Volume 47(2):15-26, 2007 - AntWiki Zool

Volume 47(2):15-26, 2007

1 MuseudeZoologia,UniversidadedeSãoPaulo,CaixaPostal42.494,CEP04218‑970,SãoPaulo,SP,Brasil.E‑mails:a:[email protected];b:[email protected];c:[email protected]

Basiceros scamBognathus (Brown, 1949) n. comB., with the first worker and male descriptions, and a revised generic

diagnosis (hymenoptera: formicidae: myrmicinae)

rodrigo machado feitosa1a carlos roBerto ferreira Brandão1B

Bodo hasso dietz1c

AbstrAct

We propose the synonymy of the monotypic neotropical myrmicine (Basicerotini) ant genus Creight‑onidris Brown with Basiceros Schulz, and describe for the first time the worker and male of B.scam‑bognathus n. comb., known thus far only by alate gynes. We also provide information on the distribu-tion of this species, a revised diagnosis for Basiceros, and a revised key to workers and gynes of this genus. The few known data on the biology of B.scambognathus are summarized.

Keywords:ants,Basicerotini,Creightonidris, Basiceros,key,synonymy,workerandmalede‑scription.

IntroductIon

ThemyrmicineanttribeBasicerotiniBrownin‑cludes seven nominal genera: Basiceros, Creightonidris, Eurhopalothrix, Octostruma, Protalaridris, Rhopalothrix,andTalaridis(Bolton,2003).Brown(1949)recognizedthesegeneraasdistinctfromDacetini;althoughtheseantsaresimilarinappearanceduetoconvergenceincharactersheldincommonbymembersof bothtribes(Brown&Kempf,1960).Basicerotinihasastronglydisjunct distribution, occurring in the New World(primarily Neotropical, with one species in Florida,USA)and in theMelanesian region (Australia,NewCaledonia,Fiji,Samoa,PapuaNewGuinea,Solomon

Islands Borneo, Malaysia, Indonesia, Singapore, Pa‑lau, Brunei, and the Philippines). Brown & Kempf (1960)alsostudiedbasicerotinematerial fromBotelTobagoIslandjustoff southernFormosa.

All basicerotine species come from predomi‑nantlymesichabitats,particularlyfromtheleaf‑litterandsuperficialsoillayers.Coloniesaremonogynousand relatively small, nesting in natural cavities, fall‑en twigs, emptydry fruitsor rottenwood.Workersforage alone, mostly preying upon a wide range of softbodiedarthropodsand their larvae (Hölldobler& Wilson, 1990). According to Brown (1974), “theadultsmoveveryslowly,andtheyfeigndeathforlongperiodswhendisturbed,rivalingtheattineApterostig-

16 Feitosaet al.:theworKerandmalecastesoFBasiceros scamBognathusn.comb.

maintheirabilitytoescapedetectionbythismeansinthe forestgloom”.Weber (1950) recordedaworkerof B. singulariscarryingadeadtermiteinGuyana,andBrown (1974) foundheadless termites inside anestof the same species in Diamantino, Mato Grosso,Brazil.

Baroni Urbani & De Andrade (1994) synony‑mizedDacetiniaswell asPhalacromyrmeciniunderBasicerotini,andsynonymizedallsubtribalnamesac‑ceptedatthetime.Bolton(1995a)revivedBasicero‑tinifromsynonymyof thethenso‑calledDacetoniniand,in1998,listedandcommentedtheapomorphiesof theDacetinitribegroupanditscomponents, in‑cludingtheBasicerotini,whichheconsidersasmono‑phyletic.

Creightonidris is a monotypic basicerotine ge‑nus establishedbyBrown (1949),basedon a singlealategyne.Intherevisionof Basicerotini(Brown&Kempf,1960),Creightonidriswasrecognizedasavalidgenusbytheauthorsbasedmainlyonitsveryspecial‑izedandaberrantmandibles,althoughtheyalsorec‑ognizeditscloserelationtoBasiceros.Theonlyspeciesof thegenus,C. scambognatha,hasbeenknownuptonowfromvery fewalategynesandasinglenotyetformally described worker (Castilho et al., in press),capturedexclusivelyincentral‑northBrazil(Delabie,2000)andsouthVenezuela(Lattke,1991).

However, since the original description byBrown(1949)andtherevisionbyBrown&Kempf (1960), severalundescribedmalesof C. scambognathafromdifferentlocalitieshaveaccumulatedintheMu‑seudeZoologiadaUSPantcollection(MZSP),fromwhich twoseriesalsohavesomealategynes. Itwaspossibletoassociatemalesandgynesbycomparingmainlythewingvenation,thesculpturepattern,andconsideringtheinformationonthespecimenslabels(Dietz,2004).

