Tachysphex austriacus Kohl, 1892 and T. pompiliformis (Panzer, 1804) (Hymenoptera, Crabronidae) are a complex of fourteen species in Europe and Turkey.

Tachysphex pompiliformis (Panzer, 1804) and T. austriacus Kohl, 1892 species subgroups belong to the T. pompiliformis species group, and both subgroups consist of morphologically similar species. The T. austriacus Kohl species subgroup comprises four species in Europe and Turkey. For this subgroup, differential diagnoses of T. austriacus and T. prismaticus Straka, 2005 are presented, and T. hungaricus sp. n. from Hungary and T. smissenae sp. n. from Spain, France and Turkey are described. The T. pompiliformis species subgroup consists of ten species from Europe and Turkey. For this subgroup, differential diagnoses of T. ferrugineus Pulawski, 1967 and T. opacus F. Morawitz, 1893, as well as the differential diagnosis and redescription of T. pompiliformis, are presented. Tachysphex dimidiatus (Panzer, 1809), T. jokischianus (Panzer, 1809) and T. nigripennis (Spinola, 1808) are resurrected from synonymy with T. pompiliformis and redescribed. Neotypes of T. dimidiatus (Panzer) and T. nigripennis (Spinola) are designed. Tachysphex bohemicus sp. n. from the Czech Republic; T. cretensis sp. n. from Crete, Greece; T. nobilis sp. n. from Bulgaria, the Czech Republic, Hungary, Poland, Slovakia and Turkey; and T. punctipleuris sp. n. from Bulgaria, Germany, Hungary, Italy, Slovenia and Turkey are described. Identification keys to all species from T. pompiliformis and T. austriacus species subgroups known from Europe and Turkey are presented. [ABSTRACT FROM AUTHOR]