bj^; THE EVOLUTION OF THE DACETINE ANTS B> WILLIAM L. hROWN, JR. AND EDWARD (). WILSON Museum of Comparative Zoology, Harvard L'ur.cynty A [»rluniii<,iy ■,\'illi>:'<is "f ''v»luli(»un\ ^tutlw.s of (fil<n)i iiioi plun'o^iful and rlh"ln^i- ,nl tlin'tnlt'}- i>i ihr tint In he Ihut'lnti !■. ^u-fn. A j>ii'iun\ tifwl inicncd fnitn Ihf ^tiuly .<f UriNii s/'r^K-s M Ihf ■.htll li<n,i ,'l>iiiafir-sul>arho<,Ui'. to axlilir l.'n^^liial fonii^tuii. Fo'i- s,/i/v it^'.o^talt'd in the tvi>/v ■'luii''-' "/ (l<t"-ti"<- tvolnlion with this ^hilt i/vn <i In-ud toward ,,!ii^<>l'luiiio\i^ pii'duliou. ifMilltii^ III fxt'cine nisfs lunon^ »\o,ieiu i<nms >n ^fuuialized urdiuii on tolli-niboUin^. Sf(o>id,n\ ilutnges luive oidtnnl in hunln,^ helini-ior 'ind m a duriuty ot inoildiolojiKdl lt'iitiue\: tlif.!- aie dfurihfd }ineft\ . }{tr>-r-,ed oi . nioic ac- iuuitrlw rounli'uiiiif'Til" rvohUion hn\ oaiinfd i'l -.''irioif, piiyletic !iui-s in ino\t of III,- (hniiiilris "f f/ns morpliolo^ual-rtiiolugKal (ondafftive ^xslein. Sudi i lunii-t's are n-l(itnrl\ ■,lio>t-'ri^^f dnd uMiull\ involve only a feu- chanuler.', nl a tune. In ,it Ifi^t ^omc iu-,lances they have pioiliued a local rei'eiud in the overall daretine trend to \{<ei inliza- tion.a-y with \e(oud,nil\ intiensed pohfihagy in some ^f)eiie> of SirumiKerivs. (:ouveri:.ence So the hit^her dacetuie inorpholo^ieiil type hri.\ occurred independently in .several other ant l>,he^: in at least one cue (Rhopak.tlirix) ethologicai convergence n also evident. IN IkODLt.riON III rtttrit Mvirs. wt- Uaw witiussecl .1 spt-c- t.tiuhir risf m iiutri-st in (onipaniiivf ^lu(ii(.-s ol anitiial lR-h.i\i(ir. Many of these siiidies lia\e aitrmpted t(i relate behavior .>l :j,i\vn speties or lii^her taxa to their pariidtl.ir eru iroiniients. to the morpholoi^y and ph\MoloHy ol tlu- aiiiiiialv 10 their ^ysteniatifs. and 10 their e\olutionar\ liistorv. Cieriainlv, the iiitenralion ot al! these approathes should be a prinnpal s;oal of ilie modern in\estisiaiion of am ■^roup. One itnpori.iii; i^iotip of .iniinals thai is espe- «i.ili\ l.ivorable lor -nth an integrated studv is that ol ilie ants- 1 liese inseits form a distinit l.iiiiil\. the Foniii<idae. in the Order H\nienop- u,.sp-hke ,n^ I he ;Mits are still iti- (ompKielv known and ar<- rather ii ns.it isfat tori ly .Lissdied, but uc beli(\e that, with more than m.iHin sp,'(ics Lind >(*\eral hundred i^enera al- r(.H!\ <t<s. ril)ed. ilu-s are rou-^hh comparable in di\er--it\ to ,1 taxoTi Muh .is the i lass \\c^. \^ is implied b\ their ]tl.iiement .nnon,!4 ihe HvnuiDptcra, the ants .nose iai)parciuK diir iiiii liie (.ret,l<^ou^,l tmm Mime L;J"iip of u,i-.ps, prob.ibK sojn.in u..^ps .ilbrd to ilu- Hmti- li phlld.M . I In ' AIMIll'^ .im ^p.,H^ ,U( .dl social ih.ii IS. p.ncrii -idull-, ■-'■.[ ilirir MtKpini- o! .ill developmental singes li\e together in groups. (ailed tolonies. In most species the colonies in- habit more or less definitely strut lured nests in the viil, in plant cavities, ete. During most of the vcar thev are conipcjsed entirely of femah>. which are nornialK cli\ idcd into two basic caste-., the cjueeiis and the workers, which tend to be specialized for different functions. Males appear in tiie colonies at cert.iiii seasons, .and are ii'.i- portani oidv in sexual reproduction. Ihe faet (hat nearlv all hinnan cultures li.ivf a conunon word tneaniiig "ant" is a tribute to the af>undante and uljicpiitv of these insects over the temperate and tropical parts of the earth. Their great numbers and relati\eiv high attiviiv rates [jlaee tliem .iniong the really important traTisforiiHTs of energv in terrestrial environ- ments. It is ag.iin their exce[)tional ahundame. as well .IS the ease with which they may be (ouih! and (ultured in (he laboratory tliat renders .uif- idea] suljjects lor biological studv. ! he most primitive .inis, like their wasp .m- (esiois. hfd (heir larv.ie on manv kinds of in- sects that ihev (,ip(ure on plants or on die ground surhne. uhile ihe .iduh workers them selves i^.nn .( Lir^e part ol their nourishnn'i^ Irom n.U.it or oih.r su-.mv substances for v^hu!l du V l..r.iL;e on ];],nns. In higher groups ol .iitiv tudiiiu is ohi II more six'i i.di/cd. Some kinds ////•: lADii I los or I III-: dki/iim: j.v/s jT't liii,iL;r .!iM(»st I riiir<l\ uii [he (iiiiik> .11 lifii.im- III Duntvi; i!k' |i.i>t ten \i\its liic |H(v, ill nn!ii.i> iKt^. uhcif lli<\ in.n hikI pl.iMl li<i.- loi tliiir h.i\ r Incii , oikIih nni; mu I) ,i ,iii(h inii niiji I. mix iiiijR-\(icu-. liiijil ii!MU>. Ill biiih \(.ni\ l\jH^ uhik- i iii^.ii;((! in l.il,oi:iiiit \ ,m<l lulit wmk in h.nc bc-c.iiR' h.nvfMiiN ,1 Mnl>. .mil niu- gr.Hi|i. ilic Liimd Si.iit^ and in bmli ili,- < )lil .mil \ru iIr' Vltiiii. l.iiM> .iikI f.us Uiimi. thu^ (-iit;af;in)» W.irkl lni|)iiv llii- liillnums; |i.i|)ri i . uiM ii in, , 111 Ihc "iii\ \n-ll-isl.il)li^h«l i.isi' III trur nop .1 priliiiniiin v Miinniini; up nl ilu- i,,iili^ ,,| ilu, i^ritiillnrc txirpt tiir th.it in.m.i^^cil b\ in. in- illort. In it wc li.ut' llii.il K. ^k(■|^ll -nine oi ilii- ^niil. <.\iiltitinn,ir\ ttt-ntls tliii^ l.ir imttil .mil 10 sfimv Other lino among tlic .nils li.ne deM-lopt-cl how iini<h ui major (I.Kilmi- iMiiiuioii 1 .m |Hedator\ in.issloraj^illi; "ariny.iiit" li.ibits th.lt be ilUfrpuited .is the oiiliiuiie <il .1 ))iiiii.ii\ li.ive .dioued them a uitler thoite ol prey, while .id.ipti\e sliilr toward UAjnii loiai.^in- ih.ti < h.ii -till othlr^ ha\e e\oked \ery narrow prey pref- a.teri/es upper phvletii lines ol ilii, irilje Ol ileiuev ,iiih .IS the /.i/Ko:;,;!! ^ wlliih leed on eipiai imporl.iiue. we h.i\e .itteinpled 10 iiidi- Miwbugs ,Onisioiii..rph.i). or the eMiess <.e«- ( .ite the iar,ne iiaps rem.iiiiin-; in inn kimuledoe ,'ii)i/iv'"n-v. belie\ed to t.iplnre termites in their ol this intelesting j^roiip ol iiiseds I Ik possi- suljterr.inean p.iss.e^es. 1 here is e\en one l.ir;.;e bilities lor Intiire reseaith seem 10 be -n-.u. both Hioiip. the C.erap.iilnini. ihal liies by raidini; lor the eioliitioiiist and loi the phs ,11 ,li i.^isi m- llle nests ol other .ims and leeding on their teresteil in the .m.thsis ol stereots ped In h.i\ lot brood, lo this i.ttei^ory ol spedalist predators In t!ie desiriptise p.irts to loliow. 11 li.i, been belon5< also tile D.uetini. a tribe ol nearly 2IIII nciessary to use sener.il tedmiial uoids mdi- kiiown speiies belonuing to the sublamily .