Dietz (2004), in his Basicerotini revision, sug‑gested the synonymy of Creightonidris with Basiceros,based on the comparison of the then undescribedC. scambognathamaleswithmalesof Basicerosspecies,especiallyastothewingvenationpatternandontheanalysisof othercharactersvariationamongbasicer‑otine ants.Our studyof the secondC. scambognathaworkereverfoundandherepresented,corroboratesDietz´sproposal.

Virtually nothing is known about the biologyof C. scambognatha. The only dealate gyne, collectedinsouthernGoiás,Brazil,andmaintainedinartificialconditions,diedsomeweeksafterconfinementinthelaboratoryof theMZSP(Brandão,unpubl.observa‑tions).Morerecently(June,2006),aparty, includingoneof us(RMF),collectedthesecondworkerof this

speciesintheleaf litterof asemi‑deciduouslowlandforestintheEstreitocounty,Maranhãostate(neartheborderwithTocantinsstate)incentralBrazil.

Theaimof thisworkistoestablishformallythesynonymyof CreightonidriswithBasiceros,andaddnewinformationonitsdiagnosis.Wetakethisopportunitytodescribeforthefirsttimethemaleandtheworkercastesof Basiceros scambognathusandtorecordnewin‑formationregardingthedistributionandbiologyof thisspecies.

MAterIAl And Methods

Although Creightonidris scambognatha has beenconsideredoneof therarestNeotropicalantspecies,we were able to find specimens in different collec‑tions,asfollows:

ANIC: Australian National Insect Collection,CSIRO,Canberra,Australia.

INPA: InstitutoNacionaldePesquisasdaAmazô‑nia,Manaus,Amazonas,Brazil.

MCZC: Museum of Comparative Zoology, Har‑vard University, Cambridge, Massachu‑setts,USA.

MZSP: Museu de Zoologia da Universidade deSãoPaulo,SãoPaulo,Brazil.

PSWC: Philip S. Ward Personal Collection, Uni‑versity of California, Davis, California,USA.

Morphological terms followBrown&Kempf (1960) and Dietz (2004). Reproductive females areherecalled“gynes”,assuggestedbyDeAndrade&BaroniUrbani(1999).Themeasurementsandindex‑esadoptedare:TLtotallength,HLheadlength,HWhead width, ML mandible length, SL scape length,CWWeber’s length,HFLhindfemur length,CIce‑phalic index (HWx100/HL), and SI scape index(SLx100/HW).Allmeasurementsaregiveninmm.

Photographs taken under the MZSP scanningelectronmicroscope(SEM)(LEO440®)wereusedtorecord morphological details of a gyne and a maleof B. scambognathus. The specimens were previouslycleaned in acetone, critical‑point dried in a Balzer(Bal‑Tec® CPD030), and sputtered over with gold(Bal‑Tec®SCD050).Afterthat,thespecimensweremountedonthetipof metallictrianglesusingsilverglue and then fixatedon stubs for the electronmi‑croscopy. The images were obtained under severalmagnifications,accordingtothesizeof thespecimenand/or structureobserved.Finally, the imageswere

PaP.avulsZool.47(2),2007 17

edited (Adobe PhotoShop 7.0®) to enhance somebrightnessandcontrastdetails.

Geographic coordinates were obtained fromENCARTA World Atlas® and the distribution mapgeneratedbyArcView3.2GIS®.

results

Basiceros schulz, 1906

Meranoplus(inpart)Fr.Smith1858:195.Ceratobasis Fr. Smith 1860:78 (junior homonym of

CeratobasisLacordaire,1848:362Coleoptera).BasicerosSchulz1906:156(replacementnameforCera-

tobasis; Meranoplus singularistypespeciesbymono‑typy);Wheeler&Wheeler,1954:112‑113(larvaedescription); Brown & Kempf, 1960:171‑172(workerandgynediagnosis);Brown,1974:132(worker, gyne and larvae diagnosis, male de‑scription; distribution and biology); Bolton,2003:183‑184(taxonomichistory).

AspididrisWeber, 1950:3 (A. militaris type speciesbymonotypy),juniorsynonymof BasicerosSchulz:Brown,1974:132.

CreightonidrisBrown1949:89(C. scambognathatypespe‑ciesbymonotypy),new synonym.

Worker:Sizerelativelymedium(TLbetween4,9and8,7mm).Reddishtodark‑brownincolor.Integumentthickandingeneraldenselysculptured;foveolateoverheaddisc,mesosomawithconspicuousdeeptoshal‑lowlysetpunctuation,denselypunctateovermostorall thegaster.Pilosityconspicuousandbizarre;sub‑decumbent hairs abundant, spatulate, squamiformorplumose;erectabundantorsparsehairsclavateorstoutandtruncate.Labrumwithfinesensorialhairs.

