The freshwater molluscs of Serbia: Annotated checklist with remarks on distribution and protection status

Abstract

We present a checklist of 86 valid freshwater mollusc species of Serbia (65 gastropods and 21 bivalves) belonging to 19 families (15 gastropods and four bivalves). The list is based on our latest research and includes data from published sources and personal communications. The most diverse family among gastropods is Planorbidae (16 species), while Sphaeriidae are most diverse within the bivalves (10 species). Ten species are local endemics (all of them gastropods), while eight are introduced species (three gastropods and five bivalves). The Danube River and its smaller tributaries harbour the most diverse gastropod community, with a total of 61 species (41 gastropods and 20 bivalves). The snail Theodoxus transversalis (Pfeiffer, 1828) and the bivalve Unio crassus Philipson, 1788 are listed as EN (endangered) on the global (IUCN) level, while the snail Plagigeyeria gladilini Kuščer, 1937 and the bivalves Pseudanodonta complanata (Rossmässler, 1835) and Sphaerium rivicola (Lamarck, 1818) are considered as VU (vulnerable) species. Of those IUCN taxa, only U. crassus is listed as protected on the national level (along with 12 mostly local endemic gastropod species). In comparison with the previous checklist of gastropods by Karaman & Karaman (2007), a total of seven species are added here: Belgrandiella serbica Glöer 2008, Bythinella istoka Glöer & Pešić 2014, B. nonveilleri Glöer 2008, B. pesterica Glöer 2008, Acroloxus lacustris (Linnaeus, 1758), Melanoides tuberculata (O.F. Müller, 1774) and Armiger crista (Linnaeus, 1758). In view of global and regional trends in taxonomy, ecology and invasive biology, an even richer diversity of the Serbian freshwater malocofauna can be expected.

Distribution Range of the Endangered Species Unio crassus Philipsson, 1788 in Serbia (Western Balkans Region), Historical and Recent Data

“…(Figure 6), in the littoral part of rivers, mostly in fine substrate but also on larger sediment fractions. Most European unionids are lowland species, whereas U. crassus can inhabit higher elevations than other unionids [19,30] and can even reach very high densities in mountainous rivers [50], which supports the hypothesis of a wider niche for habitat variables than expected [51].…”

“…It was observed that this species is generally vulnerable to environmental degradation, especially to changes in water chemistry [14]. The high level of eutrophication caused by agricultural drainage is considered to be the main reason for the decline of U. crassus [10,22,30,[52][53][54]. Our data show that the mean nitrate-nitrogen concentration varies between the study periods (Figures 7 and 8).…”

“…The data used for the analysis of the distribution of U. crassus in Serbia cover the period 1953-2019. The distribution was estimated based on all available data: (1) peer-reviewed articles, monographs, dissertations and reports [23][24][25][26][27][28][29][30][31][32]; (2) unpublished data on samples collected during field research of several national projects in Serbia (material deposited in the malacological collection of the Institute for Biological research "Siniša Stanković", University of Belgrade-further referred as the IBISS); (3) material collected during the realization of four international projects (material deposited in the malacological collection of IBISS) [33][34][35][36]; (4) BAES database-biodiversity in aquatic ecosystems in Serbia, ex situ conservation [37]; and (5) collection of unionids of the Natural History Museum in Belgrade (collector Ante Tadić)-referred to as historical data in remaining text. Data (1953Data ( -1973 In order to determine the historical distribution of U. crassus in Serbia, the museum collection of unionids was reviewed (collector of Ante Tadić).…”