An unusual male aggregation in the Odonata: an aerial mating swarm in Protoneura cara Calvert and notes on other Mexican Protoneuridae (Zygoptera)

6 Pages·2001·0.54 MB·English

by  González-Soriano, E

Odonatologica30(3):335-340 September7,2001
An unusualmaleaggregationintheOdonata:
anaerialmatingswarminProtoneuracaraCalvert
andnotesonotherMexicanProtoneuridae
(Zygoptera)
E.González-Soriano
DepartmentodeZoología,Institute deBiología,Universidad Nacional Autónoma deMéxico,
ApartadoPostal 70-153,C.P.04510,México,D.F.,Mexico
e-mail: [email protected]
ReceivedAugust4, 2000/Reviewed andAcceptedNovember5, 2000
Onseveraloccasionsaggregationswereseenhoveringhighamongtreesbesidestreamsin
Mexico. Intermittentarrival ofnonspecific $ $atsomeaggregationsandtheirdeparture,
sometimesin tandem,and theapparentabsenceofforagingwithin aggregationssupportsthe
inferencethatsuchaggregationsarematingswarms.Itremainstobediscovered whethertrees
overwhichswarmsformarepotentialovipositionsitesforthissp.,orareplacesinwhichboth
33and 99overnightFlyingaggregationsofc53inotherspp.ofProtoneuridaearedescribed
and discussed.
INTRODUCTION
Inmostspecies ofOdonatathepreferred place for thesexesto meetandmate,
the‘primaryrendezvous’sensuCORBET(1999), isatorveryclosetotheoviposition
site, whichis typically at water. In some species mating can occur in morethan
one place or opportunistically, and not necessarily at water. Adults of some
Anisoptera congregateinflighttoprey onswarming insects. Thisbehaviourmust
notbeconfusedwiththeprocessofswarming itself,andsohasbeentermed“swarm
feeding” or moreappropiately “swarmforaging”(CORBET, 1999:360). In some
species, such aforagingsite can serve alsoas arendezvous,as intheeocrepuscular
Neurocorduliaxanthosoma(Wllmsn) (WILLIAMS, 1976) and Boyeria irene
(Fonsc.) (MILLER& MILLER,1985). Inthelibellulidfliers, Miathyria marcella
(Sel.) and Tauriphila aztecaCalv., both active at mid-day, copulating pairs were
detectedoccasionally withintheforaging aggregation (GONZALEZ-SORIANO,
1997). However, flying aggregations apparently formedprimarilyor exclusively
336 E.Gonzalez-Soriano
formating, havenot beenreported forany species ofOdonata.
Here I describe a case of an aerial mating aggregation in the protoneurid
zygopteranProtoneuracaraCalv., andreportobservationsonaerialaggregations
inotherspecies ofMexican protoneurids.
OBSERVATIONS ON PROTONEURA CARA
Protoneuracarais slightlysexually dimorphic.Maleshaveadarkmetallicthorax
andanabdomenpatterned with red-orange stripes, whereasfemalesare similarly
colouredbutpaler. Sexually mature femalesareeasily distinguished frommales in
thefieldby theabdomen,inwhichsegments5-10are widenedbecauseoftheeggs
inside.
IntropicalareasofMexico,adultP. caraarecommonly seenflyingalong streams
andrivers, eitheras solitary malesor tandempairs. Inmostlocalities, malespatrol
thewater surface, apparently searching forovipositing females.Males shiftfrom
oneperchsitetoanotherwithoutseemingtodefendaparticular area.Suchbehaviour
has been termed ‘cruising’ and is employed by several other non-territorial
Zygoptera, including species of Enallagma and Ischnura (BICK, 1972) and
Neoerythromma.
Although in someplaces population density ofP. cara is high,copulation has
very seldombeen witnessed. Itperhaps occurs several meters from the water,
probably highinthesurrounding vegetation. However,Iobserved acopulating pair
perched on grasses attheedge ofa spring-fedpond nearthecity ofColima(Los
Almeales) (19°14'N, I03°43'W)on 29 July 1996.
Oviposition occurs in tandem,andtandem pairs flyalong streams and rivers
searching foroviposition sites whichconsist ofa variety ofsubstrates, including
submerged grasses,livingroots andfloating objects suchas smallpieces ofwood.
During tandemoviposition, themaleremainserect,beatinghis wings.
