Biodiv Sci ›› 2019, Vol. 27 ›› Issue (2): 149-158.DOI: 10.17520/biods.2018261

• Original Papers • Previous Articles     Next Articles

Species diversity and geographical distribution of the Chaetoceros lorenzianus complex along the coast of China

Chen Zuoyi1,2,Xu Xiaojing1,Zhu Suying1,Zhai Mengyi1,Li Yang1,*()   

  1. 1 Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory of Healthy and Safe Aquaculture, School of Life Sciences, South China Normal University, Guangzhou 510631
    2 The Eighth Geological Brigade, Hebei Geological Prospecting Bureau, Qinhuangdao, Hebei 066001
  • Received:2018-09-28 Accepted:2019-01-27 Online:2019-02-20 Published:2019-04-16
  • Contact: Li Yang

Abstract:

The Chaetoceros lorenzianus complex is composed of several planktonic diatom species that share a similar morphology with C. lorenzianus Grunow. The complex has been recorded frequently in coastal waters across the world. Recently, new taxonomic information has enriched the known species diversity of the complex from 3 to 7 taxa. However, the identities of many species comprising the complex in China is still unclear. To clarify the species diversity and provide solid identification criteria for further studies, 332 monoclonal strains belonging to the C. lorenzianus complex were collected from the coast of China. With light microscopy and scanning and transmission electron microscopy, the morphologies of vegetative cells and resting spores were observed. Hypervariable D1-D3 regions of nuclear large subunit ribosomal encoded genes were amplified to construct the phylogenetic relationship. Morphological clustering was consistent with molecular systematics, which indicated that a total of 5 species are present within the C. lorenzianus complex along the coast of China; C. decipiens, C. elegans, C. laevisporus, C. mannaii and C. pauciramosus. The ultrastructure on setae, such as the shape, size and density of the setae pores, can be used as distinguishing features among allied taxa. The morphology of the resting spores also aid in accurate identification. The previous reports identifying the taxa within the C. lorenzianus complex in China need to be reexamined. Chaetoceros decipiens and C. laevisporus are the most widespread taxa along the coast of China, whereas C. pauciramosus has the narrowest distribution, having only been recorded in Taishan and Zhuhai of the Guangdong Province.

Key words: Chaetoceros lorenzianus complex, species diversity, morphology, molecular phylogeny, resting spore, coast of China