H. langobardicus Blüthgen, 1944: Males are similar to H. compressus and H. simplex, but can be distinguished from them by analyzing characters in the mandibles and genitalia under a microscope (often not possible in the field). Females generally cannot be reliably distinguished from similar species using morphological techniques and are usually grouped into the Halictus simplex-complex.

References: Amiet F, Herrmann M, Müller A, Neumeyer R (2001) Fauna Helvetica 9. Apidae 3: Lasioglossum, Halictus. Centre Suisse de Cartographie de la Faune, Neuchatel, Switzerland. 208 pp. Pauly, A. (2017). Clé provisoire pour l'identification des Halictus Latreille, 1804 et Lasioglossum Curtis, 1833 de Belgique (Hymenoptera Apoidea Halictidae).