Theodoxus transversalis (C. Pfeiffer, 1828)

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, Zootaxa 5003 (1), pp. 1-64 : 9-10

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