Five enigmatic species that have remained unnoticed or proved confusing are treated: Bostryx alausiensis (Cousin), Bulimulus gelidus (Reeve), Stenostylus colmeiroi (Hidalgo), Stenostylus nigrolimbatus (Pfeiffer) and Simpulopsis (S.) simula (Morelet). Drymaeus (D.) cleefi Breure & Eskens is now synonymized with Stenostylus nigrolimbatus (Pfeiffer).

Basteria

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Nederlandse Malacologische Vereniging

Abraham S.H. Breure. (2008). Mysterious or confusing: enigmatic species in the Orthalicidae (Gastropoda, Pulmonata). Basteria, 72(4/6), 241–252.