The Preliminary Study On The Phylogeny Of Tetrigoidea

Since the middle of the twentieth century, the technology of molecular biology has been widely used in systematics. DNA sequences, which are not only the important germ plasm but also the recorder of evolution, appeare to be effective markers that have been useful in estimating evolution of species and reconstructing phylogeny.The Tetrigoidea, comprising eight families, is regarded as one of the oldest groups in Caelifera and closely related to Tridactyloidea. The reported studies were concentrated on the descriptions of new species and morphological taxonomy. Due to the subtle and insufficient information from morphological data, the phylogenetic relationships in Tetrigoidea are controversial.The molecular technique has been extensively applied to systematics. Unfortunately, the reported studies on Tetrigoidea using molecular technique are few. The 12S and 16S ribosomal genes appear to be promising markers that are useful to estimate the divergence in genus and family levels. In our studies, we discussed the phylogenetic relationships among 6 families of the superfamily Tetrigoidea by 16S rRNA gene; and combining 12S and 16S rRNA gene sequences to research the relationships among 6 genera of Tetrigidae, then discussed the relationships of the 5 genera by a cladistic approach based on morphological characteristics.Our results indicated that: ①Batrachidiade is one of the oldest families in Tetrigoidea. ②Dividing Tetrigidae into two families is more reasonable. ③It is feasible to combine Systolederus with Teredorus so as to consider them a genus of the family Tetrigidae. ④ The phylogenetic relationships of the 6 families are: Batrachidiade and Scelimenidae are the primitive groups; Discotettigidae, closer to a relatively primitive branch of Tetrigidae, is an intermediary type; Metrodoridae and another branch of Tetrigidae, closer to Cladonotidae, are relatively evolutionary groups. ⑤T. tubercarina may be given tribal rank. ⑥Coptltettix huanjiangensis and C. gongshanensis are the same species i.e. Coptltettix huanjiangensis is the synonymof C. gongshanensis. ?12S and 16S ribosomal genes are promising markers in reconstructing the phylogeny on the levels of genera and families.