 14), Vanhorniidae (Fig. 15), Cynipoidea (Fig. 22),
(Vespula, Duncan 1939); supraneural bridge Ceraphronoidea (Fig. 25) and most Diapriidae
(Apis, Snodgrass 1942). Chalcidoidea: arch of (Fig.29),thelaterophragmaisexcisedbetweenthe
thefurca(Monodontomerus,Bucher1948);ten- elongate apodeme (ap) and the posterior lobe
dinousarchofthemesofurca(Tetramesa,James (pn,)(statel).Inmostofthesetaxatheapodemeof
1926). thelaterophragmaextendsmediallyandhorizon-
tallyintothethoraciccavity,butinCynipoidea(cf.
Character 2. Laterophragma of mesopostnotum Fig.22),theapodemeisvertical.Theposteriorlobe
(pn2) islostinmostApocrita(incudingsomeDiapriidae),
In Neuropterida, Mecopterida, Xyelidae and but this was not coded as an additional state
Pamphiliidae, the laterophragma of the changeforthischaracterbecauseitreflectstheloss
mesopostnotumformsalobe(pn,,Figs.4,6)(state of the muscle 116 (Character 4). The anterior
0)thatextendsobliquelyintothemesothoraxfrom apodeme (=axillary lever) or associated attach-
thelateralcornersofthemesopostnotum,mediad ment for muscle 150a is present in all Apocrita.
ofthelateralattachmenttotheuppermesepimeron Additional character state changes for the
and lateral to the second phragma. The laterophragma in Apocrita are based only on
laterophragmainallofthesetaxaformstheattach- changes in the shape of the anteriorapodeme.
mentsiteformuscle 150(fu2-pn,,seeCharacter3), In Pergidae (Fig. 5) and Orussidae (Fig. 13),
muscle116(t2-pn„seeCharacter4)andmuscle137 thelaterophragmaisreducedtoanarrowtriangu-
(pnj-ba,). Theposteriorfaceofthelaterophragma lar process that forms an attachment for the ten-
formsthe attachmentsite formuscle 137(pn,-bav don ofmuscle 150 (state 2). This reduction is also
Fig. 3). Muscle137isusuallysmallanddifficultto associated with the loss of muscle 116. State 2
trace, but it is apparently lost in Pergidae and all could be derived from eitherstate or state 1.
Apocrita. In Apocrita, the axillary lever(ap) occursin a
In Xyelidae (Figs. 3, 4) and most Symphyta variety of shapes that probably have different
(Figs. 6, 8, 9), an apodeme (ap) is present on the effects on leverage of the laterophragma with re-
anterolateral marginofthelobe thatserves as the spectto thefourthaxillaryscleriteand thesecond
attachment site for muscle 150a (fu,-pn2 ). The phragma. In all Apocrita the apex of the axillary
laterophragma is functionally coupled with lever maintains a connection with muscle 150a
24S Journal of Hymenoptera Research
(fu^-piv )•TheplesiomorphicleverforApocritais muscle150a)(state4?).InFormicidae(Fig.43),the
narrow and inflected medially into the thorax as leverformsanarrow, twisted apodeme (state 1?).
foundinXiphidriidae(statel)andoccurseitherin Neither Bradynobaenidae and Formicidae were
associationwithaposteriorlobe(mostDiapriidae, broadly surveyed and other forms may exist.
Monomachidae (Fig. 14), Vanhorniidae (Fig. 15), In Ichneumonidae the axillary lever is either
Ceraphronoidea(Fig.25)andCynipoidea(Fig.22) closely appressed to the second phragma and
orwithout theposterior lobe (Tngonalyidae (Fig. similar to the lever found in Vespoidea and
23), Stephanidae (Fig. 24), Diapriidae (Fig. 29), Apoidea(state5),orrod-likeandextendingmedi-
Proctotrupidae (Fig. 32), some Ichneumonidae, ally into the mesolhorax (state 1), or inflected
Mymarommatidae, and Chrysidoidea (Figs. 34- mediallyand dorsally (Fig. 17a). A robust leveris
39) (except some Chrysididae). The axillary lever notfoundinBraconidae,includingHybrizontinae
exists in a variety of forms in Apocrita but in (Fig. 33), in which it was knob-like or short and
shapes that are difficult to separate into discrete slightly deflected ventrally (state 1), similar to
states,especiallywithoutamorethoroughsurvey Trigonalyidaeand someProctotrupoidea. The le-
of the apocritan taxa. In all cases where the lever ver of Gasteruptiidae (Fig. 26) is similar to some
was narrow and inflected medially the character Ichneumonidaebut is oriented vertically with re-
was coded as state 1. spect to the second phragma. In Oodera
In Platygastridae (Fig. 28), some Scelionidae (Pteromalidae), the lever is robust, appressed to
and most Chalcidoidea, the axillary lever is de- thesecond phragma andhorizontal (state5). This
flected ventrally (state 3). In Mymarommatidae, form of the lever appears to be convergent with
the leverisrobustand inflectedmedially (statel). Ichneumonidae and Aculeata, since in Oodera
In Sparasion (Scelionidae; Fig. 16), the lever is muscle150aattachestotheentireventralaspectof
reduced to a small cup-shaped lobe on the the apodeme as in otherChalcidoidea.
