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BelgrandiellaA. J. Wagner, 1927 is a genus comprising minute snails with conic or turriform shells that are facultative stygobionts, inhabiting subterranean waters and springs. Few specimens or even empty shells of this taxon can be found, so the taxonomy is based mostly on the shell morphology and geographic distribution. Anatomy is known for a few taxa, and its usefulness is restricted. This, coupled with a popular idea that isolation is the first factor shaping divergence and speciation of the spring/cave fauna, resulted in dozens of nominal species ofBelgrandiella, known from shells at a given locality. Herein we present shells, anatomy and four molecular markers (nuclear H3, 18S and 28S and mitochondrial cytochrome oxidase subunit I) inBelgrandiellafrom 16 localities in Slovenia, northern Croatia, and Bosnia and Herzegovina. Five sites are type localities ofBoleana umbilicata, Belgrandiella kusceri,Belgrandiella krupensis,Belgrandiella zermanicaandBelgrandiella robusta,respectively. Considering the shell and geographic distribution, we have determinedB. cf.robustaBelgrandiellacf.croatica,Belgrandiellacf.fontinalis,Belgrandiellacf.kuesteri,Belgrandiellacf.pagetiandBelgrandiellacf.koprivnensisThe shells of all, as well as penes and female reproductive organs of two putative, species have been illustrated. Molecular analysis indicates four distinct clades, most probably of species rank forB. kusceri,B. cf.kuesteri,B. cf.fontinalisandB. cf.koprivnensis. Four nominal species (B. krupensis,B. robusta,B. umbilicataandB. zermanica) and one genus (Boleana) must be synonymised withBelgrandiella kusceri, and there are no more than four valid, biological species in the studiedBelgrandiella. The molecular divergence is completely unmirrored by high morphological variability. Hence the level of endemism is markedly overestimated in these snails. [ABSTRACT FROM AUTHOR]

The co-occurrence of amphipods Niphargus timavi and Gammarus fossarum was studied. A small brook in SW Slovenia was sampled monthly for one year. Below the primary spring the brook sinks, flows for about 150 m below the surface and springs again. Gammarus fossarum never reached the stretch above the sink. Both species were found at all sampling sites below the secondary spring throughout the year, but the abundance of the two varied along the stream spatially and temporarily. Differences in life cycles between G. fossarum and N. timavi were not informative; however, the estimated reproductive potential of G. fossarum was much higher than of N. timavi. A result of the higher reproductive potential may be the dominance of gammarids in permanent waters, while N. timavi may invade a surrounding fissure system where it survives gammarid competition and summer desiccations when the gammarid population becomes extinct. [ABSTRACT FROM AUTHOR]

The Niphargus orcinus aggregate, also “subgenus Orniphargus” of the genus Niphargus, is a widely distributed assemblage of large-bodied amphipods. Although it comprises the most prominent European groundwater animals, its phylogeny has not yet been scrutinized and its monophyly has never been tested. In this study, 30 putative “Orniphargus” taxa and 14 other Niphargus and outgroup species were examined cladistically using a matrix of 71 morphological characters. The strict consensus tree constructed of 34 equally parsimonious trees demonstrated that “Orniphargus” does not constitute a monophylum. Most of the species were divided into two large clades. Both clades contain species from the western Balkans (mainly the Dinaric Karst) with partly overlapping ranges. Niphargus croaticus pachytelson and N. orcinus redenseki are elevated to species rank. Four new species are described: N. dolichopus sp. n., N. polymorphus sp. n., N. dabarensis sp. n. (all Bosnia and Herzegovina) and N. lourensis sp. n. (Greece). [ABSTRACT FROM AUTHOR]