Molecular phylogeny of Macrosiphini (Hemiptera: Aphididae): An evolutionary hypothesis for the Pterocomma-group habitat adaptation.

The aphid tribe Macrosiphini Wilson, 1910 (Hemiptera: Aphididae: Aphidinae) is one of the most controversial groups within Aphididae. We sequenced 2876 bp from one nuclear gene (EF-1α) and four mitochondrial genes (COI, tRNA + COII, 16S) from 107 terminal taxa representing 57 genera of Macrosiphini s.l. (the former Macrosiphini + genera in former Pterocommatini), including all of the recognized major genera and outgroups, and reconstructed the phylogeny using maximum likelihood, maximum parsimony and Bayesian methods. The stepping-stone method was used to evaluate various topological hypotheses regarding Macrosiphini s.l. and related groups. Our findings support both the monophyly of Macrosiphini s.l., and of two subordinate groups (Macrosiphini s.str and the Pterocomma-group), as well as the transfer of Capitophorus, Pleotrichophorus, Liosomaphis and Vesiculaphis to the Pterocomma-group-a result not previously suggested by analyses of molecular data. Ancestral state reconstructions for Macrosiphini and the Pterocomma-group suggest an ancestral primary host association with Rosales and Malpighiales, respectively, and other host associations within the tribe. Host transitions independently occurred more than once in Macrosiphini s.str. Furthermore, host-shifts between Rosales and Malpighiales may have occurred at least once in the Pterocomma-group. Additionally, the Macrosiphini phylogeny indicates that host associations are consistent also with host ecology, with a partitioning of aphid-host relationships into riparian and periaquatic habitats versus drier forest/shrubland habitats.