Table Of ContentInternationalJournalofOdonatology
Vol.14,No.1,March2011,69–82
Ovipositor morphology and egg laying behaviour in the
dragonfly Lestes macrostigma (Zygoptera: Lestidae)
NataliaA.Matushkinaa*andPhilippeH.Lambretb
aDepartmentofZoology,BiologicalFaculty,KyivNationalUniversity,vul.Volodymirs’ka,64,Kyiv,
01033,Ukraine;bCabanedeLigagneau,MaraisduVigueirat,Mas-Thibert,13104,France
(Received24July2010;finalversionreceived18November2010)
LestesmacrostigmaisastenotopicdragonflyspeciesofWesternPalaearcticdistributionthathashigh
conservationstatusalmostthroughoutitsrange.Itinhabitsmainlybrackishwaterwithatypicalplant
species,seaclub-rushBolboschoenusmaritimus.Duetotheabsenceofspecialinvestigations,thenature
ofthisinsect–plantassociationisnotclearlyunderstood,butitwassupposedthatL.macrostigmaprefersegg
layinginB.maritimus.Inthispaperwedescribetheovipositormorphologyandtheegglayingbehaviour
ofL.macrostigmaindetail.Thecuttingovipositorrevealsseveralmorphologicalpeculiaritiesrecorded
previouslyinotherlestids.Theinternalsurfaceofthevalvesrevealsrichmicrosculpture.Numeroussingle
andclusteredsensillaofdifferentshapearefoundonthevalvesandstyliandareprobablyinvolvedin
oviposition–plantrecognitionbyfemalesand/orinproductionofaneggclutch.Ovipositioniscarriedout
instemsofB.maritimusandJuncusmaritimus.Aneggclutchconsistsofarowofsingleeggsdeposited
inlinealongthelongaxisofaplant.Resultsarediscussedinthelightofpossiblemorphologicaland
behaviouraladaptationtoovipositionintospecificplantsubstrates.
Keywords: Odonata; dragonfly; Zygoptera; Lestidae; Lestes macrostigma; ovipositor morphology;
egglaying;eggclutch
Introduction
The act of egg laying is very important for the continuation of nearly all insect species. As
insectswithaquaticlarvae,dragonfliesfaceaspecialproblemofdetectingsuitableoviposition
siteswithintheaquaticenvironment.Eggsmustbedepositedinanareathatprotectsthemfrom
possiblepredators,providessuitableenvironmentalconditionsforeggdevelopment,andprovides
newlyhatchedlarvaewithreadyaccesstowaterandnutrition.
In Zygoptera, females lay eggs mainly in plant tissues using their well-developed cutting
ovipositor (Rostand, 1935). There is evidence that some dragonfly species show clear prefer-
ences in selecting plant species or even parts of plants for oviposition (Bick & Bick, 1970;
Grunert, 1995; Martens, 1992, 1993, 1994; Robert, 1958; Wildermuth, 1993). Egg laying in
specific substrates requires adaptations such as an ovipositor of certain mechanical properties,
whichisequippedwithreceptorsforexploringsuitablesites(seee.g.Matushkina&Gorb,2002a,
*Correspondingauthor.Email:[email protected]
ISSN1388-7890print/ISSN2159-6719online
©2011WorldwideDragonflyAssociation
DOI:10.1080/13887890.2011.568190
http://www.informaworld.com
70 N.A.MatushkinaandP.H.Lambret
2007).However,dependenceofovipositorstructureindragonfliesontheegg-layinghabitisstill
insufficientlystudied.
This paper aims to describe thoroughly the ovipositor morphology and egg laying in Lestes
macrostigma (Eversmann, 1836). This is a stenoecic species that occurs mainly around brack-
ish water (Jödicke, 1997; Plattner, 1967; Robert, 1958). Whereas the natural habitat of L.
macrostigma covers a wide region of the South Palaearctic from the Mediterranean to Siberia
and the CentralAsia, the regional distribution of this species is patchy and very local in most
areas (Boudot et al., 2009; Dijkstra & Lewington, 2006; Jödicke, 1997; Sahlen et al., 2004).
An important aspect of the association of L. macrostigma with brackish waters is the usual
presence of a characteristic coastal plant, sea club-rush Bolboschoenus maritimus (L.) Palla.