\l\r- narilv lound only ill i.ilher speii.ili/id iiito- iiiiiinae. one ol the nine major divisions ol the mologieal and taxoilomie iiteratuTe. I 01 the 1011- loruiteidae. We ha\e not yet iinto\ered the re \eniente oi the geiieral leader, some 1 il these l.itionships ol the Datctini to the other tribes terms are briefly explained below, of Msrniieinae: they lonn a phyleliially iso- .J/i/n/n*. Ihc eenlial portion ol the hods of filed group, oiiurriiig mainly in the trojiits and the ant (ami other Hynienopteiai. lonsistiin; ol milder temperate regions of the e.irlh. But the true thorax and the Inst true .ibdoniin.il enough is now known .ibont them to m.ike the segment, whith is fused with it. Datelini an espeeially instrmtise i ase history of Kpii^iit-N . Foraging in the open ■.vhether on gnnip evolution. the ground or arboreaih: (oiitr.iMi u unit /n /jo- in I'.l^fi I.. G. Wesson showed that the d.ieetine i^iieii . int Sinilhisliuma pergandrt (Kmery) has some l-'fn'riilr. Referring [o iiltegiiiiieiit.il s. iilptnn remarkable petuliarities in its lood-getting be- tonsisting of loveae, relatis eK Luge i n, al.ir de- havior. Workers ol this spetics prey ihielh or pressions with well defined ni.irgins. oluii bi.ir exclusivelv on springtails (toilcmbolans), width ing a h.iir on a central luberelc. they rapture b\ an elaborate inaneuser inelud- l-untiulus. The series ol segments ol the .m- iilg i.irelnl st.dking lollowed bv .1 sutlden. it.ip- teiiira bevoinl the elongate first s(|im(nt. or like closure of the mandibles. Wesson .iiid Wes- uiipe. son (ly.TO) showed that similar behavior is (,ii.^l,-r. The last major po.tion ol the bmlv; exhibiteil bv a lew odier speries of Vm((/m(iijm(i in datelines the gaster follows the poMpeliole in North .\meriia. These early observations, .ind is roniposed ol the lonrtli .ind suKeediin' vshiih have been hilly (onlinned hv Liter work, true ahtlominal segments. revealetl 'ymilhi.tuimn as one ol tile most highly Hyp,,;,,,,;,-. Foraging in hidden pl.iies. 1 iili.i sjieii.dized ol .di .int genera ol whith the habits within or beneath tovering objetts mh h is i. .il .ire known. Sinijhi\htunit. however, re)jresents litter, moss, or rotting wood u )\ l>lnh>:,hi ,, ,,! the end-produil ol but on< phvletie line ol the deeper within tile soil itsell , oWitr, i,i;,i ,0, ,. D.iietitii. Ihis large losiiMp, iliiaii liibi' (on- Mo, phoi i,j,r. \ stepwise series ol ih.ingmg Inns a rich diversity ol genera. 111. mv ol them ni.milest.ilioiis of a given ili.ii.mei is lojiouid ili-.irlv very primitive leLitive to s.mlln.humi:. throngll .1 ^roup ol relmd speries. ii,ii,l|v m ■iiid iilhers oimpving mterniedi.ile or higher terpretid .is the leMili , .1 1 miIiii ion.nv on . 1 ,miii iilivlelii posilions .111.. -,i Ihe D.iieiim ihere- /Voo/e. I he Inst segiii, in 1 n nod,. „, ,(|, .,,,, , liiri proviile ,M,lkiit , ippoi inniiies lor the 'u .list- . 1 he si, oiid 11 ii,' ,ib,ioii]in.il . -in, 111 Miidv III 111,, phvlog.nv ol iniil.mirv liili,,M,,r. /'i, ,//«•, ,.,;,■. 1 he sen, 11, 1 „ ^nu 111 ,il ■;:, mi. lilt. urAlil'l-.RI \ Itll lEn Ob HIOIJKiY ■ 9f' ^^ Wi- ^iiill 77/ a: uoi.i iiox OF nit: d.hetise as is 2hi ■ujisi" ill ;4i„u|)s. ,ucli ,i> ilif n.icniiii, piiwss- li-iT<,iri,,l .iml Mil).u-|).,iiMl. K.xkI- int"iii,.l)n,,- iilSa lu-d-joiiitid uai^c: ihf ihinl liiicilKl.imiiKil ni<ir|,li anil NViii|jhs|)if(>nail c cill.nili.il.iii, ,,ml "''""'^'"'' ■.u'^.m MibMaiKfy (Brown. I'ljlai; l-j^. il, l'u,i,lunui.,n. Rt.(trrin« „, iiucmmiciu.il ll,xn,l,u,,„n (I). Ausualiaii. Am.I m ruh. Mulptur<_M„ii,iM„i),.o(|niii( lures or Miiall pits. Workers moiiomorphi, u). Ion- iiKnulibiiLiic. Si,i;«-. riu- clons-alcd first (basal) siKiiicnt of Ni'sliiis ami forasiiis; lial)its uiikiiouii i Broun, the antenna in ,inls ami some otiier insetts. I!HK, ll).',4a); i-ii;, 9. t< oi.<,<,ic.4L sYNOPsfs OF riiK aujEii.vF GENERA -"'■>'"'"""'"-)■ ^Ustr, I li.i n. .\ri(l H riib lo 1 1 op- , , , "■•' '""'^l. Workers fei blv polsmoinlni. uiili In ll.e following se.tion ,,re iiste.i all of tile n.antlibles ol iiuenne.li.ne l,„-.,l, Nes.i,,,. „ul known subtnbes ami genera of the Datelini, f„ra,!;,„„ habits nnknown , Brown, IT.-I," Fi.. with \erv brief general statements (onteniiii}^ 7. our present kiiowletlse ol their distribution ami t:.,l.,l,„sl,uma (in, Imliii" ih~',uH,.i oui natural hislors. .Most ol these- ,^1-onps ha%e been CJn, ki.lnnnn) (1,1 nuln.lnis ,e,e, ,1 mule treated in more detail in the tasonomic and s, ribed), ,\nstralian-i>apua,i, \rid heath 1,, iro,,i. ftoloKital papers titetl at tlie end of the indi- ,al r.iin forest. Workers monomoiphu, short- Mdual sMiopses, Ihe number of speiies known niamli!)ulate, ,\ests in soil ,ind loitiie. wood in eath .genus is given in parenthesis l.„) alter one spe.ies (C, „/,„o,/,> 1-orel, nests uiih -pet ies lie generie name. ol liliMiilupiineni. For.igiug beh,,sior di\ ,Subtribe Datetiti, """" '!'«'" '""'■ 1>M><'K" » "IIhis epigu-i, and subarboreal: stime of ili, Later are ii.,iinrual Darrlon (I), Neotropieal, Tropieal rain for- f,kx1: in two trvptobiou, spe.ies „t,d,.-d eiito- est. Workers polvtnorphit, lou,g-mundibulate, mobrvomorph .ollembolans -liiowu l<|-,4,, .Nt-sts in hollow- tree trunks. Fora,ging epigaeic- Figs s III 11 arbtireal. Food: tatianid fly (Brown, 19,Ma), small .„„ ,'„,/,„,.,„„ ,.,_^, Fthiopi in \Vorkers mon a.ridid grasshopper UMuph (see Fig. I); workers oniorphie. long.niamlibulate l-rimaiiK lorest- a.tend toeeids on eaeao (Bodkin in Crawley, dwelling. Nesting ami lora.ing b.-h.itio, „,,- l.t Ml). . ' known. Aianlhogiialhui (3). .Neotropiial. Tropieal rain forest. Workers monomorphie. long man- «„K,, i , c. ,11,., , , . ., ' ^ aubtribe Strinnigeniti dibulate, Nt-sts in rotting logs. Foraging behavior unknown (.Mann. 1922: .\I. R. .Smith, 1944): Strumigenys (ini hiding 7.,i/>i./m_„ „v, :in(i l-'i,!,'- 3- Pynnii,,,) [t-.i. I,VI). Wi<lespr<:id il- iipiisami „,.,,, ,,, "•"■"1 tt'iliperate:ireas. I>riiii:,rilv hue, 1 dwelling: Subtnbe Orectognathiti -,.„,»...„,; , .... -■> some speties ottnr in gnisskind ,iml ,iriil siiiib, Orpctngnathus (IS, intluding 2 undcscribed). Workers monomorphit, in one spe.ies stioml \ustralian-,Melanesian, Wami-tcraperate and '""ilv |jol\morpliie: long inandibnliu , Nests tropieal forests. Workers primitively tnonomor- mostly in soil ami tolling wooti: ,i b vv spities phie, in one spei ics secomlarily polvniorphie: '"*■ '" :irlx)real plant i :iv ilies in ir.ipiial niin long-mantlibulale. Nests in s.>il and rotting vv-ooti, forest. Foraging hvpogaeii lo epigjt i, ,nboie:il. l-or:iging epigaeii, probably mostly subarboreal Footi: most speties :ii-(- i ollenilxilan let-tiers: a -nul notlurnal, FootI: the single speties studied '"*' -nf polvphagoiis pn-tkiiors , s. e In low| or ((>. clarki Brown) aiteptid entomobryomorph '>" vision, div feeil rm siig.nv snbsiaiues: one spe- ■ind symphvplconantollenibolans (Brow-n, I9,"),'ia, ' '" (''- v^iiov Browiii is ,i workeiless |,.irisii(- l9:-,,Sb. 19,-,8a): Fig 4, (Weber, Mlj9, l9,-,2: Wilson, Mr.ll, ]9-,t, Broun! .lrnoldi,hn ('.i, I'apuan, In.pital rain lorest, l!l''-la, I9'.4b, 19,'.")): Figs, 12, !.