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SUBFAMILY ECITONINAE
       The New World Ecitoninae, together with the Old World Dorylinae, are the legionary ants, par excellence. Their colonies may reach enormous size (up to 2.2xl07 for Old World Dorylus and up to 106 for Eciton; Brian, 1965). Colonies are nomadic. The bizarre queens lay enormous numbers of eggs at regular intervals and when the brood reach a certain level of development, the entire colony relocates to a new site. There is never a true nest, as such, but only a temporary bivouac. The available information on army ant life has been summarized by Gotwald (1982).
       The Ecitoninae were, until recently included within the Dorylinae, a group now considered to be restricted to the Old World tropics and subtropics (Snelling, 1981b; Gotwald, 1982). Wheeler and Wheeler (1985) have argued in favor of lumping all the legionary ants back into the single subfamily Dorylinae partly because that "... at least is well supported by larval evidence," even though they had earlier stated that larval characters (or their lack) should not take precedence over adult characters. As additional evidence they cited Kistner's (1972) conclusion that Neivamyrmex and the Old World Aenictus shared a common ancestry because of the relationship of their associated myrmecophilous staphylinids. While Kistner's understanding of the staphylinids may be correct, the conclusion regarding Neivamyrmex and Aenictus does not necessarily follow. The value of such evidence is elusive. Contrary "evidence" of a similar nature would suggest that the Old and New World army ants have little in common since there are no known myrmecophilous proctotrupoid wasps associated with the Old World forms, while many are ecitophiles in the New World.
       Gotwald and Kupiec (1975) have suggested that the army ants may actually be triphyletic, based on an analysis of geographic, morphological, and behavioral characteristics. Their three lineages consist of the Cheliomyrmecini + Ecitonini in the New World and two Old World groups, Dorylini and Aenictini. They specifically reject that Aenictini and Ecitonini are more closely allied to each other than either is to any other lineage; their morphological similarities are presumed to be convergent.
       The systematics of the New World army ants has been fairly stable since the massive revision by Borgmeier (1955). The few species described since 1955 are mostly included in the keys by Watkins (1976). Watkins (1988) presented a key to those army ants known to occur in the vicinity of Chamela, Jalisco, Mexico.
       The three genera Eciton, Neivamyrmex, and Nomamyrmex should probably all be recombined to form a single genus, Eciton. While it is true that these genera are separable by the features cited in the key cited below, the characters are trivial. Genera should be based on characters of a more fundamental nature and on more such characters than can be advanced in support of these genera. A detailed study of character states in the numerous species of Ecitonini must be made before any substantive conclusion can be reached; such a study is beyond the scope of this paper.
       The information presented here is the result of an ongoing revisionary study of the New World Ecitoninae, and should be considered preliminary. Although still in the early stages this information is being presented here in the hope that it will prove useful to other workers.


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Date of this version 21, July 2012
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Gordon C. & Roy R. Snelling