ItwassupposedthatadultsofL.macrostigmanotonlypreferthisplantforoviposition,butalso
usedthemtoidentifythewatersthataresuitableforlarvaldevelopment(Jödicke,1997).However,
specialinvestigationsofchoiceoftheovipositionplantbyL.macrostigmaaswellasofitshabitat
selectionareabsent.InspiteofitsstrongconservationstatusfromEuropeantoregionalscales,
L.macrostigmaisstillpoorlystudiedand,withregardtoconservation,increasingtheknowledge
ofitsbiologyisofprimaryconsequence(Dupont,2009;Lambretetal.,2009).
Materialsandmethods
Morphology
Adult females of Lestes macrostigma were collected byAlex Gumovsky from South Ukraine
(KhersonProvince,GolopristanskyDistrict,surroundingsofvillageRybal’che,saga,15–29June
2005;46◦28(cid:3) N/32◦14(cid:3) E).Fifteenfemaleswereexamined.Terminalabdominalsegmentswere
dissected in median (13 specimens) and frontal (two specimens) planes. The musculature was
examined in water under a stereo microscope by manual dissections and subsequent layer-by-
layerreconstructionsofthemuscles.Thencuticlepartsweremaceratedin10%KOH,examined
inglycerineunderastereomicroscopeOlympusC41andphotographedwithanOlympusC4040
camera,usingOlympusDP-SoftVersion3.2.ForaSEMstudythecuticularpartsofthreefemales
were washed in distilled water, dehydrated in a graded ethanol series and in acetone, critical
pointdried(OMCPD7501),sputteredwithgold-palladium(OM-SC7640)andexaminedwitha
ZeissEVO-50SEM.Ageneraldescriptionoftheodonateendophyticovipositorwasprovidedby
Matushkina(2008).
Ovipositionbehaviourandmeasuringofeggclutch
OvipositionwasstudiedduringJuneandJuly2008andinJune2009intheMaraisduVigueirat
(43◦32(cid:3) N/04◦45(cid:3) E,Camargue,France).ThissiteisaprotectedareabelongingtotheConserva-
toire du littoral and covers 1200ha that are mainly composed of marshes. Lestes macrostigma
breedsintemporarybrackishpools,wherefemalesovipositinBolboschoenusmaritimusandin
Juncus maritimus Lam. Egg laying behaviour was studied on sunny and calm days (i.e. clouds
covering less than 50% of the sky and wind speed up to 5.5m/s) from 11:00am to 03:00pm
by direct observations made with binoculars (ZeissVictory 10×42 T*FL) and reconstruction
afterwardsfromvideosandpicturesmadewithaNikonD90camera.Twenty-twofemalesmaking
708incisionsinsubstratewereobserved.OnetandemwasfilmedovipositinginJ.maritimusand
anotherlonefemalewasfilmedovipositinginB.maritimus;thosetwofilmsallowedustostudy
substrateexaminationbehaviourandthepositionofthefemaleabdomenduringsubstratepenetra-
tion.FourstemsofJ.maritimusbearingeggclutchesofL.macrostigmawerestudied.Eggclutches
weremeasuredwithaZeissStemi2000stereomicroscopeequippedwithamicrometricocular.
OvipositormorphologyofLestesmacrostigma 71
Figure 1. Egg laying of Lestes macrostigma in the sea rush, Juncus maritimus, and schema of clutch measuring.
Drawingsfromphotos:(a)lateralviewoftandemwithovipositingfemale,eggclutchispartlyuncovered;(b)dorsal
viewofovipositingfemalethatswungandrotateditsabdomenfromsidetosideduringinsertionoftheovipositor,egg
clutchispartlyuncovered,d1isdistancebetweentwosuccessiveincisions;(c)dissectionofaneggclutchinlateralview,
αistheanglebetweentheeggaxisandtheplantsurface;(d)partialdissectionofaneggclutchindorsalview,βisthe
anglebetweeneggaxisandthelinerunningparalleltothedirectionoftheplantfibres,γ istheanglebetweentheline
connectingtwosuccessiveinsertionsandthefibredirectionoftheplanttissue,d2isshortestlineardisplacementofthe
eggfromthelinerunningthroughthepreviouseggparalleltothedirectionoftheplantfibres.Arrowshowsbackward
movementofovipositingfemale.
