Psylloidea is a monophyletic group of insects occupying a basal lineage within Hemiptera. To date, the internal affiliations among major lineages within Psylloidea are not completely understood. This presentation discusses efforts to offer a better inference of phylogenetic relationships among higher groups of Psylloidea based on cladistic analysis of morphological and molecular characters. The first matrix of characters studied is based on morphological characters identified in the thorax of Psylloidea, especially those of the pleuron. While many homologous characters are identified, contrary to other insects studied, the wing articulation in psyllids does not provide much phylogenetic information. A second set of phylogenetic characters is based on nucleotide sequences of 18S rRNAs from 26 species of psyllids. An assortment of matrices is used to study influence of alignment of nucleotide characters on phylogenetic inference. An alignment based on secondary structure is found to be most rigorous to establish character homology. Results using morphological and molecular data sets, singly or in combination, infer Aphalaridae and Psyllidae are, each, paraphyletic. Some key psyllid taxa were not available for molecular analysis, and their phylogenetic affiliations remain unclear. Future efforts will focus on Liviinae, Paurocephalinae, Diaphorininae, Aphalaroidinae, Ciriacreminae, Pachypsyllinae and Euphalerinae, as well as on basal groups like Calophyidae or Homotomidae. Other insights concerning psyllid phylogeny are also presented. Phylogenetic inferences based on other taxonomic studies are confirmed by a cladistic analysis. The phylogeny presented here, although preliminary, is still a useful tool for contemplating evolutionary scenarios.
Keywords: psyllids
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