laterophragma (autapomorphic and not coded). All Apiformes have the axillary lever sepa-
In other Scelionidae and Mymaridae the lever is rated(state6)asanindependentsclerite(Snodgrass
short, narrow and medially inflected (statel). 1942). This feature was verified in all of the
TheaxillaryleverinStephanidae(Fig.24)and Apiformes examined here. The apical connection
most Chrysidoidea (Figs.35-38, also in Fig. 34but ofthemesopostnotumisweakandencasedby the
this view is slightly different) is elongate and cup-shaped basal process of the axillary lever
strongly inflected medially (state 1). This confor- (Figs. 45,54).
mation of the lever is likely the precursor to the
leverfound inApoideaandVespoidea,discussed Synonomy for laterophragma:
below. However, in Cleptinae and Chrysidinae Symphyta: lateral lobe of second phragma
(Chrysididae) the lever is reduced (state 4) form- (2ph) (Daly 1963). Icnneumonoidea: muscle
ing a short, broad process attaching to a broad bearing process of mesopostphragma
tendon of the shortened muscle 150a (Fig. 40). (Stenobracon, Alam 1951); axillary lever
In Apoidea (Figs. 45, 46, 54) and Vespoidea (Snodgrass1942).Cynipoidea:mesopostnotal
(Figs. 41, 42, 44) the axillary lever is robust and apodeme (Ibalia, Ronquist and Nordlander
strongly appressed to the inner surface of the 1989); 2ph (Daly 1963). Aculeata: axillary le-
second phragma (state 5). This type of lever was ver (Apis, Snodgrass 1957; Bombus, Pringle,
found in all Apoidea examined and is associated 1957,1960,1961);accessoryscleriteofthefourth
with a robust muscle 150a. Except in axillary sclerite (Apis, Snodgrass 1910); inner
Bradynobaenidaeand Formicidae,muscle 150ais process of mesopostphragma (Vespa, Weber
conical and attached to the lever by a narrow 1925 [states that lever turns apex of
tendon or robust and nearly tubular (Mutillidae mesophragma and theconnected axillary4]);
andSapygidae). InSierolomorphidae, theleveris anteriorprocessofmesopostphragma(MPPhJ
notclosely appressed to the second phragma (in- (Vespula, Duncan 1939). Hymenoptera: axil-
flectedmediallyabout30°),butthiswasnottreated lary lever (Matsuda 1970).
asadifferent state (intermediatebetween states 1
and5).InBradynobaenidae,theleverisreducedto Character3. Furcal-laterophragmal muscle
a rounded knob (attaching to a narrow tendon of In Neuropterida and Mecopterida, only a
Volume 3, 1994 249
single muscle (150, fu2-pn2) acts between the lost in all Apocrita without a posterior
mesofurca and laterophragma of the laterophragmal lobe. Autapomorphic losses of
mesopostnotum (state 0) (Kelsey 1957, Matsuda muscle 150a occurs in workers of Formica and
1970). In the majority of Symphyta, including Camponotus (Markl 1966, Saini et al. 1982).
