J. HYM. RES. 1(1), 1992 pp. 25-61 An Exploratory Analysis of Cladistic Relationships within the Superfamily Apoidea, with Special Reference to Sphecid Wasps (Hymenoptera) 12 Byron A. Alexander Snow Entomological Museum, Snow Hall, University of Kansas, Lawrence, KS 66045, U.S.A. Abstract . — This paper presents the results of several analyses of cladistic relationships among the sphecid wasps and bees, based on adult and larval morphology, with special emphasis on the tribes of sphecid wasps. The analyses examine the effects of: (1) alternative procedures for determining character polarities, (2) using adult characters alone or both adult and larval characters, (3) analyzing all sphecid tribes or only those tribes for which larvae have been described, and (4) equal weighting of all characters vs. successive approximations character weighting. The monophyly of bees is strongly supported, and the following groups of tribes of sphecid wasps are consistently supported as monophyletic: (a) Ampulicini + Dolichurini; (b) (Sceliphrini + (Sphecini + Ammophilini)); (c) (Aphilanthopini + Philanthini + Cercerini + Pseudoscoliini); (d) (Nyssonini + Gorytini + Stizini + Bembicini). Numerous equally parsimonious resolutions of cladistic relationships among these groups and other sphecid tribes are found. In 1 976, R. M. Bohart and A. S. Menke published a monumental worldwide revision of the genera of sphecid wasps. This encyclopedic compilation of information on the taxonomy, geographic distri-bution, and external morphology and behavior of adults represents a milestone in our knowledge of these wasps. Another noteworthy feature of this work is its extensive discussions of phylogenetic relationships among sphecid wasps, although its numerous phylogenetic diagrams are not based upon explicitly stated analytical methods. How-ever, Bohart and Menke (1976: Tables 2, 5, 1 1 , 1 3, 1 5, 16, 19, and p. 224) present numerous lists of "gen-eralized" and "specialized" states of characters considered to be "of phylogenetic significance" in various groups (usually subfamilies). The implicit message seems to be that the branching diagrams are based upon the characters in these tables. Re-gardless of how the phylogenetic diagrams may have been derived, the character analyses sum-marized in the tables do provide the kind of infor-mation necessary for a cladistic analysis. Thus, it should in principle be possible to determine how well these characters support the phylogenetic hypotheses presented by Bohart and Menke, and whether there are other phylogenetic hypotheses that would explain the data equally well or better. 'Contribution No. 3033, University of Kansas ; Throughout this paper, the informal designation "sphecid wasps" will be used to refer to all taxa assigned to the Family Sphecidae as defined by Bohart and Menke (1976). A rigorous cladistic analysis requires two types of information in addition to that presented in Bohart and Menke's tables of character states. One is a clear statement of how the characters have been polarized, and the other is a matrix showing the state of each character for each taxon. Bohart and Menke do not present any data matrix in their book, and it is not possible to construct a complete matrix from their descriptions of taxa or discus-sions of characters. In one of their introductory chapters (p. 29), they do briefly explain how they distinguished between "primitive" and "advanced" states of characters. After discussing the pitfalls of assuming that "simple" characters are primitive and "complex" ones derived, they conclude that "a study of features common in the more primitive hymenopterous families and preserved in some of the Sphecidae is the most productive way of making value judgments on evolutionary paths". This is conceptually close to a method now generally known as outgroup analysis, although more recent formulations of this method (e.g. Watrous and Wheeler 1981, Maddison et al. 1984) are consider-ably more rigorous and explicit. Bohart and Menke also do not identify which hymenopteran families they consider primitive (relative to sphecid wasps). The first explicit cladistic analysis of aculeate Hy-menoptera (Brothers 1975; not cited in Bohart and Menke 1976) presented a hypothesis of the phylo-genetic position of sphecid wasps and bees that was quite different from conventional opinion at the time (e.g. Evans and West Eberhard 1970).