Head trapezoidal, triangular or rounded pos‑teriorly; posterior and lateral head borders alwaysvisible and clearly distinct, and either rounded orcrested, or else combined into curving, continuousornearcontinuouscrestaroundposteriormarginof head.Dorsalsurfaceof headflattenedtodepressed,slightlyconvex insomespecies.Mandiblessub‑por‑rect, triangular to subtriangular, with straight, op‑posable,multidenticulatemasticatoryborders;apicalportionfromstraighttostronglybentventrally;basalportion flat and smooth to moderately convex andsculpturedinfrontalview;bladenarrowednearinser‑tion,theresultingpeduncleeitherpartlyexposedorentirelyhiddenbeneath clypeus, interspacebetweenbasalmandibularmarginandanteriorclypealborderpresent toabsent invaryingdegrees.Eyes relatively

welldeveloped(ocular indexca11).Antennalscapeflattened,broad,andlobateatthebasalportion;fu‑niculusmoderatelyclavatewith11segments.

Mesosoma usually robust. Metanotal groovepresent. Propodeal teeth always triangular in lateralview,lamelliform,short,moreorlessacute,andcon‑nected to each other by a transverse carina. Petiolepedunculate and usually with ventral carina bearingoneormoreteeth.Gastricdorsumwithamedianlon‑gitudinalstripslightlyimpressedordevoidof pilosity.AccordingtoBrown(1974)Basiceroshas5Malpighiantubules.

Gyne:Likeconspecificworker,withmodificationsex‑pectedformyrmicinegynes.Ocellipresent.Prescutumusually longer thanwide;notauli fromalmost indis‑tincttoshallowlydepressed;parapsidiallinesshinningand usually indistinct from surrounding sculpture,deeptoshallowparapsides;prescutellumwithcentralarea indistinct,scuto‑scutellarsulcusfromdeeplytoshallowlyimpressedoralmostindistinct,withtrans‑versalrugulaevaryinginnumber;lateralwingof pres‑cutellumprojectingpostero‑ventrallyasamoreorlessdevelopedhook‑like structure; scutellumsquare‑likeorsemicircular,withitsposteriorhalf alwaysslopeddown,posteriorborderconcave.Metanotummedianelevationbearsapairof specializedsetae.Forewingwithdistinctandstronglycoloredstigma;longitudinalveinsSc+R,SR,M+Cu,andApresent;SRextendsdistallybeyondstigmaastubularveinformostof itslength;MandCualsoextenddistally,initiallyastubu‑larveins,thenasspectralveinsalmostreachingdistalwing border; cross vein M+Cu either absent, as anappendixof Mor complete, thus formingopenorclosedM1cells;analveinconnectedtoM+Cunearbranchingpoint,eitherbefore,atorafter.Hindwingwith Sc+R extending shortly beyond point wheretheyconnecttoM,whichextendsastubularveinasmuchasSc+Randthencontinuesasspectralveintowingdistalborder;basallyM+CudoesnotcontinueastubularveinbeyondjunctionwithAnalvein,whichisconnectedhalfwaytoMandCubranchingpoint;tubularpartof Cuisamerestub,continuingasspec‑tralveindistally;5sub‑medianhamulipresent.

Male (modified from Brown, 1974):Slightly smallerandmoreslenderthanconspecificgynes.Colorblackwithappendagessomewhatlighter.Integumentveryfinelyanddenselypunctate,opaqueornearlyso,includinglegs,mandiblesandantennae.Headvertexwithover‑lyinglooserugulae,especiallybehindcompoundeyesandaroundocellartriangle;looserugulationalsoonalitrunk,especiallyonposteriorhalf of mesonotum


and sidesof propodeum. In some speciesparts of mesopleura smoothandshining,or rugulose.Pilos‑itycomposedof finetaperedhairs,goldenbrownincolor,mostlyerectorsuberectonbody,butalsoap‑pressedongasterandclypeusinsomespecies;man‑dible,antennaeandleghairsbecomingshorter,moreabundantanddecumbentpassingfrombasetoapexof theseappendages.