-(, 17^21. 2j. 21.. Workers inominiorphit. long ni;imlibiilali-. Nests '"- -'" in soil. Foraging diurnal, .hieliy snb.iiboreal, <lu,:,hi.inirn,j Miiiliii:il ^eini, ioiii,iinniL' l-ood: unknown, (Brown, 19')Ha): Fig, 2, two spec ii-s derivitl ind(-|K iidenilv li I unii- Snbtnbe Kpoposirnniiti ;;■"",,-"' , —'';'';-'- ""■t- mom,- ,., ^ ' ' men phi, , sh,,rMn:indilHii,iie Dm- si,i, ,,-s o /,/,o/,o,„„„,„ „,_«, Xusirahan. Wann-l,-m- ,-,„„„„. ,-„„„,. ,s a paiiliop„.,| „a„ p. msung .era e lor.-si. ^^orke,s mono, phi.. l„i,g-„,an- ,n r,.l„„g wo,„l. .o.on.ii hilsks. „,„ .-',. , ,' ■bbulate. Nests ,n soil Fotaging epigaei.. ne, b.h.v ,or „nkn..wn . Brown. Pl ,., ,.|, lb, ' L'K2 HIE or.iiiriHiY nij ifav oi hioiah.y yfi^lnnini ((ii. Neuropil ,il. iii.iiiilv loii'^i i\u-|)l for XiiMr.iii.i. New /inijiul, anil Cliilc. llo..r-(luillni^. WoikiT', moii.iiiior|)hi<, \itv M,i,tlv fori>l-<lu<lliiij.. Workirs in.,ii.)inorplii(. Miuil, iiKiiulilili^ \.Li\iM!^ Iroiii ^liorl-liiti-niudi- ^horl-mallclil)ui,ltl■. NiMi in y>il .mil roKini; 111' lo loiii;, NiM> ill roiuiij. ivooil ill «>il loM-r. uooil: a li-w spnii^ !i\i' in arboreal plant lav- illiklilill!; Miiall ihip^. i-ora,niiin (.V. »lMi/. /.vi„| im-s in iropiial ram lori-M. Fora);iii(; iiiosllv iiiostlv ii\ptn. ^[lll^l;t^ll. witil "a III l)U-,il" tailiis inpoi^aeit, wilh a tfiv spii its prfsuniahlv epi- fri-ijut-nl: iitiii/is ■\irikt-lioliI -,11111^ " li-iiiiiiijue :.;ai*ii arliorcal. looil: spciit-s ranj^t- from >tritt III pro ijptini-. Kooil. «, lar as known, is tnto- lolk-niliolan liiilirs to |)ol\plia,i;ons arlliropixl lllollr^oid (a)lk-iiil)ola. .;Bro\vn. 1948; a revision prcilalors, (Wissoii, \')Mr. Wesson and Wesson, ol this ^enns liv Krowii is lieing readied lor I'.I.'W: Brown, ]!l'),1,i: Wilson. Ml.'i4): Fi-j. 23. press.) Figs. I l-lli. :i2. (.hnn\>nrn\)>r>t'\. i'lidium^ntiex , Coilmxt'nu^, Sinitln^hunui d)ll±). Widesjiread in tropiis l\'<'hni\ltnnui. lini^jnni'iila. l't'nlii^tin/nit.(,\in- .ind warm uiiiperate .ireas throughout world rntriiynnt'x. 'I'mi^innnni'x. Mj' < 'i^ttiinui. Vhis ]^ Fi'.s 2-4. Sosit PRisiiioh l>\(tiiNr (.i\m\ Ooisdl \iews. ,,n<- ameiina omitted in eaell fimiie Fig. 2. Arnnldidi:^ 'Zrnir.wni loirker legs and |.osNTi.a- pail nl gaster niniiled. Fig. :l. .1i:it:lhn^,i„ll:uf ,,.rll,ini,. Iiead iif worker Sole basal leelb ol iiiaiiilildes. in this genus used lo ,air\ the jariae. and die lolded nigger hairs liere sili.aled on die mandibles so as 10 erei I and point forward when the maiidihles aie odciksI Fig 4. r)r,i/,.g,i„(/nii ph\llohalfi. woikei ■■irs oiiiitled. THE tJOIJ ri()\ l)l- III/-: DtCET/XE IMS HypopomyrmeK (L) (f..,.l) Ouadri strumo ( l ) Strumigenys ( L ! Neostrumo (I,L) EpitntuS (!) Trichoscapa (Sl Gymnomyrmex (S) Miccostrumo (S) Smifhistruma (S) Weberisfrumo IS) PentasUuma (S) Codiomyrmax (S) B Of q meJerita '. S) Glomy romyrm ex (S ) Codioxenus iS) Oorisidris ( L ) Kyldris (S) Serrostrumo (S) Tingimyrmex (S) C ol Ob 05f r umo (S) Mtsostruma (I) Epoposfruma (L) Hexadaceton (L) Microdoceton IlI Arnoldidrii (L) Orectognafh us (L) Acq nthognothus (L) Docaton (L) Fii.. '). Prkslmfd Ph^((j<;fny of ihe Knou-. C.fnfk\ ok I.iviNr. \m) Fosmi l)uiir\r Letters in p;irenthcsfs refer to kiini of maiidiljles: L, long; I, intennedidte; S, shnrt. a j:;r<>iip i}i •rfi^cra. related to Stmthistruma and (ultund areas. Nests Jit M;il, rotting uooil. tu -. (omainini,^ in the a^gTegaie approxini;uely often in relatively (h\ situations. Iorii;ini; In po- twenty small, short-mandibulate, niostlv tropi- gaei(. Kood: pf)l\ph,fL;i.iis .inhropod pndator <al species. The natural historv of tlie>e ^'tnera (Bnnvn. 1948. MMf): Wtlscui, l*i:(4i. IS \er\ p>oriv known. (Brown, 1948. I9r)(l, 195^a: Sriy,istruma (4-t)). Illiiopiaii \f,ii,,.;.ivian. Kori^nieier, 19J4): Fig. 22. HighU adaptable, oiturring from sa\.nina io DoriMiiris i\'). (X long-inandibnlatc form dc- iropit.il rain forest. Workers niotumioi phir. ri\ed from the short-niandil>ulate C.linu\ro- short-mandibulate. \tsts in >oil .md rotiiii" >n\rnu-x). C^uban. Tropical dei iduous forest. wood, foraging b< h (\ ior unknown (Brown, Workers nioiiomorphif, Ionginandi(>ulate. Nests 19J2a: Weber. I9J2|. in >oi| or soil <o%er. Foraging heiiavior un- l-.pit'U us (2). .Mediierranean are.i and [anan. known. (Brown. Hl'.O). Workers mononiorjWiic ; mandibles inieiTnethate /■NWi-)^, ,i^,j (li. Widelv ■^p^ead b\ ( onnnen e in !< ti'.;ih. iliis (ondiiion ,t[)p.iren!i\ <Ierr\e(l dtronyh warmer p,ins r>f world, probably oriyi M(i>rid.ni!\ in e\oluii,Hi Irom ^}lo^-ln.. -■ !i l,idate '"ling in Vtric.i. Workers m..nomorphi< . -•]}•■:■. (\pe. \,iuiral hisior\ poorlv knoun. Bioun, iii.'ndi!)ulate, Hi!;h!\ .idapi.r^ ].-, olien living m I'tpi. !'r,S!,): Fig 21, 1^84 ////•; (.n.lliTEKl.V RtAIEW OF lilOl <)(,Y IHF SiHlklHt Kl'Oi'OMKI Min in eadi figiiic. sculpture ami pilo Fk.s. f>~S. E\cn L rin\ of Hfm) wu Nf \ndibi i-s Heads ol ;\oikcis, dorsal \it.-w, ri<;ht aiucniu (niiitu oniiUfd in tiys. 7 .iiid H. I-i^. ti. h.popo>trniim sp. Fig. 7. A/rwMnn^n/i tumeri (SMU\pe|; "in this yeiius, man.tibk-s hasicall\ of the Elwp(M)n<na t\pe are shortened, broadened, and tilled in h\ iranshiteiit lamella. tlit-:i.,'h which the hasic core shape is still visible, hig. H. Colnbostnuna le'unuata, worker, ihe new inner mandihiilar margin has now tie\eloped serial deniilion leom- [>are uilh e\olntion of short mandibles in Sf-O'.truma, Figs. i:t-l5 and :U)-:!,1). Note the ■'counter- (.inient" deveiopnient of huge eyes u\ this nocturnal, foilage-foraging species. K\i(lri.\ (,1). .New C.uintM and Formosa to Ja- p.iii. J ropicil rain iort-sl .ind warm temperate forest. Nests in roiling wo<xI- Workers niono- ni«»rpliit. siiort-inamiiljulate. Ihe two New fiiiiiiea spetics are ])ermaiieiit parasites of Slnvnii^eriys tutini' KnuTv. Workers show dc- getteratc hch.ixior: ihev do not jjarlicipate in nest-huilding hut 1.I0 lietp llieir hosts with brood care and in loragiiii^; in the hitter task thev are noial>lv inethcient in comparison with the host workers. On tlie other hand, the parasite workers altentl coitids within the nest, a func- tion the host workers are not known to perhtrm {Wilson and Brown. I!t.')ti). t\(}Ll IIO.SARV IRtNDS: BHI.\\1()R.\L ( II.AR.ACIKRS IN IHF CO.ADAPMVF S\ SltAf Since tlieir origin, whith presiiinahly occurred sometime in the earlv Tertiary, the dacetinc ants :is a whole ha\e shown an evolutionary lendenc\ to shift from al>o\e ground, sub- arboreal foraging to (ryptic. thiiHy terrestrial foraging. Stuh a trtud is not untisuai in the ants. It is also \\cll niarkeil, for instante, in (he primitive tribes Ponerini and Ettatommini. Some pre\ious authors ("e.g., Haskins, \\)i\)) ha\e offered the interesting tiieorv that this trend in die Ponerini has resulted indirectly from (ompetition with more re(entlv astetidant. domi- nant e[>igatit grf.ups in the f)oii( hoderinae and Foinii( in.ie. \ similar explanation tan be en- ten. tined with ns|.