Systemutic Entomology (1992) 17, 301-329 The internal phylogeny of ants (Hymenoptera: Formicidae) CESARE BARON1 URBANI, BARRY BOLTON” and PH 1 LIP s . WA RDt Zoological Institute of the University, Rheinsprung 9, CH-4051 Basel, Switzerland, *Department of Entomology, The Natural History Museum, Cromwell Road, London SW7 5BD, U.K., and ‘Department of Entomology, University of California, Davis, California 95616, U.S.A. Abstract. The higher phylogeny of the Formicidae was analysed using 68 characters and 19 taxa: the 14 currently recognized ant subfamilies plus 5 po- tentially critical infrasubfamilial taxa. The results justified the recognition of 3 additional subfamilies: Aenictogitoninae Ashmead (new status), Apomyrminae Dlussky & Fedoseeva (new status), and Leptanilloidinae Bolton (new subfamily). A second analysis on these better delimited 17 subfamilies resulted in 24 equally most parsimonious trees. All trees showed a basal division of extant Formicidae into two groups, the first containing (Myrmicinae, Pseudomyrmecinae, Notho- mynneciinae, Myrmeciinae, Formicinae, Dolichoderinae, Aneuretinae) and the second the remaining subfamilies. Clades appearing within these groups included the Cerapachyinae plus ‘army ants’, the Nothomyrmeciinae plus Myrmeciinae, the ‘formicoid’ subfamilies (Aneuretinae + Dolichoderinae + Formicinae), and the Old World army ants (Aenictinae + Aenictogitoninae + Doryline), but relationships within the last two groups were not resolved, and the relative positions of the Apomyrminae, Leptanillinae and Ponennae re- mained ambiguous. Moreover, a bootstrap analysis produced a consensus tree in which all branches were represented in proportions much lower than 95%. A reconstruction of the ground plan of the Formicidae indicated that the most specialized of all recent ants are the members of the subfamily Dorylinae and the least specialized ones are the monotypic Apomyrminae. Introduction the ant phylogenies presented by Dlussky & Fedoseeva (1988) and Holldobler & Wilson (1990). Modern work on the higher phylogeny of ants dates Baroni Urbani (1989) camed out the first explicit cladis- from Brown’s (1954) division of the Formicidae into two tic analysis of the ant subfamilies, using a larger set of groups of subfamilies - the poneroid complex (containing characters than in any previous study. He presented a Ponerinae, Cerapachyinae, Myrmicinae, Dorylinae and fully resolved cladogram, and gave one or more synapo- Leptanillinae) and the myrmecioid complex (comprising morphies for all branchings but one. However, his data Myrmeciinae, Pseudomyrmecinae, Dolichoderinae and set yielded a large number of other equally parsimonious Formicinae). A similar scheme was followed by Wilson trees, some differing considerably in topology (Baroni et at. (1967) and by Wilson (1971). Taylor (1978) proposed Urbani, 1990; Carpenter, 1990b; Ward, 1990). Bolton an arrangement in which two members of the myrmecioid (1990~)offered a Hennigian-style phylogeny of the ant complex (Myrmeciinae and Pseudomyrmecinae) were subfamilies, derived from his morphological studies of the transferred to the poneroid complex, the latter being army ants, cerapachyines and leptanillines. His results explicitly diagnosed by two derived features of abdominal were partly congruent with those of Ward (1990), who morphology. Unfortunately no synapomorphy was ident- focused on the position of the Pseudomyrmecinae in the ified for the remaining subfamilies, renamed the formicoid poneroid complex, but there was disagreement on the complex. A lack of apomorphic characters also characterizes placement of the genus Nothomyrmecia. Finally, relation- ships within the formicoid complex of subfamilies have Correspondence: Dr C. Baroni Urbani, Zoologisches Institut been examined by Lutz (1986) and Shattuck (1992), with der Universitat, Rheinsprung 9, CH-4051 Basel, Switzerland. conflicting results. 30 1 302 C. Barotii Urban;. B. Bolton arid P. S. Ward Thus there is continuing ambiguity over the relationships to the Dorylinae by Borgmeier (1955: 54). Recent progress of the major ant clades, nothwithstanding a considerable in our understanding of ponerine morphology and sub- explosion of new character information. In this paper we familial limits make attribution to the Ponerinae untenable. attempt a cladistic analysis of the Formicidae by compiling For this reason Aenictogiton has been treated as a separate and synthesizing information on a large suite of characters, taxon in the analysis. including new data on abdominal morphology. These Aneuretinae: Aneuretus simoni. characters have been examined in a wide variety of species Anomalomyrmini: Protanilla sp. (Pakistan), Protanilla and castes. Although the analysis is basically at the level of