Memorie Rigato 37 2.Indd
Total Page:16
File Type:pdf, Size:1020Kb
Fabrizio Rigato Contributions to the taxonomy of West European and North African Stenamma of the westwoodii species-group. (Hymenoptera Formicidae) Volume XXXVII - Fascicolo II Novembre2011 MemoriedellaSocietàItalianadiScienzeNaturali edelMuseoCivicodiStoriaNaturalediMilano INDICE Introduction...................................................... Pag. 3 Materialsandmethods..................................... Pag. 4 The Stenamma westwoodi speciesgroup......... Pag. 5 Discussion........................................................ Pag. 17 Acknowledgements.......................................... Pag. 17 References........................................................ Pag. 53 Appendix1.Morphometrictables.................... Pag. 54 Appendix2.Localitydataofphotographed specimens......................................................... Pag. 56 ©2011SocietàItalianadiScienzeNaturali MuseoCivicodiStoriaNaturalediMilano CorsoVenezia,5520121Milano Incopertina: Stenamma debile (Foerster,1850).LinedrawingbyF.Rigato. RegistratoalTribunalediMilanoaln.6694 Direttoreresponsabile:AnnaAlessandrello Grafi caeditoriale:MichelaMura Stampa:Litografi aSolari,PeschieraBorromeoNovembre2011 ISSN 03762726 Fabrizio Rigato Contributions to the taxonomy of West European and North African Stenamma of the westwoodii species-group. (Hymenoptera Formicidae) Abstract - ThetaxonomyofWestEuropeanandNorthAfrican Stenamma belongingtothe Stenamma westwoodii speciesgroup isreviewed. Stenamma orousseti CasevitzWeulersseisdiscussedandsynonymisedwith S. debile (Foerster).Principaldiagnosticfea turesofthepoorlyknown Stenamma sardoum Emeryand S. petiolatum Emeryareprovidedaswellascommentsaboutthetaxonomic positionofallotherspeciesinthegroup.Twonewspecies, Stenamma siculum ,basedongynesandmalesfromSicily,and Stenamma zanoni ,basedonworkersandisolatedmalesfromNorthItalyandSouthSwitzerland,aredescribed.Inaddition, S. africanum Santschi isresurrectedfromsynonymywith S. msilanum Forelandtheinfraspecifi cform S. africanum submuticum Santschiisincludedinthe synonymyof africanum .Keystoknownworkers,gynesandmalesareprovided. Key words: Formicidae, Stenamma ,WestPalaearctic,review,newspecies,dichotomouskeys. Riassunto - Contributiallatassonomiadegli Stenamma dell’EuropaoccidentaleedelNordAfricaappartenentialgruppo west- woodii .(HymenopteraFormicidae). Vieneriesaminatalatassonomiadegli Stenamma dell’EuropaoccidentaleedelNordAfricaappartenentialgruppo westwoodii . Stenamma orousseti CasevitzWeulersseèdiscussoepostoinsinonimiacon S. debile (Foerster).Sonofornitiiprincipalicaratteri distintivideipococonosciuti Stenamma sardoum Emerye S. petiolatum Emery,cosìcomeicommentisullaposizionetassonomicadi tuttelespeciedelgruppo.Vengonodescritteduenuovespecie, Stenamma siculum ,sullabasediregineemaschidiSicilia,e Stenamma zanoni ,sullabasedioperaieemaschiisolatidell’ItaliasettentrionaleedellaSvizzerameridionale.Inoltre, S. africanum Santschiè riconosciutocomespecievalidaerimossodallasinonimiacon S. msilanum Forelelasottospecie S. africanum submuticum Santschiè inclusanellasinonimiadi africanum .Vengonofornitelechiavidicotomicheperilriconoscimentodioperaie,regineemaschi. Parole chiave: Formicidae, Stenamma ,regionepalearticaoccidentale,revisione,nuovespecie,chiavidicotomiche. INTRODUCTION Thepresentknowledgeofthetaxonomyofthegenus interpreted.Followinganexaminationoftypematerialof Stenamma ismostlyunsatisfactory,especiallybecausethe S. sardoum IrealizedthoseSardinianspecimensbelonged speciesofthisgenushavecryptichabitsandarerarely toitandthatEmery(1915),CasevitzWeulersse(1990) collected.Therefore,adequatecomparisonsbetweentaxa andDuBois(1998)weremisleadingabout thediagnostic and/orpopulationsoftencannotbe supportedbyasuffi - featuresofthatspecies,especiallyconcerningtheshape cientnumberofspecimens.ThegenusmostlyhasaHol ofthepetiolarnode.Therefore,Ipresentanewdiagno arcticdistributionwithamoderatenumberofspeciesoc sisof S. sardoum aswellasof S. petiolatum ,whichalso curringintheNeotropics(Branstetter,2009).Branstetter seemstobesomewhatmisunderstood. (l.c)hasprovidedasynonymiclistofallknownspeciesas Inaddition,Iobtainedseveralmalesandgynesofan wellasacomprehensivereviewanddiscussionofgenus unidentifi ablespeciescollectedtogetherwithalatesof S. levelcharacters. debile fromSicily.Initially,Iconsideredthattheycould TheuniquerecenttaxonomicrevisionofPalaearctic belong either to S. sardoum or to S. msilanum ( sensu specieswasprovidedbyDuBois(1998).Unfortunately, DuBois,1998);but thepresenceofaseriesofstanding thatworkoftenprovestobe fairlyweak(atleastforthe hairsalongthedorsaledgeofthescape leadsmetoassign species dealt with in this paper) when one attempts to themtoanewspecies, S. siculum . identify specimens through keys and descriptions pro Moreover, some