Head broadest across large bulging eyes (situ‑atedatorslightlyinfrontof headmid‑length)rathersuddenlynarrowedinfrontof eyesandtaperingmod‑eratelyanterad;medianvertexandocelliprominent.Mandibles relatively developed, subtriangular, withcurved outer borders converging rapidly in apicalhalf; gently down curved andweakly convexdorsalfaces.Masticatoryborders bearing 8‑12 serial teeth.Mandibles petiolate or not, when closed leaving ornotaspacebetweenanteriorborderof clypeusandmandibles;ingenerallabrumshapeasinconspecificworkers.Clypeusbroad,truncateorroundedinfront,extending to levelof frontal lobes; itsantero‑laterallobesconcave,freemarginwiththin,sharp,yellowishedge,transverseorconcaveinfrontandrounded‑di‑vergentonsides.Frontalareavariablydistinct,semi‑circularortransverse,moreorlessimpressed;rugoseorcarinateinthemiddle,andrelativelywelldelimitedbehind by an arched carina or rugulae that tend toconnect the twofrontal lobes.Frontal lobespromi‑nentandprojectingforward,lateradanddorsad,theirfreemarginsroundedsharplyinfrontandbroadlylat‑erad,antennalinsertionslocatedontheirventralfac‑es.Lateralbasesof lobescontinuedlateradassharplyraisedarchingcarinaerunningcloseneartheeyeoneachside,andthencurvingforwardtobounddeeplyexcavated,subreniformantennalscrobesboundedinfrontbycariniformposteriorbordersof lateralwingsof clypeus.Posteriorvertexborderedalongcervicallimitby lamelliformmarginbearingshort longitudi‑nalcostulae;spacebetweenthisandposteriorocellieithersteeporgradual,dependingonwhetherheadismuchdrawnoutbehindornot.Acontinuous,ornearlycontinuous,sharpbut irregular,ventro‑lateralcarinaextendsfromtheposteriorcornerof headtomandibular insertion, bordering subrectangular areaof cheekbetweeneyeandmandibularinsertion,andbounded mesad by carinate outer scrobe margin.Antennaelongandslenderwith13segments.Scapeveryshort,onlyabouttwiceaslongasbroad,itsbaseoblique,withthemoreacutelyroundedangleonout‑side, andobtuseangle inside, tapered towards trun‑cate apex; a little thicker than remaining segments.Antennalsegments2and3(countingfrombase)onlyabouthalf aslongasscape;succeedingsegmentsall

muchlongerthanbroad;apicalsegmentlongest;an‑tennalsegments8and9somewhattwisted,virtuallymakingtheantennaturnsarounditsaxis.

Alitrunk robust; prescutum with more or lessdistinctantero‑mediancarina;notaulishallowtodeepand complete, with transversal costulae. Parapsidialfurrowsshapedasfineshininglines;parapsidesmoreorlessimpressedbehind,buteachwithsharp,raisedpostero‑lateralmargin(hyalineinsomespecies).Pres‑cutellumseparatedfromscutellumbyanimpressionor transverse rowof punctures,or elsemiddlepartimpressed and not distinct from scutellum; lateralwingsof prescutellumwith laterallymarginate,pos‑teriorlypointedprocessorblunthook‑likestructure.Scutellummuch narrower than prescutellum, form‑ingelongatenear‑semicircleasseenfromabove,freebordersmarginate,butpostero‑medianportioncon‑cave; posterior aspect broadly in an inverted Y‑ orU.Metanotumnarrow,withbluntmedian tumosity.Propodeumwithdorsalfaceflat,rectangular,steeplyslopingposterad,separatedfromrectangulardeclivi‑tousfacebytransversecarina.Asseenlaterally,dorsalanddeclivitous facesof propodeummeetingatob‑tuseangle;declivitymarginateoneachside.

Petioleclavate,withanteriorpeduncleandlong,low, rounded node, usually bent slightly downwardnear base of posterior peduncle; spiracles papilloseandprominent.Postpetiolebroaderthanlongindor‑salviewandslightlybroaderposteriorlythananteradand broader than petiole; rounded above, sternumwith shallow depression; attached to gaster by itsfullwidth.Gasterwithfirstsegmentoccupyingmostof its length; four visible apical segments subequalinlength.Genitalcapsuleslender;parameresslightlybroadened,bluntlyroundedandcurvedmesadatapi‑ces,buttaperedtoabluntendasseenlaterally;vol‑sellaesock‑shaped,asusualinMyrmicinae;pygidiumand subgenital segment unremarkable, with moder‑atelynarrowlyroundedapicalmargins.

Legs slender, tibiae of middle and hind pairswithoutapicalspurs;tarsalclawsslenderandsimple.Wings brownish, with opalescent bluish reflections.Forewing veined as in the gynes. Cross vein m‑cuabsent,presentasa spur fromM,orasacompletecrossvein.Hindwingwithonly two longitudinal tu‑bularveins issuingfrommediancell (apicalabscissaof Randcu),withthetipof Scbranchingoff fromfusedSc+R(Rf1lacking).Analloop(A+Cu‑a)short,withoutaspurof A,butasafoldedlineinstead;5‑9submedianhamuli.