IntheChamelapreserve (19°30'N, 105°00'W),stateof Jalisco, on 25and 26
August and22October 1995,1observed(and video-recorded) asmallaggregation
ofP. cara flying abovethebankofasmalltemporarystream.Thegroupconsisted
of approximately 6-8 maleshovering inamosquito-like fashion(i.e.remaining in
a stationary flightin which maleskeep station) 4-5 m above ground level,2-3 m
fromthestreamedge. Theaggregation occurred inaforestgapsurroundedbysmall
trees no morethan 10m high.All hovering individualsfaced thesamedirection,
apparently againstthewind,andbriefchasesoccurredwithinthegroup.Noforaging
activity wasobserved withintheaggregation. On22October, afterfilmingthemale
aggregation forafewminutes, I saw aflying P. cara female(easily recognised as
afemaleby itswiderabdomen) enter themale aggregation. Aftera fewseconds,
she departed unaccompanied, disappearing frommy sight amongthefoliage ofa
neighbouring tree, withouthavingbeen grasped forany maleof theaggregation.
Aggregation behaviourby maleswas observeda second time inthe region of
MatingswarminProtoneura cara 337
HuautlastateofMorelos.On 11 July 19961discoveredasmallgroupof4-5males
ofP. cara hovering inthemanner describedabove, nearabankoftheQuilamula
river (18°27'N, 99°02'W). However, in this particular area which I had visited
monthly duringaone-yearperiod, mostmalesemployed the cruising behaviour
describedabove.Atthisplace Ialsoobserved aratherunusualbehaviourinwhich
malesvisitedsmalltreesandbushes growingalongthewater'sedgeandrepeatedly
dartedintothefoliage,behaviourthatisalsoprobably directedtowardtheacquisition
ofreceptive (ovipositing?) femalesbecausenoforaging activity(e.g. gleaning prey
fromfoliage) was seen during thisactivity.
Thebestobservationsandrecordings ofaggregation behaviourbyP. cara were
madeon3Marchand3 September 1997intheareaofSanBuenaventura,stateof
Jalisco(19°47'N, 104°03'W), again during monthly visits. HereIobservedalarge
aggregation(10-15males)ofP.caraabovethebankofapermanentriver inanopen
area surroundedby 4-5 trees (mostly Salixsp.) approximately 10m high.Atthis
siteIwas abletoobserve tandemformationwithintheaggregation, although Iwas
not abletoidentify thesitewherecopulationoccurred.Ireturnedbrieflytothesame
siteontwootheroccasionsin 1997andfoundtheaggregation tobetherewhenever
weatherconditionsappeared favourable.
On 19September 1998I returnedtothesamelocality andsaw atandemformed
withintheaggregation. The nextday agroupofaboutfiveindividualsformedatca
10:00hlocaltime,(ca2 hoursbeforesolarnoon)and 15minlatertheaggregation
had increasedto about 15individuals.However, at 11:15h,a sudden fallofrain
causedtheaggregation to disperse.
OBSERVATIONS ON OTHER MEXICANPROTONEURIDAE
Thefollowing notes derivefromfieldobservationsImadeinseverallocalitiesin
Mexico.
In Los Tuxtlas area,stateofVeracruz(18°35'N, 95°06'W), Iobserved in 1988a
groupofunidentifiedzygopterans flying high (ca7-8 mabove ground level) in a
swarm-likefashion farfromwater, nearthetopofaCecropia obtusifolia Bertol.
tree.AlthoughIwasnotabletoidentifythespeciesbecauseofdistance,Iconcluded,
fromtheadults’overallmorphology,thattheaggregation consistedofProtoneuridae.
InAugust 1997,inthesamearea,anothersmallgroupof3-4malesofProtoneura
aurantiaca(Lieft.)was seenhovering 3-4mabove groundlevel neartheedge ofa
smallstream.
Incontrast to thebehaviour describedaboveforcertainProtoneuraspecies, in
whichmalesformedaggregations inopensites,Idiscovered approximately at14:30
hLocalTime(ca 2.30hrsaftersolarnoon) anaggregation ofNeoneuraameliaCalv.
malesatashady placeneartheRioCoy, inthestateofSan LuisPotosi (21°43'N,
on 31 August 1999.The groupconsistedof6-8 maleshovering at ca
2-3 mabove ground level below thetop ofanunidentifiedtreearound40mfrom
338 E. Gonzalez-Soriano
theriver’s edge. Some chaseswere observed among membersofthegroup,and
individualmalescombinedperiodsofhovering flightwithrestlessintervals, during
whichamaleperched on thetipofabranch.