<(t (o {In- historv of the Dacetini .is ag.iinst otlicr nurmicines a\u\ tlic for- miiines, but the theme we wish to de\elop here is tliat this major adaptive shift, whatever its tdtimate causation, has had a profoiuid and pervasive influence on the course of evolution in the tribe. .A number of major morphological and ethological characters have been greativ mtnlified. apparently iU least in part as a result (ff the change in loraging beha\ ior. Togetlu-r these form a relatively tioselv knit (oadapti\e complex of evolving characters. 7 he specific eih ological characters invohed are the h>llowing: 1. Chang^e in hunting behavior. I lie relati\eh |)rimitive long-niandibulate forms rely greaiK on the \iolent. trap like action (Figs. 17-21) if their mandibles to secure pre\ , while their ap proach period" toward prey is relati\elv short. and their use of the follow thr<jugh stinging thrust is not invariable. The short-mandibulate forms, on the other hand, have less shocking- [jower in their manilibles and relv more >m stealth in approaching prey, in tenacity of grip following the mandibular strike, and in innnedi ate. consistent, and eflitient use of the iting. 1 he essential features of this evolutionary change can be illustrated in the contrast between the be ha\ior of Strumigt'Tiys loni^ianae Roger, a nl.i- tively primitive. l(Hig niandibuiate siruinigenite and that of the pinlogeneticallv more advanced, short-ma ndibwlaie 'I'rre hnsmpa mfmbrnnii'-ni (FnuTM. as des< rd)ed h\ VVilson ('19.54): 1 he I hen- haps a icsidt of the ng prev. ir more iiiid more direct i! . . . i his trail is p* i efficient mandible' THE ElOU TlOX OF THE DACETISE AXES \Wii(.h dif (.MririieK luiij^ and Mjpplicd v\iih pnniii- miil upital ivt-ih. 1 hev <aii Ir- i.pciu-d to .ilinost ISO and ojKTatt' WW iiimh as iniinaiiiiL' animal s|»iiiiSj tia[»s. [Note: RcccihK hc have disttucri-d that tlif m.mdihlrs ait' iotkcd into open pusnion v\lii.'n speiial rt-t-th at lln.ir l)as(-s . luh on the hHcial iahial iohcs: >ee H«s. 17-JI . U hen ap- jMuacliing a luilcmbolan, the woi ker SiminiiTtms riio\fs slowly and (aiilii.iisK. >pr(.-adni^; its man- dibles to llic iiiaxiiiiiiin anttlcs and exposing two long hairs \\\\u\i aiise from (lit- paired labral IoIk's. i licse bans extciul tar inr\\ard of the ant's ^''\ Ku.S. 9-11.'. iNDKi'EM'iNr EVOIIIION l»F Sl'0\(,lFORM AF'l'tND\<^rS l\ IHt lUO Si BIKIRfS Hcor'DSTRLMITI VM> SfRlMK.rM II KiS. !i. Hexiiditrfton irosli. hololxpc worker, ilor- sal \iew of jK^tiole, piistpftiolc and K^^ter, Fig. 10. (Uiloboslimna <iu.stialis, worker, same. Note the par- tial transformation of the postpttiolar teeth into siibmembraiioiis alae: the smaller alae on the petiole have evidenilv aiisen <le no\o, and the dorsal teeth of Hfxadniflou liave Inrn Inst. Mg. II, < n/nho->l, iinia "■iDrniiln. worker, side view r.i niidse< linii of 1kk1\. showing the cMreiiie developnirnt ol s[)oii^ifonn ap- pendages readied in llie ep<iposiniinite line. fig. 12. ^I'lirnii^fnys !/i,,irorn. worker. -^uU- \ lew of mid-sec- tion of bo<h. showing weM(le\rli.ped spongiform ap|)endages of a i\pe fiequent in the Muimigenite bne. K\obituinar\ steps leading to the sii nnngetiiie -ipix-iidages are unkntMMi, but the steps ieprcs<-nied b^ the epop.j-tininite spe< ies o( I ii;N, 'i-ll suggest "tie wav (be\ iiiav ha\e de\el<iped itt the ^lnlllliKenite bnr as well. Fics. 13-16. Evolution ov use HK\n. Mwoikifs and .\(;rrs,s<)K\ SiRtCTLRfs i\ ihe Grsis \/-ii-,tniinii Fig. 1.1 Sl>u?nigen\s j/iinairfn\ii, woiker. a iiu'tn- l)er of the V. ^undiachi group, aiuestral lo Seo- \tru»ia. Kig. 14. -V. zflekt, worker. Fig. t j. .V. "ittiijiiit. female, fnnitular segnienis of antenna omit- ted. Fig. M>. ,V. iu\llorhapha. worker. Riglit antenna omitted from each drawing. Ihe pairetl iabra! I()bes (IM-Mween the bases of the iiiandibleM are short in Sit iKutii^ftiy.. d\\i\ the trigger hairs. uhi( h at I as range-hnders to set off the spnng-snap a< tion of the mandibles, are long. With the shoriening of the mandibles in Seostruma. the labral lobes lia\e extended and the trigger haiis have been leduted (Figs. 14. I.")), presiimabh in onler better to ivith- staiul dainane from tlie \ iolent sn ut;gling of the eollfnd)olan pre\. In ,V. >fi\l!,>r}i<ij>iui ■^\^\^. Ui), liit- mandibles aie setoiuiariK elongate, with the labral iol>cs fiirlher elongateii to make up for the sh<}rtnes,s of the trigger hairs. Note (lie oirrelated (halites in length of the apital segments of the anicrniae in Figs. M. II and Hi. head and appareiuK serve as tactile range linders for the mandibles. When thev lirst ton(h the pre\. its IxmK i,s well within reaeh of the api<al leeth, ,\ sudden and (oinulsive snap of the mandibles lileralh impales it on the teeth, and diops of bem.iUmph often well out of the piimtures. If the <olleiid)olan is small or aveiagc in si/<\ the ant tilts i( into the air [and then ma\ sting il|. \il ;)nT the largest Collembola aie f]iii<kh im- mohdl/ed In this action. And sFnit;t;lini,' is (eebte and shoitlued. flu ufH, L'iit) //// (M- iHTi.iirr RiAih.n or luoi.ix.y % /^ \h.. 17, Stnuitigenys India Worker Ddis.ii \i.>v n^l(■a(i.^h.)^ving tlie iTKiTi.lihli's in [he upt-n Ht-fi) and rinsed (righi) posiiioii^. it ■■fifivts" in a loueu-d. (loiuliinti jjosniun and holds thi", siaiuc fnidh. II the xillcnibolari is In its hatk i)r side, (he worker u\<\s luins \ei\ slo\vl\ to faee it. Onte a is alif;ne<i uilh ihe ((>l!enil»olan. it begins a f(lrl^a^d movement so e\tra.)idinai iK slow that i( (an l>e detected -.id\ in peisiMfiu and careful oi)scrvalioi! Se\eral miiuiles ma\ pass i>e- fore the ant tnialh niancn\ers o\er less than a millimeters divtanee to lonie into a striking posi- tion, and it mav remain in this position for as muih as a niinute or more. . . . lidike the Sliuitii- i^fiy^, ihe I'ii(iin\capn open their mandibles onl\ to al>out a m- angle, faetile lahral hairs arc pres- ent and e\entua!U eome to ioik h the prc\ . Ihe mandibular strike is as sudden as that of ihe Snuimgey}\s. i)ui sinec it is iisiiallv direded at an appendage, it di>es not ha\e the same stunning elFeet on the (oliemholan. I hese inseets often struggle \igorouslv to escape, but the ants are verv tenatious mu\ retain a fast grip until thev are able to sting their pre\ into inuuobilitv. In sumiTiarv. Shittni>ifins lonni/imtr relics on a t<mip;traii\el\ swilt approadi u> its prev lol- Inwed \)\ A fixed action pattern that can he (haratteri/cd as \hikr-lill-\lniir. with tlic last (lenient otc.isionallv being omitted it the j)re\ is small, while I ' ■< hou d/xi inrnibuiniffra cm- ploys a more . fiuious appro.ich followed hv ^trike-hold-slniii. with the last elcnieiit ine\ itahle. It sliould be noted further (hat in I'rKhincapn the stinging tiirust follows the inaiulibiilar strike nuuh more cjuickh and is apparcittlv generally more etie(ti\e than in Strii>nr^r>i\.. Both pat- :irns, howe\er. are indi\ idiialh elletlive in (ol lembolan piedation. The Slni>nr^cn\s pattern is a()p.irentlv t\pi(al lor long-niandibulate dace- lines gener.dh. uhiie that of Tiu h'^u apn is l\]>i(ai h.r llie short-niandihnlate groups. I lie / ru hou apn pa Hern, rccpiiririg less space for ihe operation ot the nianchhies, .