title: Genetic evidence for the existence of sibling species within Contracaecum rudolphii (Hartwich, 1964) and the validity of Contracaecum septentrionale (Kreis, 1955) (Nematoda: Anisakidae).
abstract: Specimens of Contracaecum rudolphii sensu lato (s.l.) (Nematoda: Anisakidae) from Phalacrocorax carbo sinensis from northeastern and central Italy were characterised genetically and compared with those from Phalacrocorax aristotelis from Galician coasts, Spain (identified as C. rudolphii A by multilocus enzyme electrophoresis) and with specimens of C. septentrionale from Alca torda from the Galician coasts, Spain. The first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of ribosomal DNA (rDNA) were amplified by polymerase chain reaction (PCR) from individual nematodes and the amplicons subjected to single-strand conformation polymorphism (SSCP) analysis and/or sequencing. For each ITS region, C. septentrionale specimens were distinct from those of C. rudolphii (s.l.) and C. rudolphii A based on SSCP profiles and ITS sequences. Some specimens of C. rudolphii (s.l.) had the same SSCP profiles and ITS sequences as C. rudolphii A, whereas the others had distinct SSCP profiles and ITS sequences and were suggested to represent C. rudolphii B based on host and geographical origins and genetic similarity to C. rudolphii A. While no length or nucleotide variation in the ITS-1 and ITS-2 sequences was detected within each taxon, nucleotide differences of 1.8-5.5% (ITS-1) and 5.1-12.2% (ITS-2) were detected among them. The results support the hypothesis that C. rudolphii represents a complex of at least two sibling species and provide support for the validity of C. septentrionale as a separate species. The definition of genetic markers in the ITS rDNA provides opportunities for investigating the life cycles, transmission patterns and ecology of the anisakid nematodes studied herein.
authors.affiliation: School of Life Sciences, Sun Yat-Sen University, Guangzhou, Guangdong Province 510275, The People's Republic of China.
authors.forename: An-Xing
authors.initials: AX
authors.lastname: Li
authors.forename: Stefano
authors.initials: S
authors.lastname: D'Amelio
authors.forename: Lia
authors.initials: L
authors.lastname: Paggi
authors.forename: Fang
authors.initials: F
authors.lastname: He
authors.forename: Robin B
authors.initials: RB
authors.lastname: Gasser
authors.forename: Zhao-Rong
authors.initials: ZR
authors.lastname: Lun
authors.forename: Elvira
authors.initials: E
authors.lastname: Abollo
authors.forename: Margherita
authors.initials: M
authors.lastname: Turchetto
authors.forename: Xing-Quan
authors.initials: XQ
authors.lastname: Zhu
mesh_terms: D000818:Animals; D001199:Ascaridoidea / Q000145:classification / Q000235:genetics*; D001483:Base Sequence; D018509:DNA, Helminth / Q000032:analysis; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D005819:Genetic Markers / Q000235:genetics; D008969:Molecular Sequence Data; D018807:Polymorphism, Single-Stranded Conformational; D016415:Sequence Alignment; D013045:Species Specificity
chemical_list: D018509:DNA, Helminth; D021903:DNA, Ribosomal Spacer; D005819:Genetic Markers