Xyelidae and Pamphiliidae, two distinct muscles
(150a and 150b) operate antagonistically on the Synonymy for muscle 150:
enlarged laterophragma (Figs. 2,3, 4, 6). The pre- Tenthredinidae: Ilisml (Dolerus, Schizocerus,
sumed divisionofmuscle 150into twomusclesis Tenthredo, Weber 1927), 25 & 26
considered as an apomorphy for Hymenoptera (Euthomostethus,Maki1938). Ichneumonidae:
(state 1). Muscle 150a (fu,-pn^) originates on the 25 (Psilopsyche, Maki 1938); 63 (Stenobracon,
lateralarmsofthemesofurcaposteriororlateralto Alam 1951). Aculeata: 25 (Vespa, Maki 1938);
the origin of 150b and inserts onto an anterior 78(Formica,Markl1966;Apis,Snodgrass1942);
apodeme or process of the laterophragmal lobe IIdv2 (Vespula, Duncan 1939); Ilism (Vespa,
(Figs. 4, 6, 7, 9). Muscle 150b (fu,-pn2 ) originates Weber 1925); fu2-2ph (Apis, Daly 1964). Hy-
anteriorly or medially on the lateral or anterior menoptera: t-sl (Matsuda 1970).
armsofthemesofurcaandbroadlyattachestothe
marginofthelaterophragmallobe(Figs.4,6,7,9). Character4. Seconddorsal diagonal(=phragmal
The fibres of muscle 150b are often arranged so flexor) muscle
that the anteriormost fibres attach to the Muscle116(t2-pn2)isfoundattachingbetween
posteriormost or innermost margin of the the mesonotum and the anterior face of the
laterophragmal lobe, although this is dependent laterophragmallobeinNeuropterida,Mecopterida
on the size of the muscle and lobe. and mostSymphyta (Figs. 2, 3, 12, 14, 15, 20), and
Ifbothmusclesarepresent,muscle116(t,-pn,) isthereforeplesiomorphicforHymenoptera(state
isalsopresent.Lossofmuscle150b(state2)occurs 0).Muscle116,andtheassociatedposteriorlobeof
in Cimbicidae, Monomachidae, Vanhorniidae, the laterophragma, is lost (statel) in Pergidae,
Diapriidae,Cynipoidea, and Ceraphronoidea, all Orussidae and most Apocrita. It seems unlikely
of which have retained both the laterophragmal thatafunctionalcomplexcomposedofbothmuscle
lobe (presumably the formerpointofinsertion of 116 and the corresponding posterior lobe of the
muscle 150b) and muscle 116. All Apocrita have laterophragma could be regained, and we con-
lostmuscle 150b. In Anaxyelidae (Fig.10), muscle sider the apomorphic state (loss of muscle and
150b is attached totheposteriorface oftheposte- lobe)tobeirreversible.Anassumptionofirrevers-
rior lobe (versus the margin) and muscle 150a is ibility has obvious consequences for models of
retained. Because of a similar placement and at- characterstatechange which arediscussed in the
tachmentofmusclesinSiricidae(Fig. 11),itcanbe later section on parsimony analyses. Muscle 116
postulated that muscle 150a is lost and 150b re- and the corresponding posterior lobe are present
mains (state 3). When both the laterophragmal in Monomachidae, Vanhorniidae, Cynipoidea,
lobe and muscle 116 are missing, as in Pergidae Ceraphronoidea and most Diapriidae, and it is
(Fig. 5) and Orussidae (Fig. 13), it is difficult to likely that this complex is the groundplan for
assess which muscle, 150a or 150b, has been lost. Apocrita(Daly1963;Gibson1985).Thelossofthis
We could assume that muscle 150b is lost in both complex in Pergidae and Orussidae is therefore
families. However, the forward attachment of convergent with the loss in most Apocrita.
muscle150tothemesofurcainOrussidaesuggests
that it is homologous with muscle 150b of Synonomy formuscle 116:
Anaxyelidae and Siricidae. Therefore, the con- Symphyta: 21 (Euthomostethus, Maki 1938).
figuration in Pergidae and Orussidae could also Symphyta, Monomachidae, Diapriidae,
be treated as an parallel loss of muscle 150a. Be- Vanhorniidae, Ceraphronoidea, Cynipoidea:
causeofthisuncertainty,wecodethereductionto t,-2ph(Daly1963;Gibson1985).Hymenoptera:
a single muscle in Pergidae and Orussidae as of tl2 (Matsuda 1970).
