The genus Dicyphus Fieber, 1858 (Miridae: Bryocorinae: Dicyphini) comprises small plant bugs well known for their zoophytophagous diet and predatory activity, making them useful in biological control. Despite their importance in plant protection, many species remain difficult or impossible to identify. This is the case of both species Dicyphus (Dicyphus) bolivari Lindberg, 1934 and Dicyphus (Dicyphus) tamaninii Wagner, 1951, commonly found in vegetable crops in Western Europe. We have conducted a taxonomic study integrating morphological (including male and female genitalia), molecular, biogeographical, and biological data. The following new synonymy is proposed: Dicyphus bolivari Lindberg, 1934 = Dicyphus tamaninii Wagner, 1951, syn. nov. The synonymies established by Sanchez & Cassis (2018), Dicyphus bolivari Lindberg, 1934 = Dicyphus bolivari atlanticus Wagner, 1951 = D. maroccanus Wagner, 1951, are confirmed. Dicyphus bolivari is compared to closely related species. The following country records are added to D. bolivari range: Channel Islands: Guernsey, Italy: Sardinia, Monaco, Asian part of Turkey and Cyprus.