Additionally,planttissueswerepartlyremovedandthepositionofeacheggwasphotographed
insagittalandfrontalplaneswiththeNikonD90.Thelocationoftheeggwithinplanttissuewas
measuredfrompictures.Thefollowingparametersweremeasured(Figure1):(1)egglength,L;
(2) distance between two successive eggs, d ; (3) shortest linear displacement of the egg from
1
thelinerunningthroughthepreviouseggparalleltothedirectionoftheplantfibres,d ;(4)the
2
angle α between egg axis and the plant surface; and (5) the angle β between egg axis and the
linerunningparalleltothedirectionoftheplantfibres.Fromparameters(2)and(3),theangle
γ betweenthelineconnectingtwosuccessiveeggsandthefibredirectionoftheplanttissuewas
calculated.All measurements are given by mean ± standard deviation, if not otherwise stated.
Linearmeasurementsaregiveninmm.Positiveornegativevalueofangularmeasurementsinβ
andinγ signifiesdeviationtotherightortotheleft,respectively.Thestatisticswereanalysed
usingthePast2.04softwarepackage(Hammeretal.,2001).TheShapiro–WilkWtestwasused
totestthenormalityofthedata.Non-normallydistributeddataarecharacterizedbymedianand
range,andaMann–WhitneyUtestwasusedtotestdifferencesbetweentwogroups.
Abbreviations
a medialapodemeofbasalplateofovipositor
aAp anteriorapophysisofV3
b lateralapodemeofbasalplateofovipositor
c anteromesalapodemeonanteriorcarinaof9thtergite
d anterodorsalapodemeonanteriorcarinaof9thtergite
Ga gonangulum
Lam basalplateofovipositor(laminavalvarum)
M1-M8 musclesofovipositor
pAp posteriorapophysisofV3
piv internalsclerite,orposteriorintervalvula
PS9 poststernumof9thsegment
St stylus
V1/V2/V3 first/second/thirdvalvesofovipositor(valvulae1/2/3)
72 N.A.MatushkinaandP.H.Lambret
Results
Morphologyofovipositor
Cuttingvalves
Cutting valves slightly curved dorsad, with expanded bases (Figures 2–4). PairedV1 fused in
mostbasalregion.DorsalmarginofeachV1formingalongitudinalgroove(aulax),providinga
slidingarticulation(olistheter)withV2(Figure3a,c).ExternalsurfaceofeachV1withfiveorsix
transverseridgesindistalhalf,slightlyenlargedinapicaldirection.Lateralmarginsofapicesof
bothV1slightlyserrated(Figure3a,c).Numerouscoeloconicandcampaniformsensillascattered
on external surface of V1. Basis of V1 with two clusters of differently directed campaniform
Figure 2. ScanningelectronmicrographsoftheovipositorofLestesmacrostigma:(a)lateral(external)view;(b)medial
(internal)view.
OvipositormorphologyofLestesmacrostigma 73
Figure 3. ScanningelectronmicrographsofthefirstcuttingvalveofLestesmacrostigma:(a)generalview,insetsindicate
positionsof(b)and(c);(b)lateralviewofthebasalpart,insetshowscampaniformsensillum;(c)lateralviewinareaof
apicalridgesandserrations,insetshowssinglesensillum;(d)internalviewoftheapicalhalf,insetsshowmicrosculpture
of“apicallock”andpositionof(e);(e)“ventrallock”andinternalmicrosculpture,insetshowssinglecloven-hoof-like
scale;(f)ventralviewofuncovered“apicallock”.d:distaldirection.Arrowheadsmarksensilla(black),microsculpture
(white)andserration(empty).
sensilla – those in proximal cluster oriented perpendicular to long axis of V1, those in distal
clusterorientedparalleltolongaxisofV1(Figure3b).InternalsurfaceofV1withasystemof
longitudinal and oblique ravioli-like ribs along ventral margin and apical part, which probably
serve to keep the two halves ofV1 together (Figures 3d–f, 5a). Internal microsculpture ofV1
consisting of cloven-hoof-like scales and corrugations (Figure 3d–f). Expanded base of each
V2 with field of short setae externally (Figure 4a).V2 surface near basis with numerous firm
knobbles, each with sensilla inside (Figure 4a–c). Distal half ofV2 with 11 transverse ridges
(Figures 2a, 4d). Knobbles reduced in apical direction and disappearing completely near most
proximalridge.VentraledgesofeachV2formingalongitudinalrail(rhachis),formingapartof
the sliding articulation with aulax ofV1 (Figure 4e). No connection between the dorsal edges
74 N.A.MatushkinaandP.H.Lambret
Figure 4. SecondcuttingvalveofLestesmacrostigma,scanningelectronmicrographs(a,c–g)andtransmissionlight
micrograph(b):(a)lateralviewofthebasalpartwithfieldofshortsetae,insetshowssingleseta;(b)internalviewin
amiddleareawithsmoothedknobble-likecuticularprojectionaroundeachsensillumandtrans-cuticlecanalsrunning
toeachsensillum;(c)knobbleswithsensillainthebasalarea,dorsolateralview;(d)dorsolateralviewinareaofapical
ridges;(e)internalsurfaceandrachis;(f)internalmicrosculptureconsistingofcomb-likescales;(g)microsculptureof
rachisconsistingoffinger-likescales.d:distaldirection,l:lateraldirection.Arrowheadsmarksensilla(black),comb-like
(white)andfinger-like(empty)scales.
