Dissertation > Biological Sciences > Entomology > Insect morphology

Morphological and Molecular Identification of a New Species of Rhus Gall Aphids

Author YangJinYing
Tutor RenZhuMei
School Shanxi University
Course Genetics
Keywords Rhus gall aphids New species Morphological characteristics mtDNA sequence Molecular identification
CLC Q964
Type Master's thesis
Year 2012
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The Rhus gall aphids (Hemiptera:Pemphigidae:Fordinae) are the aphid group which parasitizes exclusively on the leaves of the primary host-plant genus Rhus to form galls. The Rhus gall aphids include six genera and fifteen spcies, and most of which distribute in East-Asia except for a single species Melaphis rhois in North American. We collected a new species in Jiangxi province in2009. In this study, we identified the new species by the morphological characters and molecular data, and established its taxonomic status.The gall formed by the new species is pink flower-like and locates on the basis of the total axle of compound leaf on Rhus potaninii Maxim. The features of head, chest and abdomen from15individuals of the new species were observed, measured and described. The analysis showed that a major difference between the new species and other Rhus gall aphids lies on the shape and number of secondary rhinaria. By comparing the morphological characteristics between the new species and other Rhus gall aphids including six genera and13species (including three subspecies), we found that the new species have tree cyclic secondary rhinaria on the3rd antennal segment and have one or two large oval secondary rhinaria on the4th and5th antennal segment. The new species belongs to the Pemphigidae, Nurudea referring to aphids keys in "Economic Insect Fauna of China" and "Fauna sinica".In addition, the partial sequences of mtDNA COI, tRNA+COII and Cytb genes of the new species were examined by PCR method, and totally2633bp in length was obtained, among which include1535bp COI,643bp tRNA+COII and433bp of Cytb genes. Combined with the relative sequences of other Rhus gall aphids in6genera and13species (including three subspecies), the sequences were analyzed. Using the software DNAMAN, we analyzed the homology of single and combined gene in14species. The results were the same as the results of morphological identification. The new specie has the highest homology with Nurudea shiraii and Nurudea yanoniella. Phylogenetic tree of single and combined genes were constructed by NJ method. The results showed that phylogenetic relationship of the Rhus gall aphids were consistent. The new specie was clustered with N.shiraii, but N.yanoniella was an independent clade in NJ tree based on the tRNA+COII gene. In others phylogenetic trees, the new species was clustered with N.shiraii and N.yanoniella. These results of the phylogenetic tree and morphology were coincident. The new specie has a closer relationship with N.shiraii and N.yanoniella from the genus Nurudea, and it was named as Nurudea zhengi Ren sp.

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