> -eneiallv asv.c i .(led in the Dat.tirii with <i\pn< foraging. I hose .laietines that feed iiiainK on C-.i- Nmhola .dl show a irl,nivel\ sl/.w-niolion. tammatie dnisal tiarisp.nciu view, nl head to le .ippioximatr relati.,nships of the maiidibl- s ti.isiU-s moving ihem. I he laige dorsal mils. ;, left retractor, this has Ik'C'ii tciiiovrd r.n (hi- de t<. show the iinuh smallei abdii<i.,t miisclr ting on Ihe \eiinal nndluK' of the liratl. run El()l.ril(>\ OF THE DACE'llSE A\ I'i 19 , .., ., , 20 21 lis, i',1. Dorsal \ifw ut head, rijjht aiilfima niiiilled. 1 hv lateral (oiiiiiaf ot rlir lain tjiii t\u ml sliUlill\ bt\.>Tiil ihf lalcral borclfis (.[ the ciciscil raaii.lililis near lln-ir baMs. tifi -'il, WnnjI lutt .,1 aim-iii.i |)arl <,f head lam. b.l.) shoiviiiR basal haUes i.f ikisc-d mandibles .inanci •. laniji KH nnae of dn)p]je<l lai>riiin dat. (inn. lab), and niy^er hairs Mrig. hit, 1-iy, L'l , s,nne, n[n n po silinn ,,( mandibles. When die luSKei hans are slimulaled, [he lahrum dii.ps dciiin ,nid ,dln„, (he tension ol the letiaitor miisties to pnll die mamiildes shn[ wilh a sn.ij). T^ 24 Fii.s. l.'2-24. Rn'RtsFM \ii\F. Hf\ds of Spfc ies in iiif Shori \f \mxiii i \u Sukk m SlBIRIBF SiRlMK.FMTr W'orki'is. doisal \ icws of lifad uthI [Tiaii<iibifs. One aiilt'tnia oniiltcd in c.n\] liyuii' inn,. l.'L' Cn<lii>fii\ririf\ seinicompttis. Fig. 21, SinitiiistTUina weheri, pilosiiy iiinillfd. i.'\(epi for hinj^irii^ hair>>: t!ie iiiaiulihies arc open, and (he lips of labral trigijer apparaius .\rv seen jjinjcdini^ honi heiR-ath the ( !\peu,s. V't^. 24. Ffiilritiis hexuinerjis. pilosi!^ omitted from i i^ht mandible in oidei to ^ho\v dentition. Mandibular apex in end-on \ iew shoHii in insel. 1 be iiiandibks ami Lihr.il IoIk's in this i^eiins are secondarilv elongate I'cotnparc with \efi\lr\iiiui in\lini Iniplm. \\%. hi), ,ip paientK <leiived from the S>nilfii\liutnti pattern. stc:ilth\ Malk .ipproath to tlit-ir prev. as i ^ni- Oiue the ant has st-i/rd the pre\. the seioiul p.irtd In iion-d.uetiiie ;nits {fl\li>rnyi?iui. cscajX' int'dianism ol the s[)ritii;tail tonus into Stfnnmin'i) lliat we have found to feed lo some [)lay— the furtuta or kicksprins^ oi'^aii. I'sed (■\ tent on f^oikinbola also. For protet tioii ayaiiist under i ircinnstaiue-* of more violent ti i^t urban* e. predators, fnlomobr\omoi"ph sprin^lails relv the fiirc ula tan projei t tiie tolleinboian to a first on the iieetness of their running an<I their (onsidera[)le distaine. atid tiiis ino\enu-nt tan <\trenu-!v sensitive and ner\ous escape response be made se\era] times in tapid simession, Ihe to moxeinents nearby. }l\l()in\rma atid Ste- spring nia\ ( arrv the springiail aua\ li')m the narnnm usualh i barge a sprtngtail in a clmnsv ant, or. il the atiiinai is latge enough, il nia\ rush, with mandibles open, and this approaih tarrv a dinging dadline uiih it in its leaps and r.ireK sutieeds. The lollembolan simplv dashes thus make *'- ,int*s niiitn to the nest .• :"nger lo a new position. Datetines. on the othtr hand. and more d i tin nil trip. It is (o the ant's ,id\,tniage m.ike s<, ,i,jtih\ .in approach ih.n the follenib.)- to tieiiiiaii/e the atti-.n ..( the lut(ula ..> rpii. kl\ lans oittn lemain undisturbed until sudiieuK as [>os-.ihk'. I lie SO 'i;)Og''';\ * auompli-! !ns Miu(k bv tiie mandibles. \i\ lilting their [iie\ i iear of the niouni! -miIi -'H8 I HE (.H_IHIIH[Y RHIIFAY Of HIOI 0(;Y Frr„ r,. A Shuminenys India WoKKER ^jisr.isc. » Small Isohimi,, Omumbohn I he am has caught the springtail with a convulsive snap of the nianiliblfs .mi,1 having lifted n ck-ar of .he groun.l, ,t ,lraw, its ga.ster under and stings its ptev ,„ rc'.ler ,t in 'u.ohile* Ih.ir long ,na„,liWes, so that the- furtula cannot In fact, csen polvphagons dacc-tiues will show .Icl- lontait the substrate and launch the animal. "ile aioidance of such pcxiur.unorphs as Ihev mai It the (olienibolan is not killed outright bv the "o^"- "icluding those upon uhidi thev hase ma.lc mandibular strike, it struggles, and the ant em- """^^ '" '"' accidental mandibular strikes. Iiidica- pl.ns the sting bv reaching all the wav up to the '""" •"''■' ""' P'«h.romaiphs arc protected against springtail with its gaster (Fig. L>,")) Ihe short- ""'" l""lators, including ilaieiines. bv elfcctiic n.antl.bulate forms must depentl on intmobtliz- "P''!^""'"'"' substances. ing their prev with a tpiick sting. Often the ". '•''""■'■"' '" "'""••"I "f l,„,„„ol„ry ,uln,lx lollembolan is able t,) make several jumps be- ''"""■'■' l"'"K>"e:- \s a rule, the sbortmandibu fore it suc.umbs. but Ihe bulliiiw-Iike tenacity '•"^■' '"I""'''""' ^l^ttinL". luini oxer more lim of the ants usuallv serves to tarrv them along ""' ^'"■'''""K "Trilories and are less attisc <lur until the poiv)n aits. mg foraging. \Ve have noted on a number ol cxiasions in .litterent S7r„„„g„,v« and S>„„/,„tr„m,, species " ''"-"'"'" ^'""""■■"- tnioKK.UAL iRtNO that the a,t ol stinging. „me the bods flexion <>" the basis ol limitctl ev idente. the priinitis, IS begun bv the .,nls. is tarried throtigh to-,„m- i""' i« Ih„rl„„ ,n,m«,;u,n , Roger! .ippears to pleli..n.' I.e.. to txtrusion of ihe sling ,,t full be a general pretlator on nu<lium-si/ed inset is though ihe lolleml lav have ^'-'n^ "f the higher daieline spei les. hovccser. cst.iped p.otwas through the ait. Ibis suggests -iff narrowlv restrii tetl in iheir pmlati.m at Ilie ■■...nsi.uuuatorv beba> ior" ol the ctbologists <(pling otiiv .ntoinobrsomotph ,,,1(1 svniobv ",""'"«^": '«V'- l.^""an.olle,nbolansan,l: .ling pothirouiorph It .sa.ioious fan tli.n po,l„i„„„„p|, ( ,„|„,|a . ollembol.Liis .iiid ,„her ■lispne their sceiiniig liclpl, III I, loco- tills imlnile "hV.I- '.„,/,„,.