of theV2 pair. Internal surface ofV2 with comb-like microspinations, surface of rhachis with
finger-shaped microspinations (Figure 4b, e–g). Unpaired internal sclerite (piv) small, slightly
compressedlaterallyandconnectedtobasesofbothV2bymembranouscuticle(Figure2b).
Basalplateofovipositor
Basal plate of ovipositor (Lam) represented by a group of three fused sclerites connecting first
valveswithsterniteofS8andtergiteofS9.CentralpartofLamformedbypairedgonocoxaeof
OvipositormorphologyofLestesmacrostigma 75
Figure 5. ScanningelectronmicrographsofsheathingvalveandstylusofLestesmacrostigma:(a)internalviewof
apicalpartsofovipositorshowingvalvesinrestingposition;(b)apexofstylus;(c)internalviewofapicalpartofcarina;
(d)externalviewofapicalpartofcarina;(e)fieldofcampaniformsensillaonbaseofstylus;(f)ventralviewofcarina;
(g)twocampaniformsensillaofstylus;(h)internalmicrostructuresofsheathingvalveconsistingofcomb-likescales.d:
distaldirection,l:lateraldirection.Arrowheadsmarkcampaniformsensilla.
S8 fused medially. Posterolateral part of Lam comprising paired anterior parts of gonangulum
(Ga)(Figures1,6b),andslightlymovablerelativetothecentralpartofLam.Endoskeletalpaired
medial and lateral apodemes serving as attachment points of muscle M1 and M2, respectively
(Figures2a,b,6).
Sheathingvalves
Sheathing valves (V3) ensheathing cutting valves laterally in resting position (Figure 5a).
EndoskeletalpartofeachV3withtwoapophyses,aApandpAp,bearingattachmentsofmuscles
76 N.A.MatushkinaandP.H.Lambret
Figure 6. MusculatureoftheovipositorofLestesmacrostigma,medialview:(a)internallayer;(b)externallayer.
M4andM5,respectively(Figures2b,6).ExternalsurfaceofeachV3withscatteredlong,thin
setaelaterally,ventraledgeofeachV3providedwithrowoflargeteeth,withsinglerobustsetajust
posteriortoeachtooth(Figure5c,d,f).Distaltoothlargest,withsevenrobustsetae(Figure5c,d).
TeethofV3formtogetherabearingedge,orcarina,bywhichafemaleleansagainstanoviposi-
tionsubstrateduringegglaying.MovableStabovedistaltoothofcarina,cylindrical,somewhat
swollenatbasis(Figure2).SurfaceofStcoveredwithsparseshortthinsetaedirectedapically.
ApexofStwithshortrobustsetaeformingbunchonventromedialsurface(Figure5b).Fieldof
campaniform sensilla on ventromedial surface of swollen basis of St, oriented parallel to long
axisofSt(Figure5a,e,g).Comb-likemicrospinationsonmedialwallofV3(Figure5h).Paired
elongatedsclerite(posteriorpartofgonangulum)situatedlateraltoV3andconnectedtotergite
ofS9viafusionandtoV3viahighlymovablearticulationbeneathofpAp(Figure2a).
Musculature
Musculature of ovipositor represented by one unpaired and seven paired muscles (Figure 6).
PairedM1originatingonlateralpartof8thtergiteandinsertingonmedialapodeme(a)ofLam.