Larva (after Wheeler & Wheeler, 1954): Moderatelystout; thoraxand first twoabdominal segmentsnot


constrictedtoformalong“neck”.Of thetwotypesof denticulatehairs,thelargeronehasafine,tapered,nothook‑likedapex.

revised key to Basiceros workers and gynes:

1. Occipitalmarginof headrounded,formingacon‑tinuousornearlycontinuousraisedcrest.......... 2

– Occipitalmarginof headtrapezoidalorsubrect‑angular,notformingacontinuouscrest........... 3

2. Infull‑faceview,crestcontinuousaroundposte‑riorpartof vertexandseparatedfrommedianconvexityof vertexby abroad, uninterruptedsulcusparalleltothecrest....................B. militaris

– Crest medially emarginate and confluent at thispointwithmedianconvexityof vertex............... ....................................................................B. disciger

3. Mandible subtriangular, strongly bent ventrallyand with the outer borders straight basally;anepisternumdeeplydepressed........................... ........................................................ B. scambognathus

– Mandible triangular, not strongly bent ventrally,outerbordersusuallyconvexbasally;mesopleuraatthesamelevelasthesurroundingsurface..... 4

4. Head nearly as broad as long with the occipitallobes rounded; in frontal view, intermandibu‑larspacemuchshorterthanthehalf lengthof mandibles;gasterwithfewspecializedhairslon‑gerthanthebasalpilosity.................................... 5

– Headdistinctlylongerthanbroadwiththeoccipi‑tallobesangulated;infrontalview,intermandib‑ularspacebroad,withabouthalf lengthof themandibles;gasterdenselycoveredwithspecial‑izedhairslongerthanthebasalpilosity............ 6

5. Petiolarnodeandpostpetioletotallycoveredwithdensepilosity;petiolarnodewelldevelopedandsubrectangularindorsalview;ventralcarinaof petiolewithmanydevelopedteethof differentshapes.....................................................B. conjugans

– Petiolarnodeandpostpetioleweaklycoveredwithpilosity; petiolar node subcylindrical in dorsalviewtoalmostobsolete;ventralcarinaof peti‑olewithasingledevelopedtoothattheanteriorportionof peduncle..........................B. convexiceps

6. Basal portion of mandibles with dense pilosityformedbywhitishsquamiformhairs;ventralca‑rinaof petiolewithashortedgeattheanteriorportionof peduncle............................ B. singularis

– Basalportionof mandiblessmoothandshiny;ven‑tralcarinaof petiolewithawelldevelopededgeattheanteriorportionof peduncle,followedbysmallerdenticlesof differentshapes...... B. manni

Basiceros scambognathus (brown) n. comb. (Figs.1‑4)

Creightonidris scambognatha Brown, 1949:89. Holo‑type gyne, BRAZIL: Goiás, Campinas, x.1935(Schwarzmeier) (MZSP) [examined]. Brown& Kempf, 1960:178, figs.5, 8, 10 (genus revi‑sion,typelocality);Kempf,1972:80(catalogue);Lattke, 1991:59 (record in Venezuela); Bolton,1995a:1049 (census); Bolton, 1995b:146 (cata‑logue);Delabie,2000:272(distribution);Bolton,2003:184(synopticclassification);Castilhoet al.,inpress.(distribution);new combination.

Meranoplus singularisSmith,1858:195,pl.13,figs.6,7(onlythegyne).Holotypegyne:BRAZIL:Ama‑zonas:Tefé(formerlyknownasEga),nodate,(nocollector)[notexamined].

Ceratobasis singularisSmith,1860:78,pl.4,figs.12,13(onlythegyne).

Worker: HW1.13; HL1.25, CI92.31; ML0.46;SL0.96, SI83.33; WL1.52; HFL1.30; TL6.00.Color dark brown, appendages somewhat lighter;mesopleuron,petiolarpeduncleandgasterwithfer‑ruginousareas.Mandibles smoothand shiningwithminutescatteredpunctures;innersurfaceof antennalscrobes with transversal rugulation over fine punc‑tuation;surfaceof headrugulose,therugaeforminga loose net with deep cells, with whole integumentfinelypunctuated;lateralfaceof pronotumandante‑riorcoxaewithgrosspunctuation,pronotaldiscwithpunctuationandloosenetof rugulae;mesopleuron,metapleuron, petiolar node, postpetiole and surfaceof thegasterfeeblyshiningandrathersmooth,withabundant punctures. Dorsum of head, laterobasalmandibular area, mesosomal dorsum, petiole, post‑petiole and first gastral sternite with small, whitish,subapressedandapressedspatulatehairs;hairsdenseonheadandantennal scapes, lessabundantonme‑sosoma,waistandgaster;appendageswithabundantcream‑colored subapressed spatulate hairs directedapically and becoming gradually finer towards tarsi;posteriorpartof head,dorsumof mesosoma,pos‑terolateralcornerof pronotum,abdominalsegmentsII‑VIIwithfairlyabundantshort,erect,stronglycla‑vatewhitish‑goldenhairs;distinctgroupof longfili‑formhairsprojectfromlabrum;pygidiumwithshorterecthairs.