„„. SI .pods. These preda- nbirs ol l-l,„p„^l,„m„. Coin ^'■'ivi. ,ind \:it:lhnhii,na. \lso THE bVOLUTlOS OF THE DACETISE ASTS iii9 n^y^^ W-lr' Yh.. Ii6. Slititni^etiM loritie. Showing ExTRtMi-,s of Po[,VMORi'iirN\t f\ i WOrKFR C\.STt FROM A SlNlil.E NeST SfRIFS Note the ailometric de\elopment of the mandibles and Jaterat gtii.il Itilnii the rthi lively primitive orettognathite genus Oifctofituilhut appears, on the basis of lab- oriuorv icits made on one species {(). clarki Broun), to hv speciali/ecl to Ited on collenibo- lans. A few species of hiylier dacetines. e.g., Smil/iislrurna ilypcata (Roger). :u(ept a sniull variety of soft-bodied .trtliropods in addition to tlie preferred (ollcinbolans, Ijut can still Ije safely classified as oligophagous predators. Ihe species of higher dacetines that are known to be tlear- cnt exceptions to the rule ol oiigophagy arc ex- ceptional in other wa\s, to tlie extent that they mav be distinguished as meinljers of one of the three following special < las-^es: (a) Possessing a polvinorphir worker caste, Slrunu!j;fn\\ loftm- Knierv. a notably polyphagous form, is tiie ')nlv known higher dacetine with a distinctiv pnhniorphic worker caste (Fig. 26). (b) Widely liistributed, either naturidlv or as tramp spet ic'S carried b\ man. Slrurvi^rnys loui- sianiii' Roger ranges .is a native sj>ecies from the southeastern I'nited States to temperate South America, while S. roi^fri Kmer\" ancl Trirho- \<iipa >nr»tbraniirr<t Finerv o< ( iir widcK ihrnugh the wanner parts of ihe world as tramp species (( ! Ottiirring as a member of a depauperate in sular tainia, \li unif^r)t\s >iuli'.--\ Mann. |ieitia[>s ihe most ];ol\phagous of al! the higher da( eiines, is ail ( \( e[>tJoiian\ i.iige species eiulenii* lo Fiji, ,\ cognate species fotnid wideh from Australia to the Philippines. S. a}i\lynli\ Forel. is kiiowii to l)e u lolletnbolan specialisi (lirown. nis,). It would seem that ilie above three petidiar- ities are linked in some w av to tlu loiKliiion of polvphagy. We woidd Hke lo suggest, livpothet- i<ally. that polymorphism has allowed in Strumi- ^rnys loriae the development of a large headed major subcaste that .ni < aptiue larger arthro- pcxls: diat polyphagv has illowid the wide dis- tribution of some species i.v opening up to iluni exceptional nest sites: .lud fmalh, (hat Stuani- gfffv.s rndift'x has been able to expand its |)rey range in the aljseiue of eKeciive ponerine and mvrmicine competitors on Fiji But the' consideratinu v^lleIher duse independ- ent and seiondarv modifu at ions aie ( aiis.div (on- nected with polvph.igv should not ilisttact fmm the central cjuestion. wtiiih is vvheiher the Dae c tint were pritnitivelv poKphagotis i.r olig.)phag- oiis. Nfiich depends on ihe status ol Dnrflon nr- iiiii!,rrum. It (an be arguetl ih.tt the pol\p)iag\ shou ti by this spec ies. a inemlier ol .me of die two mosi primitive living d.uetiue genera, is trulv the primitive (ondiiion lor rh<- Daceiini. and that specialization tovvard ( olleinbolan preda- tifui is ihe derived (onditiori- Howcmi. tlic op posire possibility imisi n.iuimie To be boine in mind. Sirid (ol!emi)ol,in feedm ■ ,in|,e.(rs to be L"MJ ini: OJAKlt.RI.Y litMEW Ol- lilOlOi.Y ( h.u.ii urisiit '.I sonic miIrt rfl.iti\flv priini- ii\f, rpit^.K-ti (i.KrtiTifs {<)}'', lo'^nalhus. Fpopos- hunin] iIkiI ,ui' uidciv srpar.iud pin kti( ,illv. \|')if(>\tT, liki* Ml iii.inv uilitT priiniii\L' l,i\a, Diii'-lnit pnsH^Ms. in ;i(i(lnioii to lis triilv priiiii- ii\c tt.:mius, (h.u.uicis ill. II appear to ic |jrfsi-iit ■.iL;iii(icani -.jxi i,ili/ati(Mis awav troiii llic main lm<- nl (latriiru- evolution, \ i/., in suilpliirinj^. uoiker polMiioiphiMii, (<'plialic :irti( ulaiion. arul lai\.il nioipliolou\ |\,.t- Hrown. IK^Sa: and WlueUrand Wlu cUr, V.)-y\). Perhaps new lii^lu will be shetl on this [iiohleni when the l)elKi\i()r ol Diwinn and the oilier ii\in^ dai elite genus. .lnin!/i<>i;!ia!lni\. hedmies helter known. h\()Ll.Tl().NAk\ ! k>Nns; \rORI*U<H OGlCAt, (HAR U.URS IN IMK ( OADAIMIVE ^ISIKM The e\olutioii ol tlie Daietiiii has been niarked by a series ol major inorpiioloi,'i(al ( hanges. Sonic oi these arc tiearh t(»adapti\e with the lendencv toward cr\ptii lorai^ing. (Others have no known adaptive signilit aiitt- but are so tlosely asso- eiated with the major adaptive shift that they must (ontiiiuc to be examined in this eonnetiion. Dfi tru.st' tn iizc. This has been a general tend- ency in most major groups within the tribe. As a result, the smallest dateline workers are found in the more spctiali/ed spedes of the most highly evolved suhtribe, the Dacetiii. A tendency to- ward small si/e is a general tharaitcristic of cryp- lobioiie ant groups. Shifl Irom long to shurt mandibles. 1 he primi- tive datetine mandible is the long type, (oiisisi- ing of a linear shaft widi more or less parallel margins, bearing at its apex two or three large iiKurvcd teeth. This kind of mandible is found in all lour extant subtribes and is the only one in [he Datetiti and Orcdognathiti (Figs. 1-4), in which workers and icmales have the primitive palpi with :. maxillarv and 1, labial segments; Datetiti have 1 1 aiuennal segments, the primitive (largest) number lor the tribe, in Kpopostrumiti, the long mandibular type is the only one found in the otherwise generalized genera Hexadace- ton. Kfjoposhumii. and Microdaceton, whith all h.i\e the p. dpi segmented :> and .1, and the an teiinae 'i •ei^mciiied. In the K|)opostrumitJ (Figs. <>-H| and Mrumigeniii (Figs. 13-15, .'iO-.S3). the mandiljles have e\oived via ditlerent palhwavs to shorter ivpes with serial dentition along their inner iiiaigins. Mioiieniiig ol (he mandibles in several lines m both siibuilxs is atiompaiiied bv rediKtif.n ol .tnunnal segnieniaiion hom b i<^ .'» or 1. Presuinablv. ihe shoit mandibles ,(r<- more advantageous in ibe tramped spates bumed In ihe more » r\pti< loragers. lintuilion of palf),. This is (he iiile in die Strmnigeiiiii, ail o( uiiidi have .me short segment in eadi ol the inaxillan and labial p.ilpi, ,is . oni pared to ilie other subtribes. whiih have the seg- mentation '> ma\iliar\. I i.ibi.il, Ke<iiuiioii ol ]ialpal scgmeiilanon in oilu i ant groups is ..ilen (orreiated vwth ,t sliilt irom open lo (rvptit lor- aging. l)rrriop,n,nt of antfunul uu,hr.. Ihe devel- -)pmcnl ol a longitudinal groove (strobe) into which the antennae tan be loided is well in.nked in some ol the higiier phvlelic lines ol the Daie- tini. S( robes are a (oinmon diarai lerislic of other slow-moving. ( r\ ptobir>iic invrmitine ants. lifiliulion o/ the iomj7</und r\t-s and llinr vrnlral di\pla< '■uifut by the nntrurial \< lobrs. Fhese two trends are evideiue ot the declining role of vision in the beha\ jor ot the ( ivpiobiotit form.s. l)epig>ncnlation. 