Taxonomy of shortjaw tapertail anchovy Coilia brachygnathus by jaw length and mitochondrial Cytochrome b gene analysis
XU Zhi-qiang, GE Jia-chun,HUANG Cheng,DOU Hong-xia,PAN Jian-lin, XIA-Aijun
1. Freshwater Fishery Research Institute of Jiangsu Province,Nanjing 210017 ,China; 2. School of Life Science,Nanjing University ,Nanjing 210093 ,China
Abstract: There has still been controversy in taxonomic relationship between Coilia nasus and C. brachygnathus due to similarity in morphology among anchovy Coilia. Thus, the numbers of longitudinal scales, anal pyloric caeca, and variation in the maxillary bone length were measured in 110 samples of C. nasus ,40 fin-rays, samples of C. barchygnathus and 36 samples of C. nasus taihuensis. The taxonomic status of the C. brachygnathus was discussed along with the analysis of the Cyt b sequencing of the mitochondria DNA. C. nasus taihuensis and C. brachygnathus had a relative lower ratio of maxillary bone length to head length （1. 125±0.091 vs 1. 022±0. 045 and 0.981±0. 095 ） and larger variation coefficient （8.01% and 9.77% vs 4.55% ） compared with C. nasus. Therefore, we deduced that the maxillary bone length of the anchovy Coilia might be deeply influenced by the environment and the life habit. So the maxillary bone length might not be treated as a main standard for the validity of diputed species in Coilia genus. The mitochondria DNA Cyt b sequences of the four species anchovy Coilia were direct sequenced and submitted to GeneBank. The average genetic distance between C. nasus and C. brachygnathus was 0.002, less than that between the C. nasus and C. nasus taihuensis while the average genetic distance between C. nasus taihuensis and C. brachygnathus was 0.001. Neighbor - Joining （ NJ）, Maximum likelihood （ML） and Maximum - Parsimony （MP） were employed to reconstruct the phylogeny with Engraulis encrasicolus and E. japonicus designated as outgroup. C. mystus has a basal position, suggesting that the species are more primitive than the other three Coilia in the evolution. C. nasus, C. brachygnathus and C. nasus taihuensis failed to form monophyletie class and could not be separated clearly. As good as C. nasus taihuensis, C. brachygnathus should be considered as different ecotypes of C. nasus other than a valid species separately in the freshwater.
2009, Vol. 24 