Head subtriangular. Mandible long and sub‑triangular; external margin of basal portion almostparallel;apicalportionslightly longer than thebasalone, external border strongly convergent with theapexof theothermandible,andnearlystraightmas‑


FIgure 1.Basiceros scambognathus,worker;a)headinfull‑faceview;b)bodyinprofile.


ticatoryborder;apicalportionalmostperpendicularlybentventradatmid‑length;basalportionmoderatelyconvexinsideview;adeeptransverse‑oblique,con‑vexgroovealmostdividesthebasalmandibulardiscin two, running from the masticatory margin to atleast halfway across the mandible and ending shal‑lowlythere,thegroovesconvergingwiththegrooveintheopposingmandibleatthejunctureof thetwomasticatoryborderstoformabroadVwithanob‑tuse,posteriorlydirected,apex.Centraldiscof clyp‑eus convex, its anterior border very shallowly andbroadly emarginate or concave; anterior portion of headcapsuledeeply impressedcomparedwithclyp‑

eus, forming two transverse‑obliquegroovesdeeperanteradandmeetingapicallytoformabroadinvertedV.Triangular area indistinct, glabrous; no spacebe‑tween clypeus and mandibles when closed. Centralportion of cephalic dorsum raised as large circularswellingwithdeepconcavityincenterformingthickring.Posteriorheadmarginwith shallowandbroadmedialconcavity;occipitallobesroundedandslightlyprojected.Eyerelativelysmall(cafivefacetsatmaxi‑mumdiameter)andplacedfarback,justonthedorsalmarginof antennalscrobe;scrobedeep,runningfulllengthof cephalicside;scapeflattenedandstronglylobedbasadbyprojectionof anteriormargin,apical

FIgure 2.B. scambognathus,gyne;a)headinfull‑faceview;b)bodyinprofile;c)detailof themandibulargrooveinfullfrontalview.


segmentof funiculuslongerthanfourprecedingseg‑ments.

Mesosomarobust,promesonotumonlymoder‑atelyconvexdorsally;anepisternumsetlowerthantheadjacentsurface;metanotalgroovedeeplyimpressed;propodeal spinesvery short and subtriangular; pro‑

podealspiraclewideopen,relativelyprojectedlateradanddirectedposteriorly.

Petiole pedunculate, slightly arched, with aprominent and thick node which is nearly longerthanthepeduncle,nodewithsteepanteriorandgen‑tly sloping postero‑dorsal faces, peduncle ventrally

FIgure 3.Basiceros scambognathus,male;a)headinfull‑faceview;b)bodyinprofile.


carinatewithaseriesof small,acuteprojectedden‑ticles. Postpetiole subequal in length to the petiolarnode, lowinprofilewitha long,flat,slopingdorsalfacewhichraises toa lowroundedapexposteriorlyandthendropsslightlytoitsjuncturewiththegaster;seenfromabove,thepetioleisnarrowerthanpostpe‑tioleandisoblonginshape,whilethepostpetioleissubtrapezoidal,asbroadbehindaslong,thesidesdi‑vergingposteriorlyandthenveryslightlynarrowedsothatitisattachedtogasterbynearlyitsentirebreadth.Gaster long andoval, its anteriorborder semicircu‑larly excised to receive the postpetiole; first gastricsegmentformingthegreatbulkof thegaster.

Gyne:Holotype(n=3):HW1.25(1.16‑1.24);HL1.42(1.34‑1.42), CI88 (87); ML0.42 (0.39‑0.41) MI30(29); SL1.09 (1.04‑1.09), SI87 (88‑90); WL1.84(1.85‑1.88); HFL1.30 (HFL1.28‑1.31); TL7.00(6.93‑7.03).Likeworker,with themodifications ex‑pected frommyrmicine gynes. A complete descrip‑tionof thegynewasgivenbyBrown (1949) in theoriginaldescriptionof Creightonidris.Additionalinfor‑mation is given above in the revieweddiagnosis of Basiceros.

Male: (n=4):HW0.87‑1.00;HL1.04‑1.15,CI84‑87;ML0.20‑0.23, MI(0.19‑0.20); WL1.63‑1.87;HFL1.23‑1.37. Color dark brown with somewhatferruginous areas. Body sculpture basically rugose‑punctate, except for central discs of anepisternumandkatepisternumwhicharesmoothandshiny;headcoveredwithscattered irregular rugae;alitrunkwithsparserugaeondorsalsurfaceof promesonotum,in‑feriorportionof mesopleuron,propodeumandpeti‑ole;broadpuncturesshallowlysetonlateralsurfacesof alitrunkandwaist,butslightlyfinerongaster.Longfiliformwhitishhairscoverbody,denselyarrangedonhead,dorsumof promesonotumandgaster.

