Exploring species diversity of lissorchiid trematodes (Digenea: Lissorchiidae) associated with the gravel snail, Lithoglyphus naticoides, in European freshwaters

Comparative analysis using complete ITS2 and partial 28S rDNA sequence data revealed that cercariaeum developing in rediae in Lithoglyphus naticoides represent two different lissorchiid species. One morphotype of cercariaeum is conspecific with adult Palaeorchis incognitus from European roach, Rutilus rutilus. The other cercariaeum is attributable to the genus Asymphylodora, but the species identity is not yet determined. We also generate the first rDNA sequences for Asymphylodora progenetica based on new collections from Bithynia tentaculata from Lithuania. Phylogenetic analyses of the newly generated sequences, together with information for other lissorchiids available on GenBank, showed that all representatives of Lissorchiidae form a strongly supported clade. Three monophyletic lineages, Asymphylodora, Palaeorchis and Lissorchis, were recognized at the generic level. Karyological analysis of the chromosome set of larval P. incognitus revealed a diploid number of 2n = 20. Its karyotype with subtelocentric chromosomes prevailing can be regarded as comparatively ‘primitive’, which is consistent with the basal position of P. incognitus in the 28S tree relative to the representatives of the genus Asymphylodora. The present study adds significant new information for establishing species-specific markers for the confident characterization of different developmental stages of lissorchiid species and clarification of their life cycles.

Stream section types of the Danube River in Serbia according to the distribution of macroinvertebrates

The aim of this study was to use the data on the distribution of aquatic macroinvertebrates obtained from 14 sites within a 413 km long stretch of the Danube River in Serbia to show the relevance of the bordering zone between the Middle and Lower Danube. A total of 68 macroinvertebrate taxa were observed. Molluscs were the major component with regard to species richness and relative abundance. Lithoglyphus naticoides (C. Pfeiffer, 1828) was the most abundant species and Unio tumidus (Retzius, 1788) was the most frequent species. Product-moment correlation coefficients or Pearson r coefficient was used to analyse the relation between the sites based on macroinvertebrate distribution. The data obtained by product-moment correlation served as input for cluster analyses. According to a cluster analyses Danube River in Serbia could be separated in the free-flowing sector, the stretch with a backwater effect and the area of the Iron Gate.