In synonymy:
Improphantes albipes (Bösenberg, 1902, T from Lophomma) = Improphantes nitidus Thorell, 1875 (Wunderlich, 1973b: 422, sub Lepthyphantes)
Improphantes audax (Sørensen, 1898) = Improphantes complicatus Emerton, 1882 (Chamberlin & Ivie, 1947b: 58, sub Lepthyphantes umbraticola)
Improphantes beticus (Denis, 1957, T from Lepthyphantes) = Improphantes improbulus Simon, 1929 (Saaristo & Tanasevitch, 1996b: 177)
Improphantes cacuminum (Jackson, 1914) = Improphantes complicatus Emerton, 1882 (Bristowe, 1939: 96, sub Lepthyphantes audax)
Improphantes heathi (Chamberlin, 1921, T from Microneta) = Improphantes complicatus Emerton, 1882 (Chamberlin & Ivie, 1947b: 58, sub Lepthyphantes umbraticola)
Improphantes hyperboreus (Strand, 1911) = Improphantes complicatus Emerton, 1882 (Holm, 1958b: 57, sub Lepthyphantes)
Improphantes kochi (Kulczyński, 1898) = Improphantes nitidus Thorell, 1875 (Moritz, 1973: 177, sub Lepthyphantes)
Improphantes montanouralensis (Esyunin & Efimik, 1991) = Improphantes improbulus Simon, 1929 (Esyunin & Efimik, 1999: 230)
Improphantes parallelogrammus (Simon, 1884) = Improphantes decolor Westring, 1861 (Moritz, 1968: 400, sub Lepthyphantes zebrinus)
Improphantes spelaeomoravicus (Kratochvíl & Miller, 1940) = Improphantes improbulus Simon, 1929 (Miller & Svatoň, 1978: 15, sub Lepthyphantes)
Improphantes umbraticola (Keyserling, 1886) = Improphantes complicatus Emerton, 1882 (Holm, 1958b: 57, sub Lepthyphantes)
Improphantes wiehlei (von Broen, 1965) = Improphantes geniculatus Kulczyński, 1898 (von Broen, 1966: 177, sub Lepthyphantes)
Improphantes zebrinus (Menge, 1866) = Improphantes decolor Westring, 1861 (Kronestedt, 1975b: 165, sub Lepthyphantes)