Mandibles triangular, as broad as long, stoutwith10 subconical teeth, the third and fourthonesbroader than the others; apical tooth directed out‑wardsandslightlydistantfromsubapicalone;exter‑nal margins of mandibles strongly convex at basalportionandstraighttonearlyconcavetowardsapex.Head rounded in shape. Ocelli placed almost later‑allyinthemedianelevationof occipitalborder,cen‑tralocellusprecededbydeepcleft.Adeepgrooveispresent along posterior border of clypeus at spacebetweeneyes.Centraldiscof theclypeusraisedandformingdistinctcirculararea,lateralportionssome‑what lower, anteriormargin straight to slightlycon‑cave.Eyesvery large.Antennalscrobesshallowandlimitedposteriorlybyhighnucalcarina.

In dorsal view, prescutum nearly as broad aslong; notauli shallowly impressed; antero‑medianportionof prescutumwithasmoothandshiningtri‑angular area; parapsidial furrows extending beyondprescutummid‑length;parapsidesbroadandrelative‑lydeep;prescutellumvisiblemediallyindorsalview;lateral wings of prescutellum subtriangular, withacuteandwelldevelopedpostero‑lateralhook;scuto‑scutellargroovebroadanddeepwith2‑4transversalrugae;scutellumtwiceasbroadas longanddividedby longitudinalgroovemedially.Propodeumbluntlyangulatedinsideview,notbearingteethorlamellae.

In lateral view, petiolar node subrectangularwithroundedangles;indorsalviewnodeisrounded;subpetiolarspinesvaryingfrompresentandsmalltovirtuallyabsent.Postpetiolesubtrapezoidalwithpos‑teriorborderconvexandbroaderthananteriorone.Gasterlongandoval.

comments

Theaberrantmandibleanddepressedanepister‑numof Basicerosscambognathusseparatethisspe‑ciesfromtherelatedBasicerossingularis.Originally,B.singulariswasdescribedbySmith(1860)basedonaworkerandagyne.However,thegyneisatypicalB.scambognathus,whiletheworkerseemstobeun‑related as judging from the figures (the type speci‑mensarelost).Thissituationwasonlysolvedwiththedescriptionof thegenusCreightonidrisbyBrownin1949,whenheprovidedfurtherdetails.

Inthedescriptionof theholotypegyne,theval‑ueof TLisstatedasbeing7.4mm;Brown&Kempf (1960)made an amendment to thismeasure statingthat the specimen has the gaster dilated in around0.4mm;thus,thevalueherepresentedshouldbecon‑sideredthecorrectmeasure.

Acompletediagnosisof BasiceroswasgivenbyBrown & Kempf (1960) and Brown (1974). In thepresent paper we offer a supplement to the latterin order to include the features of B. scambognathusn.comb.Weaddinformationregardingtheshapeof theheadandmandibles,anddescribeinmoredetailthestructureof thegyne’smesosoma.

Allapomorphiesof theBasicerotinidefinedbyBolton(2003)holdtrueforthespecimensof B. scam-bognathusweexamined.

Unfortunately we were aware of recent mate‑rialcollectedbycolleaguesonlyduringthefinalrevi‑sionprocessof thepresentpaper.Theywere:agynecollected at Nossa Senhora do Livramento county,northern Pantanal in Mato Grosso, Brasil, and the


workercollectedinasecondaryAtlanticForestareainLençóis,Bahia,Brasil(12°33’S41°23’W)(Castilhoet al. in press).Both specimenswereobtained fromleaf littersamplesusingWinklersextractors.

distribution

Untilnow,B. scambognathusisknownonlyfromthe Brazilian largest biomes (Amazon Forest, Cer‑rado,andAtlanticForest)andforasinglelocalityinsouthVenezuela,neartheborderwithBrazil(seemapin Fig.4). Its apparently discontinuous distributionandscattered recordsmay reflect inappropriatecol‑

FIgure 4.Distributionmapof Basiceros scambognathus.

lectingtechniquesduetoourignoranceof thespeciesbiology.

biology

B. scambognathusisoneof themostobscuretaxaof neotropical ants and virtually nothing is knownaboutitsbiology.Veryfewspecimensarerepresentedintheworld’santcollections,mostof themarealategynesandmales,capturedinwidelyspacedlocalities.

Brandão collected the first dealate B. scambog-nathusgyne inUruaçú,Goiásstate, in1995,andat‑temptedtomaintainitinartificialconditionsinorder


toobtainworkersormalesandtorecorditsbehavior.Unfortunately, the specimen died some weeks afterconfinement and the only piece of information wewereabletogatheristhatthecaptivegyneacceptedtermiteworkersasfoodinthelaboratory.Interesting‑ly, this individualwasfounddeadwithinthefungusgardenof anAtta sexdens artificialnest in the samelab,sowecannotruleoutthepossibilitythatB. scam-bognathus lives inside Atta nests (or another fungusgrowerant),whichcouldexplainthedifficultytofindthisspeciesinnature,andinpartitsstatusof rarity.

