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During parasitological studies of 23 Eurasian coot Fulica atra (Linnaeus, 1758), 91 nematodes were isolated. Three of them, found in the proventriculus, were identified as Tetrameres globosa (Linstow, 1879). This paper presents the morphological characteristics of the discovered males of T. globosa.
Revisions and redescriptions of species and higher taxa have been known in parasitology since the first description of a parasite. Usually, they are based on standard morphometric methods or more modern genetic analysis. The former are not always sufficiently reliable, while the latter often require expensive equipment, pre-defined genetic markers, and appropriately prepared research material. They may be replaced by multivariate statistical methods, in particular discriminant analysis and cluster analysis, and Kohonen artificial neural networks included in data mining. This paper presents the examples of specific applications of these methods for the verification of the affinity of nematodes. The discriminant analysis showed that it was possible to statistically significantly discriminate individual nematode species, both for males and females, based on morphometric variables. This confirmed the previously assumed division of the species complex Amidostomum acutum into three distinct species. Similarly, hierarchical cluster analysis, used for the determination of coherent groups of nematode parasites, allowed the identification of relatively homogeneous clusters of nematode species depending on their circle of hosts, and groups of hosts.
The aim of the work is to confirm the species differentiation of the nematodes of the Amidostomatidae family: Amidostomoides acutum (Lundahl, 1848) Lomakin, 1991; Amidostomoides monodon (Linstow, 1882) Lomakin, 1991, and Amidostomoides petrovi (Shakhtahtinskaya, 1956) Lomakin, 1991, which still are used in the parasitological literature as synonyms of Amidostomum acutum (Lundahl, 1848). The research material consisted of nematodes isolated from gizzards of dabbling ducks from the north-west of Poland. To confirm the species differentiation, DNA from the nematodes was isolated and approximately 630bp of the 28S rRNA gene were sequenced. The obtained DNA sequences were tabulated and then phylogenetic analysis were conducted using the UPGMA method. The results of the research distinctly diversify the nematodes of the genus Amidostomoides at the DNA level, which together with morphological and ecological differences among them (hosts from different systematic groups) enables to classify them into the separate species.
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