3. Theodoxus transversalis (C. Pfeiffer, 1828) Findings in Serbia. Neritina transversalis: Möllendorff (1873). Theodoxus transversalis: Hesse (1929); Arambašić (1994); Karaman & Živić (2001); Karaman (2001, 2005); Simić & Simić (2004); Karaman & Karaman (2007); Novaković (2012); Marković et al. (2014); Savić et al. (2016); Marković (2020 pers. comm.). Common name. Striped nerite. Morphology. Medium-sized species. Oval shaped shell has dimensions up to 11 mm. Colouration pattern is greyish or yellowish-grey with three distinct dark transversal stripes. Occasionally colouration can be uniformly brown, or black. Operculum is reddish and resembles T. fluviatilis, but it lacks enlarged apophysal plate. For more details see Glöer (2019: 53, fig. 43). Distribution and ecology. The striped nerite has mostly a Danuban distribution (Sólymos & Fehér 2011). In the past it was more common in the larger rivers of central Europe, including the Danube itself (Fehér et al. 2012). Reminders of its wider distribution range are a few isolated recent populations, viz., populations from the Dojran Lake (southern Balkan; Fischer et al. 2009), and from the Crete Island (Aegean Sea; Szerkowski, 1998). Similar to other species of the genus, it prefers hard substrate (rock, vegetation, man-made materials etc.). Smaller watercourses, and tributaries of the Danube River are considered as its main habitats in Serbia (Marković et al. 2014). Stable populations have been recorded in the Velika Morava and Nišava Rivers. Other remarks. Relict species of the genus (Bunje & Lindberg 2007). Due to decreasing population trend, the species is considered as EN on the IUCN list (Sólymos & Fehér 2011). This snail is listed in the 92/43 EEC Directive (annexes II and IV; Directive, 1992). Subclass Caenogastropoda Cox,1960 Order Architaenioglossa Haller, 1892

Published as part of Marković, Vanja, Gojšina, Vukašin, Novaković, Boris, Božanić, Milenka, Stojanović, Katarina, Karan-Žnidaršič, Tamara & Živić, Ivana, 2021, The freshwater molluscs of Serbia: Annotated checklist with remarks on distribution and protection status, pp. 1-64 in Zootaxa 5003 (1) on pages 9-10, DOI: 10.11646/zootaxa.5003.1.1, http://zenodo.org/record/5120059