| dc.description.abstract-translated | Small subunit rRNA sequences were obtained from 38 representatives mainly of the nematode orders Spirurida (Camallanidae,
Cystidicolidae, Daniconematidae, Philometridae, Physalopteridae, Rhabdochonidae, Skrjabillanidae) and, in part, Ascaridida
(Anisakidae, Cucullanidae, Quimperiidae). The examined nematodes are predominantly parasites of fishes. Their analyses provided
well-supported trees allowing the study of phylogenetic relationships among some spirurine nematodes. The present results support
the placement of Cucullanidae at the base of the suborder Spirurina and, based on the position of the genus Philonema (subfamily
Philoneminae) forming a sister group to Skrjabillanidae (thus Philoneminae should be elevated to Philonemidae), the paraphyly of
the Philometridae. Comparison of a large number of sequences of representatives of the latter family supports the paraphyly ofthe
genera Philometra, Philometroides and Dentiphilometra. The validity of the newly included genera Afrophilometra and Caranginema
is supported. These results indicate geographical isolation has not been the cause of speciation in this parasite group and no
coevolution with fish hosts is apparent. On the contrary, the group of South-American species of Alinema, Nilonema and Rumai is
placed in an independent branch, thus markedly separated from other family members. Molecular data indicate that the skrjabillanid
subfamily Esocineminae (represented by Esocinema bohemicum) should be either elevated to the rank of an idependent family or
Daniconematidae (Mexiconema africanum) should be decreased to Daniconematinae and transferred to the family Skrjabillanidae.
Camallanid genera Camallanus and Procamallanus, as well as the subgenera Procamallanus and Spirocamallanus are confirmed
to be paraphyletic. Paraphyly has also been found within Filarioidea, Habronematoidea and Thelazioidea and in Cystidicolidae,
Physalopteridae and Thelaziidae. The results of the analyses also show that Neoascarophis, Spinitectus and Rhabdochona are monophyletic,
in contrast to the paraphyletic genus Ascarophis. They further confirm the independence of two subgenera, Rhabdochona
and Globochona, in the genus Rhabdochona. The necessity of further studies of fish-parasitizing representatives of additional nematode
families not yet studied by molecular methods, such as Guyanemidae, Lucionematidae or Tetanonematidae, is underscored. | eng |
