Rung, A., Scheffer, S.J., Evans, G.A., & Miller, D. 2008a Molecular identification of two closely related species of mealybugs of the genus Planococcus (Pseudococcidae).. Proceedings of the XI International Symposium on Scale Insect Studies, Oeiras, Portugal, 24-27 September 2007. ISA Press Lisbon, Portugal 322 pp.

Notes: Morphological identification of the mealybug species Planococcus citri and P. minor, two serious agricultural pests, is often complicated by the existence of intermediate forms and a lack of knowledge of the intraspecific variation that occurs in each species. In this paper, we have explored the utility of two molecular markers, the mitochondrial gene Cytochrome Oxidase I (COI) and the nuclear gene Elongation Factor 1-alpha (Efl-Alpha) to ascertain the identity of these species, and to provide reliable characters for their identification. Results from Maximum Parsimony analysis of ON A sequence data from both genes indicate the existence of a third clade, distinct from both P. citri and P. minor, from the Hawaiian Islands. This clade, though morphologically identical to P. citri, clusters with P. minor in ca 50% of the cladograms obtained with the COI, and 80% of the dado grams obtained with Efl-Alpha. Our studies show that COI is a reliable tool which, in combination with morphological and geographical data, can be used to accurately identify these three clades in most cases. Given a few instances in which identifications from COI and Efl-Alpha were in conflict, however, our results must be interpreted with caution, and until additional studies are performed, no changes are proposed in the taxonomy of this species complex.