Arachnologische Mitteilungen 54

Dolomedes plantarius in Belarus 35 site or conditions there. It is quite probable that the specimen was on the bank of river Čarnica, but we cannot be sure (epi- gyne, Fig. 1 f ). We cannot provide exact coordinates, so the specimen is marked with “?” in the table. The sites where D. plantarius was most abundant (though we did not collect many specimens due to conservation rea- sons) were the rivers Vilija (north-west), Rasta and Biesiedź (south-east) and Zvaniec fen (south).Within all of these sites both D. plantarius and D. fimbriatus occurred simultaneously. Near Planta-2 lake, which is situated in the National Park “Biełaviežskaja forest”, only D. plantarius was found. Interesting observation concerned the appearance of the epigyne in two cases of females from Zvaniec fen.The middle bright plate was covered with a pink-brown secretion which Harms et al. (2009) believe to be the remnants of some glan- dular activity while the female was laying eggs. Another pos- sibility is that it was plain dirt. After removing the secretion there is no doubt about the characteristic features of the D. plantarius epigyne (Figs 1 p-q). However, such cases are men- tioned rarely so unexperienced arachnologists might mistake examples with secretion as a D. fimbriatus epigyne without the bright white plate. Distribution of D. plantarius in Belarus According to the geography of our findings it seems that some groups of probable populations can be determined. Yet, it is impossible to set real boundaries between them now, as many records represent only the presence of a single speci- men at a site, and distances between them are large. However, there might be one cluster of populations associated with the river Nioman and quite likely adjacent rivers and other wa- ter bodies. At least, D. plantarius was found practically along the whole length of the Nioman in Belarus. Another cluster seems to exist in the basin of the Dniepr river, including Sož, Biesiadź, and Biarezina of the large rivers that flow into it. Fi- nally, there are populations within basin of the river Prypiać. The last two clusters are probably connected to each other. Population(s) on the river Vilija are quite likely to be isolated from other populations due to geographical barriers, as well as the northern ones if they really exist (Fig. 3).The majority of D. plantarius records in Belarus are associated with rivers or channels. At the same time the Zvaniec fen population of D. plantarius seems to be substantial and such biotopes may also be more favourable for this species. In Great Britain, all populations are associated with fens (Duffey 2012), similarly Fig. 1: Genitalia of Dolomedes : a-f, h, i, k-q. Dolomedes plantarius , g, j. Dolomedes fimbri- atus, females from a. Bahušeŭka village; b. Pravaja lasnaja river, Biełaviežskaja pušča; c. Uročyšča Absoh, Nioman river; d. Jasielda river; e. Stoŭbcy, Nioman river; f. Zialonaje village; g, h. Sorhaŭcy village; i. Zvaniec fen, north; j, k. Zvaniec fen, south; l, m. males from Planta-2 lake, Biełaviežskaja pušča; n, o. males from Zvaniec fen, south; p, q. epigynes with body fluids and after cleaning, both from Zvaniec fen, south