Simultaneous analysis of the basal lineages of Hymenoptera (Insecta) using sensitivity analysis.

The first simultaneous analysis of molecular and morphological data of basal hymenopterans that includes exemplars from all families is presented. DNA sequences (of approximately 2000-2700 bp for each taxon) from the nuclear genes 18S and 28S and the mitochondrial genes 16S and CO1 have been sequenced for 39 taxa (four outgroup taxa, 29 symphytans, and six apocritans). These DNA sequences and 236 morphological characters from Vihelmsen [Zool. J. Linnean Soc. 131 (2001) 393] were analyzed separately as well as simultaneously. All analyses were performed on unaligned sequences, using the optimization alignment (= direct optimization) method. Sensitivity analysis sensu Wheeler [Syst. Biol. 44 (1995) 321] was applied by analyzing the data under nine different combinations of analysis parameter values. The superfamily level relationships of basal hymenopterans as proposed by Vilhelmsen [Zool. J. Linnean Soc. 131 (2001) 393] and Ronquist et al. [Zool. Scr. 28 (1999) 13] are mostly confirmed, except that Pamphilioidea is the sister group to Tenthredinoidea s.l. and that Anaxyelidae (i.e., Syntexis libocedrii) and Siricidae are supported as a monophyletic group, partly reestablishing the traditional concept of Siricoidea. The resulting hypothesis that best represents the combined evidence from morphology and DNA sequences is (Xyeloidea (Tenthredinoidea s.l. Pamphilioidea) (Cephoidea (Siricoidea (Xiphydrioidea (Orussidae Apocrita))))), with Siricoidea = Anaxyelidae +Siricidae. The phylogenetic system within Tenthredinoidea s.l., derived from the combined evidence, is (Blasticotomidae (Tenthredinidae including Diprionidae (Cimbicidae (Argidae Pergidae)))).