PairedM2originatingonposteroventaledgeof8thtergiteandinsertingonlateralapodeme(b)of
Lam.PairedM3connectinglateralpartof8thtergiteandanteromesalapodeme(c)onanterior
carinaof9thtergite.PairedmusclesM4andM5largest.M4originatingonanterodorsalapodeme
(d) and lateral wall of 9th tergite and inserting on aAp ofV3. M5 originating on dorsolateral,
lateralandventralpartsofS9andtheelongatedscleriteandinsertedonpAp.PairedM6divided
OvipositormorphologyofLestesmacrostigma 77
intotwofascicles,anteriorstraightM6.1andposteriorfan-shapedM6.2.M6.1originatingonV3
beneathaApandinsertingonbasalpartofV2directly.M6.2originatingonV3beneathpApand
onPS9,insertingonbasalpartofV2viatendon,andexhibitingatleastthreeregionsofdifferently
orientedmusclefibres.M7,theonlyunpairedmuscleoftheovipositor,runningtransverselyand
connectingthetwoV3beneathpAp.PairedM8attachingoneithersideofinternalsclerite(piv)
andinsertingonV3beneathofpApandonPS9.
Ovipositionbehaviour
Thefollowingdescriptionisbasedonobservationsofsuccessfuloviposition,duringwhichegg
clutchesconsistingofseveraleggswereproduced.Aftercopulation,malesmainlyaccompanied
their mates in tandem. Oviposition was mostly performed in vertically directed stems, but also
in broken and therefore horizontal or oblique directed stems of Bolboschoenus maritimus and
Juncus maritimus, either green, partially dried, or entirely dried for J. maritimus only. Height
ofovipositionsiteswassignificantlylowerinB.maritimusthaninJ.maritimus(B.maritimus:
median=100mm, n=58, W=0.92, p =0.001; J. maritimus: median=150mm, n=74,
W=0.92, p =0.0003; U=1056, p <0.0001). No underwater oviposition was observed.
Shortly after landing on a stem, females performed repetitive movement patterns that resulted
inproductionofaneggclutch.Thefemalebentitsabdomeninsoastoleantheovipositoragain
theplantsurface,segments3–4and4–5bothformingarightangle(Figure1).Beforeshestarted
toinsertherovipositorintheplant,shetouchedthesubstratewiththeovipositoruptosixtimes.
Thesetouchesmayprovideinformationleadingtoachoiceofinsertionsite(seeLutz&Pittman,
1968).ThenovipositorvalvesV1andV2protrudedfromV3andbegantomovealternately,grad-
uallypenetratingmoredeeplyintoplanttissue.Thepositionoftheovipositortipvariedsomewhat
duringthistimedependingonfemalebodyadjustmentaftertheovipositorwasdefinitelyposi-
tioned (Figure 1): between the mid-legs (B. maritimus: 20%, n=10), between the mid- and
hind-legs(B.maritimus:60%;J.maritimus:47%,n=13),betweenthehind-legs(B.maritimus:
10%; J. maritimus: 40%), or slightly behind the hind-legs (B. maritimus: 10%; J. maritimus:
13%).Duringovipositorinsertionthefemaleslightlyswungandrotateditsabdomenfromsideto
side(Figure1b).Whenitscuttingvalvesbecameentirelyinsertedintheplant,thefemalestayed
motionlessforaofcoupleseconds,onlymovingthetipofitsabdomenatverylowamplitude.
Theeggwasprobablylaidintothepreparedholeduringthistime.Thenthefemaleremovedthe
cutting valves from the hole and walked a few steps backward. She kept her abdomen curved
ventrally, but the ovipositor tip lost contact with substrate for a moment. Repetitive movement
patterns recurred.The duration of one egg deposition was significantly lower for B. maritimus
thanforJ.maritimus(B.maritimus:median=5s,n=52,W=0.95,p =0.023;J.maritimus:
median=52s,n=57,W=0.92,p =0.002;U=885.5,p <0.0003).Ovipositionwasoften
carriedoutonplantstemsthatalreadycontainedeggclutches,andmanystemswithseveralegg
clutcheswereobserved.
Eggclutch
An egg clutch consists of a row of a few single eggs deposited in one line. Eggs were 1.36±
0.07mmlong(L,min=1.22,max=1.50,n=31,W=0.98,p =0.83).Oftheeggsexamined,
8.51%and21.28%weredecayedandparasitized,respectively(n=47).Mediandistancebetween
successiveeggsinaclutchwas2.06mm(d ,n=44,W=0.64,p <0.05).Eachsuccessiveegg
1
insertionslightlydeviatedfromthepreviousinsertionrandomlytotheleftortotherightrelative
to direction of plant fibres (median γ =1.94◦, min=−6.38, max=8.46, n=44, W=0.84,
p <0.05)sothattheclutchlineranapproximatelyparalleltothelongitudinalaxisoftheplant
78 N.A.MatushkinaandP.H.Lambret
stem.Eggswereorientedinplanttissueatanglesof15.37±3.41◦totheplantsurface(α,min=8,
max=21,n=35;W=0.96;p =0.27).Lateraldeviationoftheeggaxisrelativetothedirection
offibresinplanttissuewasvariable(β =−1.37◦±7.19◦,min=−15.00,max=12.00,n=35,
W=0.96,p =0.28).