DISCUSSION
The Protoneuridaecomprise a large zygopteran family, distributedthroughout
theTropics, andthebehaviourofcomponentspecies is littleknown.
LIEFTINCK(1953) wasapparently thefirsttopointout theapparentdependence
ofprotoneurids ontrees. DAIGLE(1990) reported malesofProtoneuradunklei
Daigleperching ca3-4m high onthetipsofleavesandbranchesofshrubs insunny
glades in LaVegaProvince, DominicanRepublic. On27 July 1990, atMisol-ha,
Chiapas state,(I7°23'N,92°01'W) I discoveredalarge aggregation ofmalesofP.
cupida Calv.flying aroundbushes over smallisletsbelowawaterfall.Although no
ovipositionwasdetectedatMisol-ha,onefemaleofthisspecies wasseenovipositing
aloneinnon-aquatic vegetation growing attheedge ofasmallshadedstream inthe
Los Tuxtlas area. This observation reinforce thepossibility thatfemalesofthis
species uses non-aquatic plants tooviposit atleastinsomepartoftheirdistributional
range.
The affinity ofprotoneurids for treesand othertypes of vegetation, is perhaps
functionally related to their oviposition behaviour, as manifestby Selysioneura
corneliaLieft.(LIEFTINCK, 1953)andP.cupida (Gonzalez-Sorianounpublished),
and/or by the tendency ofboth sexes to roost at night amongst foliage. The
oviposition behaviourmay alsohelp toexplain why males(e.g. in P. caraand P.
cupida) appeartosearcharoundtreesandbushesandperhaps why malesaggregate
high in forest gaps. However, moreobservations on themovements ofreceptive
andovipositingfemalesareneededinordertounderstandthereproductive behaviour
ofthisandotherspecies ofProtoneuridae.
Theaggregation behaviourofP. camisremarkablebecauseitrepresentsthefirst
caseofanaerialmating assemblage reported forany species ofOdonata. Innone
oftheinstancesreported herewas theaggregation and hoveringofmalesseentobe
combinedwith foraging, as oftenoccurs inAnisoptera (CORBET, 1999). In our
observations of P. cam, theonly apparent functionofmale aggregation was the
acquisition ofamate. Itis thereforeappropriatetocalltheseaggregations ‘swarms’
in the sense that this term is applied to mating assemblages ofmany Diptera
(DOWNES, 1969),especially if,as seemstobethecase,theprotoneuridmales are
assembling over a visually perceived ‘marker.’
More informationis neededbeforethis mate-finding tactic canbeassigned with
confidenceto any ofthe categories ofodonatemating systems so far proposed
(WAAGE, 1984;CONRAD &PRITCHARD, 1992;FINCKEetal., 1997;CORBET,
1999).Itwillbe necessary to decide,forexample,whethertheswarming ofmales
over trees is functionally relatedtotherole oftreesas oviposition sites or ifthey
MatingswarminProtoneura cara 339
onlyuse themasroosting sites.Pending furtherinformation,itmaybeappropriate
to assign theprotoneurid modeofmate finding to mating system 3 (“Hinterland
rendezvous”) proposed by CORBET (1999: 553). A remarkablefeatureofthe
behaviourofthesemaleprotoneurids istheirabilitytokeepstationwhilehovering,
anactivity thatis energetically costly. Itwouldbeinformativeto determinehow
longeachmaleremainsinaswarm. Hoveringby Zygoptera whileforaginghasbeen
observed in Chlorocnemisflavipennis Sel.,eachadult hovering forabout 10min
and 1 m fromitsnearest neighbour (LEMPERT, 1988), and inpseudostigmatids
whenpreparingto pluckaspider fromaweb(e.g. FINCKE, 1992).