1 his tendencv is t learlv as- sociated with (rvptobiotic life in some cases, but IS also oteasirniaily associated with the secondarv development of nocturnal epigaeic h)raging, as in scjme open-country species of Colohostruma. (:h(i>i^',-.\ in auli-rinal form and pmliori: rrduf- lian of M'gmt'nlalion, thtrkfrung of fiinitulus. and increasing rrlatwe prominrmc ni terminal tunuular segment. These (hang<'s. tlosely (or- related in the higher Dacetiiii, are commonly seen in other tryptobiotic anis. Their adaptive significance is not well understood. Development of bizarre pilouly. The appear- ance of unusual setae on the bodv and append ages, shaped variously lo resemble threads, spoons, oars, t lubs, scales, spheres, etc., is a com- mon feature in the higher Dateiini. In earlier l>apers (Brown, \9M)-. \Vilsf>n, l<):>4) ue ha\e sug- gested that these- aberrant structures might serve as tactile lures for ihe prey or tactile ■■camou- flage" in trvptobiotie dacetines. but the hvpoihe- sis has not vet l)een adecpiatelv tested. Modifualion uf seulpturin:i. Ihere li.es been a flearctit trend in the Daciiini as a ivluile Irom coarse, ioveate sculpturing to relatively fine, dense, punctate sctdpturing. In a few tases (e.g. .{yuold'dri^ spp., CyninomMuirx splendens Borg- meierj another (h.inge hasotuirred: sculpturing Mas been lost aliogeiher over large parts oi the bodv. 1 btse niodific.nions ,tre c le,irlv telaied to pilositv svsleni ot the bodv, which iiiE iioniios OF lilt: daceiise as i\ j'U 111 uiiti iii.iv l« id.in-d !o(li.iiin(> ill liicnii^ani/a- ^|K■( j.ili/.uion. I lie lors.ikiiii; ol ilic .pi^.uu |.>i- tiori 1(1 im'tti.ini»ifi(.piioii: Itui die m.ittfr !iJS not .i^iml; .uc.is .iikI jii inucixil i(iulr[u\ lowiiid iKTii >iihn(ir.i to uitiiLil (A.iMiiii.iiion. i tv|)iuljio[it lile is .i (l< luid (miihiioit li-r .wn^ l)turhjl>nirnl n/ >/>r,N,-r (-;nN apprrul.r^fs. In oimm r-,liy, Crxpiu loi.t^ni- uii.iMul.u <li\ ope lis the Smniiimniii mnsl .)t llif spcncs li:i\e (level- up locxl .tnd shelter iiidus !-. the lii-iut d.ue oped till ion-. s\iiHnetri(.il sponi^e-hke ni.i-.«-s on tines lh.t[ arc but little exploited l)\ the ejiiL^aeK ihe jjetiole .iiui post petiole. .Soiiielinies these ioniis. But it also (onsijtntts .( lerie.n lioni itKijoi iii.isses .lie extended to tlie :iiitiunk ,uid .^.lsHt. ludies th.il remain in lull use o.i ,u,- i.ikeii overr, I liev are loitiposed ot iutej^umeniaiA out- by other doiuinaMi am '.^toups, ( a\ pii>l)ioiu lite ^^ou■llls. iiunit tolded and areojaled, and are has been atterufcd h\ sonu- uiiiisiial e\ ohitioiMi\ s.mietiiiies assotiated uiih glandular areas. 1 heir a(hlitive innovations, -.uili ,is bi/aiie jiiiosiiv iiui tuiurion is unknoun. Ihe siruini^euiie spe<.ies the spunj^ifonn append. e^es. hm in oihet u,i\s diat huk ueil developed sUuauus o( this sort U is rej^ressive (u-du<li\ei. espt.,iall\ uliet<- smh ,ip|tear lo have lost dieiii setondaiiiv. Their evu- (undaniental sliudures ,is die antennae, palps, hitioitarv origin is suggested bv the iiiorphoi line and eyes are involved. Iin.dly. th- ili>^opliagous pnxUued iti an independent ph vie tit line v%i[hin (<)lleinb<jlan predation s|iov\ n I. n.uiv lu'gher the Kpopitstruniiu. Here are seen lateral spines daeetines must be (oiisideri'd .1 s[jr( lali/.n ion in tiansfornied through a series ol evohiiionary the strit t sens(% vvhedier it uas (iisi .unuiied bv steps into struitures apiJioaihiiig in loim the post-chuetite lines or bv the line aiuesiial (o all siriniiigenite spongilorni appendages. (See Kigs. Daeetini. *•-!-)- <aiunter(urrent evolution, in the eases in- lifdiudDU of spinntuin. This trend is shown ferrcd, represents lor tlie most part a liteaking- vvithin all phvleiit lines, except the derivative out £roin the iiarrov\ing adapiiv e /one into u hit h Strimiigenili. the modern speeies ol whit h nearly higher daeetines appear to have moved. Ihe set- all already have the minimum fixed armament. oiidary ihanges involvetl iiulude die lollowing: Retimed spinaiion is a tommon trait of other increase in si/e, iiurease in lelaiive eve si/e. (lyinobioiu ant groups as well as, tunously, lengthening of the niantlibles and redmiion ol some groups that are high arboreal and stem- tooth number, int rease in laiitutle of food habits, dwelling (Wdson. I'.t.j^). los.s of spongilorni appendages, intreased pig- mentation (inelani/atiou) and redutiiejn of pilos IllttFKrNU.M. RAIKS T.N "MAIN S I Rt A M" A.ND ■ ,. i . ity. lo tite an example, Sli)nn!^<-uy\ nnlilcx, a "t 01 Nir Kt.LRRl-M" KVOl.L riON , ■ ■ i c i .■ hijian member oi the S. itu\trnli\ grouj), has un- Ihe eihologital and morphoiogieal tharatters dergone an increase in si/e and pigmental ion and tlestrihed in the pretetling seelions show closely ^ hroatlening oi loot! habits. \<ii all divergent assot iaietl trends in their respei tive evohiiionary iremls tan be tonsiilered as reversals ot die pri- iiistories in the priiuipal phylt^tie lines of the mary dateline trends, I he loss of stulpturing in Datetini. Only a few examples tan be tiled of several grcjups, for instame. tan be toiisidered (onspitiioiisly differeniial rates in the evoluiion neither an extension of [trimarv evolution nor a of indepeiulent eharatters. In the K|>opostru!niti, reversal of it. but rather a special trend in itself, to take a ( ase in point, a shift from long to slKirt The att|U!siiion of worker polvmorphism m.iy maiulibles is not attompanied by a signifitaiu tall in the same tategorv . letltietion in worker eve si/e. Wherever conniert iirrent evolution h.is ot On the other hand, ditlerential rates appear turret!, usually onlv a small number oi .hai.u to lie the rule during the short-range reversals lers lias been involv eti, while others belonging to in evolution {"ttiunterturrein" evolution) that the postulated "to.itiapiiv e svsuni" have re oet iir < onimonlv in the Datetini < ountert urrent mained relatively umhangtti. i<jr iiistaiKe, in evolution in this group has some I. Mtures tli.it de- the tase of Struwii^fny, nuUU'x just tiled, si/e serve speiial attention. First, it is perhaps not .nid pigmentation bav e been intreased and Io-kI 100 tonimoiipi.He 10 note that the thanges (hat habits broatienetf uiihr,iit marketl th.tnges in ottur do nt>l r< present precise reversals, in a other .haratters. Ihe wr)rkers of certain Neo strittiv geneii< sense, of the priinarv irentls. iropn al membeis ol the sb.n-t-niatidibulate. 1 rv p- ll is ii..tewonb\ (hat the piimarv trends t.in be tohioti< genus Sjinlln^h unui have taken to ,ir t h,il,n leii/ed -riter.dtv as ,1 nn.\eiiieiil (nw.ird bore.d life in epipio'. m,iN,t>s, .,nd iheii .