Discussion
Morphologyoftheovipositor
TheovipositorofLestesmacrostigmabelongstotheendophytictypethatoccursinallZygoptera,
the anisozygopteran, Epiophlebia superstes, and most aeshnids (Asahina, 1954; Matushkina,
2004,2008;Matushkina&Gorb,1997;Pfau,1985;St.Quentin,1962).Theexoskeletonandmus-
clesoftheovipositorhavebeenstudiedinseverallestids,namelySympecmapaedisca(Brauer),L.
barbarus(Fabricius),L.sponsa(Hansemann),L.virens(Charpentier)andChalcolestesparvidens
(Artobolevsky)(Matushkina,2004,2007a;Matushkina&Gorb,1997).Allthesespecies,aswell
as L. macrostigma, have the complete muscle set of the ovipositor that comprises seven paired
musclesandoneunpairedmuscle.MuscleM6showsthemostconsiderablemorphologicalvaria-
tionamongalldragonflyspeciesstudiedinthisregard.Althoughitisundividedinsomedragonfly
lineages(Calopteryxsplendens:Matushkina&Gorb,1997;Epiophlebiasuperstes:Matushkina,
2008),muscleM6oflestidsisalwaysdividedintoanteriorandposteriorparts.Moreover,thepos-
teriorpartofM6inLestinaecanberepresentedbyonefascicleinL.barbarusandL.macrostigma,
by two fascicles in L. sponsa and L. virens, and by three fascicles in C. parvidens.As a result
of contraction of M6, the valves V2 move relative to the sheathing valves. Most likely, these
movements occur during rhythmical penetration of the cutting valves into the oviposition sub-
strate,i.e.duringproducingofaneggclutch,andcanberelatedtotheexactorientationofV2.It
canbesupposedthatthemorphologicaldifferentiationofM6mayindicateafunctionalone,so
separationofthemuscleM6intodifferentfasciclesseemstohavesomerelationtoproducingof
aneggclutchofaparticularpattern.Followingthisreasoning,aneggclutchofL.macrostigma
isexpectedtobesomewhatsimilartothoseofL.barbarus(seealsobelow).
Forthefirsttime,cuticlemicrostructuresoftheovipositorinlestidswerespeciallystudiedusing
SEM.TheovipositorofL.macrostigmaisprovidedwithreceptorsofdifferentshapes.Numerous
campaniformsensillawerefoundonthebasisofV1.Arrangedintwogroupswithparalleland
perpendicular orientation to the long axis of the valve, they can detect cuticle strains that arise
inV1duringsubstratepenetration.Thefieldofcampaniformsensillaonthebasisofthestylus
onV3respondstothestylusinclination,whichoccurswhentheovipositorcontactsasubstrate.
Thesetwofields,locatedsymmetricallyontherightandleftstyli,mayfunctionascontrollersof
spatialcharacteristicsofaneggclutch,aswaspreviouslypresumedforL.sponsa(Matushkina&
Gorb, 2002a). At least some coeloconic sensilla on the external surface of the cutting valves
have an apical pore that could imply a chemosensory function for them. Robust setae on the
apex of the stylus and on the carina ofV3 contact the plant surface during egg laying and are
probablymechanoreceptors,sincetheylackanyporeontheirsurface.Severalknobbles,serrations
andridges,whichwerefoundontheexternalsurfaceofthecuttingvalves,probablyfunctionin
sawingofplanttissues.ArowofteethonthecarinaofV3formsabearingedgeinL.macrostigma,
whichfunctionstoholdthefemaleabdomenontheplantsurfaceduringplantpenetration.
Theinternalsurfaceofthevalvesrevealsasurprisinglyrichmicrosculpture.Especiallynote-
worthyisthepresenceoftworegionsofeachV1,theventraledgeandtheapicalsurface,which
havepeculiarravioli-likeribs.Locatedslightlyasymmetricallyonthetwofirstvalves,theyforma
key-and-lockdevicethatholdthefirstvalvesfirmlytogetherandarenamedthereforethe“ventral
lock”and“apicallock”,respectively.SimilarstructuresontheventraledgeofV1wererecorded