sp. (E. Malaysia), Protanilla sp. (Nepal). See note under subfamilies, it became clear to us that in order to prevent Leptanillini. the inadvertent inclusion of non-monophyletic groups it Apomyrmini: Apomyrma stygia (worker, gyne). See was desirable to expand the set of terminal taxa to include note under Leptanillini. certain genera and tribes. Cerapachyinae: Acanthostichus sp. (Brasil), Acan- thostichus sp. (Colombia), Acanthostichus sp. (male), Cerapachys biroi, Cerapachys centurio, Cerapachys dumb- Taxa included in the analysis letoni, Cerapachys edentatus, Cerapachys foreli (worker, male), Cerapachys fragosus, Cerapachys longitarsus (male), The 14 currently recognized subfamilies of the Formicidae Cerapachys rtitidulus, Cerapachys nkomoensis (worker, have been considered in the present study. These are male), Cerapachys sulcinodis, Cerapachys turneri (s.I.), all rhose recognized by Baroni Urbani (1989) plus the Cerapachys wroughtoni, Cerapachys sp. (E. Malaysia), Cerapachyinae, Aenictinae and Aneuretinae raised or Cerapachys sp. (Sulawesi), Cerapachys sp. (Nigeria), reinstated to subfamily status later (Bolton, 1990a, c). Cerapachys sp. (Zaire), Cerapachys sp. (Cameroun), In addition we have treated certain anomalous taxa, Cerapachys sp. (Madagascar, male), Cerapachys sp. whose morphological features suggest that they may not (Mexico, male), Simopone conciliatrix, Simopone grandis, be cladistic members of the subfamilies to which they are Simopone marleyi, Simopone sp. (Nigeria), Simopone currently assigned, as independent terminal taxa, as noted sp. (Madagascar, male), Sphinctomyrmex imbecilis, in the list below. Sphinctomyrmex occidentalis, Sphinctomyrmex steinheili, The majority of the characters employed in this paper Sphinctomyrmex rufiventris (worker, male), Sphinctomyr- have already been mentioned in recent literature, e.g. mex turneri, Sphinctomyrmex sp. (Australia, male). Lutz (1986), Baroni Urbani (1989), Bolton (1990a, b, c), Dolichoderinae: Azteca xanthochroa, Bothriomyrmex Ward (1990). Sources are indicated in the paragraph cor- pubens, Dorymyrmex nigriventris, Dolichoderus atte- responding to each character description. Whenever laboides, Dolichoderus bispinosus, Dolichoderus cuspida- possible the characters have been verified by ourselves, tus, Dolichoderus doriae, Dolichoderus mariae (male), by examining material in the collections of the Department Dolichoderus taschenbergi, Forelius rufus, Iridomyrmex of Entomology, The Natural History Museum (London), detectus (male), Leptomyrmex nigriventris, Leptomyrmex the Department of Entomology, University of California. pullens, Liometopum microcephalum, Papyrius nitidus, Davis, and the Santschi collection, Natural History Museum Philidris cordatus, Tapinoma erraticum, Technomyrmex of Basel. Cryptic anatomical characters, like the con- albipes, Technomyrmex taylori. dition of the metacoxal cavities, the configuration of Dorylinae: Dorylus afinis, Dorylus fimbriatus (worker, the presclerites of abdominal segments I11 and IV, and male), Dorylus fulvus (worker, male), Dorylus gribodoi tergosternal fusion of abdominal segments 11-IV, have (male), Dorylus labiatus, Dorylus laevigatus (worker, been checked by dissecting a sub-sample of specimens as male), Dorylus opacus, Dorylus nigricans (worker, gyne, listed below. These specimens, with the dissected sclerites male), Dorylus sp. (Angola), Dorylus sp. (Cameroun), either mounted in Euparal on microscope slides or glued Dorylus sp. (South Africa), Dorylus sp. (Kenya, worker, to card points, have been deposited in the original collection male), Dorylus sp. (Nigeria), Dorylus sp. (Uganda, male), from which the material was extracted. When not stated Dorylus sp. (Liberia, male), Dorylus spp. (Zambia, males). otherwise the specimens dissected were always workers. Ecitoninae: Cheliomyrmex andicola, Cheliomyrmex megalonyx (male), Cheliomyrmex morosus (worker, FORMICIDAE male), Eciton burchelli (worker, male), Eciton hamatum Aenictinae: Aerticfus aratus, Aenictus dentatus, Aenictus (worker, male), Labidus coecus (male), Labidus pruedator, binghami, Aenictus eugenii, Aenictus fergusoni, Aenictus Neivamyrmex andrei (male), Neivamyrmex californicus, moebii (male), Aenictus sp. (Bhutan, male), Aenictus sp. Neivamyrmex harrisii (male), Neivamyrmex nigrescens, (Cameroon), Aeriictus sp. (Sri Lanka, male), Aenictus sp. Neivamyrmex opacithorax, Neivamyrmex pertyi (male), (Ghana. male), Aenictus sp. (Ghana, male), Aenictus sp. Neivamyrmex swainsoni (male), Nomamyrmex esenbecki, (Zambia, male). Nomamyrmex hartigi (worker, male). Aenictogitoti sp. (Angola, male), Aenictogiton sp. Formicinae: Acropyga acutiventris, Anoplolepis fallax (Zambia, male), Aenictogiton sp. (Zambia, male). Known (male), Anoplolepis tenella, Bregmatomyrma carnosa