Phylogenetic analysis of the genus Cylicocyclus (Nematoda: Strongylidae) based on nuclear ribosomal sequence data
Seven species of Cylicocyclus Ihle, 1922 (Nematoda: Strongylidae) were collected from donkeys from Henan Province, China. Five samples of each species were selected for sequencing. Sixteen different internal transcribed spacer (ITS) sequences representing the seven species of Cylicocyclus were obtained. Sequence differences in the first internal transcribed spacer (ITS-1) among species was lower than that of the second internal transcribed spacer (ITS-2). Phylogenetic analyses were conducted using the combined ITS-1 and ITS-2 data sets from the present study and using reference sequences from the GenBank database. The MP and ML trees were similar in topology. The phylogenetic trees were divided into two clades. Clade I included 8 species of Cylicocyclus; within this group, Cylicocyclus leptostomus (Kotlan, 1920) is nested between different samples of Cylicocyclus ashworthi (LeRoux, 1924), suggesting C. ashworthi may represent a species complex. Clade II included Cylicocyclus elongatus (Looss, 1900) and Cylicocyclus ultrajectinus (Ihle, 1920); however, these two species always clustered with the comparative species (Petrovinema poculatum (Looss, 1900) and Poteriostomum imparidentatum Quiel, 1919), suggesting that C. elongatus and C. ultrajectinus represent members of other genera.
KeywordsCylicocyclus Nematoda Strongylidae ITS phylogeny
Unable to display preview. Download preview PDF.
- Du C.X., Zhang L.P., Shi M.Q., Ming Z., Hu M., Gasser R.B. 2010. Elucidating the identity of Anisakis larvae from a broad range of marine fishes from the Yellow Sea, China, using a combined electrophoretic-sequencing approach. Electrophoresis, 31, 654–658. DOI: 10.1002/elps.200900531.PubMedCrossRefGoogle Scholar
- Hung G.C., Chilton N.B., Beveridge I., Gasser R.B. 1999b. Secondary structure model for the ITS-2 precursor rRNA of strongyloid nematodes of equids: implications for phylogenetic inference. International Journal for Parasitology, 29, 1949–1964. DOI: 10.1016/S0020-7519(99)00155-1.PubMedCrossRefGoogle Scholar
- Ihle J.E.W. 1925. Verzeichnis der Cylicostomum-Arten der Equiden mit Bemerkungen über einzelne Species. Zentralblatt für Bakteriologie, Abt. 1(95), 227–236.Google Scholar
- Lichtenfels J.R. 1975. Helminths of domestic equids. Illustrated keys to genera and species with emphasis on North American forms. Proceedings of the Helminthological Society of Washington (special issue), 42, 1–92.Google Scholar
- Lichtenfels J.R., Kharchenko V.A., Sommer C., Ito M. 1997. Key characters for the microscopical identification of Cylicocyclus nassatus and Cylicocyclus ashworthi (Nematoda, Cyathostominae) of the horse, Equus caballus. Journal of Helminthological Society of Washington, 64, 120–127.Google Scholar
- Zhang L.P., K’ung F.Y. 2002. Parasitc Nematodes from Equus spp. China Agriculture Press, Beijing, 175 pp. (in Chinese).Google Scholar
- Zhu X.Q., D’Amelio S., Gasser R.B., Yang T.B., Paggi L., He F., Lin R.Q., Song H.Q., Lin A., Li A.X. 2007. Practical PCR tools for the delineation of Contracaecum rudolphii A and Contracaecum rudolphii B (Ascaridoidea: Anisakidae) using genetic markers in nuclear ribosomal DNA. Molecular and Cellular Probes, 21, 97–102. DOI: 10.1016/j.mcp.2006.08.004.PubMedCrossRefGoogle Scholar