Finally, itis interesting to note thatmalesofP. cara apparently employ atleast
three strategiesfor obtaining mates. Thecommonest oneobserved in thisspecies
throughout itsrangeistopatrolabovethewatersurface, amodeprevalent inother
non-territorialzygopterans(BICK, 1972);less common modes are theswarming
describedabove,inwhichmalesassembleinaerialaggregations, apparently waiting
forreceptive females,and searching amongst shore-side vegetation. The second
(swarming) strategy was oftenseenin someplaces (e.g. the Jaliscosites), butwas
rare inothers(e.g. theMorelossites). Thethird(searching) strategy was observed
only intheMorelospopulationandis uncommoninZygoptera. However,thelarge
maleaggregations ofP. cupida observed in Misol-hasuggests thatthe searching
strategy is probably usedby otherspecies ofprotoneurids as well.
ACKNOWLEDGEMENTS
IthankATILANOCONTRERAS, MANUELBALCAZAR,VICTORH.REINOSO(IBUNAM),JOHN
SIVINSKY (Gainesville),GORDONPRITCHARD (Calgary)and ERICK PETERSSON(Uppsala) for
commentsonanearly versionofthemanuscript.My deepgratitudetoPHILIPS.CORBET(Cornwall)for
criticismandhelpfulcommentsonalateversion ofthemanuscript.E.PETERSSONandPS.Corbetgraciously
providedwithsomereferences.
REFERENCES
BICK,G.H., 1972. Areview ofterritorial andreproductivebehavior in Zygoptera.Contactor, ned.
LibellenOnderz. 10(Suppl.): 1-15.
CORBET,P.S., 1999.Dragonflies:theecologyandbehaviorofOdonata.CornellUniversityPress,Ithaca.
CONRAD, K.J.&G.PRITCHARD, 1992.Anecological classificationofodonatematingsystems:the
relative influence ofnatural, inter- andintra-sexual selection onmales. Biol. J.Linn. Soc. 45:
255-269.
DAIGLE,J.J.,1990.Protoneuradunkleispec.nov.fromtheDominican Republic,WestIndies(Zygoptera;
Protoneuridae).Odonatologica19: 81-84.
DOWNES,J.A., 1969. Theswarmingand matingflightofDiptera.Anna. Rev. Ent. 14:271-298.
FINCKE, O.M., 1992. Behavioural ecology ofthe giantdamselfliesofBarro ColoradoIsland,Panama
(Odonata:Zygoptera:Pseudostigmatidae).In:D.Quintero&A.Aiello,[Eds],InsectsofPanama
andMesoamerica: selectedstudies. pp. 102-113,OxfordUniv. Press,Oxford.
FINCKE, O.M.,J.K. WAAGE& W.D.KOENIG, 1997. Natural and sexual selection componentsof
odonatematingpatterns.In:J.C.Chloe &B.J. Crespi,[Eds],Theevolutionofmatingsystemsin
340 E. Gonzalez-Soriano
insects andarachnids, pp. 58-74,CambridgeUniv. Press,Cambridge.
GONZALEZ-SORIANO,E., 1997. Odonata.In: E. Gonzalez-Soriano,R.Dirzo &R.C. Vogt, [Eds],
HistorianaturaldeLosTuxtlas,pp.245-255,Univ. Nac. Auton. Mex.,Mexico,D.F.
LEMPERTJ., 1988. UnlersuchungenzurFauna,OkologieundzumFortpflanzungsverhaltenvonLibellen
(Odonata)anGewdssern destropischenRegenwaldesinLiberia, Weslafrika.DiplArb.,Friedrich-
-Wilhelms-Univ., Bonn.— [Citedby Corbet, 1999]
LIEFTINCK,M.A., 1953. Thelarval characters ofthe Protoneuridae (Odonata),with specialreference
tothegenusSelysioneuraForster,andwithnotes onotherIndo-Australiangenera.Treubia 21(3);
641-684.
MILLER,A.K.&P.L.MILLER,1985.Simultaneous occurrenceofcrepuscularfeedingandsexualactivity
inBoyeriairene (Fonsc.)insouthern France (Odonata,Aeshnidae).Ent. mon. Mag. 121: 123-
-124.- [Citedby Corbet, 1999]
WAAGE, J.K., 1984. Spermcompetitionand the evolution ofodonate matingsystems.In:R.L.Smith,
[Ed.],Spermcompetitionandtheevolutionofanimalmatingsystems,pp.251-290,Acad.Press,
NewYork.
WILLIAMS,C.E., 1976. Neurocordulia (Platycordulia) xanthosoma(Williamson)inTexas (Odonata:
Libellulidae: Corduliinae).GreatLakes Ent. 9:63-73.— [Citedby Corbet,1999]