Genetically distinct populations in an Asian soldier-producing aphid, Pseudoregma bambucicola (Homoptera: Aphididae), identified by DNA fingerprinting and molecular phylogenetic analysis.

To estimate genetic structure of a soldier-producing aphid, Pseudoregma bambucicola, samples from natural populations throughout southeastern Asia were analyzed by a DNA fingerprinting technique. We unexpectedly found that P. bambucicola comprises two geographic groups, the northern group and the southern group, which are genetically distinct from each other but morphologically almost indistinguishable. Molecular phylogenetic and statistical analyses based on mitochondrial ribosomal DNA sequences demonstrated that the northern and southern groups of P. bambucicola are not closely related but constitute distinct lineages in the genus Pseudoregma. Detailed morphological reexamination revealed that the two groups could be distinguished by the number of setae on the 8th abdominal tergite of 1st instar nymphs and soldiers. From these results, it was suggested that P. bambucicola should be divided into two species. The northern group from Japan, Taiwan, Hong Kong, and northern Vietnam retains the name P. bambucicola, whereas we suggest that the name P. carolinensis (R. Takahashi, 1941, Tenthredo 3, 208-220) should be used for the southern group from Thailand, Malay Peninsula, Java, Irian Jaya, and Micronesia. The morphological resemblance between P. bambucicola and P. carolinensis might be due to shared ancestral characters of the genus Pseudoregma.