Redescription of Megalomus densistriatus Henriksen, 1922 (Neuroptera: Hemerobiidae) from the earliest Eocene Fur Formation, Denmark

Megalomus densistriatus Henriksen, 1922 (Neuroptera: Hemerobiidae) from the earliest Eocene Fur Formation (Denmark) is redescribed based on the holotype and 57 additional forewings. The assignation of the species to the Eocene genus Archibaldia Makarkin, 2023 is confirmed, as A. densistriata; it possesses all diagnostic character states of this genus. This species is one of most abundant Neuroptera in this formation occurring mainly in positive ash layers (younger) of the lower horizons of the Silstrup Member, but two specimens are found in the negative layers (older) of the lower to upper horizons of the Knudeklint Member. Archibaldia densistriata likely preferred upper microthermal to lower mesothermal mesic climate conditions similar to those estimated for A. wehri (Makarkin et al., 2003) from the early Eocene of western North America.