Phylogenetic Analysis Of The Prionini (Coleoptera: Cerambycidae: Prioninae) From China

Tribe Prionini is one of the oldest tribes in Prioninae (Coleoptera:Cerambycidae) and many species in the tribe are important pests in agriculture and forestry. Studies on Prionini were focused on morphology, especially on identification and taxonomy. Up to now, mitochondrial genes of Prionini are not studied systematicly, and phylogenetic relationships among taxa in Prionini are unknown. The dissertation analysed partial 12S rRNA,16S rRNA and COI gene sequences and discussed the phylogenetic relationship among taxa in Chinese Prionini based on traditional morphological characters, characters of hind wing venation and male genetalia, and mitochondrial gene sequences. Results are followed:DNA extraction and PCR amplification of three mitochondrial genesIn dry specimens, apparent DNA degration was found and long deposition time accelerated DNA degration. After PCR amplification based on DNA from dry specimens deposited longer than 20 years, mitochondrial gene segments were found by agarose gel electrophoresis technique. However, sequences of these mitochondrial gene segments were different from those of Cerambycidae. In the study,24 gene sequences of mtDNA 12S rRNA,16S rRNA and COI genes were obteined from 8 species of 3 genera in Chinese Prionini and a species of Macrotomini.Analysis of mitochondrial gene sequences in PrioniniBase insertion/miss was found in 12S rRNA and 16S rRNA genes, but not in COI gene. Base constitution of obtained mithchondrial genes biased towards T and A. In ribosomal rRNA gene, content of base A was higher than base T, but content of base T higher than base A in COI gene. Ratios of transition vs transversion (Ts/Tv) in 12S rRNA gene decreased when the divergence time increased. Ts/Tv ratios in 16S rRNA gene first increased but then decreased when the divergence time increased. Ts/Tv ratios in COI gene sequences did not changed distinctly when the divergence time increased. The evolution rate of COI gene was faster than ribosomal rRNA genes and the evolution in COI gene was primarily located in the third coden sites. The evolution rates of these second coden sites were very slow. Evolution distances based on diverse genes were different. P evolution distances were smaller than these true evolution distances.Dorysthenes fossatus (Pascoe,1857) was different from other species of Dorysthenes in the length of 12S rRNA gene segment and base constitutions of 12S rRNA,16S rRNA and 12S rRNA+16S rRNA gene sequences. The evolution distances and Ts/Tv ratios between Dorysthenes fossatus and other species of Dorysthenes were different from those among species of Dorysthenes (excluding Dorysthenes fossatus), but is the same as those between Dorysthenes and Prionus.Phylogenetic analysis of Chinese PrioniniThe evolution scores of these best distance trees given by Neighbor joint method were usually not the minimum scores. Weighting characters by rescaled consistency index (RC) was useful for maximum parsimonious analysis. The topology of bootstrap 50% majority-rule consensus tree was different from the best phylogenetic tree usually. The best phylogenetic tree was more influenced by substution model than bootstrap 50% majority-rule consensus tree. The topologies of phylogenetic trees reconstructed from different methods may be different. However the topology of phylogenetic trees reconstructed from maximum likehood method appeared in phylogenetic trees reconstructed from Bayesian method. The topologies of phylogenetic trees reconstructed from different characters may be not same.Chinese Prionini is a monophyletic group and should be divided into two subtribes. Genera Dorysthenes and Prionus belongs to subtribe Prioni, and genera Priotyrannus and Prionomma belongs to subtribe Derobrachi.Genus Prionus defined by morphological characters of mandible is paraphyletic. Prionus murzini Drumont et Komiya,2006, Prionus unilamellatus Pu,1987 and Prionus siskai Drumont et Komiya,2006 should be excluded from genus Prionus and constitute a new independent genus. There is close relationship between Prionus unilamellatus and Prionus siskai. Prionus gahani Lameere,1912, Prionus insularis Motschulsky,1857, Prionus sifanicus Plavilstshikov,1934, Prionus delavayi lorenci Drumont et Komiya,2006 and Prionus lameerei Semenov-Tian-Shanskij,1927 constitute a monophyletic group. There are close relationship among Prionus gahani, Prionus lameerei and Prionus sifanicus.Genus Dorysthenes defined by morphological characters of mandible is a paraphyletic group too. Subgenus Dorysthenes (Prionomimus) should be excluded from genus Dorysthenes and constitute a new genus. There is close relationship between Dorysthenes elegans Ohbayashi,1981 and Dorysthenes fossatus. Genus Dorysthenes is a monophological group after excluding subgenus Dorysthenes (Prionomimus). It is reasonable that Lameere combined genera Lophosternus Guerin, 1844, Paraphrus Thomson,1860, Cyrtognathus Faldermann,1835 and Baladeva Waterhouse,1840 with genus Dorysthenes based on morphological characters. Dorysthenes granulosus (Thomson,1860) is the primitive species of genus Dorysthenes. Subgenus Dorysthenes(Cyrtognathus) is monophological, and there is close relationship between Dorysthenes paradoxus (Faldermann,1833) and Dorysthenes tippmanni Heyrovsky,1950. Subgenera Dorysthenes (Lophosternus) and Dorysthenes (Baladeva) defined by traditional morphological characters are paraphyletic.