Thesecondworkercollecteduptonowwasre‑coveredalivealongwithotherants,severaldifferentterrestrial arthropods, and soil particles froma leaf littersample.Onceinaplasticrecipient,theworkerfeigned death upon disturbance, in typical Basicerosstyle,remainingsoforseveralminutes,andreassum‑ing movement quite slowly. Also as expected for abasicerotineant,thebodyof theworkerwastightlycoveredbyalayerof driedsoil(Hölldobler&Wilson,1986).Fromthesamesamplewerecoveredalsosev‑eralworkersof anunidentifiedApterostigmaandmanyBlepharidatta conopsworkers.

Examined material:nolocality,nodate(nocollector),[Gift from B. Bolton (BMNH) #59 74] (1 Gyne)(ANIC).BRASIL:Amapá:Amaparí,8‑10.xi.1993(W.França), [Tucano‑2] (1 Male) (INPA); (F.F. Ramos)(1Male) (INPA); (N.Bittencourt) (1Male) (INPA);9‑10.xi.1993(A.Pena)(1Male)(INPA);10‑14.xi.1993(F.F.Ramos)(1Male)(INPA).Amazonas:EstirãodoEquador, Rio Javari, ix.1979 (Alvarenga) (1 Gyne,1 Male) (MZSP); N of Manaus, Reserva Ducke,22‑26.xi.1966(nocollector),[Malaisetrap](3Males)(MZSP); 14.viii.1981 (C.B. Fairchild & J.A. Rafael),[Malaise] (1 Male) (INPA); 28.ix.1981 (J.A. Rafael),[Malaise] (1Male) (INPA).Bahia:Maracás,FazendaMariaInácia,24‑29.xi.1990(Brandão;Diniz&Olivei‑ra) (1Male) (MZSP).Goiás:SerradaMesa,ColinasdoSul(14°01’S48°12’W),2‑15.xii.1995(Silvestre;Di‑etz&Campaner), [Cerrado](1Male)(MZSP);Jataí,xii.1972 (F.M. Oliveira), [#8911] (1 Gyne) (MZSP).Maranhão: Estreito, Fazenda Itaueras (6°31’54”S47°22’16”W),12‑22.vi.2006(R.R.Silva&R.M.Feito‑sa)(1Worker)(MZSP).MatoGrosso:Sinop(12°31’S55°37’W),x.1974(M.Alvarenga),[#12306](1Gyne)(MZSP); [#12307] (6 Males) (MZSP); (Alvarenga& Roppa), [#12517] (1 Male) (MZSP); [#12551] (1Gyne) (MZSP); [#12552] (4 Males) (MZSP); VilaVera, x.1973 (M. Alvarenga), [#10253] (6 Males)(MZSP).Pará:SantarémNovo,FazendaJaburu,7‑9.i.1993(J.Dias)(1Male)(INPA);Igarapé‑Açú,i.1949(Gonçalves) (1 Gyne) (MCZC). Rondônia: 62km

S of Ariquemes, Fazenda Rancho Grande (10°32’S62°48’W), 12‑22.xi.1991 (E.M. Fisher) (3 Males)(PWRD). Roraima: Ilha de Maracá, Rio Uraricoera,18‑28.viii.1987(J.A.Rafaelet al.)(1Male)(INPA).

resumo

No presente trabalho, propomos a sinonimia do gênero monotípico neotropical de formigas mirmicíneas (Basicerotini) Creightonidris Brown sob Basiceros Schulz e descrevemos pela primeira vez a operária e o macho de Basiceros scambogna-thus comb. n., conhecida até agora somente por rainhas aladas. Apresentamos dados sobre a distribuição dessa espécie, uma nova diagnose para Basiceros e uma chave atualizada para identificação de operárias e gines do gênero. Os poucos dados conhecidos sobre a biologia de B. scambognathus são sumari-zados.

Palavras-chave: formigas, Basicerotini, Creightonid-ris, Basiceros, chave, sinonímia, descrição de operáriaemacho.

AcknowledgMents

The authors would like to thank Dr. PhillipWard for the loan of important material. The au‑thor RMF and Dr. Rogério Rosa da Silva collectedtheworkerof B. scambognathus inanexpeditionsup‑portedbyOIKOSPesquisaAplicadaLtda;wewouldliketomakeaspecialreferencetoDr.FábioOlmosandDr.JoséFernandoPacheco.Dr.NelsonPapaveroandDr.UbirajaraMartinshelpedwiththenomencla‑ture.LaraM.Guimarães took theSEMimagesandGláuciaMarconatomadetheworkerhabitusdrawing.Wewould also like to thank several individuals andinstitutions that helped or supported our collectingtrips.ThepresentworkwassupportedinpartbytheConselhoNacionaldeDesenvolvimentoCientíficoeTecnológico (CNPq). John Longino and an anony‑mousreviewersuggestedseveralsignificantimprove‑mentstothemanuscript.

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