workers of a relatively large Ste- videdbytheauthor. namma from Northeast Italy deserve to be considered as AfterdetailedexaminationofspecimensofItalian Ste- a new species, S. zanoni , together with two specimens namma Irealizedthatthediagnosesofsometaxawere from Canton Ticino, Switzerland, one of which was er- stillpoorandneededclarifi cation. roneously determined as S. petiolatum by Della Santa Inparticular,Iobtainedaseriesof Stenamma specimens (1988). The male specimen that Kutter (1971) assigned fromSardinia,whichatfi rstIcouldnotassigntoanyof to S. petiolatum is also considered to belong here, as well theusuallyidentifi ablespecies( S. debile , S. striatulum , S. as another isolated male collected in the neighbourhood petiolatum )norto S. sardoum ,asthat specieswasusually of Milano. 4 FABRIZIORIGATO Finally,Iexaminedtype specimensoftheNorthAfri (as defi ned by DuBois, 1998). It provides some new can S. africanum Santschiandofitscurrentseniorsyno diagnostic characters, together with a study of known nym S. msilanum Forel. I determined that these should males, and new keys to female castes and males are pro- be treated asseparatetaxaasthesynonymyproposedby vided. DuBois(1998)isuntenable. Inmanycasesonlyafewspecimenswereavailable This paper is therefore designed to give a better forexamination;therefore,measurementsandindicesare framework to the taxonomy of West European and North tosomeextentprovisionalastheymaynotcoverthefull African Stenamma of the S. westwoodii species-group rangeofvariationpossibleinthespecies. MATERIALS AND METHODS Measurements and indices PPL (Postpetiolarlength):inprofi le,thedistancefrom thebaseofthenode,justbehindthehelcium,totheposte Allmeasurementsweretakenbyastereomicroscope riormostmargin(Fig.1).Becauseofdifferencesinspeci LeicaMZ9 5 withanocularmicrometreandcarrierAXin mensmountingandwaistpositionthismeasurementmay ordertoworkonasingleaxialopticalpathandgetmore be unreliable.Consequently,Iusedasananteriorpoint accuratedata. thebaseofthepostpetiolarnode,whichisnotconcealed TL (Totallength):thefulloutstretchedlengthofthe evenwhenthewaistisfullyoutstretched. specimen,withfullyclosedmandibles,fromtheanterior- PeH(Petiolarheight):inprofi le,fromthetopofthe mostmandibularbordertothegastralapex.Itisthesum nodetothesternalsurfacejustbelowit(Fig.1). of:lengthofthehead(includingmandibles)+AL +PeL PPH(Postpetiolarheight):inprofi le,fromthetopof +PPL+lengthofthegaster. thepostpetiolarnodetothesternalsurface(Fig.1). HL (Head length): in full face view, the maximum PeW (petiolar width): in dorsal view, the maximum lengthoftheheadfromtheanteriorclypealmargintothe widthofthepetiole. posterior margin of the head.Whenever clypeus and/or PPW (Postpetiolarwidth):indorsalview,themaxi posteriormarginareconcaveinthemiddle,thismeasure mumwidthofthepostpetiole. mentistakenatanimaginarylinetangenttothemostpro PI1(Petiolarindex1):PPLx100/PeL. trudingpoints. PI2(Petiolarindex2):PeLx100/HW. HW (Headwidth):infullfaceview,justbehindtheeyes. MTL (Metatibiallength):themaximumlengthofthe CI(Cephalicindex):HWx100/HL. hind tibia excluding the proximal articulation, which is SL (Scape length):thelengthofthescape asastraight concealedwhenthelegisoutstretched. linebetweenitsapexandbase,excludingthebasalmost TI(Tibialindex):MTLx100/HW. condylarbulband“neck”. Morphometricdataaresummarizedintables1,2and3. SI(Scapeindex):SLx100/HW. PCI(Posteriorclypealindex):infemalecastes,thera tiobetweentheminimumwidthoftheposteriorportionof Images theclypeusbetweenthefrontallobesandthewidthofthe fronsacrossthelatterattheleveloftheantennalinsertion DigitalcolourphotosweretakenbyaCanonPower (seeSeifert,2007:143). ShotS50mountedonanoculartube ofaLeicaMS5ster- PnW (Pronotalwidth):themaximumwidthofthepro eomicroscope with PlanAPO 1.0x objective and carrier notumindorsalview. AX;severalshotsofeachspecimenwerecombinedto AL (Mesosomalength):inprofi le,thedistancefrom getherthroughHeliconFocussoftware. the point where the dorsum of the pronotum meets the B/W photographs weretakenofuncoatedspecimens cervicalshieldtothemostprotrudingportionofthepro byaJeol5610LV ScanningElectronMicroscope usinga podeallobe. backscatteredsignalatlowvacuum. PSI (Propodeal spine index): in female castes, with themesosomainprofi le,theratiobetweenthedistance fromapropodealspine’stipandthecentreofthepropo dealspiracledividedbytheminimumdistancebetween thelatterandthepropodealdeclivity.(Thisistheoriginal indexasproposedbyBuschinger(1966);althoughCase vitzWeulersse(1990)calledBuschinger’sIndexavery similarmeasurementusingtheposteriorrimofthepro podealspiracleasareference.Suchadifferenceismostly negligible). ScW (Scutumwidth):ingyneandmalethemaximum widthofthemesonotalscutumindorsalview. MnL (Mesonotumlength):ingyneandmalethecom binedlengthofmesonotalscutumandscutellumindorsal view. PeL (Petiolarlength):inprofi