Two morphs are recognized in Turkey: “heldreichi” s.s, large, restricted to Eğirdir and Beyşehir Lakes, in Isparta Province; “heldreichi fluvicola” Schütt & Şeşen 1992, smaller, living in streams and springs in Antalya, Burdur, Afyon, Izmir, Manisa, Aydin, Denizli and Isparta.
 
« This species is generally very close to N. fluviatilis, but with the small size of the spire and the mouth narrowed anteriorly, it strays from it: on top of this comes the striking colouring of the mouth. From T. von Heldreich, the Berlin Museum received a Neritine, similar in shape, but much smaller […] with a more jagged design on a more yellow-brown background, also provided with three darker zones, coming from the salt source Almyros at Herakleion in Candia (Crete). » – E. von Martens: “Die Gattung Neritina”, Systematisches Conchylien-Cabinet Bd.2:Abt.10, Nürnberg 1879, p.225.
 
Above: specimens collected on rocks and stones in Manavgat river, Hisarönü Parkı, near the ruins of the castle, Manavgat, Antalya province, S. Turkey. 5,5-7,5mm. These shells bear the jagged pattern seen on the specimens given by von Helreich. This pattern is very close to that of the fluviatilis pictured on top of the previous page. Indeed, heldreichi is now recognized as a synonym of fluviatilis.

The “Almyros” salt source von Martens is talking about is a pool located west of Heraklion; this is a brackish karst spring that is at the origin of a small coastal stream that flows into the sea on the territory of Skafidáras.