Katarzyna Królaczyk

Revision of the species complex Amidostomum acutum (Lundahl, 1848) (Nematoda: Amidostomatidae)

Most available literature indicates that the most dominant nematode in Anatinae is a cosmopolitan species Amidostomum acutum (Lundahl, 1848). However, studies on wild duck helminthofauna in northwestern Poland suggest that these birds are attacked by not one but three different parasite species, previously described as a single species. Hence the aim of this study was the redescription of the species complex Amidostomum acutum, conducted on a representative sample of parasites and their hosts. The study material consisted of 6,430 nematode individuals, isolated from the digestive tracts of 1,005 wild ducks, representing 17 species. Unsupervised classification was performed using a Kohonen artificial neural network. The analysis confirmed the division of nematodes into three groups corresponding to three species, both for males and females. Taking into account the qualitative characteristics of the parasites, one can 100% accurately identify these species. The three groups of parasites were also significantly different in their ecology, manifested in their distinct host specificity.

Streptocara formosensis Sugimoto, 1930 (Nematoda: Acuariidae) in wild ducks from the southern coast of the Baltic Sea

SummaryAlthough nematofauna of wild ducks in north-western Poland seems to be quite well known, researchers still discover species that are new for the fauna of this region and Europe in general. One of them is Streptocara formosensis Sugimoto, 1930 with distinct ecological specificity (the nematode parasites only ducks wintering in the southern Baltic Sea) and topospecificity (limited to the gizzard). During parasitological research on 1005 wild ducks representing 17 species, 13,333 nematodes were isolated, 360 of which (2.7 %) were identified as Streptocara formosensis Sugimoto, 1930. The distinguishing feature of this species from other nematodes of the genus Streptocara (Railliet, Henry and Sisoff, 1912) is the absence of a collar and a specific arrangement of deirids at the nerve ring. During the study, the nematodes were located only under the stratum corneum of the gizzard, lying down in the form of characteristic white “springs.” This is the first observation of this parasite in the nematofauna of Polish wild birds. The nematode was found in 84 (8.35 %) wild ducks representing 7 species: Aythya Marila (Aythyini), Bucephala clangula, Clangula hyemalis, Melanitta nigra, M. fusca, Mergus merganser, Mergellus albellus (Mergini). The highest prevalence (36.7 %) occurred in mergansers; the coefficient of dominance showed that S. formosensis is a subdominant species in B. clangula, C. hyemalis and M. merganser, and a rare species in other hosts. The presence of the parasite in only three out of 157 examined A. marila suggests that the greater scaup is only an accidental host for the nematode.

STOMACH NEMATODES OF WILD DUCKS (SUBFAMILY ANATINAE ) WINTERING IN THE NORTH-WESTERN POLAND

Abstract The purpose of this study was to present the structure of nematofauna community with particular emphasis on stomach (proventriculus and gizzard) nematodes in wild ducks wintering in large numbers in the North-Western Poland. Hosts (n=152) were represented by 17 species from eight genera belonging to three different ecological tribes: Anatini, Aythyini, and Mergini. Parasitic nematodes (n=14,396) were found in the digestive tract of 813 out of 1,052 birds (77.3%), with the vast majority of nematodes (93.9%) found in the gizzard (n=7,326) and proventriculus (n=6,198). Nematodes isolated from these organs represented 21 species from six families: Amidostomatidae, Acuariidae, Tetrameridae, Dioctophymatidae, Ascarididae, and Anisakidae. The most prevalent were nematodes from the genus Amidostomoides (n=6,686 individuals; 49.4%), and the most dominant species was A. monodon (5,013 nematodes).

The use of selected statistical methods and Kohonen networks in the revision and redescription of parasites

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.

Redescription of Echinuria hypognatha Wehr, 1937 (Nematoda; Acuariidae) including ecology and new hosts

SummaryReports on the presence of Echinuria hypognatha Wehr, 1937 in Europe have so far provided only general information, and therefore we present further morphometric and ecological characteristics of this parasite. In this study, the examined nematodes were isolated from the digestive tract of 1 005 wild ducks, representing 17 species from the northwestern Poland. The anatomical features of the parasite were in principle consistent with the description of the species by its discoverer and reports in the available literature. Nematodes (505 individuals) were found in 2.5 % of the examined ducks, in five species wintering in Poland: Clangula hyemalis, Melanitta nigra, M. fusca, Mergellus albellus and Aythya fuligula. The exclusive locations of the nematode were the glands in the proventriculus. The highest incidence was recorded in Melanitta ducks, and the presence of this nematode only in birds wintering in Poland indicates that E. hypognatha is brought to Poland by birds migrating from the areas of Eastern Siberia.