THE CLADISTICS OF AMAURIS BUTTERFLIES: CONGRUENCE, CONSENSUS AND TOTAL EVIDENCE

Abstract— Two data sets for 10 species of African milkweed butterflies (Nymphalidae, Danainae: one Danaus , two Tirumala , seven Amauris ) have been analysed cladistically, separately and in combination. One data set comprised 32 morphological characters, the other comprised 68 chemical compounds from male scent organs. Analysed separately, the two data sets produced six similar but non-identical minimum-length solutions. Analysed together, the combined data set of 100 characters produced a single minimum-length tree, identical to one of the three solutions for the morphological data set. The combined data produced a more informative result than congruence comparisons based on strict or combinable component consensus analysis. These results, together with re-analysis of a morphological data set for all 15 species of Amauris (which produced 12 minimum-length solutions), permit increased resolution of the existing classification of this Afrotropical genus, including the formal recognition of two subgenera, Amauris ( Amauris ) Hübner, and Amauris ( Amaura ) Geyer ( stat. rev. ). The fit of uniquely derived, unreversed chemical characters to the tree raises the possibility that stepwise additive evolution of semiochemicals may have occurred during cladogenesis of these mimetic butterflies. The implications for chemoecology and speciation are briefly discussed.