questionable homology (state ?). Based on the
presence ofmuscle 150a in the apocritan families
mentioned above, weassume thatmuscle 150b is
250 Journalof Hymenoptera Research
Character 5. Mesopostnotum and scutellar- the mesosoma) and muscle 114 passes externally
metanotal muscle overthemesopostnotumasatendonenclosedby
In Neuropterida and Mecopterida, the a sheath of connective tissue (state 2, broadly
mesopostnotum is broadly exposed medially; al- exposed and 114 external). In groups with an
though in Corydalus (Megaloptera) the external muscle and and an exposed
mesopostnotum is weakly sclerotized medially mesopostnotum(state2),theanteriormedialmar-
and appears to be split. The scutellar-postnotal gin may be shallowly or deeply emarginate (ap-
muscle(muscle114,t2-t3;absentinBittacus)passes pearing split) underneath muscle 114. In some
internally from its origin on the scutellar area of genera of Tenthredinidae and Dipnonidae, the
the mesonorum to the anterior medial margin of mesopostnotum is obscured by posterior devel-
themesopostnotum(Kelsey 1957;Matsuda 1970). opment of thescutellum,butotherwiseconforms
Within Hymenoptera, changes in thestructure of to state2 (see Character6).
themesopostnotumandattachmentofmuscle114 In Anaxyelidae, the mesopostnotum and
arecorrelated;however,theattachmentofmuscle muscle 114 are the same as in Xyelinae (Fig. 47).
114 to the mesopostnotum is unique with respect Initially,wecoded thisasthesamecharacterstate
to the outgroup, and the outgroup is scored as a (state1).However,thiscausedproblemsindevel-
separate state (state 0). opinganadditivecodingschemethatwouldforce
In Hymenoptera, muscle 114 (t,-t3) arises the anaxyelid state to be aucapomorphic and not
dorsomedially from a fan-shaped attachment on transitionalbetweenstates2and4.Toresolvethis
the mesonorum and passes medially over the problem, Anaxyelidae wereassigned anew char-
mesopostnotum (rarely under), to a narrow me- acter state (state 3), which is treated as an
dial attachment on the anterior margin of the autapomorphy. In all of the analyses, coding for
metanotum. InallSymphyta,ourdissectionsindi- Anaxyelidaeand Xyelinaeasstate 1 orstate3had
cate a posterior attachment of muscle 114 to the no effect on tree topology.
metanotum. Our observations are supported by In Siricidae, a median vertical process on the
illustrations of attachments to the metanotum in anteriormarginof themetanotum forms the pos-
Weber (1925) for Vespa (his IldlmJ and Markl teriorattachmentofmuscle 114, which isinternal
(1966) for Apis (his 70). In Eutomostethus and lacks any connective sheath. Although the
(Tenthredinidae), muscle 114 was described as process is unique for Hymenoptera, this confor-
inserting on the median membrane that divides mation isconsidered tobe a modification ofstate
the mesopostnotum (Maki 1938, his 19 & 20), but 2eventhoughthemesopostnotumisgenerallynot
inTenthredinidae muscle 114 passes through the exposed. The scutellum often extends over the
membrane to the metanotum. The attachment of metanotal process and, as in some Tenthre-
muscle 114 to the metanotum is apomorphic for dinoidea, the internalization of muscle 114 and
Hymenoptera. mesopostnotum may be secondary. Snodgrass
Determination of the groundplan condition (1910)reportedthatthemesopostnotumofTremex
for Hymenoptera is complicated by the presence cohtmba was exposed medially; however, we ob-
ofdifferentcharacterstates inthetwoextantsub- served an exposed mesopostnotum only in some
familiesofXyelidae.InXyelinae(Xyelidae)(based specimens of Urocerus. Some Cephidae (Fig. 49)
on Pleuroneura, Fig. 47, and Xyela), the also have a similar attachment to a peg-like pro-
mesopostnotum (PNJ is broadly exposed dor- cess (mp) on the metanotum.
sallyandthescutellar-metanotalmuscle(114,t;-t,) In Xiphydriidae (Fig. 50), Orussidae and
passesunderthemesopostnotumthroughasmall Apocrita,muscle114(t2-t3)andthemesopostnotum
emargination of its posterior margin (state 1, (medially)arecompletelyinternalandmuscle114
broadly exposed and 114 internal). In passes medially over the second phragma (state
Macroxyelinae (Xyelidae) (based on Macroxycla 4). An autapomorphic modification of state 4 is
ferrunginea (Say), Megaxyela tricolor Norton, found in Xiphydriidae, in which thecuticleofthe
Megaxyela aviingrata (Dyar) and Xyelicia neurotica second phragma (between the lobes of the
Ross),Megalodontoidea(Fig.48),Tenthredinoidea pseudophragma)encirclesthemuscletendonasit
and Cephoidea (Fig. 49), the mesopostnotum is passes through to the metanotum. Furtherdevel-
exposeddorsally (dependingon thecontortionof opment of the mesopostnotum and its associated