\(s 292 rill'. QU.IRTHIU.Y REVIEW OE liJDLOGY li.uc Ixfii enlarged and ^poiigilorni appendages lediiicd: but in alher lilaraiters tliey haie re- mained ivpical fur ilie genus. I'arallei changes liave cHiurred in some speeies of Slriimii^enys and Ciilobustuima (Fig. 8). .\ striking secondary lejigthening of ihe mandibles ar>d labruui fias ot- lurred in one species of \i-uilrurna (Fig. Iti). in /•:pi(ii7u.!|Fi,g. 24; and in DoiiMns mtens (.Sants- illi) uiliioul signidcant reversals in oilier nior- pliological characters. In ihe parasiric species wcirkers ha\e undergone \arious degeneratise changes in beha\ ior uithout radical modification of most of their typical -dacetinc" inorphoioL;!. al characters. C.O.WlKC.rNC.l to TJIK D.AC . 1. 1 1 .M. r \ 1*K BS OlIIKR AM c;Rcn.PS Several other plnletic lines within tli family .Mvrmiiinae shcjw notable come tcrtain of the higher Dacctini. I his re ,ub- iice ' ,' , , . ' r.»...,.c.e species to certain ot the higher Dacctini. I his resem Avcc/m vafcoiprici W ilson and Brown, the females hlance is s„ astonishinglv detailed that frequently have lost most ot their sculpturing, and the they and their relatives have been placed by ex- 29 Fic.s. 27-29. Sovir Sptcars op mr Am I «mt BcsiciKoriM tncr i«e CoNvrRc.iNr lo UicaiEK DvcrxiNrs ,!„';?■ f ,-^''""'''"""'« W™'- "Tter. side view-. \ shc,rt-ma„<lil„.late form. Fig "S RhoPalo- thux chala worker, dorsal view of head and mamlil.les. amc-iinae ..M,rl„,l escc-p, for ri t^L mels shmt tnansular nianclibjes arc the basic priiiiiiiie tsoe rii,l , t...,o,„. , i L , «"'"■'—'" ■'-'".i.-.herc.vc-isc.c.ttheS'.o^m';;..'!":,':;;;;;'''' "-i "■•■'""« -' THE F.IOLUTIOX OF THE DACETISE A\TS J' 13 -13 \^1 \ I / / 32 33 KiGS. 3()-33. Probable Modf of Evoi l tion of the Short Type <n NfANmnLE [S ihe StBIRIBE SrRL"MK.EMTl Starting with the basic Slrumigenys t\pe ot manilible. Fig. 30. sucasMM- iiKMiifuiuioiis 111 have led ihrough the 5. gundlacht proup t\pe. Fig. 31 and the Xeostrimui tvpt-. tin 'i-: to ( Smithiitruinn [\pe. Fig. 33. However, SmithistTunia almost certainly arose lioin another slot k Struntigfnx'i. and not \ia the Xeo^lruina line. \oie the changes in position and form ot (he ha tooth or lamella larrows). perieiitcd s\steni;nists witliiii ttic trihe Oacctini. (;oineTgciU groups include the gciier:i Calyplo- m\rmrx. Diuctinops, and Rhopnlnthrix (Figs. 27-29). The dai elirie like morphological < harac- ters. some or all of which are found in each of these genera, include reduction and apicali/ation of tiic ameiuial fuitii idus. redutlion of palps, narrowing of the anterior portion of the head, prognathism, development of aiuennal scrohes. nKxIifif atioii of sddpturing to dense puiutura lion. de\<lopmein of hi/arre pilositv (especialU (lavate and s<piamate hairs), reduction of com- pound eves. de|)igmenlalion, development of [»e<Ii<el!ar spongiform appendages, and develop- ment i>f prominent ril)i)ing ,it the hase of tht^ gaster. These iharacters appear to have lieen de- rived cniireiv independently in eadi group. Fur ther, in the i.tse of th<^ irihe Basiterotini the known primitive inemhers (Basit {-ros. A'.pididria) arc much less like higher dacetines than is the del iv alive genus Rhopalothrix (Brnun and Keinpf, I960). Fhe hehavior of onjv onv of ilte convergent foMTis has been studied. Workers of ihe Papiia- sian Rhopalolhrix bimi F.niery have proven to be reinarkalily similar to some of the short maiidihu- late datelines in (heir stalking beliavior. and iliev apjjear to prev in !:nge part nn ent^imobrvo- rnorpli tollembolans (W'iKon, 1957). ACKNOU'IFDCMFNTS We wish to thank l>r, P. J. Darlington, Jr. for rea<liiig the manusciipt a provetnents; v*e do not of ( uggcstnit; certain mi- e imph that he ncces- sarilv endorses all of oni lonclusioiis. We are also irulehied to Dr. E. S, Km>s for the photoytaph of Dan-ton. LIST OF LI FER.VnRE IloRi.viKiFR, T. 10'i4. Two itHi resiing liacctine ants from Brazil. Rrx-. Brasii fUol.. U: 270-L'8E Brown, \V. E., Jr. 1!!}'*. A prehiiiiiiarv generic re- 7< vision of the higher Dacetini. ent. Soc. 74; 101-129. . 1049a. Revision of the ant tube Datt I l'il::lut y.,m-i\ . llM,unn,,„,.l: hn rut: (ivakterly keview oe hioeoc.y 1'">C. f. S. TUll. Mn hI (luiiilnstruina i j-crjus I, Gualcinal.1 • f. p-34. . • Smmh, M. R. VMI. A K.i t„iheg.-,uis J,,„»/,o... .1 ih,- ant tnlx.. Daulini: I. ,„„/,„, x,av,, „i,|, ,he ,ks, ,,,„,„„ „[ a „.« ,,k "1 [.iljali, t iiiria and laiwan, A/u.s/m, i;0: I', 'It. \oc. Ilui/i , l(i; IjO-lai;. 'T„'-,, o,- ,, ., IINBIRUN, \. |M-,1. 77,, V,„/V „/ /„„„„,. 0\. J*"— " 'I- an. .nbe Dac.-cini: I,. ,„„, , nncav P,,,,. Nc« V ,t and U,„d„„. ." M".„aw„„ Ulu-ckT and ,l„»-lv related Webfk, N, A. HOT. New ant» ,.1 ,art- «,m.|a and "'•'". T"'R^i"'; f ""■ ""■ ""■• '"'■ -''"'■ ' "■''' «""" "' p"""""^ ■""- ■-<""■ ""■ ■•- . -.1. t^t^^ ision nt ihii jutgvnus SerTastrurnn. .^"ifr.. 7i- '(1-!(|-| ^f p 'm |(r.'<K I i. I JHolaf^Kdl nolc->, (,n Dacciini |}!\mcti- . I ">. ,c>,M„n „t the daretme an, genus lal,„n,h,p a,n„„g ants. f.,,,. .V.rw. ,7- i;i-|;4 ;;:-';«' ;: -"'■ "'",«"- "-'■■ " ''-"^- -■ -"^ «■ '- "--• '■««. N".« <,n .„ ,: •'■> ll.i,,ll. A prelmunary report on dace- gem from southern Ohio, with descriptions of ^"ie,'"'!,,'"!-^";!" ■"'""""■ •■'""■ ""■ ""'■ »'V'"'' ''"■""'■ '''>■''"■■ <■■"'■"■■ ^'a^''- <e^ '"- l"yh. Ihe ant genMS M,umige„js Fred. WH,:ELtR. G. C, and J. Miief, fr I%.5,P|-,1) Hie M,,th m the Kth.opian and .Malagasy regions. ant larvae of the msrrrr.cine tr.be, BaMcerottn, «,.//, .»„-.,„,„p. /„„,,„„„,, „2: 1-34. and Dacet.n.. I'syC.e. Carrd,., .Mass., 61: 111- 1")). I he hrst si.eial parasite in the ant tribe Uatetini. In^eclei Sixiiiux. 2: 181-186. . I'.r.8a iH).-,7). A supplement to the revisions of the dateline ant genera Orecto/fnalhus and Amoldiilns. with kes.s to the species. Piyche. <^ainb., .Mass.. (i4: 17-29. I'.I.Hb. A new Japanese species of the dacctine ant genus lipHritus. Muihi, 31: 69-72. . and «. W. Kemi-f. li»JO. A world revision of ihe ant tribe Basicerotini. Sludia Ent. (ns.), in press. Cr,4wlh,W. C. 1916. Ants from British Guiana. ■inn. Mag. nat. ll„l (8) 17: 366-378 H.ssKiNs.G.P. 1939. ul.tn,.„„dM,„. Prentice- Hall, New York. M.«-NN. IV. M. 1922. Ants from Honduras and 145. WiLjov. £. o. 19:50. Notes on the food habits of Strumigenys louhianae Roger illvmeiioptera: Formicidae). Bull. Brooklyn ent Sue l",- .SV 86. . 1954 (1953). I he ecologv- of some North Amer- ican dacetine ants. Ann. Soc. ent. Aine, 16 479-195. . 1957 (19.56). Feeding behavior in the ant Rhnpalothrix biroi S/alKl. Pnc/le, Camb -Mass., 63: 21-23. . 1959. Some ecological characteristics of ants in New Guinea rain forests. Ecoloicv 40 437- 447. , and \V. L. Brown. Jr. 1956. New parasitic ants of the genus Kyidris, with notes on ecologv and behavior. Imectes Sociaux, 5: 439-454.