Recent species name changes in the European Lymnaeidae: two tales with unhappy end?

Two doubtful cases of species name replacements in the family Lymnaeidae Rafinesque, 1815 (pond snails) proposed in 1990-2000s are discussed. These are: Radix labiata (Rossmäßler, 1835) vs. R. peregra (O.F. Müller, 1774), and Stagnicola fuscus (C. Pfeiffer, 1821) vs. S. vulneratus (Küster, 1862). It is shown that in both instances the name alterations were not based on the conclusive evidence and thus seem to be proposed without substantial reasons. I argue that the name Radix peregra cannot be ruled out and replaced by R. labiata. The type series of the latter has been identified in collection of the Natural History Museum of Vienna and it is shown that R. labiata is a junior synonym of R. balthica (Linnaeus, 1758). The lectotype of Limnaeus pereger var. labiatus Rossmäßler, 1835 is designated. The resurrection of the species name Limnaeus fuscus (Pfeiffer, 1821) for application to a certain species of Stagnicola is also very doubtful since this name must be treated as a nomen dubium , and any taxonomic interpretation of it is inevitable based on more or less reliable hypothesis, not on the total evidence. The replacement of S. vulneratus by its alleged senior synonym adds little to our knowledge on lymnaeid taxonomy and evolutionary relationships. It is desirable that the nomenclatorial principle of priority must not be applied to nomina dubia .

Vodní malakofauna přítoků Javorky u Lázní Bělohrad [Aquatic molluscan fauna of tributaries of the brook Javorka near Lázně Bělohrad (East Bohemia, Czech Republic)]

This paper presents results of a malacological survey of four small tributaries of the brook Javorka near Lázně Bělohrad in East Bohemia (Czech Republic). Only 15 species of aquatic molluscs (7 gastropods, 8 bivalves) were found at 31 sites during research realised in 2010, 2011 and 2012. Molluscan assemblages of all tributaries were similar and consisted of common and widespread molluscs as Galba truncatula, Radix peregra, Anodonta anatina, Pisidium subtruncatum or P. casertanum. The occurrence of endangered river pea mussel (Pisidium amnicum) was confirmed at three tributaries but only at lower parts near its inflows to the brook Javorka. The research was focused on the endangered thick-shelled river mussel (Unio crassus), and the occurrence of numerous population was confirmed at the brook Lukavecký potok. In the brook Chotečský potok a small population of this bivalve was found. Only a few specimens were found at remaining two tributaries.

Bird schistosome diversity in Iceland: molecular evidence

During the years 2002–2007, Icelandic freshwater snails and birds from different orders were examined for bird schistosomes. Only the snail Radix peregra and anatid birds proved to be infected. In total, 32 samples of bird schistosome cercariae from seven localities and four samples of adults of Anas platyrhynchos and Mergus serrator from two localities were used for sequencing of the internal transcibed spacer (ITS) region of rDNA. Based on the sequence and position in the phylogenetic tree, five species/genotypes of bird schistosomes were identified. Three of them correspond to the sequences in GenBank for Trichobilharzia franki, Trichobilharzia sp. JR-2007 from Anas penelope (isolates Pl7 and Pl10) and schistosomatid sp. JR-2004 from Physa fontinalis. The other two species/genotypes belong to the genus Trichobilharzia, but their further determination was not possible due to lack of data. All of these species/genotypes develop in R. peregra, probably the only suitable intermediate host species in Iceland. As T. franki and schistosomatid sp. JR-2004 were previously reported from other snail species, the findings from Iceland proved that, under some circumstances, bird schistosomes are able to adapt to a different snail species; some of them can even adapt to a snail belonging to a different gastropod family. High diversity of bird schistosomes in Iceland is probably linked with migratory flyways of birds, as several bird species from Iceland overwinter in western Europe as well as in North America.

A review on swimmer's itch and the occurrence of bird schistosomes in Iceland

In the past decade, swimmer's itch (SI) has repeatedly occurred in people who have been wading or bathing in ponds or lakes in Iceland where water birds and snails are abundant. Some of the affected sites were warmed by geothermal activity, and others were not. A search for the causative agent of SI, ocellate furcocercariae that have been found in Iceland only in Radix peregra snails, revealed an average infection prevalence of 1.4% (n = 12,432). Locally, infection rates commonly exceeded 6%, the highest value observed being 24.5%. A search for adult schistosomes in visceral organs and the nasal cavities of 110 water birds belonging to the orders Gaviiformes, Podicipediformes and Anseriformes revealed eggs, miracidia or adult stages of at least seven previously identifiable schistosome species in four anseriform bird species. A previously unknown species of schistosome, Allobilharzia visceralis, was detected in whooper swans (Cygnus cygnus), and classified in a new genus. In mallards (Anas platyrhynchos) a nasal Trichobilharzia sp. and the visceral schistosome T. franki were identified. In red-breasted merganser (Mergus serrator), distinct egg types belonging to two species of the genus Trichobilharzia have been found. In grey-lag goose (Anser anser) two different egg types were also found – a large Trichobilharzia sp. and small eggs of a Dendritobilharzia sp. Additionally, unidentified cercariae, probably belonging to a previously undescribed genus were detected in R. peregra in Oslandsstjörn. Taken together, the data obtained by morphological examination of eggs and recent DNA sequencing results, indicate that at least eight species of bird schistosomes occur in Iceland.